Looking for 2 Stroke tuner in N.C/S.C/VA area

[kam1996]

I am desperately looking for a good 2 stroke tuner in N.C-S.C-VA area.

I have recently purchased a 2004 Aprilia RS250 cup bike, the bike is not running 100% at the top end. I have reached the end of my troubleshooting knowledge and the local technicians have never seen an RS250 let alone worked on one.

Any help or contact will be appreciated.

Thank you

[erock768]

Could you describe what the symptoms are exactly?

[kam1996]

The bike initially had three issues:

1- When rolling on throttle in neutral the bike would bog down from idle to 4000 rpm. This issue has been resolved by a Ducati technician by syncing Crabs.

2- The RS250 should make peak power from around 8500 rpm thru 12000rpm. The bike has power jets which I checked yesterday, they are clean and so are the hoses. On full throttle at high rpm, the power kicks in strong at 8500, but dies down at 10,000 (when the power jets should kick in).
So far I have been able to confirm that the previous owner swapped the stock 270/280 main jets for leaner 250/20 jets. Why he did that I don't know. I have already ordered the stock jets and should have them soon.
My question is, would the bike still run lean (fall flat on its face) if the power jets are fine, but teh main jets are too lean? Bike is revving all the way through 12000 without much power from 10,000 through 12,000.

3- Third issue is bike is revving down very slowly between 5000 down to idle. I have been told it could be air leak, I have sprayed carb cleaner around the carbs while the bike was idling but didnt see a change in rpm. my guess is that luckily the leak is small (hopefully).

I have reached the end of my expertise and I simply do not know of any 2 stroke technicians especially with any experience with the GP bikes.(although the RS isnt really a GP bike).

My last hope is to swap out the main jets back to stock 270/280 and see if that fixes the top end issue.

[roadracer162]

Fuel/oil ratio? Type of 2-stroke oil? Check the plugs? Make sure it is completely up to operating temp.

[Super Dave]

3- Third issue is bike is revving down very slowly between 5000 down to idle. I have been told it could be air leak, I have sprayed carb cleaner around the carbs while the bike was idling but didnt see a change in rpm. my guess is that luckily the leak is small (hopefully).

Sounds like some kind of a lean issue right there.  Might want to clean out the carbs completely and/or find out exactly where all the air jets, needle jets and all are at.  Why seize and get tossed off when there are symptoms right there?  And, there's no better time to learn how to be a little more self sufficient than right now.

[erock768]

I agree with super dave in that you should probably find out what exactly the misc. carb parts are set at. Its probably best to start from stock settings and work from there so at least you know what your changing. Just based on the information that you provided in your post I have to respectfully disagree with super dave. Generally speaking (and I mean generally, in a general sense, if you know what I mean) a two stroke will stop making power or "fall flat on its face" as you described at less than max RPM because the main jets or power jets are too rich. Feeding too much fuel into the combustion chamber significantly cools the top end and enables incomplete combustion which effects power output and that "falling on its face" type feeling. Again, generally speaking, if your RS hits a wall at 10,000 RPM and doesn't rev anymore I'd have to say that you're too rich on the mains or the power jets. If you were too lean, the bike would rev phenomonally right up to the point that it would sieze which would probably be the first time you went down the front strait.

In my experience tuning TZ250s and RS125s this is generally the case. I have a very good baseline setting and a weather station from which I use to find correction coefficients to arrive at the appropriate main jet sizes. Even with appropriate main jets it may be necessary to go to leaner power jets to keep the bike from running too rich when the power jets come on resulting in that "fall on its face" feeling at ~10,000 RPM. This is often the case on really hot days or at tracks with significant elevation.

Before you go changing jetting and all that stuff I'd return the carbs to stock settings and ensure that the engine isn't leaking air. Do you have a leak down tester?  They are essential equipment for insuring against air leaks whenever you rebuild your motor.

I hope this helps. And remember, if you blow it up, you've gone too far and it not my fault :)