I am hoping to get pointed in the right direction to properly tune my carb. My engine is a 1915cc, 9.5:1 comp, W110 cam, 1 5/8" tri-mill exhaust, 009 distributor, and I believe stock or mild heads. I recently put a Weber 44 IDF single kit on it. It started right up and idled, but seemed to load up and then blew black smoke when I reved it up. I have a supertrapp muffler, so I removed all the discs. I then replaced the black fouled looking plugs with new ones and checked the point gap and timing. I also removed the carb and drilled the 2mm holes in the throttle valves like recommended on your website. It doesn't seem to blow black smoke now, but it still doesn't run right. I took it for a ride and it stumbles at take of (needs reved to go) and doesn't seem to pull real strong, but does rev up. I pulled a plug after I drove around a bit and it was not quite as carboned up, but still black. Any suggestions?

Bill

The way I jet my carbs is by reading the spark plugs. Let the motor idle for a while and pull the plugs out. If they are black its rich, if white or light gray its lean. Light brown is what your looking for. After u get the idle right then run the buggy or car at full throttle and shut it off without letting it go back to idle, pull the plugs just as you do on the idle. The spark plugs never lie. I actually had to put bigger pump jets in my 44 weber to eliminate that of idle stumble though.

Kevin,
If you don't mind me asking, is your set up close to mine? If so, what jets are you running. I am trying to find some good recommended sizes to buy and try first. Then work from there.

Sounds like your accelerator pump needs adjusted, it is pumping the gas into the intake too soon for the amount of air being allowed in at the moment, adjust it out so the gas is being pumped a little later than usual resulting in less black smoke when revving the engine.

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"Loud pipes saves lives"

I run a 36 dellorto on a 2275cc engine. They say a 36 dell is the same as a 40 weber. my jets are a 180 main and 55 idles. From my expierience the single carb setups like pretty good size main jets. Maybe this will help out some. oh and 170 on the air jets good luck.

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when in doubt use the skinny pedal!

9 times out of 10 its gonna be ur idle jets,,,what size is in it now?,,sounds like they are to big,,probally gonna need about .50 idles

I cant remember my jet sizes but what i did was order a weber book. I got mine from cb performance. It has jetting charts for both dual and single carb set ups. Im running duals now and its been 10 years since the single set up. The jetting chart in the book got me very close, close enough to run with out a problem. Thats my suggestion just get a book and youll breaze right through it.

I was having trouble getting mine to work too, same issues having to rev to take off and smoke. Only able to idle by turning the idle speed screw in a couple turns. The jets that was suppose to be in it would have been a great starting point however, it was not setup like was ordered. Here is a couple resources that helped me:

Here is a jetting chart for webers:
http://www.cbperformance.com/carbs.asp#jetting


tech page I used to tune mine in:
http://www.redlineweber.com/html/Tech/i ... ntrols.htm

The last 1915 I tuned with a single Weber 44 ended up like this.

Changed the venturi's to 32mm.

F7 Emul tubes

55 idle

130 mains

160 air corr

Had to drill out the accel pump squirters to send more fuel and this did away with the off idle stumble.

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Buy the best and cry once.

After talking to Aaron at CB performance, he recommended 155 main, 165 air, 65 idle, 0 by-pass pump. He also said to check float level. Should be 10mm from top of float to gasket and 32mm dropped down all the way. I checked the float level and it was good. I replaced the jets, drilled the 2mm holes in throttle valves like they suggest, and hooked up preheat. At the same time I switched out the points for the ignitor system and new coil. It fired right up and sounded much better with good throttle response. Haven't been out on a test drive yet, but so far it is much better already.

Been changing jets around today and running it after each change. I think I am going to stick with where I am at right now. It seems to run alright, no black smoke, and plugs are dark brown in the area where they fire. I ended up with; Air 175, Main 155, 0 by-pass pump, and Idle 65. This is a single Weber 44 IDF on a 1915cc with a 110 cam.

Are you runing velocity stacks ? If not they my help

Yes, I have velocity stacks. I drove it about 50 miles today and then checked the plugs. They are not black at the tips like they were, but they may actually be a little too light in color. I did notice it making a crackling sound above 2000 rpms under acceleration, so I am going to go up to 160 mains and see if there is any difference. I believe the crackling sound could be due to it getting a little lean on top, so hopefully the 160 mains will help out.

Update: Weather has been warmer and I have been running the rail more. Jetting was still not right. Two days ago, I changed the venturis to 32mm (from 36mm), idle 55, main 155, air 165, F-11 emulsion tubes, zero by-pass valve, and drilled the pump jets out a little from 50. After quite a few road miles, the plugs are a nice dark brown and it seems to be smooth at all RPMs. Hopefully this is it.