carb vacuum diaphram question

[remat457]

First, I wanted to say hello! I just inherited an 86 450LTD (non-running) a couple of days ago. I am glad to find this forum, as I hope to get it up and running.

Second, apologies if this has been answered-I used search but couldn't find anything applicable. My search terms could be off though.

Ok, the question...I pulled the carb needles out to take a look and noticed that one of piston diaphrams looks really warped/distorted/too big. The Haynes book says that it needs to fit into the groove. It looks like someone couldn't and bolted the top cover down on it.

Is there a trick to getting it to fit? (one went on perfectly) or do I need to replace it? It looks the whole assy is about $120

thanks!

[eaglerider]

Be cheaper to find a good used set of carbs on ebay, or from a member here that might happen to have an extra pair. And I moved the thread, as u can see.

[remat457]

Hello,
Thank you for the reply (and moving the thread).

Do you think that I could find an entire replacement set of carbs around for less than that? If so, I am not going to continue and take it apart to clean, and will start looking instead.

Much thanks!

[rustbuckett]

I'm new here, and definitely no expert on these machines (or on any subject!).

But I'm a limited-income cheapskate, and I try my darnedest to make my on-hand things work before I spend a nickel buying a replacement part.

Do you have any close-up photos you could post, of both of the diaphrams and their pistons? That might help the more experienced guys here give their opinion on whether or not tthe wrinkled diaphram is any good still or might be a wrong fit.

A couple things I do to rubber carb diaphrams is first, very gently clean them. Kitchen sink, warm gently running water, liquid dish soap, and only my fingers (no toothbrushes or whatever). Get them gently and completely clean and rinsed and dry.

then i inspect them really closely to see if they're torn or have pinholes or nicks on the edges etc.

If all looks good, I lightly coat my dry fingers with WD-40 and gently rub it into the rubber, just to make it more pliable and so it doesn't pick up every speck of lint.

then I use a hair blower/dryer and warm the rubber up. Seems to take out most of the folds, creases, etc.

Then I really gently and carefully try to place it back into the carb, using my fingers and fingernails to tuck the outer edge lip into the grooves machined into the top seat. Sometimes is tricky because just as I almost get it finished, I'll notice one area on the opposite side has popped back out of the groove and I have to start again. Patience, persistence....

Usually that gets it to fit in and even though it looks a little wrinkly, as long as the outer lip of the diaphram seems to fit correctly into the grooves, they seem to work ok.

Yours might be too stretched/worn to work though.

Good luck.

[eaglerider]

You are thinking down the right road, Rustbucket. Remat, check ebay for the carbs, or one of the members might have a set they will let go.

[Jet⚡Black]

I would beware of used diaphragms they might have pin holes or in worse shape than you already have same can be said for used carburetors.

I personally would just buy a new diaphragm for both carburetors...both because I like symmetry There's people that sell them like: jbmindustries.com/Keihin_diaphragm.html I chose that place for you to look at because they have a tutorial on how to replace the diaphragm and fix some other carburetor woes like bend caps etc.

[eaglerider]

Thanks, Jet, hopefully, they will have the ones for our carbs, and that is a very decent price they are showing.

[Jet⚡Black]

No worries, I forgot about fit...the groove diameter on ours is 67mm if anyone needs it.

[jp]

mine were wrinkly looking and hard to reinstall but work just fine

[remat457]

I really appreciate all of the help and direction!

Per Rustbucket, I snapped a few pics and posted them here: reg7tools.fortreg.com/?p=1373

If anyone has a moment, I would appreciate your thoughts. Also, probably a stupid question but in the pic there is a yellow tube which goes to the center of the carb. Where does the other end go? I had assumed it was a vent tube that attached to the bottom of the tank (so says the Haynes manual) but I see no attachments on my tank.

Jetblack, thank you for the link which has excellent directions! For $20 I am inclined to go that route!

Thanks again!

[eaglerider]

Remat....that yellow tube connected to the "T" between the two carbs is a overflow/vent. It should be routed sorta upward, and back, down towards the lower part of the frame.

[remat457]

Thanks EagleRider! Seems weird that it doesn't attach anywhere, but I am ok with that

So, the consensus on the diaphram is that I should replace it?

Thanks!

[eaglerider]

if it is damaged, I would....both of them, as Jet said.

[remat457]

Sounds like a plan. I will order them next week, unless anyone here has a carb that they would be willing to sell.

[Jet⚡Black]

While they are on order , you could try some RTV sealant in the meantime for some riding...its by no means a perm fix though.

