Gs850 engine refresh questions

[Lukeisgone]

Hello! I'm restoring my father in law's 1983 Suzuki gs850 over the winter. I wanted to ask for suggestions on what I should do to the engine while I have it pulled. Here's what I have planned so far:
-new cam chain
-new gaskets
-valve adjustment

[Nessism]

The GS850 engine is very robust. With proper maintenance it will run 100,000 miles or more.

Why are you messing with it? How many miles are on it?

[Lukeisgone]

I'm doing a frame up restoration on the bike. It has a lot of surface rust on the frame and I'm re wiring the whole bike with motogadget. While I'm doing all that I want to freshen up the engine in any way I can. It runs great right now with a slight oil leak coming from the rpm sensor.

[Dogma]

The cam chain should be fine unless it was abused by a lot of overrevving or really bad oil. Honestly, if a cam chain on an 850 was stretched, I'd consider the whole engine questionable. The service manuals will have measurements you can take when you have the cam cover off to adjust the valves. Once you know the valves are in spec, you can do compression tests. If all that's good, I'd leave it assembled.

In general, I would recommend measuring things before planning a disassembly. Most likely, the engine needs nothing more than a valve adjustment to run normally. Like Ed said, these engines are very robust. I've had the head off both my 850G and 1000G at 50,000+ miles, and neither one even needed a cylinder hone. Both heads came off for oil leaking from the head gasket. Never any internal problems other than that. (Well, the starter clutch was my fault.)

If you haven't seen the warning yet, stick to OEM gaskets for the head, base, and base gasket O-rings. Base gasket O-rings especially fail reliably if not OEM. I didn't take the warnings seriously enough. I tried Vesrah, and they failed in a matter of weeks. The O-rings are a bad compound, and they absorb oil and distort.

The link in the middle of this page has the factory service manual that covers your bike. There's also a link somewhere on that page for a tutorial to help with that leaking tachometer drive. The part number for the failing seal isn't listed in the parts diagrams, but somebody figured it out somehow and added it to that writeup.

[Brendan W]

How many miles are on it?
I would not make any decisions about replacing anything until or unless you find a problem.
Valve clearance, yes.
With the exhaust headers off have a look at the exhaust valve stems for any sign of oil leaking down from the stem seals.
Do a compression check if you like. Most wouldn't if they could get it to fire and run.
The tacho cable leak could be as simple as replacing the seal that goes in there. No need to start tearing into anything.
The torque on the head bolts might be worth a check.
With the motor out you have an easier opportunity to check the o-ring seal at the drive end of the starter motor. They eventually harden and let oil out of the generator casing to leak down the 'mystery hole' below the starter.