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1979 GS750 Blowing Blue smoke

  • Thread starter Thread starter ehkmcveh
  • Start date Start date
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ehkmcveh

Guest
IMG_7587.jpg

Having some oil leak problems. Attached is where the oil is leaking out, but bike is also blowing blue smoke and burning oil and a fairly fast pace.
Has anyone encountered the same problems? Appears Gaskets are failing... considering full gasket kit to do replacements. Any tips?

FYI the cards are in need of a Major tune also as the bike is running extremely rich at 20MPG! (that's for a different topic though)
 
ehkmcveh said:
View attachment 47279

Having some oil leak problems. Attached is where the oil is leaking out, but bike is also blowing blue smoke and burning oil and a fairly fast pace.
Click to expand...

To be honest I am not sure where to start with this!
a compression test of all the cylinders would give an indication of where you are.
if the bike is burning oil as badly as you describe then it looks like you need to take off the head and cylinders to inspect the bores and Pistons/rings for wear and go from there.
difficult to say where the oil is coming from in the photo as warm oil spreads all over the place when the bike is ridden.
 
Yeah its burning pretty bad, smoked out my garage pretty good
Burned through about a quart over 500km (300miles)

Cylinder 1: 110psi
Cylinder 2: 95psi
Cylinder 3: 95psi
Cylinder 4: 105psi

Tested with the carbs off, and kicked it over until max psi was reached, about 10-15 kicks. Added oil to cylinder 1 and re-tested at 110psi, apparently a difference in this would point to the rings (so I read)...no difference. No sure what a "good" psi reading should be... I have read between 120-150...Is this true?
Kinda wondering where to go next..
 
Is there a reason you did the test by kick starting v/s electric start? I would recommend doing the test with charged battery, electric start, all plugs removed and throttle wide open. Since the carbs are removed, then no need to mess with the throttle.;)
 
No reason, just seen on a video (mrmaxstorey) on youtube you can do it that way also.
Ok new readings, tested with full charged battery, 13.457V. Electric Start
Cylinder 1: 100psi
Cylinder 2: 85psi, would jump up to 30-60 psi then drop to 0...then reach max
Cylinder 3: 90psi, would jump up to 30-60 psi then drop to 0...then reach max
Cylinder 4: 100psi, would jump up to 30-60 psi then drop to 0...then reach max

Cranked it about 10-15 times until max psi was reached, with all spark plugs out.
 
Those number are with a cold engine I'm assuming. Warm should be in the 120-150 range but cold can be a bit lower. Still kind of low on on cylinders 2 and 3. That plus the smoking engine and oil consumption would indicate a rebuild may be in your future. Since the numbers didn't go up when you put oil in the cylinders I'm supposing valves are an issue. That's assuming that there isn't already a lot of oil in your top end. If so, then the readings are actually worse and the rings are in pretty bad shape.
 
Yeah its a cold engine.

Ok so when you rebuild the engine you would have to change out the valves and rings anyway correct.
Does anyone know of a good procedure (preferably a video) and parts list to get this rebuild done. I am new to this but got all winter :)

I think I would need a full gasket kit as-well, since I have a leak on the oil pan and another leak on where the block meets the bottom end (not sure the terminology). Buddy from work has the same issue on his 79 GS850... seems like a common issue.
 
First thing you need to do is get a Suzuki workshop manual try here all the measurements and information are enclosed for you to make a decision on what needs to be done and replaced, most on here would recommend using Suzuki parts and gaskets.
IF you can pick up a Haynes manual it may be worth while as it will explain some of the operations in simple terms but and I DO SAY BUT always cross check with the Suzuki manual and if there is a discrepancy FOLLOW THE SUZUKI MANUAL INSTRUCTIONS.
 
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The valves usually don't need to be replace if they're not burnt/bent or otherwise damaged. They can usually be just re-lapped or resurfaced if really pitted. New valve stem seals are needed. In most cases you're talking about replacement rings, honing the cylinders and replacing a number of gaskets. Haven't seen any rebuild videos. Would be nice though.
 
Shouldn't you replace the cam chain as well when re-ringing? And maybe the circlips?
 
I haven't read anything on that yet or seen (youtube) having to change the cam chain .

I read in the Suzuki Service manual that you can leave the engine in place to do piston work, rings... pg 8 posted by fastbysuzuki below
Anyways, took the cam shafts off and trying to remove the upper block, but I believe the chain guard is holding me up from freeing the block.
This is from a GS550 video but the logic is still the same https://www.youtube.com/watch?v=6X0VwcdZq7M... video 2 I think.

Does anyone how to solve this issue, trying to avoid having to remove the whole engine
 
When taking off the valve boots, 1 got seized on as I think the alignment got jarred. Got mostly up with ease.. Trying pulling on it with vice grips and a shirt for cushion... not sure how delicate these boots are. Also tried tapping it back into the socket with a rubber mallet with no success.

Has anyone encountered this
IMG_7606.jpg
 
They are precision parts, you bumped it crooked in the bore, f_cked it.
You need to gently tap the high side with a mallet harder than rubber until it's even all round.
 
beauty, worked.
compared with one beside it and the high side became obvious, couple taps
 
Anybody know a good place to get parts in Canada for my 79
Tried motorcyclecanada...not much selection...
 
View attachment 47349

Is there a proper way to clean these. I have dremel bits that can get the job done but not really sure. The instruction video I seen didn't show here cleaning it at all. I took all the carbon deposits of the piston so might as well do the valves also. They seem to be seating alright
 
About your "low" compression numbers, I have a couple of questions. :-k

1. Did you adjust the valves before doing a compression check? If not, you might have a couple valves that have clearances tight enough to leak just enough to give you lower readings.

2. How long has it been since the bike has been run regularly? I don't mean fired up to verify it's running, I mean ridden a couple hundred miles a week, minimum. If the bike has not been run regularly, the rings might be stuck, the cylinder walls might be just a bit rusty, and a few other small details that plague an engine that has not been run.

Good thing you also have an oil leak to justify changing the gaskets. I would hate to see low compression numbers after your gasket change, then watch them improve after a few hundred miles of exuberant use. :oops:

.
 
1. No compression was done first before anything. The valves will be lapped once I can get my crank case leak figured.
2. Just took it on a 250 mile ride, but before that barely rode it all year. Maybe like 2000 miles last year. Symptoms started happening after the 250 mile ride. Crank case oil leak was already there (but got worse). Started blowing blue smoke. And mileage went in the toilet.

They don't look took rusty, but after a Honning should clean that up. Got bigger problems right now (crank case leak!)
 
Have this stubborn head gasket that won't fully come off. Picture attachedIMG_7664.jpg
Is this good enough to seal?!? Just small bit of green gasket that have turned to concrete.
Have hit it with a number of things, gasket remover chemical but won't seem to budge.

Got the pistons and new rings in and want to seat the cylinder head. I do not have the specialty tool to pinch the rings... anyone have any DIY tips to sit the cylinder head
 
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