Dual Exhaust Modes

[BAMBY]

hahaaa, thats awesome! loll

personally, i would make two exhaust systems. one thats really quiet for sneaking around at night. and another thats just straight pipe for power and lotsa noise! loll
i plan to keep the neighbors happy so they are less likely to call the cops lol

Thankyou, the hunter!
for reminding me... i wanted to post about this.

i just helped a friend from school install exhaust cut outs on his T/A (trans am). exhaust cutouts are butterfly valves installed on one branch of a y-pipe right after the headers. they are opened/closed electronically via a switch mounted near the driver(center console in his case). when open, the exhaust goes straight from the headers out into open air under the car. when closed the exhaust gas follows the same route it normally would. the point of cutouts are to let the exhaust get out with out the restriction of mufflers, etc. this adds extra performance and loudness.


this led me to wonder how i could do the same thing to my minibike's exhaust (briggs 5hp engine)... just like hunter said...

well i did it... i welded a ypipe right after my exhaust port. one part goes to a old catalytic converter i used as my muffler(really quiet and good for environment too) the other part of the y pipe is a short piece of pipe with threads on the end. on the threads i screwed on a pipe cap that i can take off for high performance drag race mode and put back on for stealth cruise mode.

it works well, but the pipe cap gets so hot you cant switch to high perf mode unless the engine has had time to cool down.

can anyone think of a CHEAP way to do this without worrying about getting burnt???

one of my friends suggested to make a slide valve(piece of sheet metal that slides to open/close, but i didnt think it would seal too well and would rattle.

what would be even better is if you could have a lever to pull a cable that would open/close it ... now that would be awesome. i just have no idea how to rig that up for CHEAP!

anybody got ideas/ experience/ suggestions?

put it up... whatever you got!
BAMBY

 

[Kaptain Krunch]

Possibly using a plumbing fitting that has on/off ? One on each side of the Y fitting.

I was considering doing this on my offroad mower.

 

[freakboy]

Butterfly valve, ball valve? have two of em idk

 

[BAMBY]

yeah, i thought about ball valves too, but do you guys think they could stand up to the heat???
inside the ball valves is a "plastic socket" that the ball pivots/turns inside of that seals off water, etc. from getting around the ball. i just dont know if it would melt, and would it matter that much if it did???

watt dyou guys think?

@kaptainkrunch

Possibly using a plumbing fitting that has on/off ?

that was kinda vague, i guess you were refering to ball valves?
what did you mean? maybe you thought of something i didnt.

 

[Kaptain Krunch]

Im talking about all metal manual on/off valves, the ones that use a disc like a carb butterfly,

 

[BAMBY]

ohhh, ok cool, ive never heard of or seen them for plumbing except like gigantic ones for like 6"pipe and stuff.

cool thanks, that sounds promising!

--do you know where i can get one or can u post a pic of one plz?
BAMBY

 

[Kaptain Krunch]

The ones im thinking of are copper, but i remember seeing one in steel before. Also check out mcmastercarr, they have everything.

 

[BAMBY]

okey doke! thanks again!

 

[BAMBY]

thought id post back on my findings.

mcmaster carr is da bomb!!!!!!

1/2 of the way down on page 426 of their online catalog has EXACTLY what i have been wanting... and relatively CHEAP too!!!!!

thanks again Kaptain Krunch!
BAMBY

forums are such a great tool! wooohooo!

 

[THE HUNTER]

yay, the first thread that i have inspired someone to post! lol

i was actually thinking of 2 complete and separate exhaust systems, but i really like this valve idea!!

but i would prob go the cheap/easy route like you did with a pipe cap lol
just get yer pipe wrench and some good thick leather gloves, and you wouldnt have to wait but a few mins lol.


im kinda curious though, does a cars catalytic converter actually get hot enough to start working with a small engine on a mini-bike?

