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Which carb for a 7 mil on Alky


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I have a set of 38mm Mikuni carbs that i am not sure what they are and a set of keihin PJ carbs that measure 34.5mm. which would be the better set to run, i know the motto the bigger the bigger just curious i am new to alky, i just got the bike not long ago and it is supposed to be a 7mm stroker it had trinity out of frames and i have switched to CPI in frames and now it really bogs on the low end then picks up on the upper end. i believe that it is rich on the bottom end. It had the 38mm on it when i got it but i had the keihins i bought back in the day. the 38mm has 50 pilots and looks like 122 mains that have been drilled.

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I have a set of 38mm Mikuni carbs that i am not sure what they are and a set of keihin PJ carbs that measure 34.5mm. which would be the better set to run, i know the motto the bigger the bigger just curious i am new to alky, i just got the bike not long ago and it is supposed to be a 7mm stroker it had trinity out of frames and i have switched to CPI in frames and now it really bogs on the low end then picks up on the upper end. i believe that it is rich on the bottom end. It had the 38mm on it when i got it but i had the keihins i bought back in the day. the 38mm has 50 pilots and looks like 122 mains that have been drilled.

do the 38 mikunis say TM on the carb ? if so..there not good carbs to run on alky...if they dont say anything. then there TM's ... the TMX carbs say TM.....38s are what you wana use. id send em to a builder and have em setup

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do the 38 mikunis say TM on the carb ? if so..there not good carbs to run on alky...if they dont say anything. then there TM's ... the TMX carbs say TM.....38s are what you wana use. id send em to a builder and have em setup

Don't see anything on them anywhere except a v10 stamped in by the fuel inlet. So the must be tm's

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whats the CC is that engine?? and compression?? i have seen where the carbs are too big on a engine and it will loose horse power and be lazy. 34 Ki is a gooood carb man. I would go with the 34's myself. But once again is depends how big your engine is.

Edited by EvilBanshee
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I wish that I knew. He wasn't for sure I got it very cheap cause he needed some cash. It ran great till I swapped pipes over to the CPI's but the left carb seems to be dumping a ton of fuel in now for some reason. It has large pistons in it I will have to take the cool head back off and measure the bore. It has 150 psi on each cylinder the domes don't have a stamp in them so I am not sure what domes are in it.

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i thought all mikunis were stamped on the side of the engine side bore, or something. round would be like v38, tm would be t38, tmx would be t38x, or tx38, or just x.......can't remember. you could possibly get away with the 38's on that setup for hill shooting, but the 34's would definitely be the best choice for the ridding you have to do to get to backwoods hills, like in pa. with the 38's you would have to really train yourself on roll-on throttle, and partial throttle pulls more frequently to keep the venturri up enough. they do sound like they have been setup for alky before. i would check the domes while you are in there to make sure they can be run on alky. if you need to know the size, you can use a piece of Plexiglas with a hole cut in it. put a spark plug in the dome, and smear some Vaseline/grease around the edge to seal it a little. use a cc syringe to measure how much water it takes to fill. then you will have to subtract the deck height x piston area. I'm not 100% certain if the domes are measured minus the excursion of the piston, but at least you will have the measurements if you go to order new ones. my memory kinda sucks today, lol for the life of me i can't remember if you can't run gas on alky domes, or you can't run alky on gas domes, lol. maybe someone can step in and verify soon.

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