Piston Replacement??

5 replies to this topic
  • jmiller969

Posted October 17, 2010 - 12:13 PM


Anyone offer pro's and con's about high compression pistons vs standard piston replacement?

Thinking of replacing stock cams with Hot cams. Seems like 1 would be the way to go??

Any thoughts...



07 YZ450F major engine rebuild.

  • Family Man

Posted October 18, 2010 - 06:19 PM


From what Ive read on here there is no gain with the hot cams for your 07 they may even be meelower profile, they where an improvement for the earlier 450s though. The high compression piston will provide more power throughout. I went with a 13:1 Pro x and am more than pleased with it. Runs great on pump gas. all pros no cons as far as I can tell.

  • BBrown626

Posted October 18, 2010 - 08:18 PM


If it is the only mod then the HC piston will help with starting, gas mileage and maybe improve throttle response a touch, but you might not feel a benefit anywhere else. That was my experience (not on an '07).

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  • Slinkyman16

Posted October 19, 2010 - 08:01 AM


What compression u plan on running. If u are going with hotcams get the stage 2. But here's the big kicker. U will not get all the power out of the head unless u port the head.

I have just done the same thing with different componets and absolutely love the 07 more then I did when it was stock. I had all my motorwork done by Procircuit and used their cams and piston and valvesprings. Bike dyno ran into 60's hp range

  • jmiller969

Posted October 20, 2010 - 06:54 AM


Thanks for all the feedback. I was thinking 13:1 on the piston and sounds like stage 2 is the answer for the hot cams. That being said, not sure I have the budget to get a complete head mod. I think my valves and spring are in good shape. I have not split the case to see what my damage is in the tranny. I know there is at least one broken cog in the transmission. I see that there are some big bore kits out on the market for some reasonable pricing, budget wise would it make more sense to head that direction?



  • Slinkyman16

Posted October 20, 2010 - 07:19 PM


to be completly honest if u are going to change the cams u should change out the springs to something stiffer. i mean u can run it but u will be replacing ur valves alot quicker. You just cant go halfway and expect reliability. to keep anything thats modded reliable u will have to replace it all.

how many hours on ur motor now?

to answer ur question about the big bore kit.. again it just depends on what u want to do with ur bike. if ur a weekend warrior i would suggest modding the head/ adding a pipe and work on ur suspension. it will help out alot more then a big bore kit.

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