Installing a Exhaust vavle

[Zbike]

Quick question i want to stick exhust valve on a cbr 250 and a gs 500 i have.

Im thinking 50% restriction after the headers meet.
Solanoid for fliping the valve
Activated either by a frequency counter running of the tacho or a better yet (if possible) voltage generated by the alternator before the rectifier.

Will i see any more power in the bottom to mid range? is the question i want answered.

Any other usefull info would be great aswell.
BTW i do all the mods on the cheap so no buying 300$ shift lights for me ect ect

[ralph]

lol I had the same idea years ago. I wanted to run a gate valve in my datsun 1200 coupe with straight pipes out the side like v8 supercars so I could have the option of noise and flames at the flick of a switch...Wasnt really concerned about performance so much just thought it would be a cool gimmic. Never happened.. Too lazy. Or maybe sanity prevailed.
You are after increased bottom end performance. I reckon a tunable exhaust should be acheivable with the computers these days. Different exhausts definitely affect performance.
On a $300 budget, who knows, you may start a revolution and rewrite the record books
I wonder how many fighters out there would perform a little better with a close to stock exhaust. Some maybe. Who cares, if they look cool thats the main thing, Put your think cap on and make something. Go for it , if you acheive flames out of the header at will,youll have gone one step further than I did. If you melt a piston or two. shit happens. Will I see flames, Thats the question.

[ralph]

..... maybe some sort of sliding sleeve so you could alter the length of your pipe whilst riding. Has it been done.....Probably.

[Tony OW31]

quote:Originally posted by Zbike

Quick question i want to stick exhust valve on a cbr 250 and a gs 500 i have.

Im thinking 50% restriction after the headers meet.
Solanoid for fliping the valve
Activated either by a frequency counter running of the tacho or a better yet (if possible) voltage generated by the alternator before the rectifier.

Will i see any more power in the bottom to mid range? is the question i want answered.




Any other usefull info would be great aswell.
BTW i do all the mods on the cheap so no buying 300$ shift lights for me ect ect


Just get an exup valve of a wrecked yamaha, most of the other manufacturers have their own these days as well.

[Zbike]

Lol wasnt for flames but that's a fasinating (yet diffrent) idea.
I'm after performance in the bottom and mid range (via increased backpressure). And i think this is an easy way to do it.
And i want to build it from scratch.

[miniman1]

I agree with Tony mate, would be easier to get the setup off a Yammy, I got a EXUP control unit thingy off an FZR250 if ur interested, duno if it could be wiried to suit ur bike tho???

[Tony OW31]

quote:Originally posted by Zbike

Quick question i want to stick exhust valve on a cbr 250 and a gs 500 i have.

Will i see any more power in the bottom to mid range? is the question i want answered.



Having tested these on the dyno when they where new, I found that removing the valve did not give any decrease in midrange, and a well designed exhaust without the valve gave better results right through the range. Most of these valves are designed to get the bike through the noise regulations, and any increases the manufacturers see will be in combination with sensors and mapping, so unless you have access to a dyno you will not be able to tell if there is any benefit, and even then any gains on such a small motor will be immeasurably small.

[latheboy]

Dyno's are ghey;)..... If its sounds faster then it most likely is:D

[Tony OW31]

quote:Originally posted by latheboy

Dyno's are ghey;)..... If its sounds faster then it most likely is:D


Oh, yeah, sorry, forgot about the correlation between sound and power[:p]

[Benz]

I read somewhere about a simple setup that had a disc mounted so that it could swivel in the exhaust, allowing more or less flow,and once you were happy with the backpressure, you could just lock it in place.
I think it was more for straight out pipes on those tractor thingy's..........Hardlys
Same as an EXUP I guess....