[flathead howie]

hey hope somebody can help me out.... so i am working on a friends evo big twin and he is running a keihin butterfly carb and shovelhead points.. it will start but run very shitty unless you have half choke. i finally talked him out of keeping the shitty keihin butterfly and got him a S&S super B i know it's not the best carb right now but it's better than what he's got now.. i am sure i have the points set up bang on and it is still running like a bag of shit... it is wicked lean as the pipes get hot almost instantly. if anybody can let me know anything that would be great. i'm leaning toward the carbcause the keihin air screw will not change when the screw is turned in or out... i am going to try the S&S tomorrow and see if that makes any difference.. the guy never ran any fuel filter on the bike and never did aany maintenance on it... just rode it and now it's becoming a pain in the ass trying to get it back to running condition... thanks for reading!!

 

[zedboy]

I went through this with a kick only Evo on points & Keihin. Fouling plugs one day, rich looking the next, & a bastard to start most of the time. Went through the carb, added a Dynojet kit to try & get it dialled in, new points & condenser, coil, etc. WTF?

Turned out to be the coil, & replacing one flakey coil with another didn't help much. They don't all seem to be created equal & you need a 5 ohm one for points, 3 ohm is for electronic.

 

[pan620]

If you can adjust the air screw with no change, look for a manifold leak.

 

[ralphiejantz]

check for intake leaks first
any other tuning is all for nothing if you have an intake leak

once you have determined you have no intake leaks give the super b a good thorough cleaning
and make sure the jets are clean and everyone is set to within spec
then do a nice baseline setting on it and as per the s&s instructions which can be found on a google search
and go from there
you migh need to possibly make a jet change or something after you get it on there but start with a solid base setting and a clean carb with no intake leaks and it will make it much easier to solve any problems

 

[flathead howie]

i have already checked for intake leaks and there are non... i replaced the intake compliance fittings and i hooked up an adapter to it and put 5 psi in it... no leaks after 5 minutes. what isn't the clearest is that i have not tried the S&S carb yet as i just picked it up... i am fairly confident this will fix the issue. my buddy also confessed that when his painter cleared the tank it was a rush and very poor job ... lots of clear had gotten into the fuel system. so what i'm thinkin is that something got into the idle mixture passage and blocked it up. leaving the idle very lean and needing to run half choke just to keep it running... basically i have heard nothing good about th keihin carb and am glad i talked him into the S&S wish me luck!! thanks guys i will also check the resistence of the coil that he has on it... hope it all works out!!