I agree some carbs are difficult to get at and adjust. I have found this to be the fastest and most accurate way of getting the pilot set. Before I figured this out it was a frustrating guessinggame and you still never knew exactly where you were at.This processhas worked well for me and the guys I ride with.

 

he spent 25 minutes on the phone with me on a SUNDAY. there aren't many guys out there that will even answer their phone on a sunday never mind take the time to go out in their garage to look for jet sizes and whatnot. the fact that he did that and more speaks volumes about him and how he runs his business. trust isn't an issue. not with me anyway. i'll try anything he can suggest.

 

I do have a few things to report tonite. I have Bill's bored 34 flat slide pumper carb, and the HMF pipe.

I did think the HMF was way too loud to ride on the street, and I intend to do a lot of that. So, we used the little spark arrestor/quiet core from Yoshimura. PN TEC-SB-B The package also says Low Volumn Insert RS3-TRS. It's a screen tube about 6" long welded to a flat disc about 2 1/2 inches across, it is clamped into the muffler opening and held there by the HMF muffler's end cap. With just the screen core in, it was barely just a little quieter at 5,000 rpm. So, I picked up a bag of Moose brand glass fiber muffler re-packing. I rolled it around the Yosh core fairly tightly, and wrapped 6 or so loops around it with stainless safety wire to secure the packing. I put enough on there it was a tight fit into the muffler. Buttoned it all up, and started the bike.
Now, THIS is what I'm talking about. Lots more sound than the stock tooter, it now sounds like a trailbike thumper should, but no irritating crack and boom at all.
Ok. So now we've established the correct backpressure I'll be running. I don't know what it would "measure", I'm going by: this is as loud a pipe as I want, thus this is the right pipe set-up. So, I will jet to this standard.

I have the 127.5 MJ, with the air screw set at 2 turns open.

With the open pipe and the KLX300 snorkle, my bike had great power down low, but faded at 5000 rpm. Didn't want to pull strongly past that.

Tonite I swapped out the big snorkle for the OEM. Thus, less air. Rode the bike. Pulls strong through 6000 rpm. So, less air means better jetting from the 127.5., SO, to run the big snorkle, I'll next install the 132.5 MJ. Take a chance and jump over the 130. If this works on top end power, I will try raising the needle one notch to fatten the mid range a little bit. Most riding is done on the needle, it's only past half throttle the MJ comes into play.

This is how it goes when you get into seriously changing things on an engine. Never in 35 years of building bikes have I seen a successful pipe and air filter change (let alone a bigger carb) that didn't require jetting. They just go hand in hand.

The air boot from the airbox to the carb is MUCH easier to install if you wipe a thin coating of Vasoline on the inside edges of the boot. I put mine in tonite in 2 minutes. Don't sweat the Vasoline being in there, if there's a little excess, it'll trap dust that gets past the airfilter.

Now, the next thing I'm going to cure is the maddening bolting up the two bolts on the side of the fuel tank. There must be a better way!.

Stay "tuned"

 

i'm keeping the 250cc jug so i'll start with the 137.5. then go tothe pilot circuit once that 's all worked out. thanks for the help everyone!!!

 

Bill has a source of air screws with a small T handle built in, that you just reach in there under the carb and adjust the screw. He is working on a group buy. I know I want one. It will be invaluable when I go up to ride in the Rockies this summer.

 

Great info Bill and Bake

 

Bake - will these work on the 33mm Mikuni without hiting the starter/cases?

Guys - FYI Bill does not rejet the carb for you. It comes with the stock jetting (127.5 MJ, etc.) that they are supplied to Bill with. You will have to order jets to get the carb dialed in to your conditions. Bill is a wonderful guy and I'm happy with the work he did on my carb, he's going above and beyond helping you dial in jetting on the phone on Sunday.

I ordered allmain jets from 130 - 150, pilot jets and even a couple of needles to sort out what I'll need on my 300 jugged KLX250.

 

Where did you order your jets from?

 

yes I get it. that first post came off like i was slamming Bill. I wasn't... i've already apologized to him in a message i sent yesterday. i meant no offense to him and regret how it has been interpeted.

 

I didn't take it that way, I figured he meant to try it that way just so that it is clear which way the jetting needed to go. But I just was following up to you in that it sounded like you were going to leave the airbox lid on since that made it run better than without. That's just the litmus test to see which way you need to go on the jets. Sounds like you're on the right track though and I'm sure you'll be happier with it after you get the rest of the jetting sorted out.