View Full Version : Ditech Flat Spot

10-29-2002, 08:23 AM
hey guy's,,

I need a bit of help here, i have a 2002 Ditech that ran sweet as a nut until last week when i t developed a flat spot around 35kph.

If i'm on the flat or going downhill, it rides through the flat spot and picks up speed again,, but going uphill,, it stinks.

Its still in standard stock, and restricted. The air filter is clean, and the exhaust is undamaged.

Any ideas?

10-29-2002, 08:29 AM
could be a worn belt, thats what mine was, how many km's u done on the bike?

10-29-2002, 08:51 AM
About 3000 i reckon,,, enough to wear out the rear tyre..

How long does the belt usually last?

10-29-2002, 02:17 PM
could do with a change maybe, but more ppl will know better than me!

10-29-2002, 04:00 PM
na it won't be the belt, not at 3000km. mine went to 8000 b4 it started to go. i'm not sure what the prolem is then, i don't no how the restricted bikes act to problems as i got mine de-restricted after the first week. can anyone else help here, dutch, tiba?

Dutch Royal T
10-29-2002, 07:17 PM
Maybe your rollers are worn.

If they have a flat side, they are worn out.

DiTech is still a no-no for me.

10-30-2002, 09:03 AM
Never had anything to do with scooter engine wierdness, so i'm a bit blind when you start talking about rollers (my mum used them in her hair) and stuff.

I could strip a Fireblade engine for you though, with no probs!

Iv'e checked the usual plugs, filter n stuff,...

So,, how would i go about derestricting this thing, maybe that would clear the flat spot..

Cheers guy's.

micah apriliaforum com
10-30-2002, 10:17 AM
Remove the spacer ring from the variator...reprogram the injection system with the gameboy link software (dealer only) and go to 5.8-7.0 gram rollers.

11-01-2002, 05:17 AM

Errr,,, mmnnn,,,eh!

Where is the variator located, and also the rollers?

micah apriliaforum com
11-01-2002, 10:14 AM
The variator is located underneath the transmission cover on the left side of the motor. The rollers are located in the front half of the variator (inside the front pulley assembly) Just take off the tranny cover and have a look. It is only about 10 bolts and you can see it all.

11-01-2002, 09:19 PM
hi, it sounds like the same thing that happened to my scooter. there is a thin metal retaining ring inside the variator that got chewed up. all you have to do is open the variator, take out the remains of that ring (which is held on by 3 phillips head screws) and you will be cruising again. The ring is in there for assemply purposes, but is not necessary to keep. Also, while you are in there, do yourself a favor and put in 5.5 gram roller weights. I did this, and I got a dramatic improvement in acceleration. That lag from about 20-45 on the speedo disappears, and you get good acceleration all the way from takeoff to about 50. Hope this helps!

03-09-2003, 12:19 PM
:mad: Well just after i posted this thread, some dirty little scum bag made off with my scooter, so i never got a chance to derestrict it.

The insurance company replaced the scooter with a 2003 model, which is slower than the 2002, so i had a look at the variator.

I looked for the spacer to remove but i couldnt see it, the only washer was under the securing nut, nothing else except the
rollers and they were held in place by a plate secured by 3 cross head screws.

Is there something different between the 2002 and 2003 models?

03-10-2003, 09:12 AM
Just wondering how much slower "Slower" is.

03-10-2003, 03:15 PM

When i got the old 2002 model, it would do 45mph once it had loosened up, this one has done over 500 mile and still only does 30mph,,, what a crock of crap that is.:(

Apart from the stickers and the clock layout, i was informed by the garage that this was an identical model to my old scoot,, but a drop of 15 mph seems to say otherwise.

Even if i saw my old scoot, i wouldn't be able to catch it.

I really do want to get this derestricted, but i'm really confused about not finding anything in the variator.

03-10-2003, 03:35 PM
Yea, if your only doing 30 it's definitly still restricted. Can't your dealer derestrict it for you and update the map?

03-10-2003, 04:06 PM
I hope they'll drestrict it when i take it for a service.
But my old scoot was restricted but so much faster.

Looks like iv'e been robbed twice, once by some dirty little thieving scroat, and now by the dealers.

I'd still like to know what the difference is between the 2 variators though.

