smell of burning oil on deaccel...

[Guest]

1983 850GL. Recently changed the oil (first time since I got the bike ... have put about 500 miles on it prior to (PO had just changed the oil before I bought it). Used 15-W40 Rotilla T. When I let off the throttle has a very distinctive smell of burning oil. Nothing out of the exhaust...no smoke, no smell. Smell comes entirely from the front of the bike (I can smell it even on the highway doing 75).

The base gasket is leaking... not enough to drip on the ground, but it is weeping on the case. I would think if it the smell of burning oil was caused by an oil leak, I would smell it almost all the time...however, the only time I smell it is when I let off the throttle....and it is practically instantly as soon as I let off the throttle.

Thoughts? Something other than a leaking base gasket that would make an instant burning oil smell on de-accel?

[gsrick]

1983 850GL. Recently changed the oil (first time since I got the bike ... have put about 500 miles on it prior to (PO had just changed the oil before I bought it). Used 15-W40 Rotilla T. When I let off the throttle has a very distinctive smell of burning oil. Nothing out of the exhaust...no smoke, no smell. Smell comes entirely from the front of the bike (I can smell it even on the highway doing 75).

The base gasket is leaking... not enough to drip on the ground, but it is weeping on the case. I would think if it the smell of burning oil was caused by an oil leak, I would smell it almost all the time...however, the only time I smell it is when I let off the throttle....and it is practically instantly as soon as I let off the throttle.

Thoughts? Something other than a leaking base gasket that would make an instant burning oil smell on de-accel?

The smell could be coming from the breather on top of the valve cover.

[mhobryan]

The smell could be coming from the breather on top of the valve cover.

I did check that - it's connected.

[mhobryan]

bump...any thoughts on this folks? I suppose the smell could be coming from the exhaust pipes...I just wouldn't think it would be so quick, and pungent. I smell it literally as soon as I let off the throttle. FWIW, it didn't make this smell before I changed the oil....

[mhobryan]

I measured out the oil to a smidge over 3.5 quarts, showed about 1/2 way in the middle of the glass circle. What was unusual when I drained the oil is that the first few quarts looked more dark and murky but the last quart or so looked clean. I thought that was odd, as I did warm up the engine on the center stand for 3-5 minutes to get it warmed up.

The bike has about 12k miles on it.... I wouldn't think it would need new rings so quickly, but you never know. I think the engine has been a part before (at least the top half) as there is gasket sealer around the base gasket.

[Wingsconsin]

Oil change WITH Filter ?

Or WITH OUT a new filter ...?

Makes abit of difference in the amount of oil she can hold...

[Cipher]

I measured out the oil to a smidge over 3.5 quarts, showed about 1/2 way in the middle of the glass circle. What was unusual when I drained the oil is that the first few quarts looked more dark and murky but the last quart or so looked clean. I thought that was odd, as I did warm up the engine on the center stand for 3-5 minutes to get it warmed up.

The bike has about 12k miles on it.... I wouldn't think it would need new rings so quickly, but you never know. I think the engine has been a part before (at least the top half) as there is gasket sealer around the base gasket.

Why is their sealant on the base gasket? Is it daubed on in a futile effort to prevent oil escaping? I have never seen sealant on a base gasket that could be seen when assembled.

Is it possible that the oil filter cover gasket got pinched? Oil running down on the pipes.....
is it possible your carbs are leaking gas into the crankcase? This may account for the layered look of the oil. Does the oil smell like gas now? Did it while changing?

Oh and if you were to simply idle does the smell come? Or is it just upon decel? Does it do it when revving it on the stand? Once upon a time a cam cover bolt stripped and oil dripped out after high revving. You could see and feel that one end of the cover vibrating and leaking at high rpm. Let off and the cover would close up releasing a largish amount of oil which made its way to the pipes.

Some pics would be nice.

[mhobryan]

Why is their sealant on the base gasket? Is it daubed on in a futile effort to prevent oil escaping?

This is what I suspect, a futile effort.....

Is it possible that the oil filter cover gasket got pinched? Oil running down on the pipes.....

Dry as a bone there...don't suspect this

is it possible your carbs are leaking gas into the crankcase? This may account for the layered look of the oil. Does the oil smell like gas now? Did it while changing?

I DO suspect that this WAS happening. Previously I did not need to choke the bike at all, and it smelled rich on start up. Also, the PO had blocked off the vacuum line to the petcock. I replaced the petcock with a new one (not rebuilt) within a few days of changing the oil. It now requires choke to start when cold (albiet not long) and does not have that rich smell. That said, I would have thought that running the bike for 5 min before draining the oil would have mixed it up fairly thoroughly? Although guess kinda a moot point now...

Oh and if you were to simply idle does the smell come? Or is it just upon decel? Does it do it when revving it on the stand?

Not at idle, only on decel, doesn't matter if it is on the stand or running down the road.

Once upon a time a cam cover bolt stripped and oil dripped out after high revving. You could see and feel that one end of the cover vibrating and leaking at high rpm. Let off and the cover would close up releasing a largish amount of oil which made its way to the pipes.

Interesting hypothesis....I suspect my center front bolt may be stripped - will have to check for that.

Some pics would be nice.

Will post some if I get home before dark tonight.

As for the other question posted by Wingsconsin, I replaced both the oil and the filter.