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Discussion Starter #1
didn't want this to be my first post but i'm at my whits end with the fueling on my '85 cmx250. i bought it a couple weeks ago not able to idle but it it was running good enough to make it home . right after i got it home i rebuilt the carb and replaced the fuel filter, air filter, and spark plugs. now it'll idle and run through the rev range in neutral, bun once i try to ride it in gear i can get to maybe a eighth to quarter throttle and it'll die almost like it's not getting enough fuel. i didn't replace thee diaphragm but it doesn't have any rips in it and seems OK. if anyone can help me figure this out id be very grateful rebuilt a bunch of car and truck carbs but this is my first motorcycle carb that i've encountered
 

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Welcome to the forum. How did you clean the carb, spray, soak or ultrasonic cleaner? Often the diaphragm shrinks, gets a little stiff, and it's hard to get the lip in the groove. If it isn't sealing well, that might be the problem. Soaking it in oil of wintergreen or brake fluid should soften and expand it.
 

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Welcome to the forum. How did you clean the carb, spray, soak or ultrasonic cleaner? Often the diaphragm shrinks, gets a little stiff, and it's hard to get the lip in the groove. If it isn't sealing well, that might be the problem. Soaking it in oil of wintergreen or brake fluid should soften and expand it.
i used spray because that's all i had availible to me i think my daifeagms ok it went in the groove fine and when i push it up it returns slowly not quick like theres no vacuum. i think im gonna double check all my oem jets and put them back in to see what happens
 

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Spraying a carb is the least effective way to clean it. If you have access to an ultrasonic cleaner, they do a quick, thorough job. Second best is to soak only the metal parts in Berryman Chem Dip for a minimum of 48 hours, and longer may avoid the need to pull and soak the carb again.
 

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Discussion Starter #5
i wanna get a ultrasonic cleaner because of how handy they are i took everything apart and apparently come crud got passed my filter and clogged the holes in the needle holder so i cleaned that up and put everything back together but apparently my air screw had a crack in it and broke when i was trying to adjust it closed so i tried everything to get it out and then screw extractor broke off a piece from the sir screw threads on the carb so now im trying to figure that out lol
 

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Discussion Starter #7
yea lol now i gotto source a new carb center section found a guy near me with a spare carb but he'd only sell it if i bought 2 engine cores with it
 

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You should have told him you need three engine cores!! You definitely have a fuel management problem but I think you are on to it. I bought a new jet for a Honda single and it had some machining debris in side, could not remove it so I replaced it with another new one worked good after that.
 

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beebe101 - Seems to me, you know a great deal about carbs and are going down the right path. If you can afford to purchase a new one, I recommend that. I've got an AFR gauge on my bike. And I can solidly say that the OEM carb is a more than adequate carb for the 250. It can fuel more than the bike can take, but when tuned properly (and Honda did), it can run the bike nicely lean while cruising to help it turn in some impressive mpg numbers. And at WOT it runs a very safe rich AFR. So rich, I've downsized to the next smaller main jet. And even though I am running a more ideal AFR at WOT for maximum power, it doesn't seem to have made a power improvement (but I'm still researching).

Anyway, you seem to know what you're doing. Hoping you get it fully up and running ASAP.
 

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Discussion Starter #10
i kinda told the guy i aint buyin his scrap cause he was bein a jerk so that bridge is burned dont got room for that much stuff in the first place lol XD. im definitely gonna see about upgrading the carb im just trying to get it running with what i got , so to fix it i jb welded on a nut and spacer to replace that threaded part and it works just like it should but im having problems getting it running but that could be a even newer problem lol , got it to run on the acceleration pump where i could keep it running by flicking the throttle, and i blocked the intake partally to act like a choke and it puked out a bunch of fuel lol so im gonna ipen the carb back up and go through all the jets
 

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Discussion Starter #11
took my carb out and i realized that i forgot to put in the vacuum diaphragm spring... that might have caused the fuel spitting issue lol
 
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