03-10-2003, 06:58 PM

Something ain't right. A restricted scooter should top out around 30-35mph. This is so that it meets certain state laws for unlicensed <50cc scooters in the USA. So your correct that your new one is restriced. Your old one was certainly not restricted if it reached 45mph. Although this is a little slow so it almost sounds as if it was still partially restriced. There is alot of speedo error on these scooters most top out at 52-53 mph on the speedo derestriced which both of mine do. My actual speed is around 48mph when compaired to a BMW speedo I tested against. Seems to be about 4mph slower than the speedo indicates. This seems to fall inline with what others are getting. Does your dealer know what he's doing? I haven't seen the Variator ring because mine were derestricted when I got them but if you actually take the variator apart their should be a ring that prevents the variator halfs from coming completely together. This prevents the belt from climbing all the way up to the top of the Variator restricting your gearing and top speed.

03-10-2003, 07:00 PM

Where do you live?

03-12-2003, 07:28 AM

I live in the UK.

I could laugh it off if the speedo was out that far, but some my mates have scooters of various descriptions, and i used to beat them easily.

When you talk about the spacer washer in the variator, are you talking about a kind of bush that sits on the spindle that separates the 2 milled sloping sides of the variator walls?

If you are, then mine are ( unless they are stuck ) appear to be either pressed or part of the inner part of the variator.

Oh by the way,, thanx for all the help on this...

03-12-2003, 08:46 AM

Check out this link. It explaines the removal of the Variator ring on an Italjet Dragster.. Same proceedure.

www.italjetdragster.com/unleash.html (http://www.italjetdragster.com/unleash.html)

The ring is between the sloped sides and is on top of the pin that the variator spins on. Remove any Ring/Bushing that prevents the sloped plates from touching at the base when the belt climbs to the top of the Vaiator slopes. The ring will stop the plates short of coming together and thus only allow the belt to climb partially up the variator and restricts your top speed.

03-15-2003, 08:19 AM

Thanx for the link.

problem is, the bush on the 2003 model is 1 solid cast, with no spacer to remove.
Looks like i have to either buy a smaller bush or machine mine down.
Do you know how long the bush is on the deristricted SR50?

Whilst i was in there, i also fitted some 6.5g rollers and stronger clucth springs.
The rollers didnt have much effect, unlike the springs.

The springs just made the thing rev its bollox off until it decided to move, so they went out of the window. <img src=http://www.ezboard.com/intl/aenglish/images/emoticons/ohwell.gif ALT=":\">

tiba karotsu
03-15-2003, 08:39 AM
get a Malossi Multivar variator kit, that'll solve your lack of speed & acceleration.

03-15-2003, 10:22 AM
tiba karotsu,,Just had a look at www.beedspeed.com/index.html (http://www.beedspeed.com/index.html)

Might have to get 1 off those if i cant get a shorter bush.

Though the 54 tag is a bit tight right now.

Just been onto www.premierbikes.co.uk/ (http://www.premierbikes.co.uk/) and they reckon when they derestrict the 2003 model, they replace the plate that covers the rollers with a cover from 2002 model.

Plate cost about 5, bonus,,, i'm gonna get 1 of those.:D

There is light and end of the tunnel after all! :rollin:

tiba karotsu
03-15-2003, 12:23 PM
ah yes the calotte (cam plate) with less angle will really give less top speed 'coz the variator won't split further apart so the belt only travels a short distance from the hub pin. clever of them to restrict it that way.

03-16-2003, 08:26 PM
Really? They actually casted the spacer and the pin together as one unit? Sound's like Aprilia really doesn't want these derestriced. That's not a good sign. The Malossi Variator should solve your derestriction problem, but will give very little performance gain over a stock derestriction.

03-17-2003, 07:34 AM
Yeah thats what reckon too.

Surprising though that a few dealers i spoke to knew nothing (so they say) about the revised restrictions.

Gonna get 1 delivered this week, so might get to fit before the weekend.

10-19-2008, 10:06 AM
hey people. i have a aprilia sr 50 ditech it ran fine when i first got it but now its started to choke when on flat and even worse when going up hill. its choking like if i was running out of petrol but that has never been the problem as it does it when i have a fall tank. does anyone know what the problem is if so please say . thanks borths x

10-31-2008, 02:46 PM
Try the DiTech forum?

11-06-2008, 09:23 AM
could be the plug when did you last change the plug??

11-06-2008, 09:24 AM
if you are from uk have you tried looking on the pm tuning web site? they based in north west of england..