I have a 2006 KLX 250s and am doing some mods over the winter.

I have seen the mod using a uni filter breather mod. Can someone explain how this mod works and improves power??

Thanks!!

Stashu

 

The stock filter is cheap and restrictive.

the uni filter is of better quality, lasts longer, and flows a little better than stock.

Any time you can get more air in and out of the engine, you make more power.

 

I think the OP is talking about crankcase ventilation, not intake.

 

Hmmmm............Yeah your probably right.

I just saw "Uni" and assumed the air cleaner.

Must be talking about the crankase vent tube and adding a filter to the end of it up under the seat.

I don't think this mod really does anything. Some say the engine revs free'er because it can breathe better, but I don't know if I buy it.

 

Yes crankcase vent. Thanks for the replies

Stashu

 

Some bikes really benefit from a crankcase vent "breather" mod. I did it and couldn't tell you if it make a difference because it was done with a bunch of other work at the same time. Few report having done it, and fewer still that they noticed a difference. Probably not worth the effort. I may put mine back to stock setup.

 

I'm not aware of any claims of increased power from removing the smog equipment. it would result in lower exhaust gas temps. but it would be a real streach to claim any real world hp gain from that alone.

 

Exactly, people on various bikes talk about removing the emissions stuff from their bikes as part of the "uncorking" process. This does nothing for the power output. I challenge anyone to provide factual evidence that it does.

Also, for those that change the air filter and/or silencer, you also need to re-jet your carb. If you increase air flow and not fuel flow, it make the mixture leaner and will actually be bad for your engine. If you're not willing to pull out the carb once or twice to tune the fuel mixture afterwards, you aren't doing the bike any favors.

 

The PVC system generally achieves 2 ends: it directs blow-by gasses back through the combustion chamber, and it keeps the crankcase clean of vapours which would otherwise condense & corrode the engine’s internals. In the case of the later, the vacuum generated in the intake manifold assists with the process.

Other than the marginal weight-saving, I am with IDRIDR, linkin5, & akarob in my skepticism that removing the PVC system will yield any horsepower benefit on the KLX.

 

I may have been talking about something a little different. We have an emission system that allows additional air into the exhaust to complete combustion (and make the exhaust pipe hotter), and a crank case ventilation system that allows crank case blow-by back to the air box where it can be recirculated and burned. I removed the former, and enlarged the latter. I wouldn't remove the latter as the crank case probably needs some breathing room. But my efforts at enlarging the latter for better crank case flow was probably a wasted effort -- leave that part stock or drill out the restriction hole where the crank case breather connects to the air box.