Burning Oil

[joeadams]

For a while now, I have suspected that my 83 GS750 (27k on the clock) was burning oil and I feel now that my suspicions are confirmed. It seems to have gotten worse recently as far as consumption goes. Its not leaking anywhere.

I'll try to quantify the consumption rate:
I changed the oil and filter, and filled it up to the top of the window. I ran it a bit but didn't add any more. I then drove the bike about 65 miles that day from Ebensburg PA to State College PA. It was mostly highway type miles. The next day I took my girlfriend for a ride for probably 20 miles and then went from State College to Harrisburg which is about 85 miles all highway. I checked the oil the next day and it was below the bottom of the window. During this time I had 3 cold starts. I know that the filter took on some of the oil but not how much. I filled it back up but I didn't measure how much oil I put in it. With a few trips to work (4 miles) a run of about 20 miles and a trip to Manheim and back (70 miles) the oil level has once again dropped noticably (3mm-5mm)

It smokes pretty badly when you start it up cold and continues to smoke until it is warmed up then it stops or so it seems. It is definitely way more noticable when cold. Hoomgar and the big red are witnesses to this. The bike runs good from what I can tell, perhaps I can get someone to take it for a ride and let me know what they think of how it runs.

Anyway, Hoomgar suggested that its probably the valve seals which are bad due to it stopping the smoking when it is warmed up. I also talked
to Duanage about it and he suggested that it may be better to just buy a new head on ebay and just switch them out. Or if the new head
needed work I could do it without having to tear my bike apart. I saw a head on ebay and the guy wanted $50 for it and I've read others who
got way better deals so I'm going to wait. I'm going to be in the middle of a move pretty soon here and I'll be having to buy new furniture
etc. so budget will be a bit tight. I know I don't have the tools necessary but the plan is to get the tools I need over time and get the job done right. I have another bike to ride now so no rush really. The only problem would be that the bike won't be in a enclosed garage come June 1 so having the engine ripped apart for more than a day or two would be undesirable.

The method of attack I'm considering here is:
Compression check ( I suspect this will come out OK but is it possible that bad valve seals could cause low readings?)
Valve clearance check (This is pretty routine maintenance that hasn't been done.)

It will depend on how those things come out as to what would happen next. I am a novice at this stuff. This would be the most technical job I've taken on but I feel that I should be able to handle it. I would like to get any possibilities out of the way before I got buying another head or pulling the current head off.

Is there something I'm missing in the attack plan?
Is there anyway to inspect the valve seals without pulling the head?
What tools are necessary for someone like me (complete novice) to successfully replace valve seals without totally screwing up something?

Any other suggestions or hints are very much appreciated.

[Guy]

Bad valve stem seals won't affect compression at all. If you do a compression test and it's low you're probably getting oil up past the rings. If it's high you're probably sucking oil down through the inlet stems. Either way, you'll need to pull the head to see what's going on. 27,000 miles is quite low for these bikes though, and stem seals would seem the most likely culprit, especially if it's burning oil after standing for a bit. Bear in mind that when you fill up to the top of the window with oil after a filter change, the level will drop quite a bit after the oil circulates and fills the filter.

[joeadams]

Bear in mind that when you fill up to the top of the window with oil after a filter change, the level will drop quite a bit after the oil circulates and fills the filter.

I am aware, thats why I mentioned it. I think that helped cause the drastic oil level drop.

Bad valve stem seals won't affect compression at all. If you do a compression test and it's low you're probably getting oil up past the rings. If it's high you're probably sucking oil down through the inlet stems. Either way, you'll need to pull the head to see what's going on

Are these two different things that you are talking about here? By inlet stems do you mean the intake valve stems? I apologize for not know what I'm talking about very well.

[Guy]

Sorry, I've been a bit clumsy with my explanation. They're the same. What I'm saying is that if the compression's ok, and the engine's using oil, the most likely cause is for the oil to be sucked down past the inlet valve stem oil seals, down the stems and burnt in the combustion chamber. The vacuum caused by the descending piston helps this along. It doesn't happen with the exhaust valves so much, because the exhaust port is under positive pressure. For this reason, many engines don't use valve stem seals on the exhaust valves at all.

