Do you need to run the factory air box on these lt250r's Or can you hang a foam or K&N air filter on the end of carb? I'm not doing any wet or muddy riding. strictly Flat track. I've been told I wont run right.????

 

you shouldnt have any problem with running a clamp on filter. but you may need to re-jet.

but why not just remove the lid? the stock box flows very well without it...

 

I didn't really think of that......... and looks cooler LOL!!! Just wanted to make sure it wouldnt have an effect on it. And I have plenty of jets to find what I need. Thanks

 

Hey since I'm here I still have'nt got this thing to kick start. Now I'm getting a backfire through the carb at high rpm. I should'nt be to lean, I'm running a 240 main jet (stock is 210) I'm still thinking cdi box?

 

now carbs confuse me a little, but im pretty sure that if its too rich at wot + high rpm that means the main is too rich, no?

 

Well today we pulled to start it and it ran like crap at first, boggig back fireing through the carb, and like the flip of a switch it it cleared and was absolute perfect. Rode it for 2 hrs or so all kinds of power, wheelie with the touch of the throttle, no bogging, no back fire, ran like it should. Shut it down for a split second to see if it would kick start..................no go, pulled it 2 feet and fired right off and was screaming again. I don't get it how something can run so strong and work perfect but wont kick start. I'm still saying CDI, it is only recognizing the full advance spark timing. Not the low RPM like starting and idle. what you guys think? Anybody know if there is a wire to jump to keep the timing in full advance?

 

that is EXACTLY WHAT MINE DOES!!!!!! if you find the fix, PLEASE let me know!!!

 

i have heard of CDI boxes going out, since we are talking about 20+ year old bike it would be worth a try.

However it sounds more like a jet issue. have you rebuilt your carb and replace all the jets, pilot, starter jet? If it runs good above 1/2 throttle that is usually means your jet needle and main jets are fine, just your idle circuit might be off.

check this out, answered alot of my carb questions.

Carb Tuning - quadracerhq.com Forums

 

Hey thanks for the tip, but I've been the carb 5 times now and finding no issues each time. I've since tore the jug off again. I had it bored .20 and new piston and top end kit should be here tomorrow. I found my compression tester was not correct. I borrowed one and found that I had 75lbs of compression. Thats why it wouldnt kick start. couldn't kick it fast enough. you know what they should be? I heard 110lbs up to 200lbs of compression???? Oh and I have CDI box on the way too. Gotta love ebay!

 

I think compression should be in the 125-175 range, but could be wrong. I know anything lower than a 100 is bad.

I still think if your pilot jet is not right #, that is your problem. If it ran good, at mid to high rpm, that is usually the culprit.

Was there scoring in the cylinder?