PROGRESS REPORTS

Engine Rebuild

Pretty obvious what we’re looking at here. This is the engine as it came out of the frame – waiting to be torn apart.

First remove carburetor and intake manifold, then the rocker covers.

Got one of the heads off.

With the head off we can see all the carbon deposits on the top of the piston.
Guess I have to ride it a little harder and burn the carbon out of it.

Both cylinders off. The rags are stuffed in there to keep foreign objects out.

Both pistons removed from the rods. (I removed the rags just for the photo, but they were definitely in there while I was prying the wrist pin retaining rings out of the pistons.)

Speaking of retaining rings – I really couldn’t see how to get these things out of the pistons (I know I’m really showing my ignorance now, but maybe someone else will run into this sometime and remember what I discovered.) As you can see, there is a small relief on the end of the spring clip so that you can pry it up and out of the groove. Of course when it is in the groove you can’t see this little relief and I kind of found it by accident while digging and prying on the clip trying to get it out.

Here is a picture of the rear piston - definitely need new pistons. The pistons that are in it now are only .010 over, so there is plenty of meat left in the cylinder walls if they need to be bored.

So, once again, I’m off to Custom MC with the heads, cylinders and pistons. I will have them do a complete valve job, check the cylinders for taper and bore them if necessary, new pistons and rings.

March 23 Update

I got the cylinders back and all they had to do to them was hone them out to accept the .new 020 over pistons. When I picked up the cylinders they said that they should be washed out with soap and water then use an oil-soaked paper towel to get the honing grit/dust out of the cylinder bore. So I scrubbed them out with a brush in some soapy water and was really surprised at how much dirt and grit was in the bottom of the bucket after washing them. Then I started with the oil-soaked paper towel and was again surprised at how much dirt was still in the cylinders. The picture below shows the progressively cleaner paper towel after about 5 iterations of cleaning.

Here are the heads after Custom MC finished with them. They did an awesome job (IMHO). The valve seats were re-cut (none had to be replaced), two new exhaust valves, new valve guides (new style with seals), rocker shaft bearing caps had just a little bit of material taken off the surface so that they fit the rocker shafts tighter, then they were honed out.

One of the fins on the front head had a piece broken off and they replaced the missing piece so that you can't even see it - even if you know where to look.

The exhaust spigots were in terrible shape and they cut off the old spigots and machined new ones out of aircraft aluminum tubing and welded them back on the heads.

End of report

This page last updated on December 18, 2006