crankcase vent smoke

[Shovl]

hi,my shovel was making some knocking noises and seemed to have lost power, so I took off the heads, replaced rocker arms and blew out the oil passages. when I put it back together it starts easy and runs strong (seems like the knocking went away too) but after it heats up there is a lot of smoke coming from the crankcase vent. any ideas what I did wrong? thanks

[Wide]

Is it smoking from the case or exhaust?

You may have clogged a vent opening or your judt getting some blowby
Also dont fill the oil to the top, they tend to smoke


Hope this helps

[Shovl]

smoke is coming from the crankcase vent. when I rev the engine it makes more smoke

[Wide]

thats blowby, you need to set uo something simular to a PVC system on a car. This is quite normal but if gets real bad its a pre to bad oil rings

Lots of folks dump the breather into the intake to burn it

[Heretic]

My crankcase vents go to a small aluminum radiator overflow catch can under the seat. it is about the size of a beer can....This catches any liquid oil that happens to get out of the engine. The open side of that feeds into an angled tube welded into my exhaust.......There is enough of a low pressure created, it actually draws out crankcase pressure

It is an old drag racing trick, and it works well on a bike

[Shovl]

why am I getting blowby now when I didn't have that problem before I rebuilt the top end? I used compressed air to blow out the oil passages in the crackcase. is there a check ball or something like that in there that I may have lost? thanks

[junior]

the only check ball is in the pump. try pulling a sparkplug and looking at the pattern that the oil is leaving on it. if the oil is completely covering the insulator, take a look at rings or blowby. if it is only on half (indicating a drip) look at a valve guide or seal.

it sounds like you left the jugs on. a good thing to do in most cases is if you pull the heads, yank the jugs too. run a hone through the bore, check for taper and re-ring and replace the base gaskets. just a thought-

also- does your breather go to the a/c or a draft hose? if you go road draft, do you have a filter r one of those hayden vents?

let us know and we can see what's what.

j

[Shovl]

if a possible cause is a valve guide seal then I'm going to put my money on that. I put on all new ones, and I think one wasn't seated right. it was holding the valve stem tighter than the guide flange. thanks

[Wide]

The guide seals are always going on Shovels.
When they go they tend to smoke out the exhaust not the CC.
Something to consider

Was thinking what Junior said about rings, even if you just remove the heads you can upset ring position enough tio get them to unseal a bit. That can deffinatly cause the blowby

[Shovl]

just to answer Junior's question, the crankcase is vented through a hose. it was open ended when I bought the bike 7 years ago, was always pissing oil and making a mess. I put a filter on the end of that a couple years ago and it never caused a problem. Sounds like one way or another I have to take that engine apart again