huge main jet??

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cr2504life

Member

May 17, 2004

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• May 19, 2004

• #1

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.

 

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Dragmeistr

Sponsoring Member

Oct 14, 2002

149

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• May 19, 2004

• #2

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.

 

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cr2504life

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May 17, 2004

141

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• May 20, 2004

• Thread starter
• #3

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

 

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whyzee

Never enough time !

LIFETIME SPONSOR

Dec 24, 2001

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• May 20, 2004

• #4

cr2504life said:

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.

Click to expand...

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.

 

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cr2504life

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May 17, 2004

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• May 20, 2004

• Thread starter
• #5

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.

 

Last edited: May 20, 2004

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fuzzy

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Jul 26, 2002

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• May 20, 2004

• #6

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...

 

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cr2504life

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May 17, 2004

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• May 20, 2004

• Thread starter
• #7

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

 

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Dragmeistr

Sponsoring Member

Oct 14, 2002

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• May 20, 2004

• #8

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?

 

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Moto Squid

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Jul 22, 2002

853

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• May 20, 2004

• #9

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.

 

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cr2504life

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May 17, 2004

141

0

• May 21, 2004

• Thread starter
• #10

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?