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View Full Version : Rough running...could the answer be THIS simple?



Haribolman
11-25-2003, 02:16 AM
I was reading through the September 2003 edition of "Twist & Go" Scooter magazine a couple of days ago when I stumbled across this gem in the story "Secrets of the Aprilia Ditech".

Quote: "Another thing to watch is that you don't press the starter button within five seconds of turning on the ignition key because it takes that long for the fuel pump to prime."

Now I found this information VERY interesting, because I've NEVER waited for the fuel pump to finish priming when starting the bike. I usually switch on the ignition and then hit the starter button after a second or two, WHILST the fuel pump is still priming. It NEVER occured to me that I had to wait, or that it would make any difference. After all, the starting instructions in the Aprilia manual say to "ensure the injection check warning light goes out" before hitting the starter button. But the warning light won't go out UNTIL the starter button is hit!!! (I just love accurate instructions!) So I've never waited any length of time between turning the key and hitting the starter.

Anyway, I decided to try waiting for the fuel pump to prime to see if it made any difference. Guess what? It's been three days since I've changed my starting technique and IT'S WORKED BEAUTIFULLY!!!! The bike is now running fine right from cold. It just pulls away from a cold start without any hesitation or spluttering at all. It has power and strength at start that it never had before. I'm VERY PLEASED with the improvement for my bike now feels the way it should have all along!

I'd love to get feedback from you to see if this works for you too, or if it's just a one-off situation. Could it be that the answer really is this simple? (Of course, the quality of petrol being used and the condition of the sparkplug will probably still have some effect. And it's possible too that maybe water in the injection unit will still be a problem. Or maybe this technique somehow prevents water from collecting in the first place. Who knows?)

Jebediah
11-25-2003, 08:53 AM
what do you think that, that ˙˙brr´´ means?

fuel pump! you HAVE TO wait!

end of story!

boyaani
11-25-2003, 09:08 AM
My dealer told me to alwas wait for the feul pump to finish priming.

PAUL
11-25-2003, 11:48 AM
damn, ur dealer must have sucked... How dumb was he NOT to tell you about the fuel pump??? pfff, glad u know now though... good luck

Haribolman
11-26-2003, 03:35 AM
Well, now I'm feeling like I'm the only Ditech owner who didn't know about the fuel pump priming. The dealer never told me, but that may be because he delivered the bike to me late one day after work and he drove 100km from his shop to get to my place (and 100km back!) So he was probably a little bit worn out!

I've owned a lot of two-stroke scooters, but this is the first one I've had with an ELECTRIC fuel pump. All the others had mechanical pumps, just turn the key and press the button!

Anyway, I'm still interested to hear from anyone who has been having rough running problems and whether they've been waiting for the fuel pump to prime, or whether they've been making the same mistake I have. And if so, did their bike improve when they started waiting for the pump to prime.

MrMow
11-26-2003, 11:29 PM
Dude, I'm pretty sure it tells you in the instruction manual to wait until it has primed.. its standard practice in a Fuel injected vehicles.

Haribolman
11-27-2003, 02:28 AM
MrMow, the exact wording in the instruction manual is "ensure the injection check warning light goes out " before starting. So no, it doesn't tell you to wait until it is primed, because the injection check light NEVER goes out until you start the motor!!!!! Can ANYONE tell me why Aprilia asks you to wait for the light to go out before starting when in fact it will only go out AFTER starting? Anyone? Anyone at all???

And no, it is not standard procedure in fuel injected vehicles to wait for the fuel pump to prime. My fuel injected Mazda can be started as soon as the ignition is turned on...no waiting involved.

I am amazed that all the people on this forum that were having problems with idling and rough running of their bikes have not responded to let me know how they've been starting their bikes. I'd love to hear from ANYONE who was/is having problems with their bike to see whether they've been making the same mistake I have. And if so, did changing their start-up procedure solve the problem. My bike is like a different bike now. It's running smooth, taking off well, idling well, accelerating great and it's even gained a couple of km's top speed.

So come on people, let's hear from you. All those poeple that responded to scoot'nfasts thread about the water build up in the compressor affecting the bike performance , where are you now?

phidauex
11-27-2003, 03:18 AM
I'll add something.. I've always waited for the sound to finish before starting, and I've never had rough running problems, or difficulty starting while cold. Sometimes it takes holding down the starter for 2 or 3 seconds when it is below freezing, but once it starts, it stays running, and doesn't give me any grief like sputtering or stalling.

As an experiment, since it is very cold right now, I'll start the scooter up a few times without waiting for the pump to finish, and I'll let you know if it has a harder time starting up or not.

I know one thing that was changed in a recent software revision (2.6.1 I believe) was extending the length of time that the pump runs for before starting. This was done to help fix problems with rough starting.

