Oooohmaaan?

[80hondaf]

Well, I am just getting around to tearing down my 1980 cb750f and when removing the cam cap bolts three of them broke off. Any suggestions?mad

 

[amc49]

Only what it takes to get them out................some if lucky simply unscrew but how to without tightening the end up so it seizes? Use a very sharp pointed object and sometimes you can unscrew them, past that it's drill baby, drill. Try easeouts but if overstressed those break easy in that size and even worse then as you can't drill an easeout.

Commonly overtightened, the book spec was too high for the cheap crap metal of the bolts. Use more like 6-8 ft.lbs., they strip at 10.

If serious about fixing the issue then go here...............

http://www.cb750c.com/modules.php?name=Your_Account&redirect=viewtopic&t=301

...and register to join for free, then look up genesound who posts all the time, he sells much better allen head bolts there that will NEVER break and cheap as spit. The OEM bolt used there blows.

 

[80hondaf]

Well, I bought a set of left handed drill bits and drilled out one of the bolts all the way through, torqued as much as I dare on it with an easy out and even put heat to the head around the bolt and it won't budge. Can these be drilled out big and helicoiled ? If so I'll find a machine shop and have them do it.

 

[amc49]

Yes, one can do that...................whatever you do, bear in mind the head and those caps are a matched assembly, they are machined as one part. That can affect decision making with caps..............

 

[80hondaf]

Thanks again amc, I dropped it off at a cycle shop I do business with today, the owner said he's done this before. They work on a lot of vintage Japanese bikes.