I know the lowered it in the BF750 engine to 8.8-1 instead of 9.9-1 why? Too much power if they left it higher or what? If I do decide to get a 10.5-1 compression ratio what difference in heat and reliablity am I going to notice?

 

There are 2 theories that I've heard on why Kaw. dropped compression on the BF 750...one is that they detuned it so folks would not get hurt and sue Kaw (pulling big wheelies on pavement, etc.) and the other is that Kaw. wanted to keep the motor cool (lower compression generally equals less heat production than a higher compression motor).

Yes, you will notice a significant difference if you up the compression. My buddy Traindog71 on another forum dropped some JE 12:1 pistons into his BF750 last December (and Hotcams - Stage 1) and he said the performance difference is very noticeable. I've heard of a few other folks doing the same thing too.

Happy trails...[img]i/expressions/face-icon-small-smile.gif[/img]

 

I'm guessing a heat issue because I have never gotten my radiator dirty and mine still runs a little on the hot side as far as me feeling heat against my leg. The fan comes on quite regularly and if it had a higher compression ratio it might overheat.

 

Have you thought about getting ceramic coating on your header pipes...that may cure your leg discomfort problem.

 

Mine is totally the oposite I can still count on one hand how many times the fan has kicked on! I ride a lot in mud and it never gets the radiator dirty. I only notice it kick on when puttin around the house and when it idles. With the higher compression would you feel it would be too much heat for a reliable trail machine?

 

Hey, also is there a noticable rev/sound difference with the higher compression? Can you tell by just listening to one ride around?

 

I've heard my friend's BF750 running with JE hi comp pistons, Hotcams and aftermarket exhaust and it woulds VERY COOL! Had a much different sound than stock.

 

While I want to have a cool motorcycle reving sound i am not to sure I want risk reliability.

 

Good point, but anytime you modify your quad, you are risking reliability...that is the price we all pay for mods. Of course, some mods are more risky than others...part of the reason I went with Wiseco 11:1 pistons instead of the 12:1 JE pistons for my P650 is b/c of my concern about too much heat being created from the JE pistons (well, that and the fact that JE costs more $$).

Happy trails...[img]i/expressions/face-icon-small-smile.gif[/img]

 

You are probably right. Mine tends to run hotter than my 700prairie, and the 700 I though ran hot.