lots of carbon on cyls. and valves

[Anonymous]

i am replacing the topend gaskets on my 82gs650g, and there is a lot of carbon build up on the tops of the cylinders and on the valve faces, is just brushing it all off going to be sufficient, or should i take everything apart to clean the parts thoroughly. i dont really feel like tearing the head apart, cylinders i wouldnt mind, but then id want to get new rings while they are out...and less money spent is a good thing.


any input appreciated, Ian

[Dink]

Seeing as you are replacing the top end gaskets, and are therefore gonna need to replace the base gasket or it will leak, you might as well de-coke it and polish the piston crowns and the valves whilst you are there, no point half doing the job.
Dink

[Anonymous]

you dont think going to the point of replacing rings is worth the trouble?...it still seems to have decent compression.

Ian

[Hap Call]

you dont think going to the point of replacing rings is worth the trouble?...it still seems to have decent compression.

Ian

If the compression was good before the teardown, I would leave the rings and would not hone it either. Just clean the carbon off the chamber without disassembling the head and put it back together.

Hap

[brs127s]

I was always told to replace the rings if you pull the jug off the crankcase. Have I been misinformed? The reason I ask is because I picked up a spare set of pistons, jug, and head for my 850. They only have 2700 miles on them. I looked everything over really closely, and see no wear at all. If I ever have any top end problems, would I just be able to replace the gaskets and drop the spare top-end on?

Also, would it be a good idea to replace the valve seals? They have very little wear on them, but I am worried about their age.

[Anonymous]

I would replace the base gasket, rings, and valve seals. All of these items are cheap. Don't forget to break the glaze on the cylinders so the new rings seat properly.

[SqDancerLynn1]

No matter how carefull you are the seal of the block will be broken and it will be advisable to replace the base gasket. You have to buy a top end set of gaskets so you will have the gaskets. You can resuse the rings, but if it has more than 25K miles I would hone the cyl and replace the rings. just make sure the rings and pistons go back into the same cylinder. You should take the head apart to replace the valve seals so it would also be easy to clean at that point and lap the valves

[Hap Call]

The way I'm looking at it is that if the compression is good and since the rings are already set to the present jugs I wouldn't replace them unless I broke a ring somehow. You must insure that the pistons keep the same rings and go back in the same holes that they came out of.

You may get in there and find sometime not quite koser, and if that's the case, I would agree with Swanny and replace the rings (only after deglazing).

Brandon, in your case, if you are sure which holes the pistons and rings came from, then reuse the rings since they only have 2700 miles...if there is any doubt, replace the rings.


Hap

[Anonymous]

ok, now i did each cylinder at a time and i got all the carbon off with some fine wire brush action, and cleaned the ring grooves out with 220 grit sandpaper...is that the "deglazing" that you are talking about??


also, on my #4 cylinder, there is detonation damage...this means the cylinder is running too lean right?, what adjustment on the carb should i make.(the damage isnt bad, just some minor minor pitting...more so than the other cylinders)

Thanks, Ian

[Dink]

What colour is the insulator of the plug from that cylinder, it is probable that you will need to richen that cylinder slightly but you need to be guided by the plug colour, it may be an ignition or an air leak issue also.
Dink

[Anonymous]

ok, now i did each cylinder at a time and i got all the carbon off with some fine wire brush action, and cleaned the ring grooves out with 220 grit sandpaper...is that the "deglazing" that you are talking about??

No - you should never use an abrasive to clean the ring grooves. The best way is to use some high quiality soaking carb cleaner. The next best method is to use the old ring and gently remove the carbon.

Using an abrasive like sand paper will remove material from the psiton in the ring groove and change the tolerances.

I don't liek to use any kind of abrasive on the pistons - wire brush, etc. Carb cleaner - the stuff in the bucket is perfect. Dip them and rinse the carbon away -> no damage.

Deglazing is basically using a set of honing stones on the cylinder walls to break the glaze and add a crosshatch pattern so the new rings will break in properly.

[Hoomgar]

I was following this because I am going to sell my old stock GS1000 pistons and rings on ebay and want to clean them up first. But I am not sure I follow well enough to know, what is the right way to clean them up shinny new looking? I see a lot of what some have done but what is it that I really should do to make them look nice so they will sell better?

They are in very good servicable condition but have that black crap build up on the tops of them. I can put a picture here when I get home.

Thanks guys, I know one of you know the best way to safely do this without damaging them.

[Hap Call]

I was following this because I am going to sell my old stock GS1000 pistons and rings on ebay and want to clean them up first. But I am not sure I follow well enough to know, what is the right way to clean them up shinny new looking? I see a lot of what some have done but what is it that I really should do to make them look nice so they will sell better?

They are in very good servicable condition but have that black crap build up on the tops of them. I can put a picture here when I get home.

Thanks guys, I know one of you know the best way to safely do this without damaging them.

I would never use piston rings that were already used....they been already seated against another cylinder wall and I would doubt that they could achieve a good seal again with a different cylinder. The pistons, that's another story, I would soak them in kerosene over night and using a brass brush clean them carefully, making sure not to leave any abrasions on the sides of the pistons. There are also products that can be used to loosen up the carbon like stuff used to clean fuel injectors.

Hap

[Hoomgar]

I would never use piston rings that were already used....they been already seated against another cylinder wall and I would doubt that they could achieve a good seal again with a different cylinder. The pistons, that's another story, I would soak them in kerosene over night and using a brass brush clean them carefully, making sure not to leave any abrasions on the sides of the pistons. There are also products that can be used to loosen up the carbon like stuff used to clean fuel injectors.

Hap

Thank you sir Thats what I wanted to know if I should use cleaners at all. I have several soft brissle brass brushes and a whole pantry of solvents and cleaners. Including good old kero. I will sell just the pistons as I agree the rings are not a item used. But I see guys selling them on ebay so I will most likely still offer them with the piston purchase at no charge just for grins. The engine had crank issues when we tore it down, the top end was near perfect. I only rebored to get more displacement.

What should I ask for the stock pistons? They are in near perfect shape other than the carbon. And I want to auction my stock 26mm carbs too. What are they worth?