I can't forget that this CV carb and its' related intake components were matched up to provide 15-16 compliant horsepower. We are asking the same items to produce 20+ hp with our "uncorked" KLX's. Perhaps that is all wrong - Perhaps you are on the right track in modifying all the components from the intake port on the head to the airbox to get more flow. It's terrible that you don't have a Dyno available. My dyno testing confirms that my seat-o-pants dyno can detect a 1hp gain.

 

If you use a pod filter removing the airbox, jet up, and then port the intake of the head along with a larger diameter (or perhaps smoother i.e no bumps) intake boot on the head side of the carb, then hp can be acheived.

 

How come all you guys need all this horsepower?

 

I'm just doing it to give myself something to do, but the lack of a dyno or even someone to go through the gears regularly with can be frustrating. I may look into a couple of lap timer sending units to place along the road and a receiver unit/timer on the bike.

So while I am waiting for the box of mods to arrive from the USA I'll shift towards some bling for a change by adding CRF dual exhaust and try and find a 4.5 inch wide 17" back rim to replace the 4" wide rim that came on the bike as I convert it back to 17's front and rear..


I may get away with using the CRF header if I can heat it and take some of the bend out of the U section up front. There's a YT vid showing a guy at Yoshimura? bending exhaust sections with a torch and what I'd guess is a rosebud tip.. if a shop in town or the next town up has the equipment to do it, I'll give it a try. Only a few dollars to have them heat it up so..

The CRF headers seems to be the same bolt pattern and OD where it goes up against the head, though i think the header itself is a smaller OD than the 1.5" that's on my bike now. if I can't get the U bend opened up I'll just use what I have and shorten my header accordingly.

Changing the air box boot to something straighter seemed a natural thing to do and cost about $4 to try plus the time. Though I wasn't necessarily expecting to actually feel a gain over such a little thing, sometimes little things add up. I'll play with that idea later on this year

 

4.5" rim wit a bigger tire will for sure slow down the bike

 

I think you'll find that a single exhaust into a dual exhaust will not get any HP. But it will look cool. Then you'll need 2 mufflers, which will mean extra #'s.

 

Hey Richard, a 4.5 rear is going to be a big squeeze. I'm running a 4.25 now with a 140/70 and had a few boggles. I ended up spacing out my rear sprocket 6mm and my front 3mm for chain clearance, as well as offsetting wheel slightly to the right. All good now. Looks great from the rear with the big meat.:-D

 

I already have the complete CRF dual exhaust including mufflers from eBay

 

Could be, but it'd depend on the tire brand/size? From what I've seen there's quite a variation in tire widths even when the tire size is the same; 140/70 for example. I looked some brands up, or maybe found a post on a forum listing a bunch of them months ago and have it saved in an email to myself somewhere. Widths between brands but of the same size were often very different.

It was probably 140s from different manufacturers since I've read here that a 150 was all but impossible on a 2007

I was going to look for a 4.5 rim here in the Philippines or in China online, then go back and make sure I can find a tire with a narrower tread width or overall width before I bought the rim..can't remember how they are listed right now.

Ya too big tire might be slower. Can't fit too large a tire in there anyway.

 

Found the short list I started months ago. I think I measure a max of 6" for tire width based on the 18" knobby that's on the bike now, but I guess I'd gain a little wiggle room with a 17" rim

Tire size:150/60-17

Distanzia = 5.8" tire width on a 4" rim

Conti SM = 6.3" tire width on a 4" rim

Pilot Power = 6.46" tire width on a 4" rim

BT003 = 6.3" tire width on a 4" rim

I'm not having any luck finding a 4.5 rim so far, just 4.25-not much of a gain over the 4" I have now. There were some 5" rims in Thailand or China but that could really be asking for problems..