Cracks in diaphragm rim

[nbriles2000]

So I'm pulling my carbs apart, cleaning em and rejetting them for the first time. It doesn't look as bad as i assumed it would, but I noticed some small cracks along the edge of one of the diaphragms. I tested it by putting a finger firmly over the oval hole on the front of the carb and it indeed leaks a little bit. Is there a good way to repair the cracks or a place where I can buy replacement ones? I dont want to buy a new slide assembly because they're damn expensive! Also, my carb boots are a little cracked up, is there a good way to seal those off?

 

[vectra]

diaphragms and carb boots can be found on ebay around $30 for a pair

 

[bcware]

I've heard of people using things like Shoe Goo on the diaphragms, but for reliability I'd replace both with new. Where one crack forms others are soon to follow.

My friend had a diaphragm fail on his old honda; a few hundred miles later the other one ripped.

 

[domains]

If you can't find any you can try this... http://jbmindustries.com/Yamaha650.html

I had to place alittle crazy glue because they turned but better than 200$ the dealer wanted for 1.

Ebay had none for my model at time

Mine was a 82-83 BS34CV 73 mm OD of Diaphragm , but need to check to be sure.

 

[drewpy]

NRP do them. based near me in the UK

 

[xschris]

Mikesxs has them for $90

 

[nbriles2000]

Paying $90 is exactly what I'm trying to avoid lol
I'm going to try jbm and see if I can figure out which size I need. I'm a little wary because I dont see the xs360 or even 400 anywhere on any of their lists and I'm not sure which diaphragm I need

 

[domains]

You have to check how wide your diaphragms are...

Or look on carbs for model... models are

BS38CV 77 mm OD of Diaphragm
BS36CV 73 or 77 mm OD of Diaphragm
BS34CV 73 mm OD of Diaphragm
BS34SS 70 mm OD of Diaphragm

my 82 was 73mm but my 82 could have 81 carbs example check to be sure

 

[yanialia]

So, if my diaphragm is 73 mm, how do I know if it's a 36 or 34?

 

[frwinks]

good info here:
http://jbmindustries.com/

 

[kevingkruse]

I bought some diaphragms from jbm, fits nicely, very cheap and good quality. Although after about 2 months of using them, my carbs started acting funny so I opened them up and noticed one of the diaphragms had a pinhole in it. I don't know if I just got a bad one but I told them and they sent me a new one for free. But for $14 a diaphragm, its a good deal.

 

[sly409]

Does anyone know what the main differences are between bs34cv and bs34ss? I have a 79 xs400 and I just thought it was bs34. I read that there are 2 versions. Is this what they are referring to when they state bs34ss vs bs34cv? Trying to figure out the right size diaphragm before I order from that JBM site.

 

[xschris]

The 77-79 uses the smaller slides so 70mm is what you want

 

[sly409]

Thanks chris!

 

[sly409]

Hey you know what, I used a cheap plastic rule to measure the diaphragm dimensions on the carb body and it came out to 73mm. Is it possible that I have a different model carb that would be causing this?

 

[xschris]

I measured a 77-79 and a 80-82 and get 73mm on the top of the seat. The size of the slide are where the size difference is. I have never ordered the jbm ones before so how they get 70 and 73mm If the carbs you have are the style with the idle mix screws exposed and aluminum tops then they are the stock 77-79 models. Carb on right is the 77-79 and a pic of the 77-79 slide in a 80-82 body you can see that it is very loose. About a 2mm gap. The slide on the 77-79 is 28mm and the slide on the 80-82 is 30mm.

 

[markjs]

I actually got a KZ750 running nice with cracked diaphragms; I used grey RTV gasket seal. Worked great, did it super thin and very carefully.