View Full Version : Chadman's Carb Manifold

12-16-2010, 6:33 PM
So about a month maybe a month and a half ago a member of the Kz Twin Owners Forum asked me to build him a carb manifold for his 79 kz400. It took me some time to track down the parts that I needed and for us to figure out how to bridge the continent between us then the cold hit and my shop became an icicle so it is now finally done.

So part of the issue with getting him this manifold was that he lives in california and I live in North carolina which would not be a problem accept that his frame and motor were very different from mine. I asked him to make me a template with the mounting holes and the placement of the intakes so that I could make him an accurate part.

I then transferred this onto a piece of wood that I could use as a jig
here you can see the two legs set in my jig ready to be tacked.
Tacked together ready to be knotched for the spout
Here you see the legs knotched and the spout ready to be tacked on
I tacked everything and checked that it was all straight before fully welding it.
Then I cut everything about to length and realized that I might want to check with chad to make sure that this thing was not too big for his frame.
Thankfully he said that he thought it would be fine.
Now I had to make the mounting Flanges-
I asked Chad to send me his intake boots as well so that I could use them to trace the flanges. I went ahead and drew them both out on a piece of 3/8" Stainless that I had and begun milling the intake holes- I do this with a hole saw- Gives a pretty clean hole and they are not too expensive.
After I got them cut out I put the manifold together using the template that Chad had made as a guide and I tacked the legs into the mounting flanges.
I flipped the thing over welded all the way around the inside of the flange. Here you can see I have cleaned up the surface but not the interior of the tube. Unfortunately I did not take any pictures of the bottom after I cleaned the inside but I assure you I made sure there were no obstroctions
I took some photos to show Chad that it was done before I painted it.
Im not the best painter in the world but This should protect it from rust very well.

It is now sitting in the Living room so that the paint can dry and I will be shipping it out early next week or this weekend.

12-16-2010, 7:54 PM
I can dig it man... Looks like you've been able to fine tune some of your skills.

PS, haven't seen hide nor hair of your ride in a while, hows' it coming along?

12-16-2010, 8:20 PM
Yeah, I havent had a lot of time to work on it. currently I do not have a head gasket that will seal to give me good compression and seal to prevent oil leaks. Its one or the other but not both. Trying to solve that problem as we speak. I will have some time to work soon. Taking some extra time off around the holidays. Will post pictures.

12-17-2010, 8:24 AM
intake looks good man, using the board for a jig is a slick idea that I'm going to have to remember.on the one i built for an xs i welded it all up with everything bolted to the engine. what a p.i.t.a. that was.

12-18-2010, 9:57 PM
think you could make one shorter? my homebuilt is works fine but is ugly (soldered copper bits). and if so how much would you charge for said piece?

12-20-2010, 3:56 PM
This requires you to ship me a Pattern to work from unless your motor is either a 76 d3 or a 79 B? I dont remember.

Yes I can make it shorter. What size would you need it and I can see how the bends would work out.

Im also thinking that I will need to use mild steel for the mounting flanges. But other than that it would be the same.

THanks for your interested. (I always wondered how the soldered copper ones held up. Seems like the vibration would kill it.)

12-30-2010, 11:54 AM
Chad let me know that he recieved the manifold just before christmas. Said it looked good and seemed like it would fit but hasn't been able to mount it yet. I will update when he lets me know how it works.


01-19-2011, 10:07 PM
Here is another one. This is for a 75 still the kz400. Hopefully a local member will be bringing his cb350 over to have me build one for it.

Before i catch hell I know the welds are not the prettiest in the world. I laid down beautiful welds the first pass but then found a pinhole and I didnt wnat to leave it up to chance.
He asked for it unpainted. so this is the final product. I wire wheeled and sanded it so it should be ready for paint when he gets it.

01-20-2011, 6:31 AM
Great write up! Thanks for taking the time to photograph and post. I would really like to see a shot or two of the finished manifold on a bike. You do good work, yer skills is showing.

01-20-2011, 8:45 AM
Source some weld els. You could make these things way more compact. Sch10 would still be relatively easy to work with. That or get some donuts. You could get all of your bends out of one 1/4'ed donut.