Puch Kstar exhaust porting question

I looked in the cylinder and saw that at BDC the exhaust port doesn't open quite all the way. I'm only getting 42 mph out of this 70cc kstar kit with a 15mm bing/grandpas intake, boss pipe, 16/42 gearing, and running a 78 jet on my e50. If I add some base gaskets to raise the exhaust port window and transfers enough for the piston to clear will my top speed increase? (I already ported the top of my exhaust port 2 mm)

Re: Puch Kstar exhaust porting question

What I mean by already porting the top of my exhaust 2mm is I RAISED the exhaust port window by 2mm using a dremel

Re: Puch Kstar exhaust porting question

gaskets or trim yr piston crown.

Re: Puch Kstar exhaust porting question

The last kstar I got 2yrs ago needed 2mm base spacing for the piston to clear the exhaust port.

Re: Puch Kstar exhaust porting question

> pat splat Wrote:

> -------------------------------------------------------

> gaskets or trim yr piston crown.

Yessss

Can we see pics?

I have used the thicker gasket material on treats to bump spacing pretty easily without worrying about stacking gaskets. Just have to be careful cutting the thicker material.

That boss pipe does not like a lot of blowdown. I got all mongo years back and ported a 65cc kit with Tommy yo about as big as the bore would let me go and it was terrible to 32-34mph even on a 2 speed. I remember gps the take off. It would finally start ripping after a few blocks but everyone was long gone. Slapped a Proma on and woke the kit up. Kit is still ripping hard off the line on an e50.

With mild porting you would benefit more from an estoril, DOS, or Treats pipe. (edited)

Re: Puch Kstar exhaust porting question

Overpriced Parts /

> Thomas Peffer Wrote:

> -------------------------------------------------------

> I looked in the cylinder and saw that at BDC the exhaust port doesn't

> open quite all the way. I'm only getting 42 mph out of this 70cc kstar

> kit with a 15mm bing/grandpas intake, boss pipe, 16/42 gearing, and

> running a 78 jet on my e50. If I add some base gaskets to raise the

> exhaust port window and transfers enough for the piston to clear will my

> top speed increase? (I already ported the top of my exhaust port 2 mm)

Boss pipe many times has 2, 3 or more inches of uncut header just crammed in there half assed made, if you split the weld and cut the excess header off and re-weld it it’s a whole different pipe

But ya kstar kits are goofy made that’s why I go with dmp, airsal, Athena, metra kit or TCCD as far as piston port kits go,

TCCD and metra kit (if you can find iron lined one) needs base spacing but just so it don’t hit the head,

A k 70cc star needs spacing then decking/removing a few mm from top of cylinder or a countersunk head, Way too much work, I don’t know why they just don’t cast them correctly moving cylinder up a few millimeters, considering they been made wrong for all these years

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