xj 750 carbs

i have an 83 xj 750. i cant get it to run unless the choke is on all the way. if i give it throttle, it dies. i cant seem to find a good running set of carbs, are there other carbs that will work? or do i just keep fiddling with these?

 

sounds like your main jets are clogged. how long was it sitting before it last ran well?

 

a long time. the carbs are off another type of bike, im not sure what though. its a long story. ill give the main jets a cleaning and see what happens. thanks!!

 

It's unlikely you will "find" a running set of carbs - carbs on a 30 y/o motorcycle must be cleaned and the rubber bits must be replaced. And not just ANY carbs work. What was wrong with the carbs that came with the bike?

You CAN rebuild and clean the carbs so thoroughly that the bike runs like new. Search for "Whole 9 Yards" carb cleaning thread by RickCoMatic - it's involved but only YOU can do it right.

 

its a long story about the original carb. i literally just went through and did a quick cleaning on what i have. it runs now, just crappy. one float is stuck for sure, so i need to go back in. thanks for all your info and help.

 

on these mystery carbs, the smaller jet by the main jet have rubber caps in them. all other multi carbs i hace worked with have not that these. can anyone tell me why they might be there?

 

i dunno about the caps - but from your description of what the bike does, it sounds to me like your pilot jets are clogged, not your main jets.

 

i blasted every orifice out with cleaner and air. in the morning im going to take then apart and remove the rubber plugs, hey seem to be defeting the purpose of a jet. hopefully this will hake headway. ill keep everyone interested posted

 

since you haven't put the carbs back on yet - i'd recommend at least removing the all the jets and soaking in carb cleaner. while they're soaking, you'll have time to take the top end apart and polish the slide bores. and since you've got that much apart, you might as well pull out your emulsion tubes and make sure those are clean.

if you're really feeling bold, you can remove your idle mixture screws and make sure they're all clean and you have all the right parts assembled in the right order.

since it runs with choke, you can probly leave the enrichment plungers alone - course, that's all easier to clean with the carbs off the bike . . .

someone might chime in about verifying float height, too.

i sure would hate for you have to pull those carbs off again (and again, and again . . .)

 

Sounds like you have a set of Mikuni carbs, possibly off a GSX750, the rubber plugs cover the pilot jets.
Leave them out and you will never start it.

A few pics?

Float height on Mikuni cv's is about 21mm from where the gasket sits on the body to the straight bit on the underside of the float

 

they are mikunis. luckily this is a bobber and pulling them off and putting back is real easy. and i have extra bowl gaskets. im a muscle car guy and can rebuild bench tune and set up dual holleys in my sleep (done it...lol). motorcycle carbs drive me batty. i really thought about a custom manifold and something with an accelerator pump.

 

ok, ive come to the conclusion these carbs are junk. ive wasted too much time on them. im gonna have to break down and get some. thanks to all who gave advice