CB125t: 2-into-1 exhaust

[sid201]

Hi folks,
After watching the two hour at Mt Wellington the other week and thinking about it for a while before that, I'm building a CB 125 bucket- got the bike last weekend(cost a bottle of Jim Beam) and would have had th engine running today but the battery was stuffed.

I've got a plan for the seat and a mate and I sorted the wiring and stripped 90% of the crap off today.

The one thing I'm not sure about is building a 2-1 exhaust- I'm thinking about this as as one of the silencers is U/s
Anyone got any advice?

<a href="http://s50.photobucket.com/albums/f334/sod201/?action=view&current=pic012.jpg" target="_blank"><img src="http://i50.photobucket.com/albums/f334/sod201/pic012.jpg" border="0" alt="Photobucket"></a>

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[TZ350]

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Great looking bike, lots of possibilities. Purchased in the true Bucketier style.

2 into 1 into 2 is apparently the go. John Conner has built many of these bikes and has a realy gun setup that is easy to make. He is the guy who runs Buckets at Mt Wellington.

Someone is sure to have his contact number and PM it to you.

[timg]

Awesome - another CB125t. Keep us posted on progress and how you go. Cheers.

[Skunk]

John's number is on the AMCC website.

[sid201]

thanks - I've e-mailed John this morning

[speedpro]

John's pipes basically are two seperate pipes with a common muffler. Don't forget the 125Ts have a 180deg crank. john's pipes do sound good, especially with the sprint cam in.

[TZ350]

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I think he uses the original headers. Makes it much easier. Not sure what length though.
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[SHELRACING]

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I think he uses the original headers. Makes it much easier. Not sure what length though.
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Now that's what I call a bucket, and the seat's already cut down.

TZ's right the fornt pipes are cut down, and the reversed ie left to right - right to left. make two oval end plates, make the outer casing from aluminium. Rivet it all together. Not forgetting some exhaust packing.

As it happens I sold one a couple of monts back. Here's a pic to help you out.

[sid201]

Thanks for that-I got Info off John as well and should be able to knock something up when things are quiet..got a call this morning to let me know that the Battery was in stock so I'll try and get the Beast started today

[dangerous]

For best results a 2-2 is the best set up I have measurments if you want... how ever most go ror a 2-1 like I had (see profile album) they dont run the best at lower revs and have a miss sound to them but its not really a problem. K14's 2-1 seems to be beter than mine p/m him for measurments.

[Buckets4Me]

Also you may want to talk to John about the ignition
he knows more than most about these beasts and
knows how to make them fast and reliable

[sid201]

well the bugger starts--throttle cable's stuffed so I'll replace that.
Dangerous- any dimensions and pictures of your 2-2 exhausts would be appreciated as I'm still not sure what I want to do

[dangerous]

well the bugger starts--throttle cable's stuffed so I'll replace that.
Dangerous- any dimensions and pictures of your 2-2 exhausts would be appreciated as I'm still not sure what I want to do I sold it two weeks ago but I still see it about... it works well on a std engine the other measuments I have are to suit a highly strung 150T, but remind me and Ill measure up.

[sid201]

cheers....

[cmac]

For best results a 2-2 is the best set up I have measurments if you want... how ever most go ror a 2-1 like I had (see profile album) they dont run the best at lower revs and have a miss sound to them but its not really a problem. K14's 2-1 seems to be beter than mine p/m him for measurments.
Hey Dangerous
I'd be interested in the 2-2 measurements you have.
Seems like I should talk to John about ignition as well - or have you sorted all that?

Cheers

[dangerous]

Hey Dangerous
I'd be interested in the 2-2 measurements you have.
Seems like I should talk to John about ignition as well - or have you sorted all that?

Cheers

yours (was mine) is CDI the earler bikes were points so apart from tearing the fly wheel out and making it a toatle loss... I wouldnt bother, as soon as you look at taking it out more you will loose relibality, I have the specs for the 28hp engine but they dont last long and this engine is what the 2-2 is designed for so proberly not as eficent as whats on it.

Now can you post up the header length and diameter, length of cone and dia at the header and were it maxs out, the reverse cone you will have to shine a tourch up the pipe and take a guess as the muffler hides it.

[Sully60]

muffler

What is this muffler thing you speak of?

[dangerous]

What is this muffler thing you speak of?

ohh well just a steel tube the same size as the largest section of cone 150 or there abouts long with a perferated pipe in it and a smaller exit hole... believe me a straight megaphone is way way to loud.

ohhhhhh, man were you taking the piss LOL :Pokey:

[Skunk]

I rate the straight megaphone at 120db - speaking from experience...

[Sully60]

I rate the straight megaphone at 120db - speaking from experience...