 

[BAMBY]

you only get one chance to inspire someone with a post... lol

yeah, the pipe cap is fine and all, easy and cheap too, i just dont like having to get out my thick leather gloves that i bring with me everywhere (sarcasm)(lol) just to get to high perf mode. :rolleyes3:

the pipe cap is only ~3-4" from my exhaust port, so it heats up fast too so its not like you have too much time. takes like 3-5minutes for the cap to get that hot.

im kinda curious though, does a cars catalytic converter actually get hot enough to start working with a small engine on a mini-bike?

you'd be surprised. the first time i ran my engine with the cat on it, i could feel the humid air coming out of it cause it was reacting really well (one thing cats do is turn unburn hydrocarbons in to h20 and co2.) the exhaust might be a little hotter (or theres just more exhaust whiping through faster) because i am usually going from 4000-5300 rpm, but the cat actually does heat up. it takes about 15-20 minutes of running/driving for the WHOLE cat to heat up. the part of the cat closest to my exhaust port heats up quick then gradually spreads to the back.

but once that mother heats up... you better not lay a hand on it or you WILL pay. you have been warned... it will burn the crap out of you. not only that, but its like a footlong by 4" wide so, its not that hard to accidentally hit. i mean that whole thing gets scorching hot after you ride it for a while.

BAMBY

ps the cat sounds good too, not too loud, but a nice low toned rumble... ohhh yeahhh

 

[THE HUNTER]

ok, ill take your word on the catalityc converter thing, as ive never tried it lol

but you might try some expanded metal or something around the cat. idk how concerned you are with how your bike looks, but a super cheap way would be using rabbit wire (chicken wire is too weak, and the holes are too big) to keep you from bumping into it.

 

[BAMBY]

you dont want to see my bike... all made from bed frame angle iron... its a fun ride but its ugly. its got a spot in my heart tho.

i built a second seat over the cat on the back of the bike so its not that ez to reach now. that kind of protection isnt really necessary now though... besides if youve been burnt once by hot metal, you been burnt a thousand times... no big deal once you get used to it

though if it was still exposed, id jump on that expanded metal, i would have shaped it to fit the cat and stand it off like a half inch... that would look soooo bad a$$. thatd be awesome.

 

[THE HUNTER]

is it as ugly as my scooter? lol

i found some expanded metal in the trash once! it was all shiny and everything!! lol

but yeah, i know what you mean, ive been burned like a million times, same thing with cuts. i have so many scars on my hands idk what most of them are from! lol
i get a cut and start bleeding and ppl are like "oh that looks bad, shouldnt you get a Band-Aid or something?" then im like "nah, its nothing" then wipe the blood off on my pants XD
but hey, i rarely get sick, and never get any infections or anything (i barely ever wash out cuts/scrapes)
i guess it helps to build my immune system lol

 

[modelengineer]

I made one in my garage. Works really well.

With the final pipe removed. It exits about 50mm in front of the rear right tyre. Quite loud.

 

[THE HUNTER]

cool, what do you use to open it?

 

[EagleTalons]

Looks like an electronic exhaust cutout. How much did it cost?

 

[mike75925]

i don't know if this will peak anyone's interest but they have exhaust valves as well. kinda like the old preheaters on ford manifolds. they act similar to a turbo/stall convertor, my fzr600 had one and the thing would come up in curves at 70mph with a car on either side! not cool! they hate idle, but roar under acceleration. it is a form of dynamic exhaust that will allow you bottom end grunt while giving you top end spend all in one!!! watch your tuning

 

[modelengineer]

Yes, it's electrically operated.

Looks like an electronic exhaust cutout. How much did it cost?

I made one in my garage.

It didn't cost me anything. Having the extra pipe welded on the exhaust was $40 AUD, with the downpipe (not shown in pic).

 

[BAMBY]

modelengineer, thats a slick job you did there!
do you have any pics of it blown a part or in pieces or of building it. please share if you do! that looks really good.

the hardest thing for me is to get the butterfly disc to SEAL even a little bit with the "housing"