My Goldflash has developed a severe oil leak which seems to be coming from the top end. The bike was a good starter first or second kick usually and was running pretty well. I went on holiday & it stood for 3 weeks, when I tried to start it it wouldn't go & I had to replace the spark plugs. Went for a ride and found oil all over the rocker box. cylinder head, carburettor & electric ignition unit. Clean it all off and tried again with the same result. Tightened rocker box nuts & bolts, test ride & same again. Removed the cylinder head & found oil in the combustion chambers & some evidence of head gasket blowing. Carried out a decoke whilst the head was off, fitted a new head gasket R replace head & rocker box. I haven't tried again yet as I am not sure that I have found the cause. Anyone got any thoughts?
Hi,
Could the oil have seeped down in to the crank case? This would make it difficult to start and could cause oil leaks due to pressure in the engine. Also oil could overwhelm the rings and get in the combustion chamber.
Did it smoke when started up?
Dave.
Hi Dave, no I didn't see any smoke on start up
Hi,
You may just have to ride it again but first check the oil level in the tank and note the level. Even if it is a bit low then leave it and go for a short run. This will give any oil in sump a chance to be pumped up to the tank. Check the level when you get back to see if it higher. If so then it could be that the engine is wet sumping. This could cause the the oily top end.
If you regularly run the engine or go for as ride then you may not have noticed but leaving it for 3 weeks could have been long enough to make a difference.
Dave.
Not so sure that the problem is wet sumping, normally if too much oil in the sump caused by wet sumpng then on start up the excess oil comes out of the crankcase breather hole which is behind the primary case. Take my A7 as an example I can let it stand for 2 weeks no problems on start up , but leave it for over 3 weeks then on start up the oil comes out of the breather hole and makes a right old mess on the garage floor but does not cause any problems with oil leakage in the rocker area. It could be a problem with crankcase breather causing pressure to build up in the engine thus causing the oli leaks and forcing oil up past the rings into the combustion chamber also normally oil in the combustion chamber would cause smoke on start up.
In terms of the oil on the cylinder head, I would have thought it is unlikely to have come from a leaking head gasket. Although the bike's slip stream tends to spread leaking oil making it difficult to identify the exact origin, I think it is unlikely that oil leaking from the head gasket would have risen above the height of the gasket to spread on to the cylinder head and rocker box.
Hopefully, whatever problem you had has now have gone away. However, if you get the same problem again, it would be worth checking the oil hasn't leaked out of the exhaust ports. If oil had found itself insider the combustion chamber when you tried to start the bike, or oil had leaked past the valve guides, it could have ended up in the exhaust ports and then seeped out past the end of the exhaust down pipes to eventually be blown out when the engine was running to coat the cylinder head.
This explanation might sound very unlikely but I have a bike that does this and, at the same time, does not produce any tell tale smoke out of the exhaust. If this is the explanation, it is probably just unfortunate to have happened when the bike was left for 3 weeks and probably nothing to worry much about.
Thank you all for your suggestions. I have measured the depth of oil in the tank on several occasions it varies from 63-73mm below the top of the filler neck. At the same time the sump volume when drained varies from 2 Fluid ozs to 7 Fluid Ozs. Today was 63mm & 7 fluid ozs.
Unfortunately I haven't been able to do a test run as it won't start. The plugs are sparking but seem dry so perhaps it is a fuel issue. I was using a dummy tank. Perhaps I need to connect the main tank and try again, Currently fitted with a new Concentric Premier one which it ran very well when first fitted.
An up date on my Flash. I have now managed to start it and on the first run I still had traces of oil in similar places. Decided to try and give it a thorough clean with degreaser etc to get rid of any residual oil from the outside of the engine.
Great news it seems to have done the trick as it is now running okay and no signs of an oil leak. So all I'm left with is the puzzle of what was the cause of the leak. Gut feeling is wet sumping it is only a guess.
The story has a plus side though after removing and refitting the rocker box several times I have devised a system, using two thin strips of wood to support the box whilst I use grease on the rocker cups and a mirror that seems to work well for me.
Thanks again for all you suggestions as to the cause and ways to fix it.