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which 290 kit?

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In september I had the oil pump fail on my 07 yz250f, and it fried my crank. I decided i should do a total rebuild, for winter project. My question is, which 290 kit is the best, and which cams to run i have stage 2 hotcams and stock cams,or go to stage 1? I mostly trail ride.

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Thanks swede73... i checked out lukes. he does have great prices. will be ording 12.1 je and stage 1 intake cam, and new crank.

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Thanks swede73... i checked out lukes. he does have great prices. will be ording 12.1 je and stage 1 intake cam, and new crank.

Standard compression is 12.5:1. Wiseco do a 13:1 piston which will run on pump gas. Is there any particular reason you would want to run at a lower figure? Just curious.

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Hmmm....having never saw a 83mm JE piston in the flesh, so to speak, I can't really give a definitive comment on that. Any 2 ring JE pistons I have come across, only have 1 compression ring. The 2 ring referring to 1 comp ring & 1 oil ring assembly. If anyone has fitted one lately, chime in....i'd like to know for sure.

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12.1 because I thought the 13.1 would require race fuel. I will be getting the 13.1piston now that I know it doesn't, also I will be installing a rekluse clutch.

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100% I know the 12:1 JE is 2 compression rings, and the oils rings, and the Wiseco is 1 compression ring and oil rings.

I'm educated now...

12.1 because I thought the 13.1 would require race fuel. I will be getting the 13.1piston now that I know it doesn't, also I will be installing a rekluse clutch.

It'll run sweet on pumped gas at 13:1.

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Just FYI.......the JE 290 kit from atvunlimited (ebay) has 2 compression rings (plus oil) also and is stated as being a 12.5:1.

Its a nice piece and should be durable.

just arrived today:thumbsup:

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Just FYI.......the JE 290 kit from atvunlimited (ebay) has 2 compression rings (plus oil) also and is stated as being a 12.5:1.

Its a nice piece and should be durable.

just arrived today:thumbsup:

I started off with using that JE 2 ring piston a few years back, and switched to a single ring Wiseco design but started having issues with the single ring piston rocking in the bore. I inspected my cylinder around 10 hours and started to notice the wear on the cylinder from the skirt, after 40 hours of B class sand racing my cylinder needed to be re-plated because of the wear from the skirt rubbing the cylinder on the single ring Wiseco. I am now back to the JE 2 ring mostly because the skirt is 8mm longer than the single ring Wiseco I was using.

The 2 ring JE just seems like it will be more reliable in the long run, especially for people hard on their motors.

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