'85 GS450L - grey smoke from exhaust / oil leak from generator cover & shift shaft

[Guest]

Hey everyone. I was wondering if I could use everybody's expertise to try and troubleshoot a problem I'm having with my bike. I recently purchased the bike off a friend of mine for a steal of a deal. Everything seemed to run fine until about a month ago, when I started noticing that the right exhaust would billow grey smoke. I suspected an oil leak so I kept a close eye on it and discovered the following:

1. the bike would billow grey smoke when the bike had been running for awhile (~10-20 mins) or sitting unused for a short period of time (1hr+),
2. the smoke only came from the right exhaust but every once and awhile, the smoke would come out from the left exhaust briefly but never both at the same time,

[WHEN I GET A CHANCE, I WILL UPLOAD THE VIDEO OF THE GREY EXHAUST COMING OUT OF THE BIKE]

3. the grey smoke was not noticeable when moving faster than 5mph,
4. the grey smoke would intensify (we're talking big plumes of smoke) when I came to a stop and idled the bike, especially after slowing down from high speeds,
5. the grey smoke would smell like burning oil.

About two days ago, I decided to buy some cans of spray-on engine degreaser (plus other various fluids) and clean up the bike / do some maintenance. I cleaned the chain, underside of the generator/crankcase cover, and any other spots I noticed oil stains and/or crud. Afterwards, I re-oiled the chain and let it sit for a few hours. Then, I kept riding the bike for a few days and checked the underside of the bike again. The good news? The bike shifts better and I think I found the source of the oil leaks.

I noticed that the shifter shaft is leaking oil (yes, oil - it's black and it smells like engine oil). The shifter shaft and exhaust below it are coated in a thin film of oil and crud.


1.a. LEAKY SHIFT SHAFT OIL SEAL: The gear shifter and exhaust, coated in oil and black crud. Note the oil spots along the pipes - they're located directly below the sites where the oil is dripping from the leaky shift shaft oil seal and down the gear shifting lever respectively.

The left, back underside of the crankcase cover (perpendicular to the base of shifter shaft) is also coated in oil and has a bead of oil hanging from it.


1.b. LEAKY SHIFT SHAFT OIL SEAL: An underside view of the gear shifter and crankcase. Note the droplet of oil on the underside of the crankcase - it's positioned right below the base of the shifter shaft.


I intend to replace the shift shaft oil seal and see if that fixes the first leak. Easy enough.
However, I also noted that oil is also leaking from one of the bolts holding the generator cover in place.


2.a. UNKNOWN LEAK ON LEFT, UNDERSIDE OF GENERATOR COVER: A sideview of the generator cover and crankcase cover showcasing another oil leak. Note the glossy oil streak below the generator cover - it's close to where the generator cover and crankcase cover meet.


It too is coated in a thin film of oil and crud that extends from the bolt and downwards.


2.b. UNKNOWN LEAK ON LEFT, UNDERSIDE OF GENERATOR COVER: A zoomed-in side view of the generator cover and crankcase cover showcasing another oil leak. Note the oil leak - it's right at one of the bolts holding the underside of the generator cover in place.


2.c. UNKNOWN LEAK ON LEFT, UNDERSIDE OF GENERATOR COVER: A diagram of the underside view of the generator cover with the aforementioned bolt.

I'm not too sure what's causing the leak so I'm left to ask you all, what the hell do you think it is? My best guess is a leaky gasket but that's just pure speculation at this point. I'll remove the cover when I get a chance and peak inside.

Any thoughts or suggestions?

[Brendan W]

I would take off the sprocket cover and see if it isn't the seal at the drive sprocket.
I would leave the screw underneath alone until the biggy is fixed. The big leak may be responsible for the oil in different places.
On a general note about covers with gaskets. Pay careful attention to the screw lengths in the parts fiche. If they get mixed up or replaced and the wrong length used you can have a 35mm bottoming out in a hole intended for a 30mm screw. It will stop maybe 0.5 mm short and then the temptation is to nip up to stop the leak and that's when threads get stripped.

[ohshift]

Mmm, interesting. I'll take a peak at the drive sprocket and post an update with photos when I can. It might take a few weeks as I'm out of town but when I get back, I'll check it out.

Fair enough. I had the same sneaking suspicion as well.

Good to know. I'm fairly careful (and a bit OCD) about these sorts of things but thanks for the heads up. I intend on creating a laminated diagram sheet where I can carefully lay each piece when I disassemble the covers. A diagram reference sheet that's fluid-proof has worked wonders for me in the past.

I plan on restoring this bike to proper working condition and then passing it along to the girlfriend. She used to ride and I'm already starting to outgrow the bike's engine. It's a beautiful Eurostyle bike but 450cc just isn't going to cut it for me in the long-run.