'79 GS850 what did I get myself into?

[canuckxxx]

I am not entirely new to GSResources but it has been many years since I last posted here. Had a '77 GS750 and another '79 GS850 8 or 9 years ago that I posted about.

Anyways, I picked up this '79 GS850 that is in a very sorry state. Maybe I should have passed on it but it has a decent OE exhaust so I figured $100 was worth a gamble. Besides we are facing 5 or 6 months of winter and I need something to do.

Seem that it was partially taken apart about 5 years ago and then left outside. The Heads and cylinder block were remove and a rag to cover the open crankcase.

So right now I'm trying to see what I have without spending any more money. The engine won't turn over so I'm going to pull the engine and open it up. Question: I have removed the 4 bolts that attach the driveshaft to the output shaft. When I move the engine will that joint separate?

What I dearly need now is a service manual for this bike. Any suggestions on a source?

Thanks
Brian

 

[canuckxxx]

The pistons were in numbered plastic bags but still got we so the wrist pins are in the pistons and rusty. The pistons are salvageable I think so I want to clean the rust of the pins so they will slide out. Is there some chemical that I can soak the pistons in that will devolve the rust but not harm the piston?

 

[80GS850GBob]

Try a gallon of evaporust for soaking those pistons in...

 

[Jrgunn5150]

I have quite a bit of success using simple vinegar over a period of time to remove rust.

 

[Steve]

The pistons were in numbered plastic bags but still got we so the wrist pins are in the pistons and rusty. The pistons are salvageable I think so I want to clean the rust of the pins so they will slide out. Is there some chemical that I can soak the pistons in that will devolve the rust but not harm the piston?

If you find that they can not be rescued, I have four standard bore pistons that I just removed from my bike. :-k

Nothing wrong with them. I had gotten a deal on some brand-new OEM pistons some time ago. I was opening up my engine to replace gaskets, so I figured it was as good a time as any to also replace the pistons and rings. You will need at least four circlips, I would probably splurge and get all eight.

These pistons have about 30,000 miles on them.

.

 

[limeex2]

Use Metal Rescue, imo works better than Evaporust. Vinegar is a acidic. Acid and aluminum are not a good mix.

 

[canuckxxx]

If you find that they can not be rescued, I have four standard bore pistons that I just removed from my bike. :-k

Nothing wrong with them. I had gotten a deal on some brand-new OEM pistons some time ago. I was opening up my engine to replace gaskets, so I figured it was as good a time as any to also replace the pistons and rings. You will need at least four circlips, I would probably splurge and get all eight.

These pistons have about 30,000 miles on them.

.

Thanks for that Steve. I'm not giving up hope on these pistons just yet but it's nice to know there is another option, other than buying 4 new ones.

 

[canuckxxx]

Thanks for the advice on rust removal. I will see if I can find some Metal Rescue or Evaporust.

 

[fixmybrokecomputer]

+1 on the Metal Rescue. I've used it and it is good.

 

[canuckxxx]

As I said in my first post this bike was partially disassembled years ago and then left for dead in the elements. I am guessing that a re-ring job was being attempted. With the cylinders removed and those 4 holes open to the elements there is oily dirt going into the crankcase and the top of the crank and con rods.

My first instinct was to try and clean this by pouring some solvent in and let it drain out the bottom. But I'm thinking that this dirt is not as harmful as any dirt or grit getting into the main and big end roller bearings. The best way to blush anything out of those would be to activate the oil pump and pump clean oil through. So I removed the clutch assembly and the oil pump drive idler gear. This exposes the end of the oil pump shaft. A piece of 3/8" hose fits over the end of the is shaft which allows me to spin it with and my drill. So poured a couple of liters of 15-40 Diesel oil in through a cylinder hole and spun pump with drill and waited for oil to squirt out of the 2 holes that feel oil to the top end. It was pumping but oil was pouring out the oil filter cover. I tried to tighten but the bottom stud is stripped. So now I'm focusing on replacing that stripped stud.

Here is the oil pump shaft that I am driving, in a clockwise direction.

 

[canuckxxx]

So now I'm trying to remove the bottom oil filter cover stud. I have 2 nuts jammed together on there but they both turn. Any suggestions? It's only a 6mm stud so I don't want to have it twist off. I was thinking of putting the propane torch on the aluminum around the stud...what do you guys think?

 

[Nessism]

Heat the stud, not the aluminum. And use some penetrating oil. Do it a few heat cycles if necessary. The idea is to break the chemical bond holding the parts together. And don't force the removal as it seems you know. Do that and the stud will break off.

 

[canuckxxx]

Success! I managed to get the stud out by heating the aluminum under the stud and getting some better nuts to jam together and really tightening them down. No I just need to get a new stud.

 

[canuckxxx]

Also have to get new filter and 0-ring. Will try local Suzuki dealer first.

 

[Steve]

While you are at it, why not get THREE new studs?

Splurge, get the OEM nuts, too.

Minimal expense, and knowing that the fit will be perfect is priceless. :encouragement:

.

 

[canuckxxx]

While you are at it, why not get THREE new studs?

Splurge, get the OEM nuts, too.

Minimal expense, and knowing that the fit will be perfect is priceless. :encouragement:

.

Good idea. Very easy now with engine out on bench.

 

[canuckxxx]

I had another '79 GS850 about 10 years ago. When I finally got it running I had a problem with the clutch really stickingfd when shifting into 1st gear. I remember learning then that the '79s had a problem with too much oil flowing to the clutch and the solution was to restrict this flow. I made a mod to reduce oil to clutch and then it worked as normal.

Trouble is, I don't remember how I did this...does anyone know what I'm talking about here? Some kind of restriction put into the oil supply to the cluch. I'm pretty sure it was GSResources where I found out about it.

Thanks in advance

 

[Nessism]

I've never heard about an oil flow mod on the '79 850, nor do I understand how oil flow to the clutch could affect sticking. If you find a reference to that mod please share.

Oh, and if you haven't figured it out yet Basscliff's website has the OEM manual for your bike.

 

[canuckxxx]

I've never heard about an oil flow mod on the '79 850, nor do I understand how oil flow to the clutch could affect sticking. If you find a reference to that mod please share.

Oh, and if you haven't figured it out yet Basscliff's website has the OEM manual for your bike.

If I find the clutch mod reference I will definitely share it.

I found an owners manual on Basscliff's site but not a service manual. But there is a service manual for GS650G so I'm using that for now. That is a very useful site for sure.

Brian

 

[canuckxxx]

Some things I have discovered about my new-to-me GS850:

-The cylinder head is in very nice shape. All valve tappet shims are in the higher thicknesses 2.70 to 2.80 region. The valves seat have not been lapped too many times, if ever, because they are fairly narrow. The valve seals need to be replaced. Question: is there a special tool for pulling the old valve seal off?

-One of the friction plates in the clutch is worn down to bare metal on one side so need to get one of those. Other plates appear as normal. Also I am missing the STOPPER RING (item #7).

-Pistons are in good shape, and fit in cylinders good, so I will reuse, but 3 out of 4 the wrist pins are pitted from rust. So will need replacements. Need new rings too.

-The PO had sold the carburetor rack so I will have to find some VM carbs in usable condition.

-Both side covers have cracks in them. I think they are made of ABS...is there a way of fixing them?

-The rear tire is a Dunlop Elite and looks to be in almost new condition but manufacture year is 2009 so is a bit old. The front is old and cracked.

Overall I'm pretty happy with the condition of this bike. I shows 50K kilometers which is pretty low.

If anyone has any of the above mentioned parts please email me.

Brian