I will shortly start making the inlet manifold for my x-flow, so that I can use my bike carbs. I've pretty much worked out how I'm going to do it, but I still have a couple of questions for people who's done the same thing themselves:

1. What thickness of aluminium did you use for the base-plate? (the bits the pipes go into, that is). I was thinking of 1/2" (12mm) as that's roughly the thickness of the cast manifold I've got at the moment.

2. As I don't want to dismantle the existing manifold yet (you have to drain the engine coolant) I was planning to use a new manifold gasket as a pattern - does this sound reasonable? It's the only thing I can think of, short of finding a knackered old x-flow head to play with.

Good fun, though... I'm now getting into the old "when I do this, I'll have to do that, and that, and that..." phase, having realised that I will no longer be able to vent the crankcase into the manifold, so I'll need a catch-tank system. Also, I plan to replace the mechanical fuel pump, and convert the Megajolt system to TPS (for which I've got to find a plug...), and so on.

Sheesh!

David

Oh yes... new throttle and choke cables too, of course, which cannot be bought off the shelf!

[Edited on 28/9/07 by David Jenkins]

12mm is a good thickness for the flange.

As ally is so soft one tip is if after welding you have a bit of bowing put some sand paper on a bit of glass and rub. Cheaper and quicker than taking it to a machine shop.

i used 10mm ali, which still distorted and had to be milled flat. i would be carefull making the openings as big as the gasket as generally the gasket openings are a little bit larger than the ports which will then leave a sharp edge unless you are thinking of then porting the head to match.
i re-attached the crankcase breather into the back plate of the air filter so didnt need a catch tank.
Rescued attachment zx6 carbe 1600CVH.jpg

That's a tidy piece of work (I had a look in your photo archive for the other view!).

When I originally rebuilt the engine I matched all the ports to the gaskets so there are no sharp steps - but there may be sudden widenings!

I used 12mm plate for the manifold because thats what I had . Gasket worked for the pattern as well . If I was doing it again I would bolt the plate to a spare head before welding which may? cut down on distortion . I had some distortion after welding but managed to bolt manifold to spare head with a piece of 12" wood between the 2 which pulled the plate so it was nearly flat then faced it up on a surface plate.

I intend to make some form of jig to hold everything together and in-line, as there will have to be some 'interesting' curves in the pipe before I've finished! I'll try and make the main plate as stiff as possible - I've got some massive steel angle in the garage that'll do just nicely!

I made my crossflow manifold from 10mm steel, I cut it to the same profile as the gasket and found that although it warped a bit when i welded it it pulled down flat when fitted.
Paul.