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Crankcase breather blowing

Posted: Tue Sep 24, 2013 8:47 pm
by Pete
2008 Electra X with 5000 and highway kit is puffing nicely through its crankcase breather. The breather just has a duckbill on the end and all of the environmental can and tubing has been taken off. primary chaincase breather exits over the back of the gearbox and looks OK.
The crankcase breather exits over the drive chain. The oil level is deliberately run on the low side to avoid the excess being blown out over the back of the bike which it now is.
It seems to be puffing through the crankcase breather in time to the engine which leads me to think that there is a problem with the piston and/or rings. I've ordered a compression tester before taking anything lots apart unnecessarily.
Any experiences, thoughts or ideas welcomed! Hopefully (clutching at straws here I know?!) I'm missing something obvious......
Many thanks Pete

Crankcase breather blowing

Posted: Tue Sep 24, 2013 8:57 pm
by Alan R
Hi guys ----------- Sorry PETE but at first glance it does seem to have all the hallmarks of piston ring blow-by...I wonder,does our hosts CLASSIC breather mod kit also fit the Electra X ???...That would be a worthwhile purchase if it does....Meanwhile keep a light hand on the throttle and see what readings the Comp.Tester gives...

Crankcase breather blowing

Posted: Tue Sep 24, 2013 9:17 pm
by p
Don't forget your crankcase expands and shrinks by half a litre with every stroke of the engine; surely any "single" will huff and chuff from it's breather - my Bullet certainly does, and has for the last 20,000 miles without detriment.......

Crankcase breather blowing

Posted: Tue Sep 24, 2013 9:35 pm
by p
...... I've never contributed to the idea of runing oil level low - after all on our bikes it is the level in the tank, not the crankcase like a car engine. More oil means cooler oil and greater dilution of contamination. Oil starvation will wreck bores as well as bearings, so I would be inclined to top up and rely on the scavenge pump to maintain correct amount of oil in crankcase.

Crankcase breather blowing

Posted: Wed Sep 25, 2013 5:26 am
by Phil Ashbrook
When I bought my bike the engine was shagged out from low oil levels , the big end and bore were still OK but every moving part in the timing case including all the gear pinion shafts and on the verge of oil spindle fail , all the rockers and cam followers wrecked .
After a pretty expensive rebuild ( I replaced every moving part ) I keep the oil level on the high mark of the dip stick , on the new engine what came puffing out the duck bill was normal .
There is one more air hole and that is a hole to the oil tank so I imagine would be the tank overflow , it spits back only enough to spray the underneath of the dip stick cap as I have made the hole a bit bigger to help it breathe a bit better .

Crankcase breather blowing

Posted: Wed Sep 25, 2013 7:31 am
by Frank
I experimented with various methods of breather systems trying to reduce the blocking from emulsified oil whilst minimising the oil loss from being blown out. I found having the main pipe discharging over the chain meant that it was too low and so a lot of oil was pumped out. In the end I kept the catch can with the crankcase breather attached which is mounted high enough to minimise oil loss and already has a duckbill inside. All the other pipework was disconnected and drain hoses made from the can to drain near the battery hose. Result is no more blocked pipes and just a little spat of oil on the ground after a run when the can drains itself. What happened to the timing case pipe? Ideally it should breathe in there and out the crankcase breather.