MB - Drive bolt repair work


I did a bit of a special 250, Reed Valved, 5 Speed motor this year just before we got our new drive bolts!

Yes guess what the early version bloody bolt snapped. 6 out of 500 from memory, not a bad failure rate but it happens! We've check the spec and material and don't know why the older standard bolts have snapped, one of those things I guess.

Now we improved the bolt in every way to make them bullet proof.

As I should, I offered to strip the bike and replace what was needed. But the customer is a dealer in his own rights and just couldn't get time to come to drop it off and said he would send in the parts for inspection. So it turns up today and the side cover is in the usual mess. When I did the engine there was a hair lined crack in the same area which I had repaired before polishing. Where the damage was the welding rod is stronger than the casing and a bead both sides held it together otherwise there would have been a big hole which I've seen before. Some question is welding strong enough? I reply it's stronger than the alloy around it. So with a bit of cleaning, welding, grinding and final polishing in house it was as good as new. Apart from the usual pin holes where the alloy is crap around the weld. And all done the same day. The good news is the new downward adjusting top chain guide which the customer commissioned is still perfect.






























Mark Broadhurst any questions email Mark@mbseriousoutdoors.co.uk