rod length vs port timing

clay /

i did it again. i made 75 changes at the same time and don't know which one fucked me. i don't even know where to start.

the first motor had a 50mm stroke crank that i built from a 40mm chinese crank, it broke twice. i got sick of the vibration and breaking and put a stock (chinese) crank in it. this changed my displacement from 79.8 to 63.5cc. and it ran great, except for the vibration at 8-10k. i pulled it apart and removed about 80% more material from the balance pad. while i had the crank apart i noticed the cracks in the big bearing cage and the trough in the bottom of the big rod hole. i had just found a rod that used cage free rollers (they grew up on a nice farm) in the big end but it was 3.9mm shorter. no problem i said, ill just chop 3.9mm off my 7mm cylinder spacer. how about a few ring land ports while i'm in there, YES! i probably did some other stupid thing that i cant even remember since i was too stoned to be working on motors anyway.

the cylinder is a 70cc kstar? with reeds and the carb is a vm22?

i strongly suspect my port timing is way off, when it had a 50mm stroke it had 178deg of exh. i never checked it with the 40mm stroke when it ran good with the other rod. where should i be with a shorter stroke than all of you guys. (besides with fat girls)

Subject Written By Posted
  rod length vs port timingTopic by: clay clay 01/20/10 05:11PM
  Re: rod length vs port timingRe: clay clay 01/20/10 05:20PM
  Re: rod length vs port timingRe: Flagrant - Flagrant - 01/20/10 05:38PM
  Re: rod length vs port timingRe: clay clay 01/20/10 06:10PM
  Re: rod length vs port timingRe: Flagrant - Flagrant - 01/20/10 06:37PM
  Re: rod length vs port timingRe: Graham Motzing Graham Motzing 01/20/10 10:22PM
  Re: rod length vs port timingRe: clay clay 01/21/10 01:01AM
  Re: rod length vs port timingRe: mattology - mattology - 01/21/10 01:14AM
  Re: rod length vs port timingRe: clay clay 01/21/10 12:03PM
  Re: rod length vs port timingRe: mattology - mattology - 01/21/10 01:13PM
  Re: rod length vs port timingRe: clay clay 01/21/10 03:27PM
  Re: rod length vs port timingRe: Flagrant - Flagrant - 01/21/10 03:38PM
  Re: rod length vs port timingRe: clay clay 01/21/10 04:19PM
  Re: rod length vs port timingRe: Flagrant - Flagrant - 01/21/10 05:21PM
  Re: rod length vs port timingRe: Flagrant - Flagrant - 01/21/10 05:26PM
  Re: rod length vs port timingRe: clay clay 01/21/10 06:10PM
  Re: rod length vs port timingRe: clay clay 01/21/10 07:52PM
  Re: rod length vs port timingRe: mattology - mattology - 01/21/10 08:08PM
  Re: rod length vs port timingRe: clay clay 01/21/10 08:20PM
  Re: rod length vs port timingRe: clay clay 01/21/10 08:46PM
  Re: rod length vs port timingRe: clay clay 01/21/10 09:18PM
  Re: rod length vs port timingRe: clay clay 02/05/10 12:57AM
  Re: rod length vs port timingRe: mattology - mattology - 02/05/10 01:15AM
  Re: rod length vs port timingRe: mattology - mattology - 02/05/10 01:17AM
  Re: rod length vs port timingRe: clay clay 02/05/10 09:40AM
  Re: rod length vs port timingRe: macelius-san macelius-san 02/05/10 07:45PM
  Re: rod length vs port timingRe: clay clay 02/06/10 11:21AM
  Re: rod length vs port timingRe: clay clay 02/07/10 01:02AM
  Re: rod length vs port timingRe: mattology - mattology - 02/07/10 01:05AM
  Re: rod length vs port timingRe: clay clay 02/07/10 01:12AM
  Re: rod length vs port timingRe: clay clay 02/07/10 01:14AM
  Re: rod length vs port timingRe: mattology - mattology - 02/07/10 05:58AM
  Re: rod length vs port timingRe: clay clay 02/07/10 09:51AM
You must log in before posting to this forum.

Click here to login.