Topic: Strange use of bolt on valve cover question (with Picture)

[albertaboy]

Hey all.

Is that hex bolt factory? I doubt so. I can't find it now, but I think, somewhere, I read some guys replace the factory screw in an attempt to stop a leak?  If so- is it effective and should I re use it?  I bought a S.S. Allen head set to replace the factory screws.  Thanks for your help.

[GammaFlat]

It certainly looks like someone lost the screw and that was the best they could find. 

[albertaboy]

It certainly looks like someone lost the screw and that was the best they could find. 

I wondered that too. I forgot to write in the original post that the PO put one on the other side too, (same location- if you know what i mean). lol.

[Patrick]

Maybe he did that so it wouldn't look like he was using the only bolt he could find....

Patrick

[MCRider]

There is no potential leak in that area that I've ever experienced. What I have seen is that the stock screw is overzealously tightened, or a too short one is used and the threads in the head are stripped. The fix short of removal and a helicoil, is a 1/4-28 SAE bolt, which can be forced into a stripped 6mm hole with good effect. 

I can't tell from the picture, but that is my suspicion. If so, you're new allens won't thread in there. Tell people you've done it (the hex head bolts) for contrast and artisitc license.

[albertaboy]

There is no potential leak in that area that I've ever experienced. What I have seen is that the stock screw is overzealously tightened, or a too short one is used and the threads in the head are stripped. The fix short of removal and a helicoil, is a 1/4-28 SAE bolt, which can be forced into a stripped 6mm hole with good effect. 

I can't tell from the picture, but that is my suspicion. If so, you're new allens won't thread in there. Tell people you've done it (the hex head bolts) for contrast and artisitc license.

Good info and thanks. I'll check that out.  Yes as my bike won't be stock, I can get away with the artistic license story. Good idea. Cheers.

[Mars]

There is no potential leak in that area that I've ever experienced. What I have seen is that the stock screw is overzealously tightened, or a too short one is used and the threads in the head are stripped. The fix short of removal and a helicoil, is a 1/4-28 SAE bolt, which can be forced into a stripped 6mm hole with good effect.

The PO over tighten these bolts on my CB400F, and I'm wondering if you'd recommend the same deal on that bike? I am actually getting an oil leak from there because the bolt can't grab any thread, so it's just not in place.

[754]

Deer Whistle mounts.??

[MCRider]

There is no potential leak in that area that I've ever experienced. What I have seen is that the stock screw is overzealously tightened, or a too short one is used and the threads in the head are stripped. The fix short of removal and a helicoil, is a 1/4-28 SAE bolt, which can be forced into a stripped 6mm hole with good effect.

The PO over tighten these bolts on my CB400F, and I'm wondering if you'd recommend the same deal on that bike? I am actually getting an oil leak from there because the bolt can't grab any thread, so it's just not in place.

Well...I can't recommend it but... it may work. It has worked for others, including me. ITs going to grind up some metal in the hole, running the 1/4-28 into a hole it wasn't meant for. But the way the rocker box on a CB750 is made at least, the debris cannot escape into the engine. I would run the 1/4-28 in a few threads, back it out, clean it off, and repeat, 2 turns at a time. You're shooting for 6 to 8 full turns to get a good pull. Less is not enough, more is wasted.  The easiest way to strip the hole in the first place is to use a too short screw that only grabs 4 full turns or less, it will strip for sure.

I read somewhere early in my life that 8 full turns is the ideal rule of thumb. Less is risky, more does not allow for more torque or only marginally so, and so is wasted.  Try it on your bike, all production fasteners turn 8 full turns. (I think I've got that right)