So there you have it, prime them fuel pumps, people! I just got in the habit of letting the sound finish before starting. It is like waiting a few seconds for glow plugs to warm up before you can start a diesel in cold weather.

peace,
sam

Haribolman
11-27-2003, 04:16 AM
Thanks for your feedback Sam, that's what I've been waiting to hear...confirmation from someone else to see what they're experience is. I'll beinterested to see if you can "simulate" the rough running problems. When you start it up without waiting, take it for a short ride and see if it hesitates from take-off and if it stalls when idling.

And yes, version 2.6.1 increases priming time from 5 seconds to 8 seconds and also quote "allows the engines to run hotter for smooter running, because they tend to overcool in cold climates which is another reason behind the plug fouling." (from the Twist & Go Magazine article).

I've got the previous version upgrade (I think it's 2.5) which allowed my engine to rev higher, but it doesn't increase the priming time. At my next service I'll be getting 2.6.1 (which has only recently been introduced to Australia) so I'll see if that makes any further improvement.

Thanks again Sam...anyone else care to comment on their starting experiences?

Jebediah
11-27-2003, 12:51 PM
i really cant see the mechanichal difference in scooters IF U START a scooter.

i really think that it doesnt effect the motor if u start the engine with waiting for the fuel pump or not waiting, as long that you start the motor

you have to wait because two thing; you need air pressure and if u start a motor without waiting you can get your ignition coil wet and the motor will not start!

am i wrong?

like i said, i cant see the difference in a motor´s behavior as log that it starts:bitchslap

ditechspain
11-27-2003, 02:16 PM
The injection light was changed to stay on until the motor started during one of the software upgrades this year. I agree it might have been nice if someone had pointed this out before I rode all the way back to the dealer to get the fault fixed.

I guess it will take Aprilia time to get the manual updated. I have always let mine run until the throbbing stops, except if I have only stopped for a short time. It takes less time than putting your lid on and fixing it, so I don´t understand the need to start it before the sequence is complete. It runs a bit rough for the first 25 yards, then clears. . It is due for its 8000km service next week.

It is not really fair to compare the ditech injection to ordinary fuel injection. In ordinary fuel injection the fuel is just squirted into the inlet tract which is at partial vacuum and sucked in by the vacuum of the piston dropping or the vacuum in the charging chamber/whatever in a 2 stroke. However on the ditech it is squirted into the piston after the ports have closed and the actual compression process has started, so it is being squirted into something that is probably at more than atmospheric pressure which would explain why you need more fuel pressure.

My old dad used to say "As a last resort, and only as a last resort, read the instructions" Seem to be a lot of people on this board who follow that philosophy!

phidauex
11-27-2003, 04:29 PM
Here is a little theory as to why the engine might run rough if it is started before the fuel pump primes.

Imagine the process..

The fuel pump primes, bringing it to 100% pressure. Then you start the scooter, and each time the injector opens, the fuel pressure drops to maybe 50% after the fuel has been sprayed into the engine. Then as the engine is rotating into its next stroke, the fuel pump is pressurizing again, and by the time the next cycle begins, the pressure is at 100% again, ready for another burst of fuel.

However, say you start your scooter before the priming is complete. On the very first cycle, the fuel pressure may only be 60% of its max. It is enough to get things started, but not ideal. Then, after the injector sprays, the fuel pressure might be down around 20%. Then as the next cycle comes around, it repressurizes, but only has time to get it back up to around 60% before the next cycle.

See what I'm saying? Starting with too low of pressure might mean that the engine isn't able to get itself back up to full pressure. This is just a little conceptual experiment, and I don't know if this is how things actually work in there, but it is how I imagine that problems might occur if you start before the pump primes.

Its thanksgiving around here in the states, so I haven't had a chance to get the scooter out and test to see if i can simulate rough running, but I'll try to do it soon.

peace,
sam

phidauex
11-27-2003, 04:30 PM
BTW, I always read the instructions, but I take their advice with a grain of salt, knowing full well how mistakes are made, or things get updated without updating the manual, etc.

peace,
sam

MrMow
11-27-2003, 05:39 PM
AH yes, actually, I seem to recall on very early Ditechs the light did go out.
With BMW bikes (I've had 2) you have to wait until the computer and injector has gone through its diagnosics before starting. My car (Mini Cooper S), its advisable to wait until all of the 'startup' lights go out, let the computer check everything, then start, it makes a difference for them, so maybe I've been trained!

Jebediah
11-27-2003, 11:52 PM
hm..good teory....but..one glich:

that means that the motor wouldnt never get the right mixture? then i wonder that Haribolman ditech is still living

:rolleyes:

Haribolman
11-28-2003, 04:16 PM
Good responses guys!!

