Leaky 850 Mk II

I have had the same problem yesterday, bike has been oil tight for 5 years and oil is dripping off the right hand frame tube and onto the centre stand.

I did about 100 miles on it yesterday, and did clean up the bike with degreaser before setting off so i might see the problem, but it was dark when i got back and i am at work today (arrgh)!

Checked all the fixings etc, but suspect the oil tank, as i have got through 2 petrol tanks since i have had the thing and it never goes wrong by halves!

Let us know what it was.

Mike

Is it clean oil thats dripping? Definitely engine oil?750 or 850? Oneplace on 750's is the rear of the casesat the barrel joint. On some 850'swith porous heads 2-3 fins down at the front but that is supposedly more of a damp spot than a full leak. Case joints, barrel joint, head to barrel at the push rod openings, 2 x 5/16" frontstudswhere they break into the head inside. Other spots are the CB/camshaft seal (obvious when the cover is removed), lead entry on timing side to CB/trigger plate. Unlikely to be chaincase since you think its from the front but if the seal isgoing it could be overfilling the primary and pushing out oil through the4th gear felt seal. Timing covers don't always seal well at the bottom (mine needs sealant despite surfacing). Oil feed adaptor also a possible spot for leakage as is the relief valve. Good luck, it took me 6 years to get mine dry, now it rusts! Worth looking at a one way valve on the breather. It won't cure bad leaks but it will keep a slight seeper basically leakfree.

Just a thought, it may be from the chaincase. Oil can escape through the gearbox shaft seal, and drip down and makes a real mess. Poss check oil level in there, and if its over full, take out the timing plug/clutch adjustment plugand start the engine. If you can hear a puff puff noise then the left crank seal has gone and engine oil leaks into the chaincase, and crankcase pressure will force it out as the chaincase it not vented. Alternatively clean it all off, and run it for a while, then sprinkle talc powder over the lower part of engine and that will show up where its coming from. You may well have to put it on centre stand and get your head underneath to see whats going on.

I have had experience of all the above. Good luck.

Previously wrote:

I have had the same problem yesterday, bike has been oil tight for 5 years and oil is dripping off the right hand frame tube and onto the centre stand.

I did about 100 miles on it yesterday, and did clean up the bike with degreaser before setting off so i might see the problem, but it was dark when i got back and i am at work today (arrgh)!

Checked all the fixings etc, but suspect the oil tank, as i have got through 2 petrol tanks since i have had the thing and it never goes wrong by halves!

Let us know what it was.

Mike

I've had this one on my IIA Roadster (twice) - the oil tank bottom fixing cracks due to poor anti-vibe mounting and you can't see the problem, just a small pool of oil. To test it I blocked all the ports on the tank and applied a foot pump to the breather vent whilst holding the tank under water (not as difficult as it sounds) - a string of bubbles shows the problem. Quick trip to local engineering firm - small plate welded around the bottom mounting - now leak free.

Steve