Drilling Crank Case Vent Hole??
#11
RE: Drilling Crank Case Vent Hole??
ORIGINAL: bmwhd
You are correct. There is a CAT in the stock pipe. Removing the air injection system might have a small impact on the performance of that but it's main purpose is not to raise exhaust temp for the CAT but rather to burn un-burned hydrocarbons right as they exit the head. In general, removing this piece of junk does nothing but good. Less weight, less chance of a vacuum leak down the road, reduced header pipe temps.
ORIGINAL: mrphone
So is it a good or bad thing to drill out the vent hole??!! What if you keep the stock exhaust??
From previous posts:
I just spent some time comparing parts drawings of the '06 KLX250S cylinder head and airbox with those of the '06 KLX300R. Our bikes have an air injection system that's not present on the KLX300 or the older KLX250s. This includes a valve that draws air from the airbox into the exhaust valve area during the exhaust stroke to increase exhaust gas temperature. It's the first thing you rip off a modern Bonneville because it makes the pipes turn blue.
The purpose of the air injection system is only to help pass the EPA. There is also a catalytic converter in the exhaust pipe!
Removing the air injection system won't make a darn bit of difference in how the bike runs but it will lower the temperature of your exhaust pipe a bit if you care about that. Mine's already blued significantly.
Todd, are you sure there is not a CAT? The owners manual says it has one. If so, would the cooler exhaust tend to adversely effect the system.
Yes, you're correct. There is a CAT and lower temps would be bad for that. I'd not mess with the air injection unless you change exhaust systems.
I only bring this up so folks will understand why their pipe is bluing so fast underneath the heat shield and for future reference in case you decide to swap out the head and cylinder for those from a 300.
So is it a good or bad thing to drill out the vent hole??!! What if you keep the stock exhaust??
From previous posts:
I just spent some time comparing parts drawings of the '06 KLX250S cylinder head and airbox with those of the '06 KLX300R. Our bikes have an air injection system that's not present on the KLX300 or the older KLX250s. This includes a valve that draws air from the airbox into the exhaust valve area during the exhaust stroke to increase exhaust gas temperature. It's the first thing you rip off a modern Bonneville because it makes the pipes turn blue.
The purpose of the air injection system is only to help pass the EPA. There is also a catalytic converter in the exhaust pipe!
Removing the air injection system won't make a darn bit of difference in how the bike runs but it will lower the temperature of your exhaust pipe a bit if you care about that. Mine's already blued significantly.
Todd, are you sure there is not a CAT? The owners manual says it has one. If so, would the cooler exhaust tend to adversely effect the system.
Yes, you're correct. There is a CAT and lower temps would be bad for that. I'd not mess with the air injection unless you change exhaust systems.
I only bring this up so folks will understand why their pipe is bluing so fast underneath the heat shield and for future reference in case you decide to swap out the head and cylinder for those from a 300.
#12
RE: Drilling Crank Case Vent Hole??
This medium does have its limitations. You are correct on the CAT of course. I guess I should have just said up front that I don't care if it functions optimally or not as I'm fixin' to junk it as soon as my Muzzy shows up
#13
RE: Drilling Crank Case Vent Hole??
ORIGINAL: bmwhd
I guess I should have just said up front that I don't care if it functions optimally or not as I'm fixin' to junk it as soon as my Muzzy shows up
I guess I should have just said up front that I don't care if it functions optimally or not as I'm fixin' to junk it as soon as my Muzzy shows up
#14
RE: Drilling Crank Case Vent Hole??
On fourstrokeworks.com under the engine heading there is a kit available to get the same results without the oil in the airbox danger for 35 bucks.
im thinking it can be done at your local auto parts store for 10 bucks
im thinking it can be done at your local auto parts store for 10 bucks
#15
RE: Drilling Crank Case Vent Hole??
I had my bike on it's side at elast 5 times on Sunday. Once facing slightly downhill. It sat in that postion for several minutes while I wrestled the rear end around so I could pick it up. Another time I have to make a U-turn on a 4 foot wide trail on a steep hill. Yup, yet again she was on her side for a few minutes while I carefully (so the bike didn;t slide down the hill, turned her around that hard way.
I never saw any smoke out the tail pipe and the oil level was still at the full mark when I got home. The one time it took a few minutes to start since the engine must have flooded being upside down... but no smoke. I can only conclude tha oil does not easily leak out the breather when the bike is on it's side... or that a small amount of oil escapes, but is easily drained out of the airbox or absorbed by the air filter.
I never saw any smoke out the tail pipe and the oil level was still at the full mark when I got home. The one time it took a few minutes to start since the engine must have flooded being upside down... but no smoke. I can only conclude tha oil does not easily leak out the breather when the bike is on it's side... or that a small amount of oil escapes, but is easily drained out of the airbox or absorbed by the air filter.
#18
RE: Drilling Crank Case Vent Hole??
Alright Guys I just drilled the Vent hole with a 3/8" bit. So that parts done. It was tedious, but not all that hard. Now I am worried to death about all the plastic pieces that came out with the bit. It seems like there is alot of the plastic just hanging inside still connected since we were not able to use a drill to drill it in and get all the plastic pieces out. Am I over worrying or will this seriously mess up the bike. I used a vaccum but I don't think that it pulled all the pieces that are still connected to the airbox just dangling there. I did it exactly like you guys, so should I go ahead and start her up, I don't understand what else I could do to make it more clean in there?
#19
RE: Drilling Crank Case Vent Hole??
I removed the air filter and scooped them out with my fingers. Otherwise, plastic bits should just burn up in the motor. ABS Plastic is non abrasive and like all plastics it's a hydorcarbon. Worst case you foul the plug, but I even doubt that from just a few bits of plastic.
#20
RE: Drilling Crank Case Vent Hole??
Holy crap, why do they make it so hard to move the freaking metal screen out of the air box, my god. They put all those bolts in the hardest to reach places that my wrench could not reach. I got the 1st two off the top then had to pry my hand down to where the hole was drilled out in, and then pull out the little plastic scraps. Oh, and I also found some oil had made its way to the airbox, and this was before the airbox mod, whats up with that??