Yes, it's hard to understand why Aprilia changed the Injection Light to stay on until started...it makes more sence to have it go out when the pump in primed and the bike is ready to start. Then at least you wouldn't have to listen for the sound of the pump, which is hard in a noisy environment. But more annoying is the fact that Aprilia didn't print a correction (possibly an insert) for their instruction manual. Heck, the last printer I bought had 3 seperate pages of ammendments to the instruction book.

Anyway, I like phidauex's explanation of why the ditech motor may run rough without proper priming. Don't know if it's correct or not, but I had been thinking something similar this week. The machinary I use at work is run by a combination of electricity and air compression (as the ditech is) and we have heaps of problems if the air pressure is too low (or too high...or unclean). But when the air pressure is correct and the air is clean it runs as sweet as a nut.

My bike is definitely running better now. Not only smoother, but it's engine note has changed (it sounds quite good now...like a bigger bike!) and the bike has more torque. It needs less revs to maintain or change speed than it did before. It's pulling better up some of the hills around here too. So overall, I'm wrapped. It's running so well now that I'm now VERY impressed the the Ditech motor. Before now, I just thought it was a bit of a technological wank!! But no, it's actually a sweet motor and I like it! :)

Like Jebediah was saying, let's hope that the first 7000km's of riding it the wrong way didn't do any damage!

P.S. I'm still waiting to hear from anyone who's still experiencing rough running problems. What is your starting procedure?

Haribolman
12-03-2003, 03:29 AM
Well, it's been a week since I posted the first message in this thread and amazingly not a single sausage has come forward to admit that their rough running problems are caused by incorrect starting procedure.

Where are you all hiding? Wasn't there a lot of people having problems with their Ditech, or are you all too embarrassed to admit you were starting it wrong all along like I was.

For the record my bike continues to start, run and idle very well.

Quite enjoying the positive change! :)

Jebediah
12-03-2003, 09:46 AM
hm, haribolman, you´re discovering hot water!

stop speaking about it, like it is a BIG; BIG thing...

in my opinion...you´re a big full; despite you not-knowing about the fuel pump...i still think youre a full :gunner:

Haribolman
12-03-2003, 02:32 PM
Yes Jebediah, of course you're right! I am a BIG full! (whatever that means!!!)

But it is interesting that you replied, because you were the last person to post a reply to scootn'fast's thread "Ditech Oil and Choking problems finally figured out", in which you were asking him how to clean the fuel pump.

So what happened? Did you clean it? Or, like everyone else on this board, were you too embarassed to admit that you had been starting your bike the wrong way too!

My point is that not a single person has come forward to admit that their rough running problems were solved the minute they allowed the fuel pump to prime. The false ego is a massive obstacle to overcome, especially when you're in a male body and that is why NO ONE will admit they were making a mistake.

But at least I've solved the problem and now people can enjoy riding a smooth, consistent ditech without having to spend any money, time or effort to fix the problem. That's what most people would call a BIG DISCOVERY!!!

Best thing that happened to dancing since feet!!!

PAUL
12-03-2003, 02:35 PM
I think everyone was told when they bought their ditech to let it prime before starting, and you were the only one that didn't know... it doesn't have anything to do with embarrasment...

Get over it dude, we all know you have to let it prime. you didn't at first, now you do and your problem is solved.... what else do you want? i really don't get it...

Jebediah
12-03-2003, 03:58 PM
uu...nice to know...

did anyone noticed, that ditechs weel are round? :bitchslap

Haribolman
12-04-2003, 01:41 AM
And still no one has come forward to prove me wrong.

I rest my case.

(Thank you...you've been a wonderful audience!)

Jebediah
12-04-2003, 03:47 AM
Get over it dude, we all know you have to let it prime. you didn't at first, now you do and your problem is solved.... what else do you want? i really don't get it...

Haribolman
12-04-2003, 03:55 AM
That's true....I am a fool...thank you for noticing.

So....what does that make you....hmmmm?

Jebediah
12-04-2003, 04:04 AM
i dont know..but i think that im not a fool :o

like every1 here :rambo:

JRTURBO
12-04-2003, 06:24 AM
Hi there

Harry is right regarding the starting procedure, the manual says turn the ignition on and wait for the check light to go out and the start the bike.

unfortunately Aprillia changed the software and the check light now will not go out untill the engine has started. you should only in theory have to wait for the pump to stop buzzing if the bike has been left standing for more than a couple of hours. if you stop the bike after riding it and restart after only a short while no need to wait as pressure in the injection will still be sufficient to run with out a problem.

