huge main jet??

[cr2504life]

hi, I just bought a 97 cr 250 and it didnt' have the power i thought it should. I took the carb off and it had a 235 main jet in it and i think the stock is around 175 or something. It is running rich. It has a procircuit pipe and a uni air filter. What could be the reason the original owner went with such a large jet. Also what would be a reasonable size to try, im afraid of seizing the motor.

 

[Dragmeistr]

I run anywhere between a 172-178 depending on altitude etc. So to me, a really safe jet would be like a 185. So long as he had the stock needle etc. in the carb.

 

[cr2504life]

the slow jet is also big, 85, could there be a reason he is using such huge jets

 

[whyzee]

hi, I just bought a 97 cr 250 and it didnt' have the power i thought it should. I took the carb off and it had a 235 main jet in it and i think the stock is around 175 or something.

Maybe it's the exchange rate, was the bike purchased in the US? :laugh:
seriously, you should be in the 170 - 180 rrange on the main. start rich and work twords lean.

 

[cr2504life]

They bike was bought very close to me in Saint John NB, Canada so exhcange rate doesnt' affect :laugh: . Ok Ill try a 180 main to start. What should I start with for the pilot or slow jet, and would a #42 power jet be ok, thats what is in it now. Thanks for the help.

 

[fuzzy]

The bike could be a big bore, just watch the recommended jetting at first...May end up with something inbetween what you have and the recommended....

Big bores usually need bigger mains, and leaner pilots...

 

[cr2504life]

Could I have a possible air leak and if I do how do I know, well better yet how do I find it?

 

[Dragmeistr]

You could do a leak down test. If you dont want to spend the money on the equipment, maybe you have a local shop that could do it for you?

 

[Moto Squid]

I'd be concerned that he fixed the symptom of an air leak and not the problem. Crank seal maybe?? Call the guy and ask him what the heck. Who knows, though, maybe it could be a bigbore.

 

[cr2504life]

can you spray carb cleaner on the left crank seal to check if it is leaking or is this not a good idea?, and to check the right seal could you submerge the vent tube for the tranny to see if it is leaking?