The short version - Has anyone used the Cranckcase breather mod to help solve starting problems?

The long version - So, I changed my oil this weekend. After filling the oil up I started the bike. For the first time since I've owned the bike, it started on the first crank and went into a smoooooth idle. At first, I was like "DamnThat'sSomeGooood Oil!". Next, I realized I was being sprayed by this damngood oil. I looked down and realized I had forgotten to put the filler cap back on. I shut it off and put the cap back on, and it went back to the same difficult starting. Thus, I'm thinking a crankcase breather may solve my starting problems. Thoughts?

 

Nope...nothing to do with it. I've experimented on KLR650's and KLX's with a couple of different breather setups ranging from just making the opening bigger to installing a one-way PCV valve. While the KLR has more debate about crankcase pressures, especially as to how it "might" affect oil consumption, the KLX has no such issues. I opened up the hole in the airbox a bit on my KLX at some point when I installed my 300 cylinder, but it didn't change anything about engine starting. The best evidence seems to point to the fuel delivery in the choke circuit and/or the KACR bleeding off too much compression for cold start-up.

 

So why the Duece did my bike start so easily without the oil fill cap?

 

Luck?...moon phase?...you were holding your mouth just right?...who knows. Crankcase pressure inherent in the KLX design during cranking rpm's just isn't going to be the factor in the starting issues that some of us have had with the KLX. Crankcase pressure on most any 4-stroke engines will generally only become a factor at decently high rpm, and even then only in more extreme situations. Now, of course I'm assuming that you at least have the existing OEM hole in the airbox as supplied by the factory, and that it's not plugged shut.

You said you just changed your oil. Did you lean the bike way over to the right to allow access to the oil filter so you wouldn't have oil dribble down the engine case on the right side?

 

TNC - You might be onto something. I didn't change the filter, but I leaned the bike waaaaay over to the left to drain the oil. (because of my ongoing kickstand troubles, this was easy to do but I digress)

Thinking float level?

 

I only mentioned that because this leaning and even shaking of the bike has been a method employed by many over time to assist in a cold start on the KLX. Yes, it could be a float level issue...too low...or the leaning allows the fuel level to go higher than standard to a point where the starter jet and pilot circuit can pick up fuel easier which could aid in the cold start. I often kid deej by calling that method "the KLX hokey-pokey" in honor of that old children's song and dance.

 

The cold-start hokey pokey eh?... just when I start to think I'm understanding these bikes I learn something new!

 

KLX650 eliminates a bit of oil blow-by consumption by routing their breather up above the cam cover. It runs down hill on them making any condensed oil run into the air box and drip out the drain if the plug is pulled off the drain line.

I've not tried the PCV yet to try to cut it a bit more, but hey, no drips no runs no errors...

 

Not sure if this affects the carb version, but this is in the EFI service manual:

"To maintain the correct fuel/air mixture there must be no leaks in the DFI system. Be sure to install the oil filler plug after filling the engine oil"

 

Well its saying to have correct A/F mix there must be no leaks in the digital fuel injection system and not to forget the filler plug. :S