CR? compression ratio? Been a while but usually around 16-17:1 if I remember right.
Squish can be .010 with no problems.
How much did you shave your head before rechambering?
How high you raise/widen the exhaust? Transfers?

 

Guess I'm pretty safe at 13:1, I raised the exhaust port. By 4mm and widened it by 2mm. took .040 off the top of the cylinder and .022 off the head but I am running .055 base gasket to get to the .028 squish. I left the outer edge of the squishband, just narrowed it and changed taper. Exhaust port is opening at 95degrees ATDC for a duration of 170 degrees and the transfers at 121 degrees ATDC for a duration of 118 degrees. Putting the blowdown in at 25.5. I also took 100grams off the mag. Seems to really like to rev but rider weight plays a huge difference in take off ability!!!!

 

Oh ya, transfers were just cleaned up only changed via thicker base gasket. Cases were also mildly ported just by cleaning up casing flaws and blending reed cage tunnels. Also modified reed cage to sit .060 lower in engine in turn allowing for a little more opening till the hit cases. Stock carb.

 

Have you played with the timing?

 

Yes, timing is advanced 1 degree.

 

Cool. Stage 2 kit is about the same exhaust port height. I don't deck the cylinder any. I shave the head .060 and rechamber . Stock base gasket. Stock head gasket.
I widen the transfers more than I raise them.
A lot of work decking the cylinder/thick base gasket.

National kit I deck .032 and shave the head .090. The rest.. well....Ancient chinese secret.

So what about clutch's? Whatcha do? (Other than what was talked about)

 

As for clutching I've tryed lots of things, lightened shoes, as low as 160 but running 185 now, different springs on the shoes different springs in the secondary, lengthened pin tracts, machined taper on the variation, (back to stock now), lots of experimenting!!! Next big project (this winter) want to build my own sheaves for the converter (larger diameter so the belt will just clear the case, was going to play a little more with the shift angle while doing this! maybe I should just get u to port my cylinder and be done for good!!!👊

 

"maybe I should just get u to port my cylinder and be done for good!!!
I was thinking that. But I do the complete motor including clutchs.
Ya, you did a lot of testing.
Tell me about these springs you put in. I'm one of the few that have aftermarket big springs.

 

Awesome - another LT80 Techy!!!


Did you brace the case - can't tell from your pics...

 

I did not brace the cases, my son rides in enduro races, not any large jumps along with good shocks hopefully it will not crack, have spare cases so if these fail I will definitely reinforce the next set. I've only seen a couple cracked cases in 10 years of working on these quads. FYI these is no real competitive mx racing up here in Ontario, that could be why!