Tuesday, August 24, 2010

post number 136

After some closer inspection I found out that my intake valve cages were leaking and causing a vacuum leak in the rear cylinder, which was probably the culprit in my heat difference. you can seethe gasket discoloration in this pic. I had one of my friends in North Dakota laser out some different
This is the intake valve pocket, the black area is where gasses were blowing out. I did not have a good enough seal between this piece and the cylinder. I spent about an hour per head lapping them into the counter bore that they sit in on the cylinder. They fit well now, and will seal up with the new gaskets that my friend Neil Lasered out for me!

Here is a pic of the lapped in intake pocket. I think that the "90 percent done, 80 percent left to go" phrase applies to this situation

I also faced the hold down nuts on the surface plate. I punched the cylinder clearance out to .008, I think that this in conjunction with the improvements on my intake seals will help me out with a smoother and cooler running engine. I am still learning a ton of good info about spacke motors every day! I should have everything back together tomorrow afternoon, I will post some videos of the bike with the timing reset and hopefully being ridden.


  1. Hmm looks like blowback was reducing combustion, right? Partial combustion means cooler. Hmmm. Verrrrrry interesting. Thanks, Paul Venne

  2. Hiya Paul. I was thinking that the vacuum leak let too much air in during the intake stroke, making that cylinder run lean and hot. Then it blew some out the gasket leak during the combustion, making it look black. I dunno.

    Matt will probably get it running fine tomorrow with the new copper. I'm still trying to get some copper gaskets made to fit Excelsiors... I should try Matt's buddy with the laser.