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which Hi comp Piston

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hi im going to get high comp piston, which one is best and what comp can i run on premium unleaded?? whats the difference in rings??

Probably dumb questions to you but i need help:worthy:

thanks Ollie

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JE, Wiesco, and Pro Circuit all make great high compression pistons. I dont like to go over 14:1 and as long as you dont you will be fine with pump gas. Stock compression on the 08 is 13.5:1 as it is. Wiesco also runs only 2 ring lands and they run them closer to the top of the piston for more compression. They only run 2 ring lands so there is less friction between the piston and the cylinder to help it rev quicker as well. As for the ring lands the top one is just the compression ring and then the second one is the oil ring made up of two small rings and a spring that goes between the two. I cant remember how the other two manufacturers high compression pistons are configured. Hope this helps. :lol:

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thanks is it just a drop it in process or will jetting and other things need to be changed??

if so what???

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thanks is it just a drop it in process or will jetting and other things need to be changed??

if so what???

Just put it in and thats it. I have never had to rejet because of a higher compression piston. Granted as I said I dont go much higher than 14:1. Good luck. :lol:

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I had the JE 13.5:1 in my bike over the last 40 hours. It's a great race piston, it is lighter than the stock piston, and because it only has one compression ring it has less friction so it allowed the motor to rev faster. However, after 40 hours when I did the rebuild, I could see that the piston started to rock slightly. Unless your racing and willing to do a top end every 40-50 hours, I would stick with a piston that has 2 compression rings and the oil ring since I would assume it would stay true in the cylinder longer. That's just my assumption though.

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you can get an OEM 13.5 from north county yamaha on ebay for about 110 or 120 bucks. comes with gaskets for the cylinder and rings too.

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A JE you can get up to 14.1 compression ratio, comes with rings as a kit for $209. I emailed them for when I rebuild mine.

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go with the OEM, thats what I used its cheap, OEM parts always last a long time, and it give your bike that extra power without having to change anything else at all:thumbsup:

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I'll be replacing my JE at 40 hours as I could feel the engine getting a little softer at the end of the season. I'm going with the stock '08 piston and a new timing chain as long as I'm in the engine.

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