Diagnosis Help

[250r4life]

So I picked up an 88 250R a few months back.

Been to the dunes a few times and the bike will start easily, idle all day long, and dunes great. Winds out great through all the gears, no loading up, no cutting out, just seems to run great.

Problem I am having is at the hill. If I go to race the hill I launch in 2nd, it winds up and spins the tires but a moment later drops on its face, Revs drop, keep it pinned, and it creeps back up to the powerband and then takes off. When I shift to 3rd no problems whatsoever.

I'm not over paddled- just have some skat track edges and they are worn. If i am creeping around in 2nd and then punch it it acts normal.

However, dropping that clutch and going it reacts perfect for a moment, spins the tires and goes, and then just falls on its face.

Any ideas?

[jst]

Couple questions
What gearing are you running and tire height?
What about compression?Do you need a rebuild?
Sounds like a possible power issue.

[wilkin250r]

Man, that's a tough one to figure out without being in person and seeing the effects of various changes.

My first thought is that it's over-carbed.

[fearlessfred]

sounds like a fuel deliver problem,tank not vented,low float level,splash gaurd missing at mainjet?

[C-LEIGH RACING]

Your not running fast enough speed, once that gear tops out in rpm & then when you shift, the engine is falling under the rpms for the porting.

Need to know carb size, jets sizes, sprocket sizes, tire OD, compression & porting specs.
Neil

[250r4life]

Pro Circuit Pipe, 162 MJ, 45 PJ, Stock 34 Carb, K&N filter with lid off.

Running 20 inch skat track edges and I believe stock gearing.

Was told no porting and it feels like a stock R. Feels strong and has good compression when I kick it, although I have not tested the actual PSI.

Whats weird is like I said, I launch in 2nd and can initially get it to break the tires loose and spin, and then while still in the powerband it falls on its face and drops out of the powerband, climbs back in and then takes off from there and is fine when i shift to 3rd and scoots up the hill just fine...

[wilkin250r]

So it only does it when you dump the clutch? It's got enough gumption to break the tires loose initially, but not enough to keep them spinning?


Does it have a CR250 ignition, or a lightened flywheel?

Try a cheap and easy experiment. Forget the paddles, and try the same experiment in the sand with knobbies. I'm kinda curious if it does the same thing with almost no traction.

[250r4life]

correct... it breaks them loose and spins them like you would like/expect, and then loses it somehow...

It does not have the CR ignition, and having ridden and owned other 250Rs i dont believe the flywheel is lightened...

yeah i guess i could try that even on the street for that matter and see what happens.

[C-LEIGH RACING]

Stock engine explains it all.
Neil

[250r4life]

Originally posted by C-LEIGH RACING
Stock engine explains it all.
Neil

Had I not had years of experience riding 88-89 250Rs at the dunes when the bikes just had pipes, filters and jetting I would probably agree. By no means am I claiming to know more than you Neil.

However, both my buddy and I (that both had stock motor R's) used to run 20 Inch Sand Stars and we were able to launch and get to and through the whoops quicker than the 450s... the 450s would run us down after that but we could launch with/better than the best of them.

That being said, its hard to believe that my inability to launch with Skat Track Edges (less wait and grip than sand stars) is due to a piped R not having enough power.