Topic: Camshaft fasteners were fingertight

[bertoxxulous]

Hey,
I'm using the off-season to fix a top end oil leak. This is the first time I take that section of the bike apart, and I'm now discovering that the previous owner was sometimes a gorilla, other times a... Jellyfish? 3 out of the 4 nuts securing the top part of the cam bearings were only fingertight, while one of the bolts' threads were gone. Also, while the 4 bolts that secured the towers to the head were all reasonably tight, all threads came out with the bolts.

I'll of course clean all the bolts and holes, and helicoil them, but I'm a bit concerned about what damage or excessive wear this uneven tightening can have caused. The bearings and camshaft seem OK (though there is slight pitting on some lobes). Is there anything I should inspect while I have it apart?

The good news is that I found the source of the leak. Check out this very weird puck.

[newday777]

The stripped threads are common for not using a torque wrench.
Use Time-sert thread repair as apposed to helicopter. Much stronger.

[PeWe]

Puck have silicone sealer (RTV)?
I add that on mine. (CB750)
Loose nuts and bolts might be bad threads after tighten too hard.

Honda has specified very high torque on those M6 bolts in aluminium threads.
I tighten max 9Nm despite Wurth "Time sert" thread inserts.

[seanbarney41]

This is all fairly common stuff to find.  Cam is probably ok, if you post some good pics, we can probably see any damage.

[Stev-o]

Oh, the joy of finding issues that the PO was responsible for! 

Consider yourself lucky that you found it before something catastrophic happened. [I was not]

[BenelliSEI]

I once found a length of 1/4-20 threaded rod replacing a bolt in the cam box (the rebuilt cb750 that is going in the Rickman)! I often amazed by what some people will do!

[willbird]

I once found a length of 1/4-20 threaded rod replacing a bolt in the cam box (the rebuilt cb750 that is going in the Rickman)! I often amazed by what some people will do!

In the 1970's and even 1980's in the good old USA finding metric bolts and especially on a Saturday was not a simple thing. Especially fun on some of the GM cars they used a mixture of Metric and Imperial.


Bill

[BenelliSEI]

I once found a length of 1/4-20 threaded rod replacing a bolt in the cam box (the rebuilt cb750 that is going in the Rickman)! I often amazed by what some people will do!

In the 1970's and even 1980's in the good old USA finding metric bolts and especially on a Saturday was not a simple thing. Especially fun on some of the GM cars they used a mixture of Metric and Imperial.


Bill

I always recall the first time I worked on a JEEP brake caliper bracket that was held on by a 15mm bolt head. Took me an hour to even find one!

[bryanj]

Use thread sealer on the outside of inserts and studs to stop oil wicking down the threads

[PeWe]

I plugged the outside of the stud holes visible in the spark plug cavities with JB Weld when head was off, after studs were tightened.
Not too thick , Honda spark plug socket to go free.
Cam studs fastened, high temp thread sealer on stud threads, Loctite 272 on thread inserts to head.
Should not leak there.
Rubber pucks got sealer to head. I Used high temp RTV last times.

[HondaMan]

I once found a length of 1/4-20 threaded rod replacing a bolt in the cam box (the rebuilt cb750 that is going in the Rickman)! I often amazed by what some people will do!

You'd be shocked to know how many times I've found that in these top ends!
When it happens I use the Keenserts so I can drill out past all that damaged area, tap an 8mm hole, and get back a solid M6 in the end. It does require countersinking the hole for the Keensert, so a few bucks must be spent for tools to 'do it right'.

[PeWe]

I have heard about M8 studs for cam.
This must be to handle the too high tightening  torque.

[bertoxxulous]

Thanks for the input guys. I will not worry too much about the camshaft, then. I considered helicoils for the threads, since they are much cheaper in EU, but I decided to do it properly, and ordered time-sert, high-temp threadlock, and teflon thread sealant, so I can fix up all the threads. Probably well worth the $150. I'll be following hondaman's book for the reassembly, applying hondabond-equivalent where applicable.

[HondaMan]

I'll be following hondaman's book for the reassembly, applying hondabond-equivalent where applicable.

Thanks!
The only place that should need sealant there is the edges of those round pucks. Any non-hardening sealant will work fine.