Anyone tried this on a KLX yet ?

I was thinking about this while reading the plastic oil al gore appeaser thread and i don't know why it never occured to me before.

On my ZX6R i disabled the "Kleen air" system alot like the smog delete on the klx, BUT with the Six i ran the crank vent tube to the valves at the front of the engine thus creating a crank evac system. I don't know if it really helped at all but i do know that on serious engines (top fuel, etc) you can create some pretty serious HP gains by sucking out those "cranky gasses"

If i am to understand the theory correctly, there is less gain on mulitcylinder engines since while some pistons are going down other are going up and more or less "equalizing" the pressure (especially inline four like my ninja where its ALWAYS two going up, two going down).

Anyone got any thoughts on this or am i just inhaling to many crank fumes ?

 

Hmmm. Interesting question. Hard to say. Maybe Marcelino or some of the other experienced techs will have something useful to add on the subject...

 

Some of the best threads and discussion on this issue are on KLR World. This is where the concept actually began, and the most serious experimentation occurred...even a dyno chart at one time. This was for the KLR650, but the principle would be the same on any single 4-stroke.

I did it on my '01 KLR650 for oil consumption purposes, and I think there is some merit there. That engine was frequently known to consume a fair amout of oil at higher rpms. The KLX250/300 doesn't have this issue as any kind of pattern, so I haven't pursued it and won't. I guess I have crankcase venting posting fatigue on the issue at this point. There's a wealth of info on that site if one is truly interested in knowing all there is to know about the subject.

I will add that a guy named "KLR Cary" from Schnitz Racing...the 685/705 KLR big bore kit...had some of the very best insights on the whole deal. Unfortunately Cary was killed in a motorcycle accident a good while back.

 

Could you give the cliff notes version ?

I did it on the Six simply because it was a matter of pulling a hose and sticking another in its place. If there really isn't a gain then i'm not going to bother sourcing a length of hose to rig something up. I'm lazy like that

 

Sounds interesting.

 

I put a PVC one-way valve in my KLR's system...which vents into the air box. It doesn't hurt anything, but, I'm not prepared to claim in helps, either. If you don't have blow-by from bad rings, I don't think it's going to do much.

Multi cylinder: I think it could decrease pollution somewhat, at least, compared to just putting a crankcase vent filter on the end of the hose.

Single cylinder: think about turning the engine over by hand....when the piston is going down, it's compressing the gases in the crankcase...or, it's pushing the gases out the crank vent hose (assuming the pressure is higher in the crankcase than in the hose). When the piston is rising, it's aspirating ambient air through the hose into the crankcase (unless there is a one-way valve in the hose).

In a hot, running engine, I envision there being an oscillation in that hose that doesn't quite equate to the volume of the piston displacement because the piston is moving faster than the air can escape and re-enter the crankcase, however, the relative pressure inside the crankcase oscillates between a little less than ambient air pressure (when the piston is rising) to a little more than ambient air pressure (when the piston is descending). The net effect is nil...unless there is blow-by. THEN, the net effect would be to have gases escaping through the vent hose. If these gases were being directed to the air box , this would allow them to go through the combustion chamber, which would result in these gases having a chance of being burned somewhat, rather than being released raw into the atmosphere.

If you begin with a cold engine, a think there will be a net movement of air/water vapour out of the crankcase as it warms up.

It certainly isn't a blown dragster situation.

 

LOL!...yes B58, this was one of the most fascinating descriptions of crankcase pressure and relief efforts that are often done in a blown fuel dragster engine. KLR Cary gave firsthand knowledge how often they even used driven or powered evacuation systems to relieve crankcase pressure in extreme engine conditions. He was the first to admit that the KLR was hardly in that category.

I had one of those 650's that used a decent amount of oil when flogged. It ran noticeably better than the 3 previous KLR600/650's, so the compression rings seemed to be doing their job. Either an oil ring issue or something else was helped by doing the PCV valve on that bike. It cut the oil consumption by about half in a very consistent manner. The claims that it yields a power increase are just silly IMO, and a couple of decently knowledgeable folk on the KLR World forum will argue against you vehemently if you say so.

 

I missed the top fuel crankcase venting discussion...if Cary led it, I know it was based on good experience.

I agree that power increases from this modification are beyond my logic, but, the other day I was talking about cams, and didn't even think about something as simple as Duration! So, I'm certainly no expert...

If it reliably dropped oil consumption, that's a good enough reason to do it on the KLR650!

 

You guys are confusing me.

You seem to be talking about hooking up a PCV valve to the crank vent, i'm talking about actively sucking the crank gases out.

It probably won't make a bit of difference in all reality but i might just give it a try for kicks.

 

No, I understood. We're talking about reducing and/or trying to create negative crankcase pressure in either case. Just a different way to skin the same cat. No noticeable power influence was evident in the KLR650 dyno test. Another guy actually came with an elaborate way to measure crankcase pressures and any fluctuation, and it showed no great pressure imbalances. I don't know. I still don't know how or why...at least for sure...why I and some others had an oil consumption drop. The whole deal sounds like a funky snake oil scam. The KLX is not an oil burner whatsoever, so for me it's a moot point now.