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Discussion Starter · #1 ·
Hello! I'm a Noob to posting on this forum; thank you for all the advice I've taken from previous posts!

I have a 1982 KL250A5 that has a severe hesitation when the throttle is applied. I've cleaned the carb (everything is clear), the boot appears to be tight, and I think that the problem is tied to a shot diaphram on the carb. I've seen a previous post on a short-term fix, but I'm looking for a long-term fix. Does anyone know where to find a replacement diaphram or what carb can be used as a replacement on this bike?

Thanks in advance for your help!
 

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GHOSTRIDER
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3,361 Posts
Any fix is short term,anything after that is borrowed time. Ive used RTV silicon and latex glove material to patch diaframs and it worked quite well. Some guys are using Gorilla glue and nitrile glove material to make the same patches to diaframs. You can hold the existing diafram up to bright light and see any cracks or holes in the rubber. Any money spent on a used carb is a gamble because they may very well have a bad diafram as well. Make your patch small and on the top/cover side of the diafram and start saving the money to go ahead and replace the diafram with the new $175 dollar replacement. Do not run gasoline with 10% ethanol as it will break down and harden rubber diaframs over time.
 

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276 Posts
These CV diaphragm carbs are nice instruments when new, but for those who like to run decades old machines, they are an expensive nusiance. Some of the very early Honda CV carbs didn't have a diaphragm, but just a very close fitting piston. They were all metal, a bit heavy for snappy throttle response, and expensive to manufacture.

I like the nitrile glove fix, and will use that on my next occaision. Good tip.
 

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I ran these "diaphragmless" carbs for two years on one of my old Hondas, and all was well. What was the source of the irritation? Did dirt sieze the pistons or did they wear and not work right?
 

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elr658: Help me out a bit. a "bane of existance" is a thing or person causing irritation in life. But you've got a set of these carbs that have run for 165000miles? I can't tell whether you think these "diaphragmless" CV carbs are good or bad. Elaborate if you have a moment. Thanks.
 

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Eddie Lawson is God!
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Very bad. Very very bad. I hate them. Few are better versed in four stroke tuning OR are more diligent than I, but I lost patience with these carbs MANY years ago. The adapter sleeves to run VM29s are made of unobtanium or one of my MANY sets of VM29s (Or anything else Mikuni that's a VM and fits a GS 750-1000 or KZ650-1000) would be on this bike.
 

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Eddie Lawson is God!
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VM 33s are spaced to fit different bikes by Mikuni. An A1 fits Zooks and Kaw 650-1100 So Kaw carbs WON'T a Honda. VM33A4s fit 1100Fs.

VM29s fit Suz and Kaw 650-1100s. If you want them to fit a DOHC honda, you need Manifold Adapters. Evidently, they are more rare than the holy grail.

I had one in my hand, and a stack of $100s. AND a friendly machine shop. He STILL wouldn't go for it.
 
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