If you start ther bike with out waiting for the pump to prime, you will find it will be dificult to start and run rough for the 1st couple of seconds as pressure is still building up, and possibly stall, expect no further problems other than that.

regards

Joe Rubido

Jebediah
12-04-2003, 01:18 PM
i agree with jrturbo...

the pressure rises when you ride.. ;)

DVD Plaza
09-12-2004, 09:45 PM
Originally posted by Haribolman
Well, now I'm feeling like I'm the only Ditech owner who didn't know about the fuel pump priming...Anyway, I'm still interested to hear from anyone who has been having rough running problems and whether they've been waiting for the fuel pump to prime, or whether they've been making the same mistake I have. And if so, did their bike improve when they started waiting for the pump to prime. I was never told this either, but I've always waited. Whenever I turn on either my SR50 or my Commodore I can hear a small motor wirring away for around 5 seconds - I have always waited for it to stop, assuming it was obviously pumping oil or fuel or something, before actually starting. My SR50 can be a little more tricky in a noisy environment, since I can't hear the motor doing whatever it is doing, but I can feel a minor vibration whilst holding the brake on so I wait for that to stop then start her.

So yes I've always been doing it, but no it hasn't prevented me from starting to have stalling problems. Once I've ridden down the driveway she runs beautifully - my problem is simpy that she will stall whilst warming up in the morning. Strange thing is she lives in my dining room (yes you read right) so it's not like she's in the cold - yet she will only do the stalling in the morning not in the afternoon aftering sitting outside all day...

apriliabigbore
09-12-2004, 10:43 PM
I bought mine in Phoenix, AZ, have had rough starting problems for the last 3 yrs, and I WAS NEVER TOLD TO WAIT by the dealer. I will start trying that tomorrow...

*My dealer also denies any knowledge of updates to the original software and put SR50 carb roller weights in my scooter...:mad:

enorth
09-13-2004, 07:29 PM
Im glad someone has dug up this thread as I am perplexed to the reason my scoot runs like a race bike somedays (well.. you know what I mean) and like a tractor on others. This morning I rode the bike away from home where it is always allowed to prime (I turn on the ignition then wheel it backwards for a bit before starting) and it run great. Stopped to fuel up, then run like shit all the way to work.. I think I might of keyed and started straight away. I have never worried too much about priming.

This might explain a lot.. so I hope this is what is happening.

Haribolman
09-13-2004, 11:53 PM
Originally posted by enorth
Im glad someone has dug up this thread

I am also glad my thread is being revisted because it marks the second time that something I was shot down for (thanks Jebediah!! :bond: ) ends up being proven correct. It never ceases to amaze me!! ;)

Enorth, when you stopped to fuel up, how warm was your bike? If your motor had been running for a little while and you only stopped it for a few minutes to refuel, it should still have strong fuel pressure even without waiting for it to prime. But it's worth trying to see if it eliminates your problem. The other question is, what petrol are you using? It's not Shell, is it? If it is, change immediately to Ampol, Caltex or Mobil.

enorth
09-14-2004, 12:14 AM
I'd driven the bug around 2 km before stopping for fuel. Would of stopped for 5 minutes then gone again. it run so poorly after I stopped that I actually pulled over and stopped for a minute. I am going to experiiment with this a little and report back in this thread.

Im using caltex premium.. never put anything else in it.

DVD Plaza
09-14-2004, 12:45 AM
Originally posted by Haribolman
The other question is, what petrol are you using? It's not Shell, is it? If it is, change immediately to Ampol, Caltex or Mobil. Whoa wait a minute... what's the matter with Shell? I've only ever put Shell Premium into my SR50 - is that the reason for my problems? What's the problem with Shell petrol - you have me concerned now...

Haribolman
09-14-2004, 01:13 AM
Originally posted by DVD Plaza
Whoa wait a minute... what's the matter with Shell? I've only ever put Shell Premium into my SR50 - is that the reason for my problems? What's the problem with Shell petrol - you have me concerned now...

Chris, my bike used to run like shit. I'd start it up and ride it for a few minutes and as soon as I had to stop at a set of traffic lights, it would stall. Nowadays it runs as sweet as a nut (with a VERY slight hesitation on first takeoff in the morning). Three things made the difference.

1) Fuel pump priming...we all know about this!! :D

2) Petrol quality. I was mentioning my running problems to an Aprilia mechanic and the first question he asked was, you're not using Shell Optimax are you? Apparently many bikes (not just ditechs) react poorly to the additives in premium unleaded petrols. He said that all premium unleaded petrols (not just Shell) were a problem and that the bike would run fine on regular unleaded. He was right. From that day I refuelled with Ampol/Caltex/Mobil regular unleaded and I haven't looked back! The bike actually runs MUCH better and smoother (and it's cheaper). Two other mechanics later confirmed what he told me.

3) I changed to semi-synthetic oil and noticed a slight improvement in overall start up, idle and rideability.

DVD Plaza
09-14-2004, 03:35 AM
Originally posted by Haribolman
From that day I refuelled with Ampol/Caltex/Mobil regular unleaded and I haven't looked back! The bike actually runs MUCH better and smoother (and it's cheaper). Two other mechanics later confirmed what he told me. Hmmmmmm... just plain old regular unleaded? You sure?


