Airbox Connection Help

Hi there.

I have two 1981 KZ750 (4 cyl). Neither had the airbox installed, and one has pods. I am trying to get one of them back to stock, but I am having a heck of a time trying to figure out all the vacuum lines.

On one, all 4 nipples on the carbs were connected together and then connected to the fuel petcock. On the other, two nipples are capped off and the one goes to the petcock and then the other goes God knows where!

Does anyone have a picture of the airbox with the stock connections? I do not have the ports on the valve cover.

Thanks for any help with this.

Peter

If no ports on the valve cover then connect one carb nipple (usually carb #2) to the vacuum nipple on the petcock and put caps on the other 3. Block off - I used a bolt - the hole in the airbox at top centre front.

If ports on the valve cover then you can run a tube from one side to the other and do as above.

Sounds like you have a non US valve cover with no ports. We never got that anti smog stuff up here.

Kawasaki.com & Partzilla have diagrams.

Does the bike have the Kawasaki clean air system? If so, typically, #1 & #4 are connected to tubing from the clean air stuff, #3 is capped, & #2 has the petcock vacuum line. Without the clean air tubing, you'd cap the unused vac ports. If no vac petcock, cap that port as well.

Note: according to the diagrams for the 81 750E, the carburetor overflow tubing should be routed to the airbox - there are a couple of grommets & Y fittings for making the connections.

Thanks for the info. I think I can put it together based on the info you have given.

I do not have the ports on the valve cover.

What used to go through that hole at the top centre that has been suggested I block with a bolt? Did one of the vacuum lines go there?

Thanks again for the help.

The hole at the top/front of the airbox is for a fat clean air system tube. There should be a large nipple for accepting the tube. If you don't have the clean air stuff, then you'll need to plug that hole.

The hole at the bottom/front of the airbox is for the crankcase breather tubing - there should be a grommet there. I would connect it to burn the engine fumes. The grommet should be available at the dealer or the auto parts store might have something.

I have all the pieces with the airbox. It just doesn't have that clean air system. I think I should be able to set it up now.

Thanks again.

Well, I have the airbox back on the bike and the carbs installed (there must be an easier way to get those carbs back in. What a pain!)

What is the reason behind connecting the carb overflow tubes to the airbox? Is that simply to prevent
fuel from dripping onto the engine?

Also, at the very bottom of the airbox there are two holes. One is for a tube to go straight down (I am assuming to drain any fuel that may get into the airbox from those carb drain tubes) and then another one (the one my finger is pointing to). Is that just left open to drain any water that gets into the airbox from the top when the seat is open or something?

Thanks again for all the help.

I think the big hole is to drain water to help keep the air filter dry. The other one is for whatever collects inside the airbox - water, fuel, or oil n stuff from the crankcase breather.

As to why the overflow tubing is routed to the airbox, it's probably so that some of the fuel can get burned by the engine as it evaporates? Some models, such as my 81 650, have the overflow tubing routed behind the engine & forward of the swing arm, towards the ground.

Ok. I figured that bigger whole was a drain and not an input of some sort.

All the bikes I have ever had just run the overflows to the ground, but your explanation sounds good to me! I guess guess who run pods must direct them to the ground. I will connect them to the airbox to stay stock as possible.

Thanks for the reply.

Mid life crisis wrote:
All the bikes I have ever had just run the overflows to the ground, but your explanation sounds good to me! I guess guess who run pods must direct them to the ground. I will connect them to the airbox to stay stock as possible.

.

I run the overflows to the ground between engine and swing arm. I just went out and checked and see that I plugged those holes in the air box where the overflows used to go.