Sick GS1100GK

[jjmaag]

I have a 1982 GS1100GK with 30,000 miles that I have a ping noise under load on, at higher RPMs not the lugging the bike in 5th ping.
I have rebuilt the carbs (very clean), had the gas tank boiled and sealed, checked and cleaned all electrical conections for the coils and have good spark, resealed the airbox, checked the carb boots and replaced the o-rings, adjusted the valves, replaced all the exhaust gaskets, syncronized the carbs. All helped the power but nothing changed with the ping. The plugs are a nice light tan with a WOT chop.

I pulled the head and cylinders bent on finding a problem internally. The valves, pistons, rings, cylinders, chain and guides all look good except for a heavy carbon coating on the pistons and domes.

I am now in the process of measuring the cylinders and pistons and found that my Clymer manual has the incorrect data for the cylinder bore and piston diameter for the 1100. Could someone please post the correct engine specs for me?

[focus frenzy]

get rid of the carbon it is your enemy and is a major cause of ping.

as you have the head off, what is the color of the exhaust valves?

clean the ring of carbon off the top of the cylinders above where the top ring reaches and slowly run a finger nail up and down and see if you can feel a ridge on any of the cylinders. this is the old school first step to tell if a hone or bore job is needed as this ring will be exactly original in size and where the top ring comes to about 5 or 6 mm from the top will be where the most wear is found.
with only 30,000 miles on it there should not be any appreciable wear in the cylinders and a fresh set of rings and a light hone should do the job.

[jjmaag]

Thanks for the reply.

The exhaust valves are a nice light tan and the intakes are darker almost black.

I checked the top of the cylinder and have no lip that I can see or feel.

I just found my problem with the manual, it was me (shock), I failed to look in the supplemental information area. I guess I was tired last night and didn't notice I was looking at the GS1000 info.

This issue has been driving crazy. Is the pinging sound pre-detonation caused by the carbon reducing the squish gap between the head and pistons?

[focus frenzy]

it takes up volume raising comression but generaly not anything apreciable unless realy bad, but what it does do is get real hot and glows red hot and that pre-ignites the mixture causing knock.

a weak ignition can also cause it, have you done the ignition power by pass relay mod?

[jjmaag]

I have not done that mod yet. I did check voltage at the coils with it running and only had a couple of tenths voltage drop from the battery so I dropped that from my list of possible causes.

I also leaned towards the carbon issue because it seems to run real warm like it can't dissapate the heat from the cylinders. I don't remember the extreme heat off the engine, like when your stopped at a light, when it was new. I would guess if the heat can not soak through the head and pistons because of the carbon layer it is going to run hotter.

[jjmaag]

Does anyone know what gaskets you get in the Suzuki gasket sets? Does it include the base, head, and chain tensioner gaskets? What about valve seals?

[Redman]

JJ,

I can not really help you too much with your technical engine related question. But you are getting advise from a very knowlodgable fellow there.

I got a gasket set for 850G, was Veshrah, it did have valve seal set. Also had tensioner gaasket, but not the 2 orings in the tensioner.

Hey, GK.... 82.... black .... Lansing.....
Might that be the GK I saw in Muskegon at Muskegon Bike Time last July?

http://www.thegsresources.com/_forum/showthread.php?p=863854#post863854

http://www.thegsresources.com/_forum/showthread.php?t=129342

.

[jjmaag]

Thanks for all your input.
Redman, I have not been to Muskegon on the GS since 1985 when my father owned it but we do like to camp at Pioneer Park every year. My GS is Brown also. I would like to know who owns that black one in the photo. She looks like a real beauty.

[silverhorse47]

Another perspective, shamelessly stolen from the net:
"To lubricate an intake valve, tiny amounts of oil have to run down the valve stem. Over time, this oil is deposited and heated on the intake side of the valve, forming a carbon cone. This has multiple effects on the intake event, The carbon changes the aerodynamics of the intake event-namely causing higher gas speed and a change in the direction of intake and swirl, which affects the combustion process.

The IVDs also act like a sponge, creating a delay in fuel control. This delay not only creates a temporary enleanment on acceleration but also causes a temporary enrichment on deceleration. When the throttle is closed, the intake manifold vacuum goes high, pulling the fuel out of the carbon sponge. This affects fuel control."

Bnet

It sounds right to me.
S.

[jjmaag]

A little follow up.... the upper end is now rebuilt with new rings, cleaned pistons, and a fresh valve grind. I have 300 miles on it and not a hint of the old ping.