Where is the CL77 crankcase vent/breather

Snakeoil · Post by **Snakeoil** » Sat Sep 05, 2015 10:08 am

Hi guys. Been away for awhile wrestling with other bikes.

A friend has a CL77, I think a '66. He blew his counter sproket seal out and is concerned that his crankcase is not venting. I've never bothered to look for the vent on my engine an I'm not at home so I cannot look.

The manual shows a tower arrangement as an oil separator and then an exit port to a PVC type valve. But the drawing is not such that I can tell where the vent valve is located.

I assume that since the tranny and crankcase share the oil that the tranny is also vented thru the crankcase venting system.

Where is that valve located on the engine?

I was thinking that rather than the valve being plugged, that it is stuck open and the engine is sucking in air and that is what blew the seal out.

Thanks,
Rob

G3 · Post by G3 » Sat Sep 05, 2015 11:40 am

Hi Rob,
And yes it has been awhile for you! Hope all is well.
Isn't the breather tube the one at the rear side of the cylinder top cover? The interior head/cam chain path through the cylinder casting cavity open's up to the bottom end. And I'm not so sure it has a "valve" of any sort.

R100 · Post by **R100** » Sat Sep 05, 2015 11:40 am

From what I have read that crankcase breather system was only in the very early years.
It was then changed to venting through the cylinder head cover.
http://images.cmsnl.com/img/partslists/ ... 1_9564.gif

Snakeoil · Post by **Snakeoil** » Sat Sep 05, 2015 2:53 pm

Hmmm... I thought it was the other way around. Early engines had the hoses coming off the heads and later models had the oil separator tower and exited somewhere low on the engine case. I went back to my CL77 Parts book and you are right. The tube and the fitting are shown as part of the head cover assembly. So the venting arrangement in the manual must be for the early CL72 style or could be a carryover from the CA engines.

G3, all is well, here. I've been busy with a couple bikes. One is a '47 EL Harley that I bought 7 years ago, stripped it down, cleaned everything and this winter/fall, finally put it back together. I'm still waiting to get the engine and tranny back. Should have it done this year sometime.

I also bought a Ural sidecar rig because I made a ridiculously low offer and the seller accepted it. Did not run, 3 flat tires and pretty filthy. But it cleaned up nicely, very nicely actually, and with about 2 weeks of sorting out all kinds of minor issues, got it running and rode it for a good portion of the summer. But it needs attention and a few weeks ago, a bearing started screaming. So it's down for now and the engine needs to come out. Always wanted a sidecar rig and after I got over the teething problems and learned to fly the car, it is a hoot to ride. Even the wife likes it. So, I've been ignoring my Hondas.

I need to check out my CL77 for the upcoming Hurricane Giro the weekend of Sept 18. Then, I'll probably take my CB160 to Asheville for the Motorgiro USA event down there.

I've been riding my '39 Indian Four all summer. It never fails to put a grin on my face.

Getting back to the crankcase vent, turns out my friend has a tube coming down from the head and it breaths well. No valve that he could find. Might not hurt to put a PVC valve on that vent and try to pull a small vacuum in the crankcase.

Thanks and regards,
Rob

OldScrambler · Post by **OldScrambler** » Sat Sep 05, 2015 6:55 pm

The upper case has a vent-hole on the right............dumping into the open space under the side-case-cover about even with the drive-chain. You will find it real fast if you lay the bike over on its right side...............

Yes, the earliest C and CA models had a breather tower at the rear of the crankcase.

rrietman · Post by **rrietman** » Sat Sep 05, 2015 7:52 pm

Really?upper case vent hole? I don't think so. just the very early motors had the vent tower on the rear of the case, along with the 10mm spark plugs. of course that's just my recollection, I could be wrong.
Randy

OldStan · Post by **OldStan** » Sat Sep 05, 2015 10:48 pm

OldScrambler wrote:The upper case has a vent-hole on the right............dumping into the open space under the side-case-cover about even with the drive-chain. You will find it real fast if you lay the bike over on its right side...............

Yes, the earliest C and CA models had a breather tower at the rear of the crankcase.

That hole is from the valley into the side cover, NOT from the crankcase. The only breather, except in the very early models, is off the top of the cylinder head.