Engine covers like the alternator, clutch, and valve covers are usually attached to the engine with small diameter steel bolts that thread into the aluminum engine block. Eventually you will probably overtorque one of these bolts and the threads in the engine block will strip.

The best way to permanently repair this problem is with a helicoil insert kit, but there are times when that repair is not easily done on the spot. You don’t always have a fresh cover gasket or the right size of thread repair kit on hand but need to temporarily solve the problem.

The trick here is in knowing that the threaded area of the engine block is often deeper than the length of the bolt, and if you can find a bolt that is slightly (1/8"-1/4") longer than the original bolt you can often screw into some undamaged threads!

You need to grab as many new threads as possible but avoid using a bolt that is long enough to bottom out and cause more damage. Compare the length of the old and new bolt and try to gain 4 or more threads in length. Then slowly screw in the new bolt and see if it grabs new thread. Don’t get greedy and tighten it too much, and be careful not to bottom out. If the new bolt seems to be a touch too long add a few washers to shorten its reach and try again.

If this works you have just bought yourself some time until you can repair the damaged threads properly. And the next time, go easy with that wrench when screwing those small engine cover bolts into aluminum engines!

All these tips, and many more, can be found in The Motorcycle Handbook along with more complete explanations on many aspects of motorcycles and motorcycling. 63 illustrated chapters of practical, down-to-earth information you won’t find anywhere else! Just click on The Motorcycle Handbook link for more info and some excellent reviews.

John Hanney