Re: Carb upgrade for stock-ish qt50 as first mod.

Jack Rutherford /
This single post is part of a larger thread. Start from the top or view this post in context.

Blowdown would not change as all ports were raised 1.5mm (the same amount) by the 1.5mm spacer although, come to think of it, since the purpose of the spacer was to expose more of the exhaust port (as the piston covers quite a bit of it at BDC), the spacer may actually have increased blowdown. I removed 1.5mm or thereabouts from the top of the cylinder. Just using stock head so squish would be the same assuming I took off the perfect amount from the top of the cylinder - which I probably didn't. If anything, you err on not taking off enough so you don't have any issue with the piston hitting the head - the minor loss of compression is actually helpful in fighting high engine temperatures. so if you lose 10 or 15 psi, no big deal.

You can always shave the head down to regain that lost compression if it's keeping you awake at night or take a little more off the top of the cylinder.

Anyhow, I haven't even tried to widen the exhaust port yet. I found a machinist who charges me $20 a cylinder to take material off the top of the cylinder. Beats the hell out of spending $200 on a bigger kit and matching head and I could probably get it to a top speed similar to that $200 kit. (edited)

This single post is part of a larger thread. Start from the top or view this post in context.
Subject Written By Posted
  Carb upgrade for stock-ish qt50 as first mod.Topic by: Rob LaFreniere Rob LaFreniere 04/10/19 04:14PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Jack Rutherford Jack Rutherford 04/10/19 08:16PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Rob LaFreniere Rob LaFreniere 04/11/19 11:49AM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Bill Mazzacane Bill Mazzacane 04/11/19 07:06PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Bill Mazzacane Bill Mazzacane 04/13/19 04:38AM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Jack Rutherford Jack Rutherford 04/13/19 10:03PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Jack Rutherford Jack Rutherford 04/11/19 07:16PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Bill Mazzacane Bill Mazzacane 04/11/19 08:54PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Jack Rutherford Jack Rutherford 04/11/19 07:26PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Jack Rutherford Jack Rutherford 04/11/19 11:53PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Jack Rutherford Jack Rutherford 04/12/19 12:06AM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Rob LaFreniere Rob LaFreniere 04/12/19 09:33AM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Bill Mazzacane Bill Mazzacane 04/12/19 07:24PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Jack Rutherford Jack Rutherford 04/12/19 10:50PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Rand Jacobson Rand Jacobson 04/13/19 07:02PM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Bill Mazzacane Bill Mazzacane 04/14/19 04:37AM
  Re: Carb upgrade for stock-ish qt50 as first mod.Re: Jack Rutherford Jack Rutherford 04/15/19 07:26PM

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account