whoppes27 Posted September 10, 2012 Report Share Posted September 10, 2012 Hey guys, just bought a new bike and had it delivered from Montana. It's a alky 421 cub that's drag ported by rdz running oof rdz pipes. It has 38mm mikuni flat slide carbs on it. His elevation was 3300ft but also rode at st anthonys which is around 5000ft. Here in MI my elevation is 600-800ft. He said it was tuned pretty fat but I'm just looking for some opinions on these carbs and typical jetting for this elevation. It currently has 50 pilots and .115 mains. I haven't checked the needles yet. It is also running a pump if that makes any difference. Here's some pics of the bike and carbs. Any help is appreciated. I'd like to get this ready to run at the track this weekend. Quote Link to comment Share on other sites More sharing options...
whoppes27 Posted September 10, 2012 Author Report Share Posted September 10, 2012 I agree I think .115 will be way too small. Any reason the dump was recommended to be larger then the main? And how about your pilot? I fired it up yesterday for the first time and it was spitting a little raw fuel at idle and just off idle. This is my first alky bike so I'm new to this. Quote Link to comment Share on other sites More sharing options...
whoppes27 Posted September 11, 2012 Author Report Share Posted September 11, 2012 Thanks special, I was just curious why a lot of people go bigger on the dump vs just drilling them the same size. Little update: it has 6FJ47 needles maxed out and non adjustable power jets. The power jet has caps you take off and replace a jet which it currently has .093 in it. Anyone else? Quote Link to comment Share on other sites More sharing options...
whoppes27 Posted September 11, 2012 Author Report Share Posted September 11, 2012 Found the dumps are also .115. I made a few short launches with it and it seem to run great so I might buy some new plugs and check it where it's at. Here's a vid of it, how's it sound? Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted September 12, 2012 Report Share Posted September 12, 2012 i dont know anything about those carbs my only advise is chop it with what its got and adjust from there ,there is alot of advice on here to show you what a proper burn is an alky plug Quote Link to comment Share on other sites More sharing options...
camatv Posted September 12, 2012 Report Share Posted September 12, 2012 dont need to do plug chops on alky to see the jetting or heat affect's those have fixed powerjets in them. i'd highly suggest getting a adjustable pj put in you may not find a lean out spot til its too late and you have damaged the top end. if it ever just falls flat out or "shuts off" its wayyy to lean. put in new plugs and watch your burn rings.. i'd also suggest going to a 125 dump and main and clean it up with smaller slow jets and adjustable powerjet. you need to get it too rich then work your way back down.. if you can get the carbs so rich it wont hardly run you at least know you are safe to tune it DOWN its much easier to go rich to lean instead of lean to rich.. Quote Link to comment Share on other sites More sharing options...
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