Where's the oil leak

bobber · Post by **bobber** » Fri Apr 29, 2011 11:34 am

A few months back I finished a complete rebuild of a G5 and took it for a MOT about 10 miles away. The engine was smoking like crazy for the first few miles but this died down and wasn't smoking by the time I reached the MOT station. However, there was oil sprayed all over the rear end of the bike and particularly the rear wheel. The bike passed the MOT and I had the same problems on the return journey i.e. very smokey for the first few miles and oil sprayed all over the rear end. I cleaned it up when I got back and the bike has sat in the garage ever since as I've been working abroad. A fair amount of oil has dropped into a drip tray during this time. I've now got the bike up on the bench but not quite sure where to start; has anyone got any ideas what the problem might be or where I should start looking? I've had a look over the bike but there is no obvious leak; some oil arond the sump plug but that's about it.

1608 · Post by **1608** » Fri Apr 29, 2011 12:04 pm

Probably from the crankcase breather then if no signs of a leak. How about running it whilst on the bench. The bores may need time to bed down, but it shouldn't throw that much smoke/oil out. What is the exhaust end like.

bobber · Post by **bobber** » Fri Apr 29, 2011 12:27 pm

There's a moist oily residue inside the exhaust pipe (black). The crankcase breather makes sense but what would cause the oil to blow out of there and assuming that is where it's coming from, what would you do to fix it?

cbranni · Post by **cbranni** » Fri Apr 29, 2011 3:27 pm

Hi Bobber........have you tried adjusting the oil flow to the inlet valve, screw it all the way in and slack off by sixth of a turn, when you say rebuild .......did you strip the engine? what was the condition of bore, piston and rings, sounds like build up of pressure in crankcase due to worn bore, rings etc, and blowing out through breather onto chain then spraying the back wheel.
I'm no expert, but if I was you..........I'd take head and pot off and have a check............keep us informed
Colin

jajo57 · Post by **jajo57** » Fri Apr 29, 2011 7:30 pm

I'm with Colin on this one. Sounds very much like a pressurised crankcase. If you did the rebuild, what ring gap did you use, and did you make sure that the rings were 120 deg. apart when you put them in the piston?

Richard

wilko · Post by **wilko** » Fri Apr 29, 2011 7:51 pm

Wetsumping. By the way, it's proven that rings rotate in use so don't worry about it. That is why they peg two stroke rings so their gaps aren't overlapping the ports.

rex.webb · Post by **rex.webb** » Fri Apr 29, 2011 8:03 pm

Do lightweights Wet Sump ?
Never had one but , ? someone will know.
Wedding Fever allmost over .
Ride with Care and Live Long

1608 · Post by **1608** » Fri Apr 29, 2011 11:25 pm

What wedding!
I must have been cutting the lawn and missed it, never mind eh!

jajo57 · Post by **jajo57** » Sat Apr 30, 2011 10:04 am

Wow....I'm impressed, your lawn must be the size of Hyde Park.

1608 · Post by **1608** » Sat Apr 30, 2011 12:30 pm

I wish, but I also found my time better spent cleaning the bike.