Wih nothing else to do, I was reading old posts. I found the one about more hp if you run an intake tube instead of a carb mount K&N. Soooo, I went to work in my makeshift shop and made a 2 1/2 inch tube that went on the carb and angled down and out over the swing arm mount. I reattached the K&N at that point. Now the filter is in open air and not restricted by being against the frame on the bottom and covered by the bottom of the seat on top. The bike ran great low and mid range, but would bog on full throttle. I did not have a jet kit with me so I took out the intake tube and went back to the carb mount and the bike ran great. (Just ask a few modded Raptors and Banshees that were at Pismo last weekend. LOL) So to my question. Does a full throttle bog indicate Lean because more air is getting to the carb? The plugs were crispy white on the porcelain. I am hopeing that now that the carb is getting more air at the top end that I can get a few more hp by re-jetting. Any thoughts from you whiz kids out there?

 

if you run the tm45 try the 150 main.

 

Sandman
Thanks for the quick post. Yes, I run a Mikuni 45 and currently have a 145 in it. I think I will have to play around with a bigger main jet and go from there. I hate to think that I will have to mess with the pilot, needle and clip position as it would mean a lot of runs in the creek bottom. No dyno around here.

 

you are exactly right, when you go from 3/4 throttle to full and the bike falls on its face you are very lean. you are at least 2 main jets lean, go up on the main one at a time until you reach the point you can feel and here the rpm and power pick up, and that's where you belong. when you're lean enough to stumble at full, you will also notice that bike actually speeds up when you back of to 3/4 throttle. as you go up on the main, notice the difference at each full throttle run - you'll go up to being just flat with no gain from 3/4 to full, but "flat" is not where you belong either, so go up another jet, and keep jetting up one at a time until you get all the power you can and then stop. if you think you like it, but up one more size to see if there's anything more to get, but don't realize any gain from it, go back down. jetting up with no gain means you're rich. you can be a jet rich with no ill effects other than excesive soot.

 

Hightower

Great info, I will get to play in the sand this weekend. I hope I don't scatter it. They always run best just before they break. LOL

 

I think the idea of running the stock intake tube (snorkol) was the fact that they are tapered, that allows a bigger clamp on filter & the air velocity gain. I'm not sure how much gain you will see out of a nontapered intake tube, I hope it works out good for you. Please keep us posted.
Joe

 

Country Joe

Thanks for the post. The way I'm looking at it is; The more fuel, burning at the right rate equals more heat equals more hp. If I have to go up at least two jet sizes with the intake tube, I should be making more hp. I quess time will tell. Wish I had access to a dyno then I could give you guys some numbers.

 

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MK45 with direct mount K&Nm main at 142.5, bike ran great. Installed intake tube and started jetting up. Got to 155 (the largest I had with me) and the bike really came to life. I still think it needs a little more to be right on but I am more than pleased with the result. I don't know if it was just moving the filter out from under the seat or if I stumbled onto some kind of ram effect with the length and diameter of the tube, but whatever it sure made a noticable difference in power and throttle response. I will get to go to Pismo on Memorial weekend and that will be the acid test. [img]i/expressions/face-icon-small-happy.gif[/img]

 

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