Crankcase ventilation

Bottom End (crankcases and crankshaft)
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jack moghrabi
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Crankcase ventilation

#1

Post by jack moghrabi »

Description: Should I route the crank vent back to the air filter at this point

Good morning from S. Florida:

In the interest of moving forward towards a '63 that leaks less I'd appreciate some advice in respect of the crankcase ventilation system. Currently my crank vent is not routed back into the air filter assembly--she just breaths out into the open. Basically this is the way I've always had and ridden her. The motor, internally, is good and tight with about 3000 miles ( I figure) on new rings so she is not blowing out excessive oil out the vent--just vapor mist as the motor pulses and ,as near as I can tell, like she's supposed to.....Should I route the crank vent back to the air filter at this point? Any thoughts/advice would be appreciated. JackMO!
VPH-D
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Re: Crankcase ventilation

#2

Post by VPH-D »

You must be running a belt drive, otherwise your vent tube is dumping onto the primary chain. I've always drilled a hole in the inner primary cover and routed a hose back towards the drive chain. Is your chain oiler turned off?
VPH-D
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Re: Crankcase ventilation

#3

Post by fourthgear »

Jack-
You can run your crank vent to the carb. ,but if you put it to the outside of the filter ,you will be cleaning your filter a hole bunch , not to mention it will drip oil from the filter when its over filled and if you run it to the inside of the filter it will just gum up your throttle bore with oil in short order . If you have it to a pre- 65 primary( tin ) it will still come out at the bottom back end of the primary where there should be a drain hole or tube just for the stuff to come out . If you are running a belt and have it routed to the back of the frame it will still spit as you say , some put a filter on the end of the breather hose to clean things up a bit and there is also available a oil separator that has a small catch basin or cup that you can remove to drain every so often( about every ride ). I have the breather vent filter that I have not put on yet ( too busy doing other things on the scoot ) You have to remember that that breather also sucks in air some and filtering it could be beneficial to the cleanliness of the motor and oil . I know I probably didn't answer your question , but you do have some choices.
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Re: Crankcase ventilation

#4

Post by 108 »

jackmoghrabi, I have a ' 48 with a belt primary and the oiler turned off but also wanted to stop the drip/oil loss from the vent. I tried three design systems during the summer of '04 before comeing up with the winner. Here it is- a hose comes off the vent,makes a u-turn inside the primary,out the back and up over the rear pan to the oil tank to a 's' shaped 3/8" tube epoxyed through the top of the tank left of the fill cap, pointing forward. Inside the tank it points rearward about 1/2" from the wall of the battery box. THis blows all the oil right back into the oil tank- a perfect place for it . Then, the "clean" vent air goes out an identical tube in the right top of the tank (4" away from the other tube), over the other side of the pan , and down into a tube through the back of the 4" air cleaner . This tube makes a u-turn inside the filter back into the carb - it will actually touch the choke plate when its closed . What little oil vapor reaches the carb it easily sucked in. I rode over 1,500 miles this summer with no noticeable drop in oil level. An alternative might also be to route the outlet hose to the rear chain.
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Re: Crankcase ventilation

#5

Post by jellero »

i run a rubber hose from the breather back behind primary and past tranny and it hangs down. i don't get any noticeable oil from it and my belt runs clean. no oil on drive chain, i use chain wax, so my whitewall, wheel is nice and clean as well. replaced all tranny seals so no leaks anymore. j
jack moghrabi
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Re: Crankcase ventilation

#6

Post by jack moghrabi »

Hey gents,

Thanks for the savy replies. All of them. I apologize for the delay in my response; I've been away from the computer. Anyway, "WOW" in respect of the various alternatives presented here. I'm definitely impressed with how each individual finds his own solution with an item like this.....I guess I wasn't too clear from the beginning as far as my current set-up. Yes, the motor is a stock '63 with a tin primary and chain. I actually have the primary chain oiler completely shut-off at the oil pump. I have nothing going to the primary (no steel tube coming out of the oil pump front cover and no hose going into the tin primary). I actually get enough oil onto the primary chain from the oil seepage behind the front motor sprocket. Been riding her this way for a few years now. Now and again I'll pull off the outer primary cover and I'll dab some grease onto the primary chain. You have given me things to think about. JackMO!
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