Re: Moby porting

PAULVOLIO /
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The pmfm actually started out as a 25 mph ''b'' model and I was able to break 50 with it.

I generally followed the guide in the wiki but payed a lot of attention to the case halves.

The 25 mph cylinder has bigger transfer port windows which saves a lot of tough porting work on them. You want to raise the exhaust port by quite a bit and lower the intake by the same amount.

You can widen the intake window by a lot because the piston rings never travel over it but the exhaust can be much less forgiving so dont go too far to the left and right about 2mm either side.

The ''devil horns'' on the crankcase halves needs to be matched up and you can open them up to the pont where they will still maintain a seal.

I also milled the head by about 3mm with wetsand paper and a perfectly flat patio block and I use high quality Hondabond grey silicone for a base gasket and no head gasket.

Contrary to what has been said you can mod the exhaust with a larger exit pipe. I used an old small bottle jack pump handle and welded into the endcap and removed the first baffle then trimmed the exit pipe to fit in the upper of the three holes.

You might have better luck with an after market pipe though just nothing huge or you will have no low end.

This single post is part of a larger thread. Start from the top or view this post in context.
Subject Written By Posted
  Moby portingTopic by: RJ (SoB) RJ (SoB) 05/05/09 09:52PM
  Re: Moby portingRe: PAULVOLIO PAULVOLIO 05/05/09 10:33PM
  Re: Moby portingRe: RJ (SoB) RJ (SoB) 05/05/09 11:10PM
  Re: Moby portingRe: PAULVOLIO PAULVOLIO 05/06/09 07:47AM
  Re: Moby portingRe: Andy Andy 05/06/09 08:43PM
  Re: Moby portingRe: RJ (SoB) RJ (SoB) 05/06/09 11:07PM
  Re: Moby portingRe: RJ (SoB) RJ (SoB) 05/08/09 12:24AM
  Re: Moby portingRe: RJ (SoB) RJ (SoB) 05/12/09 02:52PM
  Re: Moby portingRe: finny finny 05/12/09 06:39PM
  Re: Moby portingRe: steve steve 05/12/09 07:42PM
  Re: Moby portingRe: Mick Baltards Mick Baltards 05/13/09 01:45PM
  Re: Moby portingRe: RJ (SoB) RJ (SoB) 05/13/09 10:08PM
  Re: Moby portingRe: Jesse Stephenson Jesse Stephenson 05/13/09 10:37PM
  Re: Moby portingRe: RJ (SoB) RJ (SoB) 05/13/09 10:58PM
  Re: Moby portingRe: finny finny 05/13/09 11:14PM
  Re: Moby portingRe: steve steve 05/14/09 01:34AM
  Re: Moby portingRe: Jerry Franek Jerry Franek 05/14/09 01:12PM
  Re: Moby portingRe: finny finny 05/14/09 03:14PM
  Re: Moby portingRe: steve steve 05/14/09 04:30PM
  Re: Moby portingRe: Jesse Stephenson Jesse Stephenson 05/14/09 06:20PM
  Re: Moby portingRe: Shalerrr rrr Shalerrr rrr 05/14/09 06:27PM
  Re: Moby portingRe: Mick Baltards Mick Baltards 05/14/09 06:31PM
  Re: Moby portingRe: Jesse Stephenson Jesse Stephenson 05/14/09 07:04PM
  Re: Moby portingRe: Iain James Iain James 05/14/09 07:55PM
  Re: Moby portingRe: steve steve 05/14/09 08:24PM
  Re: Moby portingRe: Jesse Stephenson Jesse Stephenson 05/14/09 09:35PM
  Re: Moby portingRe: finny finny 05/15/09 04:47PM
  Re: Moby portingRe: RJ (SoB) RJ (SoB) 06/08/09 01:03AM
  Re: Moby portingRe: Mick Baltards Mick Baltards 05/16/09 09:29PM
  Re: Moby portingRe: finny finny 06/08/09 03:25AM
  Re: Moby portingRe: Jesse Stephenson Jesse Stephenson 06/08/09 05:35AM
  Re: Moby starting issuesRe: RJ (SoB) RJ (SoB) 07/11/09 10:38PM
  Re: Moby portingRe: RJ (SoB) RJ (SoB) 06/08/09 03:11PM
  Re: Moby portingRe: RJ (SoB) RJ (SoB) 06/08/09 04:24PM
  Re: Moby portingRe: RJ (SoB) RJ (SoB) 06/08/09 10:32PM
  Re: Moby portingRe: Jesse Stephenson Jesse Stephenson 06/09/09 01:41AM
  Moby starting issuesRe: RJ (SoB) RJ (SoB) 06/17/09 04:54PM
  Re: Moby starting issuesRe: Iain James Iain James 06/17/09 05:47PM
  Re: Moby starting issuesRe: finny finny 06/17/09 11:42PM
  Re: Moby starting issuesRe: RJ (SoB) RJ (SoB) 06/18/09 12:15AM
  Re: Moby starting issuesRe: D-wight! T. D-wight! T. 06/18/09 10:47AM
  Re: Moby starting issuesRe: RJ (SoB) RJ (SoB) 06/18/09 09:05PM
  Re: Moby starting issuesRe: finny finny 06/19/09 09:54PM
  Re: Moby starting issuesRe: RJ (SoB) RJ (SoB) 06/19/09 10:12PM
  Re: Moby starting issuesRe: jack jack 06/20/09 05:22PM
  Re: Moby starting issuesRe: steve steve 07/12/09 12:17PM
  Re: Moby starting issuesRe: finny finny 07/13/09 02:06PM

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