1981 GS650G sat for almost 20 years

[Grimly]

Made my own battery strap from a strip of inner tube and a bit of galvanised fence wire.

[bbrad1775]

Made my own battery strap from a strip of inner tube and a bit of galvanised fence wire.

Genius, thank you.

[bbrad1775]

Well, I put a new battery in it this afternoon and it actually turned over after I jiggle the clutch lever. I wonder if the switch is loose or if it is just that way. Anyone have that issue with the clutch lever? Didn't let it try to start for too long as I don't know what the oil is like in it. Tomorrow it gets new oil and a filter. Then I'm going to hook up an auxiliary fuel tank to bypass the petcock and see if it will actually start. Compression sounded good while it turned over, no galloping.

[bbrad1775]

IMG_0254.jpg
here is a picture if the bike when I went to pick it up.

[hank2]

Just wanted to mention that the 1981 GS 650 G has a one year petcock setup. The vacuum and fuel ports face the opposite direction of the 82-83 models. Difference is that 81 models did not have a fuel gauge and have the petcock located differently. I haven't seen any aftermarket petcock that would work for the 81 model. Perhaps something could be done with 90 degree fittings.

[bbrad1775]

Just wanted to mention that the 1981 GS 650 G has a one year petcock setup. The vacuum and fuel ports face the opposite direction of the 82-83 models. Difference is that 81 models did not have a fuel gauge and have the petcock located differently. I haven't seen any aftermarket petcock that would work for the 81 model. Perhaps something could be done with 90 degree fittings.

Thanks for the heads up. Are there any conversions available? Do the 81 and 82-83's bolt up the same?

[KiwiAlfa156]

One thing I'd recommend before attempting restart an engine that has sat for a long time is to pull the plugs and rotate the crank slowly through 2 x revolutions by hand to make sure that everything turns smoothly and that a valve hasn't stuck in a position to contact a piston. Runs some penetrating oil around the plug threads before attempting to unscrew them. I lost 3 out of four plug hole threads to galvanic corrosion on an 1100 engine that sat for close to 25 years and had to get them re-threaded, so did a full rebuild before restarting.


That being said the 650G that hadn't run for over 16 years started after a good carb clean (new pilots), fresh oil and filter. It turned buttery smooth by hand.

As did the 750S that was dead for 10+ years

[hank2]

Thanks for the heads up. Are there any conversions available? Do the 81 and 82-83's bolt up the same?

Any conversion would be what you can cook up. I haven't done it, but someone once suggested removing the back cover and flipping it. That may get one port oriented correctly, but not the other (fuel, I think). I would suspect that the 81 style and the 82-83 style have exactly the same mount pattern.

You might try playing with the petcock and applying some mild non flame heat to it. Mine is pretty stiff if I haven't flipped it to prime or reserve in a good while. Your's may be essentially well glued shut with old fuel junk however. Could always try eBay but make sure it's an 81 and know how that should look.

Many things are unique to the GS650G shaft models from other GS's. A few things are unique to 81's or early 81's. I've used the listings on the Suzuki section on Partzilla. Many gaskets and other items that were still available 3 or 4 years ago are now NLA. Then it's a part number search on eBay.

If, by any chance you need an outer air box complete with lid and the impossible to find filter holder birdcage, I have a spare. Good luck, they're fine middle weight bikes and were loved much in period magazine tests.

[bbrad1775]

One thing I'd recommend before attempting restart an engine that has sat for a long time is to pull the plugs and rotate the crank slowly through 2 x revolutions by hand to make sure that everything turns smoothly and that a valve hasn't stuck in a position to contact a piston. Runs some penetrating oil around the plug threads before attempting to unscrew them. I lost 3 out of four plug hole threads to galvanic corrosion on an 1100 engine that sat for close to 25 years and had to get them re-threaded, so did a full rebuild before restarting.


That being said the 650G that hadn't run for over 16 years started after a good carb clean (new pilots), fresh oil and filter. It turned buttery smooth by hand.

As did the 750S that was dead for 10+ years

Two questions.
how do I turn it over by hand?
How will I know if a piston is stuck?

Thank you for the advice. Planned on doing plugs anyways will pick some up tomorrow.

[bbrad1775]

Any conversion would be what you can cook up. I haven't done it, but someone once suggested removing the back cover and flipping it. That may get one port oriented correctly, but not the other (fuel, I think). I would suspect that the 81 style and the 82-83 style have exactly the same mount pattern.

You might try playing with the petcock and applying some mild non flame heat to it. Mine is pretty stiff if I haven't flipped it to prime or reserve in a good while. Your's may be essentially well glued shut with old fuel junk however. Could always try eBay but make sure it's an 81 and know how that should look.

