Monstrous oil usage GS650G

[Anonymous]

I've been the owner of a 1983 GS650GT for a little over a year now, and apart from some small things the machine hasn't given me much problems.

That is: except for the fact that the oil-usage is about 1 liter per 300 km (ca. 200 miles).
The machine is burning the oil; it doesn't leak (significantly), and the blue smoke from the exhaust would make your average two-stroke bike-owner jealous...

The dry compression is between 9.7 to 10.3
for all cylinders, which should be good (is it?). This prompted me to conclude that the oil isn't entering the combustion chambers at the pistons.

My next step was to check the air-filter box, to see whether the oil would enter the air-filter (and thus the carbs and the cylinders) through the air-tube from the top of the valve cover. However, the air-box was clean.

I next replaced the valve-seals. This also gave me an opportunity to have a look at the condition of the camshafts and cylinders, and they looked good and smooth.

However, changing the valve-seals hasn't solved the problem at all: the oil-usage is still about as high as before.

Now my question is the following: Given that the oil is burned, how can it enter the combustion chamber, given that the compression is good, the valve-seals are new and the air-box is clean?

Any advice is appreciated.

Thanks in advance,

A somewhat desperate GS-owner

PS: Please also reply to niek@bergboer.net since I check my mail more frequently than this forum.

 

[WifeofDink]

Have you checked the condition of the Oil Rings the other possibility is that you have an inward blown head gasket, both of these will cause the problems that you are having.

 

[Anonymous]

Hi NH,
hope I dont get this proble, got a GS650GD,
I have the original shop manual for GS650G, the GT is not specifically listed.
It is for ALL 81-83 GS650G models SO I got this for you.
standard compression (10-14 kg\cm2) limited to 7kg diff of 2 or (142-199psi 100psi limit with 28 difference.
you are under std so ...
worn cyl wall, piston/rings, rings stuck in grooves, valves/seals, head gasket.

by personal experience, I have seen this on my truck, wrist pins went on heads, they overheated and coagulated the oil in the cavity of the head, No smoke, No leaks, just always going to No oil.

hope this helps.
Stimpy

 

[redliner1973]

Also, broken rings can cause this, is it all cylinders oil fouled on the plugs or just one?

 

[focus frenzy]

definatly time for new rings and probably pistons,as stimpy posted you are out of specs on your compresion.
when I got my 1000g it also burned oil at a very high rate, just like yours and upon removal of the head I was surprized to find the cylinders had hone marks and the pistons looked like they didnt have very many miles on them. (I had bought the bike from a frend who had just got it and didnt have the time to get it running, it had been sitting for six years)
the previouse owner had put in new pistons and rings (stock size) and had the cylinders honed, but the cylenders were slightly outside the maximum limit suzuki called for, I went ahead and ordered 1mm over sized pistons and rings and when they came in I had the cylinders mach bored to the new pistons and that did the trick, good as new.