wondering if anyone knows what causes the bike to bog and die when given full throttle. Only runs right choked, even warm. Unchoked, I can "nurse" the revs up, but not quickly. Float level? Clogged jet?

I set the air screws to 1.5 turns, and sprayed some carb cleaner in while running, but problem persists.

Seems too lean.....but the bike didn't run lean when I got it. What changed?

Any help.ideas most appreciated
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1993 NSR250R SE MC21
2010 KTM 990 SMT
2004 KTM 300EXC
1996 Honda XR250

is the bike in a stock state? Airbox, oil injector, carbs/jets, etc..?

cgallant wrote:is the bike in a stock state? Airbox, oil injector, carbs/jets, etc..?

Drilled out airbox. Expension chambers. Still injected. Not sure what was done to carbs when the bike was built out, but it ran fine for a while - - then devleoped this problem.

See it here:
http://www.youtube.com/watch?v=ozhtRS73MOw

Thanks
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1993 NSR250R SE MC21
2010 KTM 990 SMT
2004 KTM 300EXC
1996 Honda XR250

Well its an NSR you can't have this bike without removing the carbs at least once...
You should open them up to see if there is any dirt in the jets and see what the previous owner(s) have done in there with jets etc.....

Is it just boggy or is it running on one cylinder?
Could just be a fouled spark plug.

{.bLanK}GoD wrote:Is it just boggy or is it running on one cylinder?
Could just be a fouled spark plug.

No, both cylinders are firing. It seems to be a lean condition. I say this because it runs better when choked. Question is what's causing it. I have heard to clean the pilot jet, and if that doesnt work, check the crank seals. Needless to say, I hope it is simple as a clogged jet.
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1993 NSR250R SE MC21
2010 KTM 990 SMT
2004 KTM 300EXC
1996 Honda XR250

modcit wrote:

{.bLanK}GoD wrote:Is it just boggy or is it running on one cylinder?
Could just be a fouled spark plug.

No, both cylinders are firing. It seems to be a lean condition. I say this because it runs better when choked. Question is what's causing it. I have heard to clean the pilot jet, and if that doesnt work, check the crank seals. Needless to say, I hope it is simple as a clogged jet.

I checked the plugs.....both a nice tan color. So, that's not it.

Next I will take the carbs off.
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1993 NSR250R SE MC21
2010 KTM 990 SMT
2004 KTM 300EXC
1996 Honda XR250

have you checked the filter in the fuel tank???? mine did this and it was blocked with crap.

My bike does the same thing. Can you explain where the filter is and if there are replacements available?

There is a filter screen connected to the fuel tap and pokes up into the inside of the tank.
Check it's condition and it's not a silly idea to add in an inline fuel filter too.

hmm, with open carbs should be crackin from 1200 revs... seems like you have an issue. id be lookin at seels between carbs and bottom end perhaps. After the bog down, she sounds nice, although taking a while for the revs to die off (lean, as you mentioned).

Good luck with it
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