Clean-out of oil galleries in crankshaft?

[Anonymous]

Hi Folks,

I have a sneaking suspicion that the major repair I had to do last year (replace barrells and piston #2) is heading for a repeat this year. This is on my 1981 GS1000G.

My suspicion is that the oil gallery that sprays oil onto the inner walls of this piston, and onto the cylinder wall, is not spraying. This makes the piston heat up and the surfaces grind each other away.

This bike has a history of:

Previous owner #2 has piston #2 disintegrate. He takes bike apart to fix it then sells it when he loses patience repairing it.

Previous owner #1 buys bike as box of bits, starts repair, loses patience, gets a local mechanic to put it together. He rides the bike for a while then sells to me.

I ride bike for a while until oil consumption gets too much for me, the motor is getting super noisy, and it becomes very obvious that something serious is wrong. I find piston #2 partially melted and think that the mechanic had put in a shonky piston. Serious damage to cylinder and I replace the barrells and piston.

A year later and the oil consumption is rising. Recently I had a real problem of plug #2 oiling up and have since run some decoking petrol additive through the bike. Also leaned up the carbies and set float levels evenly. The bike now gets good fuel consumption (19 Kms to the Ltr - up from 14) and the plug hasn't oil up since.

But the oil consumption is now a litre every thousand kilometres and the crankcase vent tube is puffing again. And the exhaust is giving me a rhythmic puff of smoke on idle, suggesting that one cylinder is burning the oil.

So my latest thought is that piston #2 is not getting its cooling lube through the crankshaft and the cylinder wall is wearing away again.

Does anyone know where the crankshaft oil channels run?
Do I need to split the cases and take out the crank?
Does somebody have a crank out of the motor that they can check for me?

I need to get this problem fixed properly this time but I won't know for sure what is happening until I lift the head and barrells again.

Thanks
Kim

[Anonymous]

This isn't an answer to your question but you've got the exact same problem as the guy in "Zen and the Art of Motorcycle Maintenance"

Steve

[Anonymous]

This isn't an answer to your question but you've got the exact same problem as the guy in "Zen and the Art of Motorcycle Maintenance"

Steve

I've got that on PDF format on my computer somewhere. Maybe it's time to print it out and read it. :-)

Kim
What is the sound of one pdf printing?

[Dink]

Kim as I understand the way the oiling system works, the oil sprayed under the piston skirts is taken from the bigend bearing supply so it may mean a total strip down of the crank to clear it.
Dink

[Anonymous]

I think Dink's right on that one, unfortunately you're looking at a teardown of the bottom end to completely clean it.

[Clone]

The piston should still be getting enough splash and oil fling to lubricate it in the barrel. Tear the motor down and clean the galleries, replace piston yadayadayada. THEN check the carb on 2 before you drive it for any length of time. She could be running lean and hot.

[Anonymous]

The piston should still be getting enough splash and oil fling to lubricate it in the barrel. Tear the motor down and clean the galleries, replace piston yadayadayada. THEN check the carb on 2 before you drive it for any length of time. She could be running lean and hot.

#2 is not lean & hot, it's black and gungy and oiled up and either not firing at all or only running about ten minutes on a new plug until it oils up again. Well, it was until I sorted the carbs, but the oil consumption rising to this level has me worried.

Kim

[Clone]

The oiling up is not causing your problem. If the cylinder doesn't fire it doesn't build up heat. The heat in the cylinder is causing the oil ring to loose tension which will then cause increased oil consumption, carbon build up and then scoring. The source of the excess heat is the main problem.