carb farts

[merc]

still getting carb farts.
I did not change the main jet. (must be a 170? because it's stock)
I changed the slow jet to a 45.
changed the mufflers to cycle shack slip ons, last year.
The air cleaner is the one that comes with the Big Sucker without the backing plate or oil return into the carburetor holes.
Using one of those oil breather horseshoes to vent to the ground.
I tried playing with the mixture screw and the idle screw without much luck. Still farts. I have to use the enrichener to keep it from farting when cold.
Even after it gets hot it will do it when the rpms are on the low side.
I think the next step would be to shim the needle. How is this done and what do I use for a shim. Please be explicit in your instructions because I do not have a clue what we are talking about but can follow instructions.

[dodgenbullets]

Hey Merc. Shimming the needle affects the mix at about 1/3 to 3/4 throttle postion. Carb farts happen just off idle. Therfore shimming would not resolve the carb fart issue. In fact these are very difficult to eliminate completely thru jetting alone. I would refrain from jetting overly rich on the A/F mix and pilot just to eliminate carb farts.

Ignition timing was where I found the solution. Thats what Moco tried with a little sucsses. They would reflash the bikes as they came in for service with a slightly differnt map. I have zero carb farts using a TwinTec TC88 ignition module using turbotas modified map. More timing off idle.

[CaptEvo]

This is a post by Turbota that agrees with dodgenbullets. Here is a link to the whole thread.
http://xlforum.net/vbportal/forums/s...ad.php?t=39544



11th October 2006
Turbota
Line 'Em Up !


Join Date: Nov 2004
Location: Philippines
Posts: 4,195





Just my opinion, but you guys are trying to stop the carb farts by making the engine run pig-rich.

The big problem you have is not a fuel problem, but not enough timing right off idle.

For you 04-06 guys, shit-can that stock ignition module and buy a Daytona Twin Tech TC88A module. I will email you a reprogramed advance curve that will not only make the bike run stronger, idle better ... but will get rid of 95% of your off-idle carb farts.

Then stick those stock needles and jets back in your carb and get it running with the correct Air Fuel Ratio (AFR) it's supposed to have ... Although going up one size to a #45 on the pilot jet is a good idea.

Another suggestion would be to replace the stock CV carb with a Mikuni HSR42 carb. You will get much much better throttle response ... no, you won't reintroduce carb farts either. And you will have the best luck with the needle and jetting just as it comes out of the box .... no more messing around with the carb.

Ron,