Many things are unique to the GS650G shaft models from other GS's. A few things are unique to 81's or early 81's. I've used the listings on the Suzuki section on Partzilla. Many gaskets and other items that were still available 3 or 4 years ago are now NLA. Then it's a part number search on eBay.

If, by any chance you need an outer air box complete with lid and the impossible to find filter holder birdcage, I have a spare. Good luck, they're fine middle weight bikes and were loved much in period magazine tests.

I thought about pulling it and soaking it in penetrating oil.

I did notice the air filter was soaked with what looks to be oil and there was electrical tape on the cover. What are common problems with them and ehat is thr filter holder birdcage?

[KiwiAlfa156]

Two questions.
how do I turn it over by hand?
How will I know if a piston is stuck?

Thank you for the advice. Planned on doing plugs anyways will pick some up tomorrow.

Remove the ignition sensor/ATU cover on the left hand side of the engine (3 screws round cover on the end of the crank). You'll see something like this



A large nut held in with a smaller bolt. The large nut is there just to manually rotate the crank.



Only rotate the crank in the normal running rotation (clockwise when your looking at the nut)



The crank should rotate relatively easily, remembering that your also pushing and pulling the pistons up and down, rotating the camshafts and easing and returning the valves to their seats under valve spring tension. What you are trying to sense is any grinding that might indicate corrosion in the bore (unlikely unless the thing has been stored outside uncovered in the elements) and mechanical interference, i.e. a hung up valve stopping a piston advancing though top dead centre. This will be obvious. And again unlikely in my experience. Valve springs are under a high amount of tension and oil while it does dry out to some extent doesn't turn into glue. Sludge? you'll find that coating the bottom of the oil pan not clinging to a valve stem.

Go slow for the first two rotations (720°) of the crank. The cams rotate at half crank speed. So you need 720° of crank to ensure 360° off the camshafts. If you can go around twice, your more than likely golden.

[Rich82GS750TZ]

Darryl, I know you’re “down under” but I’m sure you meant to say that the ignition cover is on the RIGHT side of the engine. We always talk about Left/right and cylinder/carb #’s 1234 from the POV of sitting on the bike.
We don’t want him taking off the stator cover just yet.

and I know this is off-topic and nothing to do with getting this bike running, but could we see some pics of the 750S, maybe in another thread. We (I?) never ever see those.

[hank2]

I thought about pulling it and soaking it in penetrating oil.

I did notice the air filter was soaked with what looks to be oil and there was electrical tape on the cover. What are common problems with them and ehat is thr filter holder birdcage?

The filter media is supposed to oiled. Not dripping in it of course. Gets washed.in solvent, dried, then well dunked in 10w40, then squeezed out. Plenty of of patting down to remove excess.
Just oily but not dripping. Is the cover taped on because the top and/or bottom attaching clips are missing? The bird cage sits inside the air box horizontally. It's what the foam filter is mounted over. Last I looked, the air box cover clips are still available. Likely the foam filter itself as well. I last used a UNI filter for the application and it was fine.

[bbrad1775]

The filter media is supposed to oiled. Not dripping in it of course. Gets washed.in solvent, dried, then well dunked in 10w40, then squeezed out. Plenty of of patting down to remove excess.
Just oily but not dripping. Is the cover taped on because the top and/or bottom attaching clips are missing? The bird cage sits inside the air box horizontally. It's what the foam filter is mounted over. Last I looked, the air box cover clips are still available. Likely the foam filter itself as well. I last used a UNI filter for the application and it was fine.

Good to know. Couple questions for you.

What solvent is used to clean it?
how long are the filters usually good for?
Are there after market filter options?
What is a UNI filter?

Will check the clips on the box tomorrow.

[hank2]

Good to know. Couple questions for you.

What solvent is used to clean it?
how long are the filters usually good for?
Are there after market filter options?
What is a UNI filter?

Will check the clips on the box tomorrow.

My Suzuki shop manual (from 1981) says to use gasoline, which I do. Not so wise, say many. I generally have some K1 kerosene on hand, I would think that would be slightly safer.

I would guess a life span of many years if the filter is kept cleaned and re oiled every year or so. And not ripped. Likely not 40 years

There may be other aftermarket air filter choices for this bike than UNI, but I doubt it. GS650G is a very old, long gone model. UNI is an aftermarket brand and I'm surprised they still have this model.

https://www.denniskirk.com/uni/air-filters/1981-suzuki-gs650g.mmy

Looks like Suzuki no longer has the GS650 air filter element. I believe they did a couple of years ago. It was quite a bit costlier than a UNI.

https://www.partzilla.com/catalog/suzuki/motorcycle/1981/gs650g/air-cleaner