Crankcase venting

Gator xs2

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I just read a interesting article on the xs650 crankcase venting. From the early design to the best they could come up with over the years. According to the article the earlier venting, quote “ leaked like a true Brit” That’s me. Anybody got some ideas? Besides a catch can?
 
I understand that the oil level plays a large part in blow-by. You can try running a bit less oil. I'm sure more technical responses will be forth coming.
tim
 
Thanks Tim. I saw that. Yamaha actually recommended cutting back to 2.5 liters. They still leaked. I’m thinking of venting it into a non structural part of the frame. But that may be a bad idea. And there goes originality. Thanks. Maybe it’s just gonna have to leak. The article I read said to keep the vent tubes away from the wheel. Oh well. Thanks again Tim.
 
It's a gravity thing. Connect your vent tube to a 6 foot long tube, mount the 6 foot tube so it sticks up into the air. The air will exit the tube and the oil will drip back into the engine. :shrug:

Scott
 
Thanks Scott. I was wondering about that.Where am I supposed to run a six foot tube? Down under the bike and back up? Seems like it would puddle up like a snorkel.
 
Thanks Scott. I was wondering about that.Where am I supposed to run a six foot tube? Down under the bike and back up? Seems like it would puddle up like a snorkel.

Yep, that would be the problem, snorkel is the right term.

I don't understand the whole system, no matter how much I read here. On my Honda's very little oil gets into those trash cans, mostly condensation vapors, and that takes a long, long, long time to accumulate.

Scott
 
When I change oil I put 2 quarts of oil in and have no blow-by. I have two XS650's and they both like it like that.
tim
 
I use the 2500cc quantity on the case, I have no oil blow by. I also use a 1 way valve (yes, it's the right way round!), to try and prevent positive crankcase pressure.

Edit, one of these guys, if anyone is interested, 12mm ally, small enough to have inline.
415G2o8w9OL.jpg

https://www.amazon.co.uk/EsportsMJJ-Aluminum-Booster-Non-Return-Inline/dp/B075NGQBKC
 
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It's a gravity thing. Connect your vent tube to a 6 foot long tube, mount the 6 foot tube so it sticks up into the air. The air will exit the tube and the oil will drip back into the engine. :shrug:

Scott

You can also make the "snorkle" multi-purpose by adding a bright red safety flag. This will greatly improve your visibility will riding.;)
 
Thanks Tim. I saw that. Yamaha actually recommended cutting back to 2.5 liters. They still leaked. I’m thinking of venting it into a non structural part of the frame. But that may be a bad idea. And there goes originality. Thanks. Maybe it’s just gonna have to leak. The article I read said to keep the vent tubes away from the wheel. Oh well. Thanks again Tim.
I have also thought of using the frame backbone as a "catch can", oil air separator!
 
+1 re. 1-way valves. Testing by pro tuners has pretty well debunked the claim that they'll increase power, but they'll definitely reduce oil loss out the breather. I use the Krankvent valve from ET Performance (no longer available, manufacturer appears to be gone too). With the crankcase filled to the top mark on the 1977 dipstick there's almost no oil loss between changes, even after prolonged highway speeds. There are less expensive breather valves available with members reporting good results. A quick search will turn up plenty of good information.
 
Going to try this route myself after (I think) 5twins suggested it along with a pair of UNI filters. Very close to getting it on the road. Will post up my thoughts after I've had a chance to run it a bit.
 
I'm using a brake vacuum check valve from like an '88 ford F150. It fits, and then I think it's 1/2" vinyl tubing down to the crank case and back up (U-shape) around the spine of the frame, ending between the pods. That tube is topped with a small K&N type gauze breather filter. Seems like there's always a scunge of oil film around that part of the bike, but it doesn't bother me much. I also did the old what's-his-name (Mitten?) mod to the breather itself and that may have been a mistake. Oh well, stuffed it with loose, coarse-grade steel wool.
 
On my 75 it was missing the cam chain adjuster cover. I picked up a complete 80somewhen engine at a salvage yard. I used the complete adjuster on the 75 .
I tried the mods to the 75 breather. Didn't help much. I took the breather off the 80+ engine. I added the Dorman power brake valve and ran a 3/8 inch hose from there down, like stock. I don't notice any drips out of the hose, end always dry.
I have been thinking of making adapters that fit the carbs that move the Uni-Filters back a bit so I can add fittings to hook the breather hose to like the later models do. This way any blow by in the engine can be drawn back in the carbs and burnt.
Leo
 
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