'75 Commando 850 Camshaft

Hi guys,

I hope someone can give me some advice. My neighbor and I were trying to get my mom's old commando running and somehow he managed to shear the contact breaker cam bolt off in the end of the camshaft :shock: . I'm assuming the whole camshaft will need to be replaced. I found a local shop that will work on British bikes. Any idea what kind of labor costs I could be looking at? Where's a good place to buy replacement parts?

Thanks for your help

Not to worry. A properly handled extractor can get it out.

TAKE CARE and use new, sharp tools. Carbide drill bit and sharp extractor.

We did try to extract it but unfortunately it was not with new sharp tools. It did not go well. Lesson learned.

Well it may not be as bad as you think.
1. I have never found a 75MKIII with a hard cam...so
2. You probably would have had to change the cam any way sooner rather than later. A very high percentage of MKIIi were dead by 10k miles or shortly thereafter.

I have a NOS MKIII 75 with 6 miles on it (never registered) that will get a new cam before I run it on the road.

I have pulled an engine out of the frame, split the cases, reassemble and reinstall, and running in about 8-10 hours. That will go up significantly if it is a dirty mess and you will have a lot of cleaning and component inspection & repair time.

cam source? somewhat contraversial
megacycle-stellite hardface will make stock grind to order
norvil-steel
norton andover-chilled iron

Have you tried drilling it out? The bolt isn't hard it should drill quite easily. Centre it carefully, start with a small drill an work up in size until you start to touch the cam threads, you should now be able to pull or scrape them out.

Best of luck you've nothing to loose now.

Cash

We did and I'm afraid it did get off center and I'm pretty sure we marred the threads in the cam. I thought about drilling it a little bigger and tapping it but I'd never trust it.

I suggest that you remove the cylinder head and barrels and check the cam lobes for wear?
850 Mk3 factory manual: http://britmoto.com/manuals/Manuals/850_man.pdf

As dynodave said, there's a good chance that one or more of the cam lobes will be showing signs of wear if it's the original camshaft.