Remove/Replace 1980 GS850 motor with minimal disassembly

[Dave_A]

I've got a 80 GS850L with one motor in it...

I've got a complete 2nd motor I'd like to swap in (also 80 850).

Reason is low dry compression in one cyl of the current motor, and a busted off exhaust stud on the same cyl - indicating the bike was probably run lean for a LONG time...

So... The question is, what is the MINIMUM amount of stuff I have to take off the engine to get it out?

Valve cover removal is NBD... But I'd rather not be dealing with removing the cylinders, for example....

Is there a way to do a 1-for-1 stock engine swap without a top-end tear down?

[Steve]

No problem.

As you suspect, it might be a bit easier if you remove the valve cover, but it might not be necessary.

You will have to remove the airbox, but probably not the carbs, although you will have to remove the cables, and it's easier to remove the cables if the carbs are partially removed.

Remove the exhaust system.

Remove the driveshaft. Although it sounds like a lot of work, it's easier to remove the driveshaft if you remove the rear wheel and the swingarm.

I think you will have to remove the right footpeg and the rear brake arm.

Have a strong friend or two nearby to help, that is NOT a light engine.

Don't forget to check the valve clearances on the "new" engine, and that you will likely have to sync the carbs to the "new" engine.

.

[Dave_A]

Thanks

That's what I wanted to know...

I've done this with a GS450 ($100 bike with blown motor + $80 450 engine from E-bay... Sold for $700 fully re-assembled and running), but I thought I had read somewhere that the bigger bikes required more teardown... Guess not - which is a good thing, now that it's time to do my personal bike vs a 'make some extra cash' project...

Was expecting to have to do valves & carbs.... But it should be worth it to have all 4 cyls in-spec & all 4 exhuast headers properly bolted on....

Fortunately, the exhaust was replaced by the P.O. so the biggest 'bear' of it all (exhaust bolts) is a non-issue - they come right out...

[Buddy]

I think the manual says the valve cover has to come off. I've pulled a 80 850G, 80 1000G, 81 850GL, and a 82 1100GL and have removed the valve cover first on all of them. Hope thet helps.

Buddy