Top End Noob

Valve guides should be measured for wear, might not need to be replaced, new guides means more expensive machine work (new seats cut). Cam chain should be ok unless there are tons of miles on it, there are measurements for it to check to see if it is stretched too far. Have you had the exhaust off? Do you know if the bolts are frozen or not?

Thanks for the tip.

I will need everything in the first list but the piston rings and maybe the shims for sure. Nevertheless, I will probably pace out the buy orders, as the work progresses.

[hampshirehog]

I'd wait until I'd pulled it apart before buying anything - things might be worse or better than you thought.

Pop photos up on here while you're doing the strip down; we can all argue (sorry, offer advice) about what we would suggest you do.

Now starts the Winter of my discontent . . .

Well, I need my head examined. This is all new to me, so I am starting a thread for advice and to recount my adventures (those who cannot do, . . . ).

Here are the basics:

1978 GS750 with VH 4-1 and K&N Pods.

Known Issues:

A PO botched a spark-plug expansion on the No. 3 cylinder such that the expander is forever grafted to the plug instead of the cylinder head. Even if the bike were running flawlessly, I need to pull the head to rehab that expansion. I have the Sav-A-Thread kit for this, but cannot do the work with the head in place, or metal bits will fall into the engine.

Of course, the engine does not run flawlessly. The No. 3 plug shows oil-fouling, so something is up in there. It also idles a bit rough, even after much trial-and-error in jetting and carb cleaning, and I think that No. 3 cylinder is a culprit. I could not get a compression test because the tool will not thread into the badly expanded plug hole. It almost fits, but not quite.

The other three cylinders have low compression but not terrible – showing about 110 psi on a dry test.

Da Plan:

• Pull the head and cylinder block
• Inspect and repair/replace valves
• Inspect and repair/replace piston rings
• Clean everything up
• Replace all gaskets and o-rings
• Win valuable prizes

Shopping List:

To prep for this project, I plan to obtain the following:

• Valve compression tool
• New piston rings
• New valve guides
• Extra shims to readjust the valves when done
• High Temperature RTV Silicon (to lock in the new insert)
• New gasket set to put it all back together
• New exhaust header bolts (the current ones are pretty rusty and may not survive the encounter)
• New exhaust gaskets

Some engine cleaner/polish to pretty her up a bit

Other possible items:

• New chain? The current chain looks OK, but what do I know?
• Cylinder honing tool? Still looking into this, and if it is too expensive, I may opt to have a bike shop do any honing needed. Same goes for valve lapping, and other machine work.
• New valves, if any are damaged, bent, etc. Should I just swap the valves "while I am in there"?

I have the Service Manual and the Clymer's Guide for the bike. Unlike the carb cleaning/rebuild guides, I have not found any "walkthroughs" for this endeavor. If there are any out there (I am looking at you, BassCliff), please advise.

Otherwise, as I begin this adventure, what am I missing?


Pointers, tips, anecdotes, mockery are all welcome.


TIA