I've got a 14:1 piston, web 109 cams, ported head with 37mm intake and stock exhaust valves, ported intake, stock carb, and stock exhaust with end cap. does anyone have a similar set up that I can compare notes with. I'm currently running a 172.5 main, needle all the way up, fuel screw 4 turns out, and stock pilot. It has awsome low end but I'm currious if my jetting is right on the big end, I started out with a 190 main and it was flat so I've worked down to a 172.5 but a little scared to go leaner than that. Any help will be greatly appreciated.

 

With this much invested I would suggest taking it to a dyno and having them fine tune the jetting

 

I plan on it this week, but wanted it to be as close as possible

 

will knobby tires give inaccurate dyno numbers?

 

Air lid on or off?
With all your mods you either have to get larger snorkel tubes(remounted anywhere-not under the tank lid) or run with lid off- that means also the rubber gasket between lid and airbox.
You should be in the 180-190 range if you got the air.

 

Stockbomb, do you know how fast you would be with a good carb on there? But I would guess in the 180ish range. Depending on temp, and altitude. I would bet your not getting enough fuel through the mid range, you probbably need a larger nozzle or smaller needle, just guessing though, good luck Jed

 

I am running without the airbox lid, and snorkles removed. I started out with a 190 and it was really flat on top end, so I started jetting down. The guy that did my head work said I should be jetted leaner than before the head work because of the extra vacuum created from the porting. I was running a 172.5 before, but that was before piston and cams.

I know I need a carb, but spent all the cash I had in the motor while I had it apart, it really ticks me off to know how much better it could run with 1 little 46mm. bolt on.

 

A friend of mine had a stage three with stock pipe, modded end cap, stock carb. he had it tuned on a dynoended up with a 160 mikuni jet . But it was also only 42 HP. Stock it was 40 on the same dyno. Get a carb to make use of all that good stuff inside.

 

The ported head makes it impossible to advise. Different porting techniques want drastically different jetting. It is the one variable that makes armchair jetting impossible.

If you run knobby tires on the dyno, don't even look at the hp and torque numbers. Just use it to get the O2 readings and accept that the hp numbers don't mean anything. If you don't run Hoosier or American Racing tires, DON'T tune for peak torque or horsepower numbers, tune the O2. The HP and Torque reading will be erratic.
Example: If you add a carb which is known to add 5-7 ft-lbs of torque on Hoosier tires, then swap to knobbies, the dyno will often show less torque than stock because the increased actual torque spun the tires even worse.

Good luck
222

 

I did numerous plug checks today with 170,172.5,175 and it seemed to run the best with the 170, the color was the same with all 3 settings, light greyish to light tan. The broblem I'm having is in 5th gear it takes a long time to reach the rev limiter,does this indicate a lean or rich condition on top end, I'm running stock gears with stock size tires. I'm a little hesitant to go any leaner on the main, but maybe I should???? any thoughts??