[Judeyramone]

So how do you replace them, anyway? The old one was shredded, so I just tore it off, but I can't figure out how to get the slide apart. Does it come apart, or do you just stretch the new diaphragm on? My manual is no help (it's a cb360 Clymer or Haynes manual, but the bikes use the same carbs). The only carbs I've rebuilt were Amals, and of course they're not cv carbs. One carb was okay, and I'm not pleased to have to replace this one. I've heard they're pricey.

 

[bfd]

Judeyramone
The rubber diaphragms aren't replaceable on those carbs. The top of the slide is rolled over the rubber and isn't removeable, without trashing it anyway. I tried.
bfd

 

[joe c]

but, they do sell the diaghram seperately. so theres gotta be something to that. i have never been able to figure it out either though.

jc

 

[krapfever]

If you can't find a decent used set, consider getting some 28mm Mikuni VM's from Sudco. Reliable, tunable and new.

Honda go sideways!

 

[joe c]

if hes racing it, some rule books dont allow aftermarket carbs.

sirius consolidated has them sometimes. i probably have about 8 (used) of them. if you need, drop me a note.

jc

 

[Judeyramone]

quote: if hes racing it, some rule books dont allow aftermarket carbs.

Racing? Haha! Not yet, but hanging around here is starting to give me some dangerous ideas. This is a street project I'm working on with my 5yr old son.
I love to put some new Mikunis on it, but they're not in the budget quite yet. Has nobody replaced a diaphragm? Like you said, they're available new, so one would assume...
Joe, are you talking about used carbs? Or diaphragms? I'm gonna need something, I just don't know what yet.

 

[joe c]

i have some used diaphrams.

(ok, lets fucking have it.....and no, they dont have holes in them)

ill check my stash tomorrow an see exactly what i got. i usually pull carbs apart and save that stuff. i know i have a coffee can with a bunch of them in there.

me

 

[snorkelfork]

hello everyone, this is my first post...

have you already purchased a new diaphragm? i know sirius consolidated recently began selling them and i am curious to know what material they are made from. from the photos they do not look to be of the same stuff as the OS. these look like rubber and if they are you may be able to coax them on over the hump with a little stretch.

...connoisseur of slack...

 

[bfd]

I'd sure be interested in what the part is. The slides I have have the top rolled the rubber, kind of like a big rivet. I have one that is unrolled and it sure doesn't look like it can done a second time without cracking it. Maybe there is a different version early or late?
bfd

 

[Judeyramone]

bfd, that is exactly what my slides look like. They came off a '68 or '69. Sirius has them - $85/pair buy it now, but that's a lot of $$$ to find out, after the fact, that they can't be replaced. Snork, I was thinking the same thing about the stretching. Maybe I'll e-mail them. I'm surprised with all the 350s here, that nobody's done it. Then again you are all Mikuni enthusiasts. I, on the other hand, am just trying to get a stock motor running. Since you all seem to have replaced your cv carbs, if anyone has a parts carb or two laying around they might wanna sell? Or just the slide w/a good diaphragm? Yes Rosko, your check is in the mail - I owed my friend George Budros some $$$, & he said WU it to him, he'll see that you get it... Damn, I really need to take care of that.

... And before anyone starts a rant, I did look this up in the search beforehand.

 

[Geeto67]

a cheap way to get mukuni VM carbs is to buy a used set off of kawasaki h1's. A little smaller than 28mm (26mm I think?) but they are there, easy to rebuild, easy to tune, and I think you can use the K0 cb750 4 into 1 cable to operate them on a inline 4 engine.

not that triple parts are cheap these days, but the later 73-76 H1s and KH500s are still inexpensive.

 

[bfd]

Judeyramone
I think most everyone here racing these bikes has to run stock carbs per the rules for that class. Quite often ebay has them for $20-30 for a set so it's worth the gamble.

I tried the liquid electrical tape repair before and that works if the cracks are very slight. The tape makes the slide less pliable so it doesn't move as freely but it allows you to save a slide that's not too bad
bfd

 

[snorkelfork]

$20 to $30 is what they were going for this time last year. as of late i have seen a number of usable pair going for well over a hundred.

i just checked the prices at sirius for a pair of diaphragms and it is $45 not $80

...connoisseur of slack...

 

[joe c]

finding a decent set of those cv carbs cheap on ebay is nearly impossible now. we have our eyes open for them alot of the time now.

whods thought eh?

jc

 

[snorkelfork]

jude i just noticed you said yours are off of a 68' or 69'. it is my understanding that those carbs had issues with air flow that caused damage to the phragms. in 70' they made minor adjustments to the venturi to correct the issue. the later carbs have 3D stamped somewhere on the body.

it's been a year since i gave this any thought so before you believe me or anyone flames me. you/they should look into it...


...connoisseur of slack...

 

[Judeyramone]

I'm looking on eBay. Ironic, since I have 3 motors w/o carbs. Bought the parts bike these came from specifically for the carbs.

 

[smurph74]

Digging up this old topic to find out if anyone has replace their diaphragms yet with the Sirius ones. I just got a set from them and have been searching all over to find a write up on it. I bid on several sets of used carbs on ebay and they went for well over $100. Thanks Stephen

 

[snorkelfork]

have you asked sirius what the process is? i know it involves cutting the lip off the top of the slide to put the new one on but i don't recall what holds it on.

 

[smurph74]

No I have not asked Sirius yet. I have read that diaphragm tears can be common and everyone recommends Sirius or purchasing used carbs and crossing your fingers. So I thought people have already done this procedure and was curious how they did it and if they had any tips. Or if there was any outcome from this post.

 

[fortenfury]

I just bought a set from jbmindustries.com. I've replaced the old ones and the new ones fit great. Haven't gotten them back on the bike yet but when I get everything up and running I'll post pics and details.

I thought rebuilding the carbs was doable with just the manual and a clymers but I was wrong. I'm so lost