Originally posted by Haribolman
I changed to semi-synthetic oil and noticed a slight improvement in overall start up, idle and rideability. Can I change my oil at any time? My bike is only up to 1118km and hasn't had a single service yet - gave the dealer a call, thinking it was due at around 600km, but they reckon it doesn't need to go in until 4000km. Anything I can clean/tune myself - what are these comments about buildup on the spark plug? I'm not mechanically minded - electronics yes, programming yes, but mechanics no...

Haribolman
09-14-2004, 04:36 PM
Originally posted by DVD Plaza
Hmmmmmm... just plain old regular unleaded? You sure?



Mate, there's only one way to find out if it'll work for your bike!

There's a few people on here who have switched to regular unleaded and found their bike's run better. I'm not the only one!

jamie
09-14-2004, 05:01 PM
from brand new i was running premium unleaded, i just thought the slight abrupt idle was normal,hard starting..the odd stall...
I was amazed when putting regular unleaded in how smooth the engine idled, and not a single misfire...

regular unleaded.. its the bomb:banana:

Haribolman
09-15-2004, 01:05 AM
I'm now of the opinion that new Ditechs should come with the following sticker prominently positioned:

For best performance and smooth running, use REGULAR unleaded petrol and SEMI-synthetic oil ONLY! ALWAYS PRIME FUEL PUMP BEFORE ENGAGING STARTER!

Imagine the hassles a simple sticker like that could have solved a few people!

DVD Plaza
09-15-2004, 01:41 AM
Plus the euro models should also have...

Don't replace our stupid useless 15W headlights with higher wattages - we didn't design it to withstand the heat

Haribolman
09-15-2004, 01:45 AM
Originally posted by DVD Plaza
Plus the euro models should also have...

Don't replace our stupid useless 15W headlights with higher wattages - we didn't design it to withstand the heat

Good point!!

Have you tried regular unleaded yet?

DVD Plaza
09-15-2004, 02:02 AM
Originally posted by Haribolman
Have you tried regular unleaded yet? I have a full tank of premium so it'll be approximately 2 weeks before I get to fill her up with regular unleaded :(

DVD Plaza
09-24-2004, 03:48 AM
I'm virtually drip dry on fuel so I'll be filling her right up with regular unleaded tomorrow... hope you guys are right ;)

Hoping to do an oil change too - noticed the manual says the first one should have been at 500km but I'm at nearly 1300km... oops!

enorth
09-24-2004, 05:24 AM
Originally posted by DVD Plaza
I'm virtually drip dry on fuel so I'll be filling her right up with regular unleaded tomorrow... hope you guys are right ;)

Hoping to do an oil change too - noticed the manual says the first one should have been at 500km but I'm at nearly 1300km... oops!

oil change ?? you mean top up ?

I have been very conscious about letting the pump fully prime before starting and basically have not had the rough running behaviour happen to me once. Looks like there is definately something to it !!

Had a little scary moment today on the scoot.. riding along at 60km/h and all of a sudden the motor starts to bog down.. I wind the throttle but there is definately something wrong.. get off the throttle and the back end has a big wobble.. flat tire.. oh boy could of been goodnight mr chips :( Bloody nail

anyway.. a couple of guys were right behind me that work at the same place I work, we load the scoot into their ute and I get to work. The local dealer picks up the scooter from my work, replaces the tube and I get a service done.. they even washed it for me $120 bucks.. cant complain about that !!

DVD Plaza
09-24-2004, 05:27 AM
Originally posted by enorth
oil change ?? you mean top up ?No I'm planning to change it - the manual says it should have been done at 500km so I'l nearly 3x overdue?

enorth
09-24-2004, 05:57 AM
ah ok.. what is the point of changing the two stroke oil though ?? it is there to be burned with the fuel.. I just run mine down and went and bought some motul scooter oil.. scooter still runs ok hehe

DVD Plaza
09-24-2004, 06:35 AM
Dunno - why do they say to do it then?

DVD Plaza
09-24-2004, 07:27 AM
Crap - just read it all PROPERLY and it is saying to top up, not change. Duhhhh...

Okay so is it still wise for me to be buying oil, likely different than what is already in there, and topping up - or should I change it the first time then top up thereafter?

In either case, how do I know how much to top/fill up in there?

ditechspain
09-25-2004, 07:44 AM
DVD, You change the final drive transmission oil at the first 500 kms, not the two stroke engine oil. I think the point is to wash out any little bits of swarf that might be left from the machining of the gears.

DVD Plaza
09-30-2004, 08:15 AM
Haven't been any cold mornings since I switched to plain unleaded so hard to tell any effect it has had. This morning, however, she was struggling again though.

