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Posted by: XCredrider

I recently got a 250r that was jetted for summer weather in Indiana with 20:1 oil ratio. It has a stock carb, boyesen reed cage and reed, kran it racing mid and top porting, cool head, and full FMF pipe and silencer with a K&N filter and outerware.
It had a 155 main jet in it.

Well it was low on comp. so i put in new rings and it was perfect clearences. I also put in a cr 250 gasket in it and took off the snorkle for the air box. I also moved to Florida with the gas mixed at 32:1.

My question is where will I have to go my jetting. I read in the manual that you go down 1 main jet size for sand riding which is where I ride. So im not sure where to start with my jetting. It runs good now except at the top end. It cuts out and won.t pull past about 3/4 throttle. Will i have to change my jetting because of compression? If so which way. Let me know if you guys have any idea. I know you cant tell me which jets to run but maybe which way to go. Thanks in advance and sorry for the long post.

Kody

Posted by: zedicus00

shouldnt hafta change jetting becuz of the compression, the rest of the things you said will effect it though. i would go one or 2 richer on both jets, you will just hafta play with it in that range until its running right.

Posted by: ESR350r

Where are you at in Indiana? I am in West Lafayette.....

Posted by: Dave83

The top end cut out could be due to the increase in compression.This could be detenation because of low octane or spark plug gap too wide.Check the compression,if its above 190 youll need to run around 101 octane above that your looking at 108 or higher.Gap the plug at around .021 for the higher compression.Dont worry about the manual,let the plug tell you where the jetting is at.With the mods you have Id start at around 160 and do the plug chops.

Posted by: jonc623

you are also closer to sea level in florida to i would bet and that will affect your jetting too

Posted by: XCredrider

thanks guys... I think it will be the compression and not enough octgane. I will check the comp tonight probably. ESR350R I am now in Florida. I just moved there about 3 weeks ago. I love the weather here!