Carb intake manifolds. Recommendations?

[Garrett411]

Hey Ya'll


I'm looking to get some new intake boots (manifolds) for my '79 with stock 38 carbs. The stock originals that came on the bike worked fine for most of the summer but into the fall they began to get more cracked and the bike started pulling vacuum in the right side causing some pretty bad popping. I bought some chincy ones at the time hoping for a quick fix and they turned out to be even worse. When tightened onto the head they bowed like the bolt holes were to far apart. Anyways those turned to dogsh*t broken fingers so i'm not sure what to do. Any ideas on some decent new boots that will fit my stock 38's? Or a way to engineer the originals so that it's rideable?

Thanks everyone.
Garrett

 

[retiredgentleman]

Hey Ya'll


I'm looking to get some new intake boots (manifolds) for my '79 with stock 38 carbs. The stock originals that came on the bike worked fine for most of the summer but into the fall they began to get more cracked and the bike started pulling vacuum in the right side causing some pretty bad popping. I bought some chincy ones at the time hoping for a quick fix and they turned out to be even worse. When tightened onto the head they bowed like the bolt holes were to far apart. Anyways those turned to dogsh*t broken fingers so i'm not sure what to do. Any ideas on some decent new boots that will fit my stock 38's? Or a way to engineer the originals so that it's rideable?

Thanks everyone.
Garrett

Are you sure you have air leakage from the carb manifolds? The first few years I had my bike, I had air leakage. I suspected the manifolds, but it turned out to be the throttle shaft seals, and the sync. access screws on the carb bodies. I'm still using the original stock manifolds, because they fit very well, and allow no air leakage.

I tried the manifolds from Mikesxs.com once, and they fit so badly, causing lots of air leakage, that I quickly removed them and went back to the original manifolds.

 

[grizld1]

To answer the question asked, you can buy quality mounts from 650 Central or JBM Industries. Neither source offers mounts with vacuum barbs however; you'd need to run with your petcocks on "Prime," convert them to manual operation, or replace them.

 

[CDNTX650]

I have a pair of tour max ones on my bike now and seem to be of Oem quality. They were older stock though. So newer ones may be more of a gamble?

 

[grizld1]

Right you are! Those boots are made in Japan, and they're still OE quality. "Tour Max" is K&L's distributor label.

 

[CDNTX650]

Very pleased with the quality. The only reason I switched from my jbm ones is one of the barbs came out and I like syncing by guage . I don't use the metal shrouds however. So I made an l bracket from a breather bolt to the carbs an used rubber washers on it so it has a bit of cush.

 

[ThatXS650Guy]

I just replaced mine with the ones from MikeXS. They were TourMax brand without the barbs. I like having a vacuum petcock so a 3/16" drill bit took care of that.
http://www.mikesxs.net/parts/yamaha-xs650-carb-holder-set-2-bs-38-1974-77-oem-447-13565-01-447-13555-01

 

[kevski]

I got a set the same as mikes sells for my 79 without barbs, i just made barbs and installed them no problems, if you bend the intake boots tightening them to the head you are over tightening them, always use new gaskets as well on these, also if you over tighten the barbs you will crack the new boots so best to use a little plumbers tape as in the photo and a bit of high temp gasket glue on the lower part of the thread, you could also use the old barbs by carefully removing from old boots and cutting a 5mm thread up them, and a 5mm thread in the boots.

 

[Garrett411]

wow! thanks for all of the replies guys! I just got a set and am going to be finishing putting the head back on my bike this weekend! Got the head lathed nice and valves lapped. Excited to get this cranky old girl back together to get some miles back under it! Any more suggestions are much appreciated!