Worse, however, is that my fuel economy has basically HALVED... :(

DVD Plaza
09-30-2004, 08:17 AM
Haven't been any cold mornings since I switched to plain unleaded so hard to tell any effect it has had. This morning, however, she was struggling again though.

Worse, however, is that my fuel economy has basically HALVED... :(

enorth
09-30-2004, 09:00 PM
Ive actually gone the other way with fuel.. I am currently running BP ultimate 98 octane fuel. I dont know if I am imagining things but my scoot seems smoother and has more mid range grunt. I would love to hear from anyone else in Australia using it.

jamie
10-01-2004, 01:31 AM
hi enorth...what state u in? not that it really matters....

personally i had a problem with bp ultimate, spluttering...the odd stall, i'm currently running plain old mobil regular unleaded.

smoooth as silk :D

enorth
10-01-2004, 07:05 AM
Originally posted by jamie
hi enorth...what state u in? not that it really matters....

personally i had a problem with bp ultimate, spluttering...the odd stall, i'm currently running plain old mobil regular unleaded.

smoooth as silk :D

Queensland..

Interesting you had issues.. I wasnt expecting any real result from it but was pleasantly surprised.

There could be other factors though.. Ive only just had a service with a new spark plug put in (a week before the different fuel) and it had been running pretty good to start. I am sure my mid range rpm power has increased dramatically.. very small throttle openings are getting me up to 55 km/h no problem at all. Remember that my scoot is a scarabeo.. 65-70km/h (true speed) is flat out derestricted.

DVD Plaza
10-01-2004, 07:16 AM
Well screw this unleaded crap. She's been coughing a splattering a bit these past couple of days, but not actually stalling... until this afternoon. Warm afternoon, never have any problems in the afternoon, when whilst warming up she start spluttering and crapping and... d e a d... as usual she only came good once I actually took off full throttle.

I'll switch back to premium but will stick with my change from Shell to Caltex, see how it goes. I'll certainly be glad to get my fueld economy back - can't believe I've almost drained an entire tank in the time I should have done half.

Surely there MUST be something else that's suddenly causing this issue for me. Dirty spark plug? Angle of alignment to the Earth's magentic field? etc...

jamie
10-01-2004, 05:40 PM
ok DVD...
don't want to sound like a know it all here....

u must remove your air/fuel injector from your cylinder head.

u also need 2 remove the black air hose that runs from the compressor to the air/fuel injector head! this hose had a tonne of brown toothpaste like substance on mine...give it all a good cleaning with petrol.!!

scootnfast gives detailed pics on the build up of crap that gets in your injector head and associated parts...i'm still having to (on the odd occasion) remove these parts and clean out the gunk...

yes it does come back to haunt you...go 2 supercheap or repco and buy some TORX BITS, u'll need them 2 remove the plastic cover that holds the fuel pressure regulator...u gotta get in there and do some cleaning as well...

don't forget 2 block off the fuel line's before removing them from the head...(vice grips and a rag so u don't cut into them!!)

obviously if uv'e done all this already, then disregard this!!

good luck regards jimmy

DVD Plaza
10-01-2004, 06:26 PM
Hey cheers mate, no I hadn't heard/read that before. I'll look into it - thanks! :)

Saak
12-11-2005, 04:10 PM
Chris, my bike used to run like shit. I'd start it up and ride it for a few minutes and as soon as I had to stop at a set of traffic lights, it would stall. Nowadays it runs as sweet as a nut (with a VERY slight hesitation on first takeoff in the morning). Three things made the difference.

1) Fuel pump priming...we all know about this!! :D

2) Petrol quality. I was mentioning my running problems to an Aprilia mechanic and the first question he asked was, you're not using Shell Optimax are you? Apparently many bikes (not just ditechs) react poorly to the additives in premium unleaded petrols. He said that all premium unleaded petrols (not just Shell) were a problem and that the bike would run fine on regular unleaded. He was right. From that day I refuelled with Ampol/Caltex/Mobil regular unleaded and I haven't looked back! The bike actually runs MUCH better and smoother (and it's cheaper). Two other mechanics later confirmed what he told me.

3) I changed to semi-synthetic oil and noticed a slight improvement in overall start up, idle and rideability.



Hi Guys,

just sifting through old threads to try and pin point my misfire problem.

Haribolman, Shell Optimax is not available in South Australia. We only get the generic shell premium here.



Hmm, still doing research. Mine is misfiring intermittantly under load. Two changes are - new pipe and a new tank of fuel...... (Giannelli Reverse and BP Ultimate) Will look into it more.


Cheers
Drew

Haribolman
12-11-2005, 04:33 PM
Hi Guys,

just sifting through old threads to try and pin point my misfire problem.

Haribolman, Shell Optimax is not available in South Australia. We only get the generic shell premium here.



Hmm, still doing research. Mine is misfiring intermittantly under load. Two changes are - new pipe and a new tank of fuel...... (Giannelli Reverse and BP Ultimate) Will look into it more.


