Thread: Exhaust pipe mod question
04-09-2015, 07:40 AM #1
Exhaust pipe mod question
I've seen posts where flow valves are added to exhaust system and fittings drilled to improve
performance & hp , does it really make a big difference?
Also there's a small hose that attaches to the top and center area on the U shaped exhaust pipe
with fittings that have a very small opening, what does this do?
Are these the fittings being drilled?
04-09-2015, 08:07 AM #2
- Join Date
- Jul 2007
- near Toronto, Canada
Depends on the engine model and the exhaust pipe version.
That small u-shaped rubber hose delivers a controlled water injection spray directly into the hot exhaust gas flow. The amount of water affects the engine performance. Changing the amount of water flow affects the pipe 'tuning' and the engine power in certain RPM ranges.
It is not a case of more water injection is better. Multiple factors involved.
04-09-2015, 08:14 AM #3
- Join Date
- Aug 2014
- Richardson, Tx
I think you are referring to the flow control valves added to prevent the waterbox from filling with water at low RPMs. This doesn't necessarily improve overall performance but would help with acceleration from low speeds as the exhaust would not have to first push the water out of the waterbox, it can just breathe freely. As to the water fitting on the expansion chamber, the only change I am aware of applies to Fuji motors, that is swapping the older 650/750 fitting to a 780 fitting. I have not read about any changes to the fitting on a domestic engine, which I'm pretty sure is what you have. Maybe another member has more input on that subject?
04-09-2015, 08:42 AM #4
going from 2000-2001 polaris revised its water cooling setup on carbed 1200's,doing this allowed for a leaner midrange,which also means a leaner top end.they opened the stinger to .090 from .071.doing this without the jetworks valve will put too much water into the waterbox at idle.these all go hand in hand to work right.
04-09-2015, 02:16 PM #5
thanks for the info guys, think i'll let it go for now.
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