Topic: Question on cam carrier bolts - CB750K0

[Magpie]

Hi guys! A question on the cam carrier bolts. In the picture below the top center bolt is there to keep the rocher arm shaft in place. The bolt goes through a cutout on the shaft so the shaft will not have any side to side movement. The threads in hole for this bolt are not great. I can snug it down and have used locktight on it. I'm afraid to torque it down to what I have done the others. Is this bolt just to steady the rocker shaft? Am I going to be in trouble with it snugged down and the others torqued? My head says I should helicoil it but is it really necessary. My OCD springs to life again!
Cheers,
Cliff.

[Terry in Australia]

G'Day Cliff, that bolt could well have been designed to stop the cam tower from flying off if you're running a really big cam, but with stockers it probably just stops the rocker shaft from falling out.

As long as your loctited bolt (loctite usually turns to liquid and washes away with hot oil, so be careful) isn't going to come out and bounce around your cam cover causing the mechanical equivalent of Hiroshima, you shouldn't have to helicoil that hole. I would, but I've only got slightly larger than average sized testicles. Cheers, Terry.

[Magpie]

My testicles were shrinking as I slowly tightened the bolt.  This bike won't see 1000 miles in my lifetime but it should be right for those miles. A friend has offered his helicoil kit. I'm sure the bolt is just to hold the rocker shaft in place too and if it does back off, it's too tall to get out of the hole, the valve cover will stop it.
Cheers Terry!
Cliff.

[Terry in Australia]

No worries Cliff, you'll be OK mate, all the best. Cheers, Terry.

[René 衛星の]

I would definetely place a helicoil. I have no idea what the forces are in the camshaft pushing it up, but have you tried pushing in a valvespring?

There are only a few M6 bolts to hold the cam towers into place.

Just go back, it only takes a few hours (or less) and place the coil. You will regret malfunctions bacause of this if you don't. You will have to unbuild the engine again. Or do you like that job? 

[Don R]

I tapped mine for 1/4" fine threads (28) you don't have to drill the stand, the 1/4" bolt will slip right through. I started the tap through the stand to get it started straight, then removed the stand and finished the job. With a bottom tap you may even be able to run the new threads all the way down so you could use longer bolts. Mine had been stripped for who knows how long, no apparent harm.
 Someone here suggested this once and it worked well for me. The root of the 1/4" thread measured bigger than the OD of the m5 bolt so I believe all the old thread was removed by the tap. Clean the holes very well and blow them dry so there is no oil or cleaner left in the holes. My PO had mixed the shorter cam tower bolts with the longer ones, I think that is why mine stripped.

[Simpson]

I think the threads should be corrected in one manner or another. The valve spring force is very strong. It could take more than a few thousand miles but eventually loosen, weaken, fail prematurely IMHO.

[Magpie]

Thanks guys. I have a friend coming over to help me with it today. I like the sound of these bikes a high rpm so it should be right and proper in there.
Cliff.

[Terry in Australia]

Thanks guys. I have a friend coming over to help me with it today. I like the sound of these bikes a high rpm so it should be right and proper in there.
Cliff.

Good idea Cliff, it's not hard to install the helicoil, so just do it right first time. Cheers, Terry.