Ditech running rough after tune up

[Haribolman]

Just had my 4000km service and two things have changed.

1. My bike now pulls away from the line with less revs needed (which I'm happy about) and
2. My bike now runs rough for the first 30 seconds or so from cold (which I'm not happy about!). It coughs and splutters and almost stalls. Then I give it some revs, let it cough a bit and then it comes clean and runs fine. Starts first go when warm and runs completely smoothly.

I phoned the dealer and told him it was running rough when starting cold and he said all 2 strokes do that. Funny...my SR50 Ditech only did it since the service. And I've owned at least a dozen Honda Dio's and they NEVER ran rough, hot or cold.

Seeing as all he did was change the spark plug, I checked the type NGK R CPR8-E and it's correct according to the service book. I checked the gap and it was only .55mm and the seting for a ditech should be .9mm, so I set it to .9, but I haven't noticed any difference. Bike still running rough when starting cold.

Any ideas folks?

Thanks

[jrturbo]

Hi there

Part of the 4000 km service is to clean the air filter sponge and reoil, its possible that the filter could be overoiled and therefore making the engine run too rich from cold, try removing the airfilter sponge from the filter casing and see if it makes any difference, check also that they havent left anything loose like the clamps on throttle housing etc.

Cant imagine what else they could have cocked up during the service.

Regards

Joe Rubido

[troutmaster1]

Can say with 100% accuracy that it is your new spark plug that is the problem. Just take it back to your dealer and demand a new one. Last time I changed I had to try two before I got one that was working perfect. I have experienced this strange occurrence twice. And a change to another spark plug(same brand!?) always did the job. Why? I do not know.

[ditecher]

I have had exactly the same problem however i stupidly let the dealer try to see what it was and so he spent $300 dollars worth of labour on it then eventualy changed the plug and it worked fine i have had this problem occur about 5 times and every time ive changed the plug its worked fine.

[Duc995]

The gap on the manual is wrong... 0.5 mm is the correct number. I changed mine to the platinum model for sale on the forum and noticed that the plug in the scooter was gapped to 0.5 mm. I tried the new plug with the 0.9mm in the manual and the scooter would choke and cough when cold. I pulled the plug and regapped to the 0.5 mm on the original plug and problem fixed. This was confirmed by Micah and ED...

[Haribolman]

Some good answers there folks.

My dad reckons that the spark plug on a two-stroke is under great stress (much more so than it would be on say a four-stroke, multi-cylinder car engine) and therefore does tend to show up the dud ones fairly quickly.

But can anyone else shed some more light on the gap size? Is the manual really wrong? Should it be .5 (the dealer had it set to .55) or should it be .9 as in the manual? If no one knows for certain I think an email to Aprilia Australia is on the cards. It's interesting that I've tried the gap on the new plug at .55 and .9 and it hasn't made any difference. Leads me to believe it's the plug itself.

And geez ditecher, $300 spent finding out it was the plug all along...nasty!

P.S. There is a great article in the June Two Wheels magazine here in Australia about scooters. They gave them a great writeup and made me feel glad I own one. But I had to laugh at the full-page ad for Peugeot Scooters. I wanted to find out if the JetForce is coming to Australia and their email address no longer works, and their website hasn't been updated for TWO YEARS!! And yet they paid for a full page ad and ran a dud email address and an outdated website address. Good one guys. What's your dealer service like? Think I'll stick with Aprilia!!

[steelopads]

I realize that this post is getting a little old, but its probably worth knowing that it is constantly refered to. I have a scarabeo. (see new scarabeo owner). Now 700kms, I have had the same roughness almost since new. I complained to the dealer and he put a new sparkplug NGKR ( the same one quoted here.) I spoke to the mechanic and told him about your web site and how the forum recommends gap at 0.5 to 0.55 instead of 0.9 (as in the book). He was surprised but didnt take me all that seriously. Said everyman and his dog quotes from something they read on the internet. Anyway, new plug went in. $30 (at his expense) Trouble is, bike still runs rough, just different sort of rough. took the bike away for the weekend and had a good cxhance to check the gap myself. It had been gapped at about 0.55 to 0.6. (OK there.) I tried every 0.05 setting from 0.9 down and it was amazing how different each setting made the bike perform accellerate and top speed, right down to 0.4. I finally settled back at exactly 0.55 as the best but it still runs rough. What do I do now. The bike has a free service at $1000. Should I jump up and down with the dealer and complain ( he is a nice bloke) or research the problem myself. When the mechanic has ridden the bike so far, he must just run it flat out and overcomes all obstacles. I just know I should be able to ride it without going full throttle. It bogs down, splutters, feels rough, and then carries on. At other times it runs OK. Top speed still about 75km/hr but it takes a while to get there

[Dragster pilota]

hariboman in da house:
But can anyone else shed some more light on the gap size? Is the manual really wrong? Should it be .5

Yepp the plug on a high reving 2-stroker should never be above 0.6 so a 0.5 or 0.55 gap is just fine on the DiTech.....

DP says: Try a Denso irridium plugg, I have only good experiences of those....