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06 YZ250F jetting for high compression piston

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Hey Eddie Sisneros and other TT members, i just recently installed a wiseco high compression piston on my 06250F. Before the wiseco piston, my jetting was a 45PJ, 175MJ and a #40 leak jet. Bike would run clean and nice, when the wiseco was installed the bike began popping and wasn't running clean in the mid to upper rpms so we figured it was too lean with the wiseco, yesterday we tryed the 180 MJ and the mid and upper rmps cleaned up but now in tight corners the bike dies on power a lot and would hardly pick up rpms at all and i had to slip the clutch quite a bit to get it out of the dead spot and into the mid and upper revs. We think it is running a bit lean still and we are going to try to move the clip position to the 6th clip (right now its on the 5th i believe). My friend thinks it is running lean, i am not sure if thats what it is though, and we won't know untill we try but i figured the jetting experts in here could help. I also posted in the yz250F forum but it didn't ring a bell to post in here untill now. Thanks in advance.

by the way, i am at about 80F to 95F with regards to Temp all year round. And we are at about sea level.

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it should not have effected the jetting enough to create a running issue.and definately not lean.

did you have the slide out of the carb any point?

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it should not have effected the jetting enough to create a running issue.and definately not lean.

did you have the slide out of the carb any point?

No we never took the slide out the carb. The bike ran fine before the high compression piston. Might i add that we installed the high compression piston while we were doing the intake valve replacement from the yamaha recall. We decided since we were going to be tearing the head down that we would drop the wiseco in there at the same time we replaced the valves. So you say it (the wiseco high comp piston) wouldn't have made it lean? We are thinking that that would be the general rule of thumb for high compression pistons, that you may naturally have to go richer on the jetting? Please let me know what you think.

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no,leaner if any thing.

i would be checking the cam timing.

The thing is, it wasn't running to clean on top, then we put in a 180MJ up from the 175, and it ran better up top, so we thought going richer was the solution there, but now the bottom end just sucks, the motor has no pull in the low rpms, requiring the clutch in almost every situation.

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check the cam timing.

Could you elaborate on that please? Is it a little early to have problems there? Do you also think we should stop on the track we are headed with the rich jetting, and start testing leaner? The main is a 180 as stated earlier, then pilot is a 45. And the needle clip is in the 5th position. We are planning on putting it in the 6th and testing there. But do you think we are heading in the wrong direction? Maybe we should put back in the 175 MJ and move the clip back to the 3rd position and test leaner settings? I also have the stock 42 PJ, do you think that might help a little?

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