Pitot tubes

[Reinhoud]

I crashed my bike about 5 months ago (P-plater doing a turn out of the blue), now I'm rebuilding it, and (try to) make some improvements along the way...

I'm going to make a new plenum with (sort of) velocity stacks, the up pipe is also something where there's something to improve.

 

My bike was running fine! The up-pipe doesn't look that great, and the inside looks even worse, so I thought may be I can improve that..

 

The pitot tubes I have in my up-pipe come from a sub-frame from a FZR250, this had a good diameter and a fairly tight bend in the pipe.

 

The plan is to make a new up-pipe and have it TIG welded by someone who knows what he's doing, but the pitot tubes are the challenge, and this is not something I'd like to experiment with...

 

No 1; is how I have it at the moment.

My question; does it matter what shape the pitot tubes have?

I don't want to use the old ones because they look like crap.

I'm not able to get a "sharp" bend in the tubes as what I have now, I can make the tubes at the right size, a / the sharp-ish bend is the problem.

 

So I've got 2 options; a 90 degree angle in the tube, like no 2 in the drawing, or a straight pipe into the uppipe with a 45 degree agle on the bottom as in drawing no 3.

 

Anyone who knows more about these things?

 

Thanks.

 

 

 

Edited September 29, 2023 by Reinhoud

[Joseph]

No drawings 

Interested in what you find out. Also whats the general diameter idea on these ?

Edited September 29, 2023 by Joseph

[Reinhoud]

20 minutes ago, Joseph said:

No drawings 

Interested in what you find out. Also whats the general diameter idea on these ?

Uuuuhhh  Fixed it.. 

[Reinhoud]

21 minutes ago, Joseph said:

No drawings 

Interested in what you find out. Also whats the general diameter idea on these ?

Not sure, 14mm outside diameter IIRC

[Joseph]

Right ! Thats large compared to a 2 inch intake ? Not that i know anything about this 

What does your plenum look like ? What kind of space do you have to play with

 

[Reinhoud]

Again, not sure about the diameter!

The plenum is 2.5 liter, twice the size of the displacement. 

Plenum isn't that great, mostly the connection to the carburetors.

 

[Reinhoud]

I'm going to make a new plenum, I want velocity stacks in it, and hopefully it's going to be easier to take it off.

I also going to follow the lines of the side covers a bit better / closer.

 

The up-pipe is goin to have the same diameter, but beter welds, and more smooth. Mostly on the inside..

[Joseph]

Ah I see, you're a but stuck

On my engine build i can do it like this, which i guess is better for airflow pick up ?

[Reinhoud]

Probably better... 

 

I'm mostly curious how much difference there will be between my drawings..

[Joseph]

Yeah it would be cool to be able to do flow tests

Could you maybe do this with your new plenum ? It would make the pitot tube come out at the back, if it clears the stacks maybe that would be a solution ?

[TLRS]

Could you do away with the situation between carbs and plenum? Using machined bellmouths+plenum that incorporate o-rings that go directly on the carbs. Might give you a bit more room and by that better access maybe? And easier to make changes for pitot experimenting.

[Reinhoud]

I already have an idea for the plenum.

 

The reason for asking is that I don't feel like experimenting / tuning again.