[remat457]

Ok, slight update. I contacted JBM and they do not make a diaphragm that will work on the CV34

QQ: The diaphram only effects idle under throttle correct?

[remat457]

Well, I found one on EBAY that looked like it was in good shape. I would have bought both, but I apparently missed the other one. I know the caveats mentioned above, but I if it doesn't work I will fork out the $200 for new ones and have an inexpensive spare.

[eaglerider]

Where are those $200.00 ones at?? If from a source other than Kawasaki, I would check with a Kawasaki dealer ....Vulcan or Ninja 500 should be the same.

[remat457]

Oh sorry, that was for a pair....actually I think it was $120/each from my local Kawasaki dealer. Good to know that the Vulcan and Ninja 500's should be the same. I will keep looking on Ebay

[Jet⚡Black]

The Mojave 250 ATV, and KLR 250 carburetor diaphragm is the same too, they just run one carburetor though. I am not sure why JBM said they didn't have one to fit; other than their buy and try policy that they can't make fitment guarantees.

The EX500 Ninja and the CVK 40 carburetor use the same diaphragm as our CVK 34 and the CVK 36 does; and JBM carries those; I would bet my life that their 67MM square grooved diaphragm will work. The only difference in all the CVK branded carburetors from the mid 80's to early 90's are the out side fuel tap fitments, bowl gasket and jet sizes, the difference in the slides if any is the drilling for the vacuum hole in the slide, not the diaphragm itself.

I'll place an order for some and give everyone a definitive answer, on the ones JBM supplies; there's no sense for members having to pay 100 bucks per carburetor, just because of some gimped up rubber that costs less than a dollar to make.

P.S. always wait until your bike is over night cold before opening the diaphragm cover to make any changes, they swell up and stretch when hot or warm, and will not fit like they are supposed to; trying to re-install them without waiting for them to shrink is why they get pinched etc.

Sorry for a late reply, I took the little lady on vacation for a few days.

[thalu10272]

OK , i found a company that makes JUST the diaphram replacement ! a big $75. for 2 . yes that's right . just to bad i already ordered oem replacements. here is the website www.motorradbay.de/index.php i hope i helps EVERYONE.

[remat457]

Thanks Jetblack and Thalu! I am very interested in how both of these options work out.

I was able to get one from EBay for $40 (shipped) and it looks pretty good, but if new options are available that would definitely be better.

I am embarking on cleaning/rebuilding my carbs this weekend. Have the first one soaking right now.

[Jet⚡Black]

If you separate the carburetors from each other, by removing the bracket...you are either going to have to bench sync the carbs or get a carburetor synchronizer or make one.

My preference is bench synchronizing, it's faster and easy to do.

[remat457]

I was worried about that so I did not separate them. I still want to do them one by one though, so only half of the assembly was soaked. Timewise it is better too since I only got to one today and will do the next one (hopefully) next week.

Thanks for the tip though!

[Blaine]

Jun 10, 2012 23:25:42 GMT -6 remat457 said:

I was worried about that so I did not separate them. I still want to do them one by one though, so only half of the assembly was soaked. Timewise it is better too since I only got to one today and will do the next one (hopefully) next week.

Thanks for the tip though!

It also saves worrying about replacing the o-rings in the fuel & vent tubes between the carbs.

[joenson]

Hi.

Did anyone actually change the diaphragm on their slides.? And will the cvk36 diaphragm fit our slides.?
I'm considering a change, as one of mine has kind of grown bigger and won't fit in the groove.? How is that possible.?? I've been VERY patient, trying to make it fit. It hasn't been a problem earlier as I have been trying different setups for my needles when I shifted to pod filters, but this time it somehow seems way too big.
So, I was wondering if it is an easy installation to put on new diaphragms. I don't really feel like buying complete new slides..

[joenson]

Well... I guess not.

Just got to try it then..

[Blaine]

May 22, 2015 1:53:39 GMT -6 joenson said:

Well... I guess not.

Just got to try it then..

You can try putting them in the freezer for a bit to shrink them.

[joenson]

Does that work ?

Somehow I hope not, as I just ordered a set of new diaphragms. But I think I'll try it out while I'm waiting for the new ones to arrive.



Thanks for the respond, Blaine

[rardar]

Has anyone actually bought those 20$ diaphragms? Just picked up a 454 for dirt cheap that's been "looked at" before and am going through the motions of fixing every darn thing wrong with it.