Cheers
Drew

Drew, do you have a Mobil service station nearby? (You probably don't have Neumanns) Anyway, try regular Mobil, or 2nd best try regular Ampol or Caltex.

Saak
12-12-2005, 03:21 AM
Drew, do you have a Mobil service station nearby? (You probably don't have Neumanns) Anyway, try regular Mobil, or 2nd best try regular Ampol or Caltex.

Still have around 80km of BP Ultimate in the tank.
Will contemplate running the JUNK (standard ULP) tomorrow to dilute the BP ultimate if indeed it was a shit tank of fuel.

I have run it on only BP Ultimate since I have had the scoot over the last three months, with one tank of Caltex Vortex. I think i got the better economy out of the Vortex, but I dont have a Caltex near me.


Anyway, I sourced a plug from my dealer today.
NGK R CPR8-E. I dropped it in and gapped it to 0.0889mm (didnt have a .09mm feeler guage)

My old plug was pretty browned up. I measured the gap and it was sitting @ approx 0.0635mm.
This plug would have been replaced 1100km ago when i had it serviced.
I'd expect to get more than this out of a plug.

Anyhow, I fitted the plug and gave it a blast around the block.
Did approx 2km at varying throttle - then dropped the plug out to have a look.
Light in colour - dont know if its lean, but then again, i only did 2kms on it.
No more misfiring, popping and farting, pulled clean full the revs now.

Will monitor it over the next few days, and drop the plug to inspect in a few days.


see pics attached.
taken on my phone in macro mode. Hope they are clear enough.


cheers
Drew

jimscoot
12-12-2005, 06:44 PM
Its more likely to be the moisture and the brown shit that accumulates in the injector assembly, causing your plugs to foul.
When you install a new plug, its only masking the problem for a short time until it fouls again and your back to square one.
The only way around this is constant cleaning of the entire injector assembly...the black hose that runs from the compressor to the injector head can be easily overlooked and actually holds quite alot of the brown sludge...
Regular cleaning is a must...I wonder how those guys are going with those in-line water traps???

g0g0
12-12-2005, 08:25 PM
Its more likely to be the moisture and the brown shit that accumulates in the injector assembly, causing your plugs to foul.
When you install a new plug, its only masking the problem for a short time until it fouls again and your back to square one.
The only way around this is constant cleaning of the entire injector assembly...the black hose that runs from the compressor to the injector head can be easily overlooked and actually holds quite alot of the brown sludge...
Regular cleaning is a must...I wonder how those guys are going with those in-line water traps???


Ok well just to confuse the issue further, i've been riding my bike for over 2 years solid now, never ever cleaned the injector/line, never had plug fouling, never had any problems. The bike has ONLY ever had a diet of 98 octaine, and AGIP city 2t..... Go figure.

Saak
12-12-2005, 09:52 PM
Ok well just to confuse the issue further, i've been riding my bike for over 2 years solid now, never ever cleaned the injector/line, never had plug fouling, never had any problems. The bike has ONLY ever had a diet of 98 octaine, and AGIP city 2t..... Go figure.


What are your riding habbits gOgO?


at the moment, mine are consisting of mainly short trips or 2 - 5kms.

Done a few longer stints of 40 and 50 kms at a time, but generally short ones between my house (Hindmarsh), work (Mile End), city and north adelaide.

Will usage patterns possibly contibute to any of the numerous issues mentioned previously???



Once I return from QLD after newyears I'll get onto sourcing the semi synth oil, draining the oil, cleaning injector etc.... it all comes down to spare time huh!!!


Cheers
Drew

g0g0
12-12-2005, 10:30 PM
I do about 30-40 k's per day, from my house to my gallery in the hinterland. WOT running most of the way. My riding habbits are the same day in day out, not that im saying that what im doing has any science to it, only contributing to what happening to me.

seefman
12-10-2007, 11:04 PM
After my ECU was updated with ( I think version 2.7 or 2.8) the bike was a pig to start compared to before. The priming cycle was longer but the only way to get it to start was to interrupt the priming cycle and hey presto she fired up. Before, with the original software, I could wait until the priming cycle finished and she fired up straight away. The injection light use to go out after the priming cycle, now, with the new software it does not. I have a 2001 bike with derestricted ECU/variator btw.........

DGoncz
10-13-2009, 01:14 AM
Here is a little theory as to why the engine might run rough if it is started before the fuel pump primes.

Imagine the process..

The fuel pump primes, bringing it to 100% pressure. Then you start the scooter, and each time the injector opens, the fuel pressure drops to maybe 50% after the fuel has been sprayed into the engine. Then as the engine is rotating into its next stroke, the fuel pump is pressurizing again, and by the time the next cycle begins, the pressure is at 100% again, ready for another burst of fuel.

