qt50 cylinder mod questions

[matt76]

i talked to the guy that owns PAX racing. i told him i wanted to do everything i could to get better low end power. i'm not worried about my top speed, 35 is fine, but i want to get there quicker. this is what he told me.

shave the cylinder anywhere from 30 to 45 thousands, not the head.
jemco pipe
tighter clutch springs
keep the qt gears
k & n air filter
no boyseen power reeds, he said he didn't like these, he said he used to modify the reeds from a KX60 to fit the qt.


what does everyone think? she's only a 50, no 60 kit yet. i have done everything except shave the cylinder. he also said porting and matching would not help much with the low end, only if i wanted more top end would i port.

[champ50]

which part of the cylinder where it mates to the engine or the head? also if ur gonna do that its gonna give it more compression, therefore needing more fuel to fire it and more vacuum to suck the fuel in and air so porting the intake and exhaust is gonna give it more power. Basically a smoother air and fuel flow through the motor and increasing its effientcy..

[supercub]

To shave the cylinder you need machine shop grade tools to mill or grind the head. If you don't like the results the cylinder is trash. Shaving the head requires the same tools but if your'e not happy you can add gasket thickness to go back to where you were. You can start with a thinner gasket. A pipe with the expansion chamber close to the cylinder will give you more top end.

[champ50]

so what end do i shave?

[matt76]

pax told me they shave the face of the cylinder that mates with the head. they have a jig there they made to accomplish this. i was clear with him that i was looking for the most bottom end power. we talked about the head shaving only for top end.
anyone have any first hand experience with this?
PAX does all kinds of upgrades for the pw's and similar other bikes.

[xrongor]

[maddog]

[xrongor]

there is no front pulley. its a QT50 with a centrifugal clutch. spings might help a little, but not nearly as much as an extra 10 cc's with higher compression.

randy

[matt76]

i have the heavy springs on there, i also have a set of extra heavy that i haven't tried yet. the rpms run a lot longer before she really takes off. but its nice.

i'm just trying to figure out what shaving the cylinder and not the head does for you. it has to do something different.

[maddog]

[matt76]

is there any difference in milling one over the other? or is it just three ways do get the same result?

[xrongor]

if you just mill the top of the cylinder, its exactly the same as milling the head.

randy

[oilyhans]

by milling both head & cylinder you increase
compression more than just shaving the head
you should also turn down the piston if you mill head & cylinder.

you can do the head real easy if you put some med/fine
wetordry paper on a piece of 1/4" thick glass plate
and rub the head on it.

oilyhans

[wuhuilin11]