head breather to exhaust

[roar]

OK I give up, do you plug the hole in the case that the hose used to go into or what?

[jordanepp]

5twins-

have you got a link to that article at 650motorcycles? I pulled my breather hoses off my original air boxes because the air box tubes were corroded and I feared that the head exhaust was forcing gunk into my carbs. (suddenly had to clean carbs again shortly after reinstalling boxes instead of cheap pods that came with the bike). Now I do get some oil leaking from these breather hoses especially at highway speeds.

[5twins]

The article you want to read is the one on 650Central by Farrell Hope.

www.650central.com/

Go to the bottom of the contents bar on the left side of the page and click on "Farrell's Shade Tree Corner". In the list of Farrell's articles, you'll find one called "Excessive XS650 Blow-by".

This is the article for modding the late model breather from 650Motorcycles but, as I said, I don't think you should on a stock or near stock machine .....

www.650motorcycles.com/XSbreather.html

[calal]

Funny, I posted "Krankvent really impressive" on this page and there it sits with no replies. Folks, none of these will come close to the power increase you'll get with an original Krankvent valve. Have fun anyway with these nickel and dime fixes...

[tomterrific]

The Krankvent is $100 vs $5 for the PBBCV. For $100 the Krankvent must be an impressive piece to look at but to impress me intellectually you will need to explain why it is better than a cheap plastic check valve from an auto parts store or a $15 reed valve from mikesxs. For what it is worth, I did not experiment with the check valve for power but to see if it slowed oil weeping. Power was only an option that might have been but probably isn't.

Tom Graham

[wideload]

Krankvent seemed a bit pricey to buy without a bit of additional information. I ran across this series of dyno tests focusing on crankcase venting here www.nightrider.com/biketech/crankvent_test.htm

[calal]

The 1/2" Krankvent kit sells for $70 at ET Performance.com. I hate to sound like a shill for them, but give Ted a call and he will explain why his valve works better. My bike is a '77 with pod filters with the correct jetting increase and a Mac 2 into 1 pipe. I tried the reed valve thing from Mike's and really couldn't feel much improvement over stock. A PCV or brake booster type valve had no effect. The power increase with the Krankvent valve was startling - I don't dyno test so I can't quote any numbers, but this is some really cheap horsepower. I was so impressed that I put one on my NX250 Honda with similar results.

[ShakerNorm]

Wideload - Nice find! You can't argue the dyno results - every pull either with or without the Krankvent was virtually identical - at least within acceptable errors...... and that's on 3 or 4 different bikes!

[tomterrific]

Dyno tests are always suspect when evaluating a performance gain. What if the gain is right off idle or at cruise or even mid-range? Dyno racing is good for bragging rights but the bragging is HP at top rpm. Where we shift! Maximun HP does no good if the engine is between gears. Performance is not always HP. In the case of the one way valve, I use it for oil control.

As to comments that engineers did not design a vacuum in a crankcase I give you decades of engine design with timed breathers (Brit bike and Harley), reed valve breathers (BMW) and one way hose (Enfield).

Tom Graham

[pops]

I'm with Tom on this. HP gain on these old bikes is mostly irrelevant. They are what they are. The more they are tweaked and fiddled and cajoled into incremental horsepower gains, the more unreliable they become and the less pocket change you have. It's like trying to turn a Yugo into a Corvette...you'll spend just as much money as the 'vette costs, but it'll still be just a Yugo. Get yourself a new four cylinder, water cooled, injected and computer controlled crotch rocket if you just have to be big dog on the porch. Otherwise, just ride, enjoy the sound and the wind in your face.

pops

[calal]

As for these "dyno tests" this disclaimer is right at the top of the page:
Nightrider was contacted by the supplier of the "Krank Vent", ET Performance. They have asked Nightrider to "retest" their products under closely controlled conditions on our two test bikes (80 CID and 97 CID EVO engines). We have attempted to meet the proper installation conditions as defined by Krank Vent. Two of the primary installation requirements listed by the company are a completely air tight engine and removal of the umbrella valves in the rocker boxes. Although Nightrider has been unable to ensure that both these conditions have been met on the test bikes some dyno testing was conducted.
To date, dyno testing has been inconclusive with no differences in dyno runs we have conducted. In support of the Krank Vent we have been unable to create a tightly sealed engine on the 97CID engine and did not remove the umbrella valves from the 80 CID engine

[jhbmx5]

HI-GUYS
I just bought a 1978 SE street tracker, no air box it has pod air filters. I noticed the double outlet breather just has rubber hoses running down below the swing arm just wide open , no filters. Should I install some kind of crankcase filters ? One on each hose ?
RIDE-SAFE

JIM

[jerry57g]

I have had trouble with base gaskets and the gasket on the cam chain adj. I installed a A.I.R. check valve . and no more problems. Made by Dorman I bought my last ones on Amazon.com 12.99 ea. They allow for the expelling of gases on piston down stroke and close on the up stroke so you actually have a vacum in the bottom. Had an old tuner tell me you can gain ~1-2 hp by ensuring you either had a check valve ono it or route it to the intake somehow.

[dogbunny]

Jul 15, 2010 18:27:35 GMT -5 jerry57g said:

I have had trouble with base gaskets and the gasket on the cam chain adj. I installed a A.I.R. check valve . and no more problems. Made by Dorman I bought my last ones on Amazon.com 12.99 ea. They allow for the expelling of gases on piston down stroke and close on the up stroke so you actually have a vacum in the bottom. Had an old tuner tell me you can gain ~1-2 hp by ensuring you either had a check valve ono it or route it to the intake somehow.

I took a look at your checkvalve -- I think you are referring to the Dorman 55050 Air Check Valve. It appears to be the same thing as the power brake booster valves, which are also made by Dorman, and which you can get at most auto parts stores for $5, and which do the same thing, and which have the same size hose fitting as the crankcase breather...

One thing about those power brake booster valves, in my experience they are prone to failure, so they need to be periodically checked, but they come with a one-year warranty.

[xsleo]

I have found that if you just put one in the end of the a long hose and let it set behind the engine it can get dirty. I just check it and spray it out with a blast of carb cleaner.
If you use a short hose to hokk the check valve close to the head and run a long hose down from there the valve stays clean.