The evidence (http://www.youtube.com/watch?v=_lh9MhofYg0) would prove your estimate to be quite conservative. Bear in mind the sampling rate of the meter is quite slow.

[k14]

Well the motogp 4 strokes are iirc allowed 130db and believe me, from 6 feet away you need more than a finger in each ear!

[Sully60]

Well the motogp 4 strokes are iirc allowed 130db and believe me, from 6 feet away you need more than a finger in each ear!

According to Skunk my bike (with the pipes open) is louder. After less than five minutes of riding with earplugs I have to stop because my head hurts too much.

[k14]

Nice! What does the meter say when you put the silencer in?

[Sully60]

Nice! What does the meter say when you put the silencer in?

Pass, I haven't bothered to try. I like to go for higher numbers not lower ones:headbang:

Did you get a chance to hear it at the BoB before I killed it? It's still louder than most buckets but it's managable and I haven't been black flagged......yet:innocent:

[Skunk]

The evidence (http://www.youtube.com/watch?v=_lh9MhofYg0) would prove your estimate to be quite conservative.
What can I say? I'm a conservative guy.


Nice! What does the meter say when you put the silencer in?

Who cares... :lol:

[dangerous]

I rate the straight megaphone at 120db - speaking from experience...

Well... that sort of racket pisses me off, not only is it not allowed on a national track... but most importantly its very un nerving for other riders and that alone is dangerous.

I do not like hearing other bikes over my own and I shouldnt have to... both major engine blow ups have been next to exsesive loud bikes the latsest being my RD blowing up, I could not here it but felt a stutter thinking fouled plug or shit in the carb I kept it pined (could not here the rod braking the piston shatering over the noise of a 350 twin with a open pipe) I locked up and I was farking lucky not to have been injered...

have some consideration for other riders.

[Skunk]

Well... that sort of racket pisses me off, not only is it not allowed on a national track... but most importantly its very un nerving for other riders and that alone is dangerous.

I do not like hearing other bikes over my own and I shouldnt have to... both major engine blow ups have been next to exsesive loud bikes the latsest being my RD blowing up, I could not here it but felt a stutter thinking fouled plug or shit in the carb I kept it pined (could not here the rod braking the piston shatering over the noise of a 350 twin with a open pipe) I locked up and I was farking lucky not to have been injered...

have some consideration for other riders.
Yeah Sully... have some consideration.

[k14]

Gee I've heard some shit before but that would have to take the cake. Yes, too loud for all tracks and that alone is the only reason.

If your maintenance is so poor that you are constantly blowing bikes up then it isn't the person with the loud exaust's fault!! :2guns:

[Sully60]

constantly blowing bikes up then it isn't the person with the loud exaust's fault!! :2guns:

Exactley, I've never used it as a excuse for blowing up my own bikes.

Next thing you'll be blaming someone in the pits for tripping over the power cord for their tyre warmers:whistle:

Not a bad troll Dangerous but please try harder next time.

[Kickaha]

I do not like hearing other bikes over my own and I shouldnt have to... both major engine blow ups have been next to exsesive loud bikes the latsest being my RD blowing up, I could not here it but felt a stutter thinking fouled plug or shit in the carb I kept it pined (could not here the rod braking the piston shatering over the noise of a 350 twin with a open pipe) I locked up and I was farking lucky not to have been injered...

have some consideration for other riders.

You would have fucked it regardless because you're so hard on gear, if you spent less time polishing and more time maintaining them it might be different

[dangerous]

You would have fucked it regardless because you're so hard on gear, if you spent less time polishing and more time maintaining them it might be different well actually... I pull the heads off the strokers every 2 meet and remove the barrels every 4 meets to be sure all is well... farked if I know what went wrong in Grey, best I can see is a jet blocked.

[Kickaha]

farked if I know what went wrong in Grey.

Rider abuse coupled with mechanical incompetence would be my guess

[k14]

Rider abuse coupled with mechanical incompetence would be my guess
and don't forget the loud opponents exhausts! :bleh:

[cmac]

yours (was mine) is CDI the earler bikes were points so apart from tearing the fly wheel out and making it a toatle loss... I wouldnt bother, as soon as you look at taking it out more you will loose relibality, I have the specs for the 28hp engine but they dont last long and this engine is what the 2-2 is designed for so proberly not as eficent as whats on it.

Now can you post up the header length and diameter, length of cone and dia at the header and were it maxs out, the reverse cone you will have to shine a tourch up the pipe and take a guess as the muffler hides it.

I'll have a measure up and post ASAP

[cmac]

I know it's been a while but....
I've made up a 2 pipe muffler that has increased midrange power quite a bit, no dyno to verify this but lap times say it all. For that reason, I wouldn't muck about with a 2 into 1 of the dimensions from Dangerous' old CB because it's not as good as the 2 through pipe.