adding high comp piston and cam make a huge difference?

3 replies to this topic
  • bluebreadtruck

Posted February 28, 2009 - 05:34 PM


I have my bike uncorked and have a full exhaust. I once had a 2002' yamaha 660 raptor atv, where I added a full exhaust, high comp piston and a hotcam... it made a HUGE difference!!!

Just wondering if it would be really worth the money to install a 13.5:1 PISTON and hotcams? I know these engines are really wound up tight from the factpry!

  • 02WR426Cali

Posted February 28, 2009 - 08:07 PM


Birdy426 says that it really makes quite a difference. He also has the big bore 444 but I think he had a high comp before that too. Ask him he'll let you know

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  • bluebreadtruck

Posted February 28, 2009 - 08:13 PM


thanks!:lol: although right now, ill just stay stock much $$$

  • Birdy426

Posted March 01, 2009 - 01:12 AM


High comp, hot cams and the full exhaust is a great combination. I did run a 13.5:1 with Hot Cams intake and exhaust (and a YZ pipe) on my '01 before I went big bore. You have more of everything all the way across the powerband. You get more on the bottom from the hi-comp piston, then a pretty good hit into the midrange, and the big end of the powerband is soooo much better than stock. The only reason I went big bore was because it was cheaper than having my stock barrel stripped, replated and honed. Of course, now that I've done it, I will never go back, but it certainly wasn't because I needed more power than the 13.5:1 and hot cams could give me.

For what it's worth, I can get away running most pump regular gas without death-rattle as well.



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