However, say you start your scooter before the priming is complete. On the very first cycle, the fuel pressure may only be 60% of its max. It is enough to get things started, but not ideal. Then, after the injector sprays, the fuel pressure might be down around 20%. Then as the next cycle comes around, it repressurizes, but only has time to get it back up to around 60% before the next cycle.

See what I'm saying? Starting with too low of pressure might mean that the engine isn't able to get itself back up to full pressure. This is just a little conceptual experiment, and I don't know if this is how things actually work in there, but it is how I imagine that problems might occur if you start before the pump primes.

Its thanksgiving around here in the states, so I haven't had a chance to get the scooter out and test to see if i can simulate rough running, but I'll try to do it soon.

peace,
sam

No, the fuel pump runs continuously once the engine starts and the regulator diaphragm in the bottom of the injector body balances the excess pressure supplied by the pump against supplied air pressure. The unused fuel flows through the return to the tank. So it has to prime to inject fuel to start, but runs continuously once started. You just don't notice the vibration of the fuel pump once started. Take off the cover and put your hand on it. Wait, I don't think that's necessary, just reach up and in the left side.

Doug

purejet
05-12-2010, 11:15 AM
I've noticed lately that the scooter seems to run much smoother if I leave it idling for about a minute or two when the engine is cold. (and waiting for the pump to stop "drrrr'ing" before starting it up, ofc). I usually have a problem with sputtering when cruising at 7000rpm, but the problem seems almost gone sometimes when I've really spoiled my scooth with smooth warm-up :D

Maybe it's just the relatively good weather we've been having lately, or the fact that I've revved up the engine very smooth and not WOT'ed from stop? I have very varied experiences with the performance whn WOT'ing. When I have a little speed and smoothly revv it up, I sometimes get incredible torque. Other times it's a little hesitant. Could be that I have variable luck with the gear-engaging.

Or could it maybe be that the fuel pressure is a bit ubstable somehow? I've pondered a bit about what this problem could be, and it seems that the reason I get smoother running when warming up for an extended period, is that the fuel pressure engine "catches up" and gets into a nice "squirting-cycle". And when I don't do the warm-up it runs a little dry? I'm no mechanic so maybe I'm not making sense at all, but it sounds somehow reasonable to me.

Has anyone experienced similar sympthoms? I have a new NKG ZMR7AP plug that I'll try out soon, maybe it will help things out.

Grenadiers
05-12-2010, 11:31 AM
I've noticed lately that the scooter seems to run much smoother if I leave it idling for about a minute or two when the engine is cold. (and waiting for the pump to stop "drrrr'ing" before starting it up, ofc). I usually have a problem with sputtering when cruising at 7000rpm, but the problem seems almost gone sometimes when I've really spoiled my scooth with smooth warm-up :D

Maybe it's just the relatively good weather we've been having lately, or the fact that I've revved up the engine very smooth and not WOT'ed from stop? I have very varied experiences with the performance whn WOT'ing. When I have a little speed and smoothly revv it up, I sometimes get incredible torque. Other times it's a little hesitant. Could be that I have variable luck with the gear-engaging.

Or could it maybe be that the fuel pressure is a bit ubstable somehow? I've pondered a bit about what this problem could be, and it seems that the reason I get smoother running when warming up for an extended period, is that the fuel pressure engine "catches up" and gets into a nice "squirting-cycle". And when I don't do the warm-up it runs a little dry? I'm no mechanic so maybe I'm not making sense at all, but it sounds somehow reasonable to me.

Has anyone experienced similar sympthoms? I have a new NKG ZMR7AP plug that I'll try out soon, maybe it will help things out.

Welcome to the Forum!! If you haven’t already done so, you should look in the Sticky “Read Me First!” in there you will find TONS of very useful information. We also have several Polls running and would like and appreciate your input!

As for the whole warming up thing… It really depends a lot on local conditions. Many have found that there scoot acts like a champ a few seconds after hitting the starter button. Others, like yourself, have found that a minute or 2 warm up seems to make all the difference in the world.

The key however is NOT to let it “warm up” for too long. Two stroke motors really don’t like idling for extended periods of time, and the DiTech is no exception!! You can and will foul up sparkplugs and clog injectors in not time at all.

:cheers:

Lonestarscooter
05-12-2010, 04:58 PM
my 2 cents is this....when i bought mine new I was told to wait for the "lion" to disappear and speedo show up on dash...also I have noticed how proper warming up avoids the "big gulp" that will happen if you don't...how many people have taken a perfectly working sr to a medicre mechanic with this issue....they then tear it apart looking for something that simply does not exists.

purejet
05-12-2010, 06:38 PM
Wainting for the dash to "boot" isn't the key here. Letting it idle for a minute, then a soft take off and cruising for a few 100 meters while before WOT'ing is what seems to make the difference for me.