Positive Crankcase Valve System

[SirFallsALot243]

I was wondering if the honda mx'ers came equipped with a PCV system? My car (a honda) came equipped with a system that recycles the unburnt gasses back into the intake of the engine, rather than spewing them back into the environment- not to mention losing all the power that those gasses could still provide. By recycling this gas, it hugely helps the environment, and gives more power. Honda car engines come stock with a system that dumps the gasses right back into the intake manifold (fuel injected... our bikes would have it dumped back into the carb). The only problem with this is that it sometimes picks up some oil, which can hurt power. With the addition of a "catch can," the oil will stay in the can while the useable gasses can be reburnt. I was wondering, in the constant quest for more power- why doesnt honda use such a system? Im sure that would help get the EPA off our backs, as well as (potentially) give a little more power.

Another thing i was wondering was why the honda thumpers dont use the patented VTEC system (Variable Valve Timing and Electronic Control). This system allows the cams (or cam) to have two sets of valve lobes. One set is smaller, to provide better bottom end and gas mileage. The second set of lobes is larger, and is electronically turned on by the VTEC solinoid at optimal RPM. Ex, my car has VTEC at 4400 RPM (out of an 8200 RPM redline). With VTEC disengaged, my car made 162.3 horsepower at the wheels. With VTEC, it made just over 200 at the wheels. While this system may give the bike a "two stroke" like hit, it would also allow the bike to have even MORE bottom end, and create more power up top. Here is a picture of my cams in my car. As you can see, the two smaller lobes are in use under 4400 RPM. Above 4400rpm, the rocker clicks in to run on the middle (taller) valve.

[vintageguy]

Sounds like you may be on to somthing there

[KKXR400R]

My car (a honda) came equipped with a system that recycles the unburnt gasses back into the intake of the engine, rather than spewing them back into the environment- not to mention losing all the power that those gasses could still provide. By recycling this gas, it hugely helps the environment, and gives more power.

I heard Eyvind Boyesen was tring to incorperate this in 2-stroke world but I havent heard anything in a while about any progress.

Good call on VTEC, I'm sure Honda will have something in the near future. Give em call maybe they'll use it!
-Kevin-

[stormbringer]

I am guessing that Honda is already testing this at their R&D facilities. They may or may not come out with it soon. I do believe they will have something of this sort on mx bikes in the next 10 years or so. For recycling unburnt gases, I bet you can make that yourself, like on the 2-strokes just reroute the powervalve vent hose to the airbox instead of into the air. I wonder if it would actually work? As far as creating more power i don't totally buy it, on the yamaha XT225 that my buddy has, it has emmision control routed to the airbox, and when he leans the bike close to the ground while riding, a crapload of oil get sucked in and clogs the airfilter killing performence. If no oil was accidentally sent, then it would work really well.

[Vintage Dave393]

I think those cams in the photo need more moly.

I don't think we have to worry about the "gases" from a dirtbike engine causing the end of civilization as we know it. Unless Al Gore has decided it's bad and wants to pay a scientist to create a result for another of his "theories".

Al needs to come by my house sometime. I'll show him my 10 year old push mower that runs LEADED VP C12 mixed with MAXIMA 927 Castor. I am able to mow the lawn, kill the neighborhood mosquitos, and get a nice castor bean buzz all at the same time. I did notice that my ice cubes melt faster, so I must be causing global warming.

[SirFallsALot243]

Originally Posted by Vintage Dave393

I think those cams in the photo need more moly.

I don't think we have to worry about the "gases" from a dirtbike engine causing the end of civilization as we know it. Unless Al Gore has decided it's bad and wants to pay a scientist to create a result for another of his "theories".

Al needs to come by my house sometime. I'll show him my 10 year old push mower that runs LEADED VP C12 mixed with MAXIMA 927 Castor. I am able to mow the lawn, kill the neighborhood mosquitos, and get a nice castor bean buzz all at the same time. I did notice that my ice cubes melt faster, so I must be causing global warming.

No, i definetly agree with you. I dont think that the cleanliness of the two stroke is whats killing it, but I do know that we get a lot of flack for it.

Originally Posted by stormbringer

For recycling unburnt gases, I bet you can make that yourself, like on the 2-strokes just reroute the powervalve vent hose to the airbox instead of into the air. I wonder if it would actually work? As far as creating more power i don't totally buy it, on the yamaha XT225 that my buddy has, it has emmision control routed to the airbox, and when he leans the bike close to the ground while riding, a crapload of oil get sucked in and clogs the airfilter killing performence. If no oil was accidentally sent, then it would work really well.

Well thats what the catch can is for. Pressure builds in the can, and separates the oil from the gasses. The gasses are sucked out the top of the can, while the oil sits at the bottom. Every 3k miles or so it fills up about 1/4 cup, so the actual amount of oil is minimal.

Heres a diagram of the PCV system on honda motors. Oh, and its called Positive Crankcase Ventilation- my bad.



The catch can goes after the breather chamber and before the PCV Valve.

[2000kx250]

Actually, the other day I was surfing the internet and i came across an awesome contraption. It is a can that hose-clamps onto the back of a 2 stroke exhaust and its called an "oil condenser". When the smoke passes through it, somehow it gets seperated from the air/oil mixture, condensed and trapped in the bottom of the container. I personally thought it was an awesome idea. Ill go and try to find the link and post back later.

[stormbringer]

[QUOTE]

Originally Posted by Vintage Dave393

I don't think we have to worry about the "gases" from a dirtbike engine causing the end of civilization as we know it. Unless Al Gore has decided it's bad and wants to pay a scientist to create a result for another of his "theories".

I totally agree. All the dirtbike and atv emissions in the world per year are not even noticable compared to all the car emmisions in the world. Even then, I do NOT believe the scientists and enviromentalists view that the all carbon dioxide built up in the ozone is mostly from the burning of fossil fuels. The enviromentalists tend to exaggerate things.

[Vintage Dave393]

[quote=stormbringer;411468]

The enviromentalists tend to exaggerate things.

Ya don't say!

[YZ125motoracer]

a pcv doesnt give you more power, its to release unburnt hydocarbons that slowly build up in the crank case, or in the case of a single cylinder engine since theres not another piston moving up when one is moving down to displace the air in the crankcase. all the bikes have some form of a pcv.thats what the black hose coming out of the valve cover is.

[FFRacing11x]

Originally Posted by Vintage Dave393

I think those cams in the photo need more moly.

Ya think Dave??? I just called my broker and told him to buy all the moly stock he could. If this guy does many engines at all I will be a rich man!!! Tdub