Carb holder gasket/sealant to cylinder head?

The carb holders on my 1977 KZ650-C1 were leaking even though they looked perfect when mounted on the engine; this cause a very rough idle. When I removed them I found microscopic cracks in the rubber on the mounting surfaces where the carb holders contact the cylinder head. I replaced them with new carb holders using no sealant, and they still work perfectly with zero leaks. They have been perfectly fine since installing them 15 years ago. See if the ones in the link below fit your model bike. If so I HIGHLY recommend you buy them and replace your old carb holders. If they don't match your bike's model you still may be able to find a new set for your bike. If you are able to get a new set you do not need to use any sealant because when Kawasaki built these bikes they used no sealant. Ed

www.diablocycle.com/Kawasaki-KZ650-KZ750...buretor-Holders.html

650ed wrote: See if the ones in the link below fit your model bike. If so I HIGHLY recommend you buy them and replace your old carb holders. If they don't match your bike's model you still may be able to find a new set for your bike.

I appreciate you looking them up but I've been looking for new ones for almost three years now. These are specific to the M1 model 750 twins and are unobtanium so far. One guy on another forum in Germany (I think) actually went to the trouble of making a mold so he could make new ones. It's usually one of the first things I replace on older bikes when I get them (My Yamaha XJ ones were $100 each!) but no go on these. I will be taking measurements to see if I can start looking by size.

650ed wrote: It looks like good stuff. Their website says it never sets. That's good, but does it become firm enough that it won't be drawn by the intake vacuum through the carb holder cracks into the engine? Thanks, Ed

You actually stated this last year, I'm thinking this may be what happened. When I first applied this sealant, you could see the carbs moving back and forth a little bit from the vacuum in the boots when cranking over and I could not detect any leaks. Now the the carbs don;t do the "dance" anymore and leaks are very evident all around the joint to the cylinder head.

While some folks on here have had ok luck with patching this is one area that might be better to bite the bullet and go new........ I was never sorry anyway.

jayrodoh wrote: I appreciate you looking them up but I've been looking for new ones for almost three years now. These are specific to the M1 model 750 twins and are unobtanium so far. ....

My mistake. I didn't remember that the M1 is a twin. Ed

This might help
jetsrus.com/mounting_flanges/mounting_flanges.html#mikunirubber

Need to say, you have sand/grid wet down the squeezed parts of the rubber intake on a flat glas welding mask insert with a 400 grit to get a straight surface.
No leaks at all until now, outer boot rubber is not brittle until now.

Scirocco wrote: Need to say, you have sand/grid wet down the squeezed parts of the rubber intake on a flat glas welding mask insert with a 400 grit to get a straight surface.

I think you are asking if I have wet sanded these lightly on a flat piece of glass? No I have not, I was hesitant to do so earlier as these are the only two I have and was thinking the sealant would hold up.

Scirocco wrote: No leaks at all until now, outer boot rubber is not brittle until now.

Not sure, I never rode the bike when I bought it. Has been a back burner project but I'm motivated to get it going. May have been leaky when I got it but the bike was complete and mostly original which was more important at the time.

SWest wrote: This might help
jetsrus.com/mounting_flanges/mounting_flanges.html#mikunirubber

Oh man, thats awesome. Hoping to get out there tonight and get them removed. Thanks!

Did you find the ones you need? If you have any questions Mike is a pretty good guy.
Steve

SWest wrote: Did you find the ones you need? If you have any questions Mike is a pretty good guy.
Steve

Sorry for delayed response! Nothing on that page that was an exact match. I'm going to document the measurements along with some pics and fire a few emails off. I have some Yamaha parts vendors that I've worked with that are willing to dig through some bins to try and match up so I'm hoping to figure something out. Google search has allowed me to find quite a fre sites that list them by size too.

Another place to look.
jbmindustries.com/