Check New Cam Chain Guide

[Signal]

I am doing a bit of work on a friends XS sidecar motor during the off season.

One thing I do as a matter of course is Heli coil the front cam chain guide bolt holes as I have seen them come loose / break off during a race meeting putting an end to the fun.

The guide on this motor is almost new so it will be reused. While looking for a quick and dirty way to align the part in the mill I decided to cut the head off a screw and put the shaft of the screw in the chuck and work backwards clamping. Pretty rough I know but good enough.

Then I discovered the holes were not bored square to the mounting surface. Mystery of why the bolt /threads break solved.

This can be easily sorted when it is helicoiled but if you are installing a new guide its worth checking.

This motor also had a problem with number 1 spark plug coming loose. The motor is apart getting a 750-kit fitted so looking at the head the plug thread looks as though it has been repaired twice and it has been botched.

The insert protrudes into the combustion chamber too far and does not sit flush with the plug mounting surface either. It is too high on one side and too low on the other, so it is not square. It is a real pig’s ear. I have already ground the combustion chamber side back to remove the excess insert.

I have a plan on how to machine the sealing surface and will post pictures.

 

[RC4MAN]

Someone else recently made comment about poor quality of and crooked attachment screw holes for the aftermarket chain guides

 

[timbeck]

Gary Hoos has the front chain guide problems from Mike's all figured out for you. His replacement guides are spot on , a perfect replacement.......

tim

 

[nj1639]

I had two of the old Mikes fail.
The first one had exceeded its return date by the time I attempted to use it, the second was installed, stripped (wtf?maybe I wasn't heavy handed on the first) and then helicoiled and installed. The first one is now helicoiled and in a parts stash.....it may get installed someday.

 

[Jim]

Someone else recently made comment about poor quality of and crooked attachment screw holes for the aftermarket chain guides

We discovered that back when RobinC (rip) put his engine back together. The conversation picks up here. If you've never read Robin's thread, put it on your list.... educational and highly entertaining.
Because the guide I got From Mikes was off more than I liked and there was no other choice at the time, I developed the "frankenguide" as a workaround. It's a joining of the XS guide and an SR500 guide. That thread is here.

Mikes guide vs stock....

This is my Frankenguide. It's installed in my SG and appears to be working just fine.

 

[Signal]

The one in the motor will be reused but I do need to get another one so Mr Hoo's it is. Thanks Tim.

 

[X77S]

The one in the motor will be reused but I do need to get another one so Mr Hoo's it is. Thanks Tim.

Just made an order myself. Feels good to order from a forum member rather than someone who makes everything in China.