650ed question

www.kzrider.com/media/kunena/attachments...00002_2013-09-08.jpg
Interesting..........I have never seen the carb vents sunk into the airfilter well. Am I missing something?

That's how mine was set up when I bought it new. The air filter baffle is shaped to hold the vent lines in place (see pic below), so I guess the vent lines were intended to be routed that way. It's been that way since day one and never caused any problems. I guess any gasoline fumes from the carb bowls are just drawn into the cylinders and burned. Ed

Where are the vents routed on your bike?

On my '78 C2, the left vent has a metal bracket to the frame next to the airbox to hold the vent tube.
Right side I zip tied like left.

Apparently, that bracket became standard equipment sometime after Sept. 30, 1977. Below is a pic from my 9/30/77 Kawasaki KZ650-C Series Parts Catalog which covers KZ650-C1 and C2 bikes up to that date. Notice the clamp is not shown. My 1977 Kawasaki KZ650-C1 Exclusive Parts List booklet and June 25, 1976 Kawasaki KZ650-B1 Parts Catalog show the same diagram with no clamp. However, at Kawasaki.com the later diagrams, such as the KZ650-F1, show the clamp (see part labeled #1 second pic below). The diagrams don't say when the clamp was put into production, but obviously it was in production prior to the F1 since RSTNICK's C2 came with one. I find it odd they only provided 1 clamp for 2 vent lines, but that's what the later diagrams show and that's how RSTNICK's bike came equipped.


RSTNICK - By the way, according to Kawasaki.com that clamp's part number is still an "Active" part, so if you wish to add a second one for the other side it is still available. Ed

It's just I would imagine that routing the vents that way would add a physical draw to the vents. I would imagine that could reduce gas mileage or at worse cause a lean/rich condition. Then again it may have no effect except burning the fumes. I'm just imagining here. I have never seen it before, but I am mostly familiar with 77 B1's. I do seem to remember a kz550 with vent tube holders molded right into the top of the airbox but they did not lead into the filter well.

The routing of the lines has never caused a rich or lean condition, but the fact that no one else seems to have seen this vent routing before made me very curious. SO, as usual, I went to the Kawasaki KZ650-B1/C1 Service Manual and looked through all the pictures. What I found is interesting. Although there is no writeup on how the vent lines should be routed, it appears that the vent lines on the KZ650-B1 bike in the manual are routed above the airbox (see first pic below) and then run to the left and right side of the airbox cap and terminate toward the rear of the bike (see 2nd & 3rd pic below). So I can only assume that dropping the vent lines into the airbox on my bike was done either at the factory in Japan when the bike was built, perhaps by a worker who didn't know where to run them; or it was done by someone at the dealership where I bought the bike when they were un-crating it. In either case it seems to work quite well as my bike has always run fine.

The later Kawasaki Service Manual, which covers the 1978-1980 KZ650 models, is very specific about the routing the vent lines between the airbox and frame (see 4th pic below), but it only says to clamp the left tube to the frame as RSTNICK's photo shows and it ignores how to terminate the right side vent.
Ed

KZ900 routing of the two hoses from carb float bowl vent nipples:







Purpose of the venting is to eliminate vacuum inside the float bowls by admitting outside atmospheric pressure into the float bowls.

Am thinking this vacuum relief would be better achieved without any vacuum being supplied at the hoses' exit ends via draw from the air box.

Good Fortune!

It doesn't make any difference how they are routed as long as they are not plugged.

I must have owned 15 to 20 Kawasaki and Suzuki 4 cylinder motorcycles in my lifetime. One of the first things I did was remove the carb vent lines along with the carb overflow lines. I never had any type of carb jetting or running problems.

On my first set of 29mm Smoothbores, I put the 4 overflow tubes into the catch tank as the rules stated for road racing. Those carbs had major running problems. Chased that problem the whole weekend. Ripped the hoses off the carbs, guess what. NO more running problems. Ever since then (1977) I have never ran vent lines, nor overflow tubes on any of my carbs. That includes, stock carbs, 29mm Smoothbores, Keihin CR31's, CR33's, FCR39's, and 36mm RS36 flat slides. Everyone of my bikes saw max RPM's in every gear every time they were ridden. NEVER had any type of jetting problem because I ripped all those stupid hoses off my carbs.

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The only way you would create vacuum in the top of the airbox like that is to stuff a rag in with it, or major suction like turbo or supercharger. Can't see it doing anything but getting any fumes that might escape the bowls.

Am thinking that hoses attached to the carb vent nipples will protect against water entry into the nipple, such as when washing the bike.

Otherwise, the hoses would seem unnecessary.

Good Fortune!