Reinhoud Posted September 29, 2023 Share Posted September 29, 2023 (edited) 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 Quote Link to comment
Joseph Posted September 29, 2023 Share Posted September 29, 2023 (edited) No drawings Interested in what you find out. Also whats the general diameter idea on these ? Edited September 29, 2023 by Joseph Quote Link to comment
Reinhoud Posted September 29, 2023 Author Share Posted September 29, 2023 20 minutes ago, Joseph said: No drawings Interested in what you find out. Also whats the general diameter idea on these ? Uuuuhhh Fixed it.. Quote Link to comment
Reinhoud Posted September 29, 2023 Author Share Posted September 29, 2023 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 Quote Link to comment
Joseph Posted September 29, 2023 Share Posted September 29, 2023 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 Quote Link to comment
Reinhoud Posted September 29, 2023 Author Share Posted September 29, 2023 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. 1 Quote Link to comment
Reinhoud Posted September 29, 2023 Author Share Posted September 29, 2023 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.. 1 Quote Link to comment
Joseph Posted September 29, 2023 Share Posted September 29, 2023 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 ? Quote Link to comment
Reinhoud Posted September 29, 2023 Author Share Posted September 29, 2023 Probably better... I'm mostly curious how much difference there will be between my drawings.. Quote Link to comment
Joseph Posted September 29, 2023 Share Posted September 29, 2023 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 ? Quote Link to comment
TLRS Posted September 29, 2023 Share Posted September 29, 2023 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. Quote Link to comment
Reinhoud Posted September 29, 2023 Author Share Posted September 29, 2023 I already have an idea for the plenum. The reason for asking is that I don't feel like experimenting / tuning again. Quote Link to comment
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