[joeadams]

So I've finally done some futher inspection and determined that its cylinder #4 that is the culprit as shown in these pictures.







Number 4 is the one on the left in all the pictures except the last one where it is the one on top. The second one is probably the best one. These plugs came out of the engine without it running and I managed to break a plug so, I couldn't run it. But the #4 is all carboned up and the others are good. They are only brown on one side of the electrode.

So, whats step 2? Compression check? Any tips, comments, or suggestions are much appreciated.

[shortlid]

'80 GS850G USING oil?

OK, usualy when I switch to 20W-50 from 10W-40 in late Spring, before the hot summer months it slows my oil cunsumption. But if I do like 600 miles ina day (like the 509 mile Maine ride last weekend) it uses about a quart. It does not smoke at start-up, or on the highway. But I found out via ratchetneck during the Maine trip that my '80 GS850G smokes alittle blue during HARD acc. like for instance trying to keep up with Jethro with his GS1100E on my GS850G with a full tank of gas and my girl on the back!! So, what is the verdict, and before you say rings she has compresion as follows #4 cyl 150psi. #3 140psi. #2 145psi #1 160psi. Not GREAT but OK for 35k and siting in a junk yard for 2 years. Plugs look S[potless and she burns even if not a little lean.

[Jethro]

Hey Shortlid, do you notice any clutch drag when you use the 20/50 oil? I've been wanting to try it for the hot weather, but am worried my clutch will not want to release.

[redliner1973]

THose plugs are not shiney black, but rather dull black. That tells me your consumption is coming through the valves, not the rings. running a slight rich, also.

[duaneage]

I would:

Check compression. If it has enough squeeze then...

Change the valve guide seals. Get a head gasket and valve cover gasket, remove the head (ask Hoomgar to help, he likes getting dirty) and change them. Sears sells a valve spring compressor tool that is suitable for removing the valve springs for around 20 dollars. I don't know what the seals cost.

I did not know you had a 4V head, those are more rare than the 2v heads and are likely to be more expensive on ePay.

If the jugs are bad I would finda another motor and swap them, probably cheaper than reworking the old one. I know that is not good news but motors sometimes go bad, especially if a PO was unkind to them.

If all else fails take the Busa out for a thrashing and you'll feel better.

[shortlid]

20W-50

Hey Shortlid, do you notice any clutch drag when you use the 20/50 oil? I've been wanting to try it for the hot weather, but am worried my clutch will not want to release.

I have to RE-ADJUST the clutch when I drop the 20W-50 in there but the clutch drag is tolarable. It is the worse when it is running hot at a light or in traffic. :x

[joeadams]

Jethro--I have 20/50 in mine now and it definitly has a lot of clutch drag when its not totally warmed up. That is on cooler mornings anyway, something that is a rarity lately.

I have too many threads for this so I'm gonna try to keep it all in this one old/long thread. Maybe I can out last some of Hoomgar's threads. Anyway, I need to check compression check yet. I intended to do that two days ago but the jerks at sears lied to me about having a compression checker in stock so I haven't been able to mess with it. Seems like a good project for tonight. Hopefully I can post some compression numbers later today.

As for the plugs, it seems only the 1 is burning oil, cylinder #4. The others are all the same color, dark brown. If they are in fact a little rich, I'm OK with that. The bike still gets 43 mpg so I don't view it as a problem great enough to justify messing with the carbs.

If the valve seals are the culprit, I should be able to run it a while so long as I keep after the oil consumption.

[shortlid]

Wally World has it?

I know you can get a china made cheap-o compresion tester from Super Wal-Marts here in NH for $20?? 8)

[joeadams]

The one at sears is only $25 and Sears is way more convenient for me to go to. I think Jethro said he had one of these $25 jobs from sears. I wouldn't have expected Walmart to have them though. If all else fails, I'll check there. Thanks for the info.

[shortlid]

Yep same one

Ya, that is the same one I have from Wal-Mart. :roll:

[joeadams]

The results are in:

#1--145 PSI
#2--150 PSI
#3--140 PSI
#4--150 PSI

I thought cylinder #4 was suspect but it seems healthy when the bike is warm.

So all signs point to valve seals?

[