crankcase breather

Hi everyone,

I'm Arjan, from the Netherlands. I've been following several threads for a while, but never posted a message.
About a half a year ago, I bought a XS650 custom, with an Velorex sidecar. The old Jawa wasn't powerfull enough to properly pull the sidecar rig.

I bought the XS rather cheap, so I had te fix serveral issues. I fixed almost all of them, but I can't figure out this one:
The bike is leaking quit some oil via the crankcase breather.
After about 5km driving, oil is leaking from the downside of both sidecovers. When I remove them, everything is covered in oil. The battery, the (main) chain, the airfilters, everything.

I closed 1 of both breather holes and put the other in a oil catching bucket. After 150km highway (@ 90km/hour) oil was leaking from the sidecovers again. (I couldn't check for leakage on the way).

I figured, that the pistonrings (or pistons/cylinders) might be worn out. Do you guys have other ideas? I don't feel much like lifting the head, if I don't have to.. Do you have any ideas to find the cause, by simple tests?

Can this have any influence:
- when the engine is hot, the stationairy RPM is about 500 RPM higher than when it's cold.
- the motorcycle is rather high geared for sidecar useage, because the sidecar can easily be removed.
- did an oil change and filled the bike with the priscribed amount of oil.
- I got some headwinds during the 150km trip, at some point I had to get back to 4th gear, because of power shortage! (almost like the old Jawa )

Are you running with the oil in the middle of the full/low mark instead of at the top line?
Where does your hose end stop, at the back bone, below the frame?
Do you have on open hose, hose with a filter, a check valve?

Welcome to the site.

denaamisarjan said:

Hi everyone,
I'm Arjan, from the Netherlands. I've been following several threads for a while, but never posted a message.
About a half a year ago, I bought a XS650 custom, with an Velorex sidecar. The old Jawa wasn't powerfull enough to properly pull the sidecar rig. - - -

Click to expand...

Hi Arjan,
Hey! Me too with the XS650/Velorex. Your bike appears to be a 1980 or later Special and they came with (or at least the North American versions came with) a single nozzle breather not the V-twin nozzle one. I stuck an automotive non-return valve on mine when I switched to UniPods.
Mine used to dribble oil like it was a Britbike if I filled the oil as the book said to. Run it so the oil just shows on the bottom of the dipstick and it don't.
I find that 17/34 gearing keeps me dropping from 5th to 4th a lot. 17/36 is good for most riding, 17/38 and the gig will beat almost anything pulling away from a stop sign but forget riding outside town limits.

If you want to know if blow-by past the compression rings is a problem, have a leak down test done; run a quick search and you'll find plenty on this. I run with oil level at the top mark and use a Krankvent breather valve that's purpose built for the application. I don't trust automotive power brake booster valves; in a few days of operation as a crankcase breather valve they get cycled more times than they would in several years of the use for which they're designed. All you can say for them is that they're cheap and much better than nothing. Remember--oil level on these beasts is checked with the cap resting on top of the filler hole, not screwed in.

1200 RPM is recommended to oil the top end 500 above adjust accordingly. A leak down test will tell you the condition of the rings. Like Fred said the bike appears to be 1980 but the 2 outlet breather is 79 and older. It might not be the original motor.

grizld1 said:

I use a Krankvent breather valve that's purpose built for the application. I don't trust automotive power brake booster valves; in a few days of operation as a crankcase breather valve they get cycled more times than they would in several years of the use for which they're designed. All you can say for them is that they're cheap and much better than nothing.

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Hi grizld1,
After I removed my bike's stock air filters and installed Unipods I initially ran an open hose to blow oil fog onto the drive chain then I took advice from this list and used a power brake booster valve instead.
And now you say they don't last and that a Krankvent is better. OK, I looked up Krankvents.
Lotsa "how to install" sites but nowhere I could find where I could actually find out which one works on an XS650, what it costs and where to buy one.
Got a link?

Fred I think this would be it.
http://www.et-performance.com/index.php?main_page=product_info&cPath=4&products_id=87

I have purchased 2 reed valves from Mikes XS like the first photo on both my race bikes with no issues. It looks like Mikes only carries the one in the second photo.

Bryan

Yep, WR, that's the one; it just mounts inline in the breather hose. The main drawback to the Krankvent valve is the price. Then there's the sound; that thing is loud. I don't mind that. It's fun to play dumb when guys start diagnosing the "engine noise" and dispensing advice. You can string 'em along for as long as you can keep a straight face, so the valve is almost worth the price in amusement value alone.

bt24 said:

View attachment 87773 View attachment 87774 View attachment 87775 I have purchased 2 reed valves from Mikes XS like the first photo on both my race bikes with no issues. It looks like Mikes only carries the one in the second photo.
Bryan

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Hi Bryan,
mikes, eh? Thanks for the reply.
I've bought from there before and so long as the parts don't have any rubber or plastic in them they're OK so long as you realize you don't get what you don't pay for.
But now I hate their catalog. There's nowhere to type in a keyword to help me find stuff.
So WHERE in mike's catalog is it?
I ain't sufficiently motivated to scan through the entire thing one page at a time to find it.

Fred, . . . you doing OK? Usually you have no trouble finding things/zippin round on the inter-webs.
For Mikes site on the left menu/tool bar scroll to the bottom, click product search.
This is the link for the reed breather.

Thanks for all the replies, very usefull!

- I filled the bike to the top oil level
- I have 2 outlets, according to my bike papers, the bike was registered in Holland in 1980.
- I run a single hose down the frame tube, with on open end (ending in an oil catching bucket).

I'll try the lower oil level first, than I will have a leak down test done. Maybe it's a combination of both: A high oil level and worn pistonrings.

Fredintoon, very nice to hear that you run a sidecar as well! Since you lowered the oil level, you don't have any leakage troubles anymore?
So it should be possible... I was afraid that the leakage was the consequence of the sidecar usage.

thanks for the gearing tips, I'll check mine and post the results.

I've been using the Mikes version for a couple years now, and it hasn't fallen apart yet. I like it, seems to do the job, no leaks. But then again I rebuilt my engine a few years back so it is in good shape, and I run the level between the lines as recomended. I did try the brake booster valves on my other bike, but I feel they are not made for the job, and will fail quite soon after installation, mine did. So guys, something from Mikes that works. I don't know who makes it, no markings on it so obviously Chinese, but what isn't these days.

weekendrider said:

Fred, . . . you doing OK? Usually you have no trouble finding things/zippin round on the inter-webs.
For Mikes site on the left menu/tool bar scroll to the bottom, click product search.
This is the link for the reed breather.

Click to expand...

Hi WER,
Mike's US catalog? Thanks, I never thought to look there.
OK then, I'll forgive Mike's US outlet but the Canadian version stays right on my shit list because their on-line catalog don't have no steenkin' search thing to click on.
But for ~ Cdn$28.50 I'll use the clues in the US catalog to dig deeper.
PS Found the bastard! What kinda retard would file an engine oil PVC under "fuel system"?

I see what you mean Fred. Just looked at xs650direct and it is kinda of a joke.

Two brake check valves on the XS, one on the Triumph, the oldest, and one on the SR500. They still work and have been on for years. In fact, I think I my have brought the power brake valve concept to the XS community as I got the idea for my Triumph from the Britbike guys. The valve has been on my Triumph for many years. Use a spritz of carb cleaner to clean it.

Cheap and available even if not the best.

Tom