Using another canister with stock MAC Headers?

[Detman101]

Good afternoon gentlemen,

I've heard that the stock canister exhaust that comes with the MAC exhaust is restrictive and may not work well with a stage-3 kit and pods.
What canister could I put on there from an aftermarket exhaust that would flow enough to use my Dynojet stage-3 kit with the dynojet recommended settings? (needle in groove#4, 132 mains, mix screws 3 turns out)

I know that for some cans I will have to use a mid-pipe. I've got that part sorted out already.

Or, if the MAC canister is too restrictive, could I just take the baffle out and have the stage-3 settings work?

MAC Header and canister I just bought...

Thank you,
Dm of mD

 

[kkesler]

No way to know how your jetting will work out until you do the work, as this type of setup is pretty rare. I am using a Yoshimura RS3 canister, a Mac header, and a GSXR1K midpipe and K&N cone filters on my GS450S. The stage three kit was still too rich, so I have gone to a smaller main (125 instead of 135) with the needles at middle-slot and it seems to be pretty close now.

You can look forward to lots of testing.


Kurt

 

[Detman101]

Kewl, thanks Kurt.
I'll take down your specs as well for testing.

One thing though...are those main jets you specified Dynojet Mains or
Mikuni Mains? I need to know this as I have:

128 dynojet mains
132 dynojet mains
and
122.5 mikuni mains

to play with during testing.


Dm of mD

 

[Anonymous]

Damien,
If you can find somebody putting an aftermarket cannister on a big bike (GSX-R750 or larger) with normally one cannister on the exhaust then you outta be close. I've gotta Hyabusa cannister on mine, but the Hyabusa has two cannisters normally. I figure that if it will flow 650cc s at the Hyabusa redline, then it will flow 750cc s at my redline (which is lower than the Hyabusa redline). It's quiet and makes power so I really can't complain. On the other hand, I don't have a Dynojet kit on my bike and have the stock airbox and filter. A larger cannister for a bigger bike will give you better flow with no appreciable noise increase. Or, if you want, I'll lend you my V&H megaphone and you can try that.

Harrison

 

[kkesler]

Well, ummm, you see, that little point has always confused me. The 125s I have are Mikunis. What came stock on the 450 are 115s (IIRC). The Dynojet kit came with 135s. When I asked my local mechanic about the sizing differences between the Dynojet and Mikuni jets, he looks at me, smiles, and says "not always...most of the time...but not always". He gave me free reign with the shop's jet box and eyeballing all three lined up in a row, the 125s do look about halfway between the others.

No help, I know, but best I can offer. Enough playing around, plug readings and test rides and you get it worked out. Mine is "close enough" now.

Kurt

Kewl, thanks Kurt.
I'll take down your specs as well for testing.

One thing though...are those main jets you specified Dynojet Mains or
Mikuni Mains? I need to know this as I have:

128 dynojet mains
132 dynojet mains
and
122.5 mikuni mains

to play with during testing.


Dm of mD

 

[Detman101]

Thanks Harrison. I will have to take a trip up to the Salvage yard with the header in the backseat so that I can test-fit mid-pipes and mufflers on saturday. Due to "yon olden girlfriend" and the rain, :evil: I'm not going to make it to the yard before then. grumble...grumble...

Kurt, thank you so much for the info on the jets. I am putting together a log of all the information I can get on just how to compare mikuni to dynojet and how it all breaks down. So far, I'm more confused than when I started. And a complete set of dynojet jets (smallest to largest) is going to cost me over 300 dollars.

I do, however, have a great lead on what set-up I should use.
The mid-pipe I need is going to be off of a GSX-r 1000 and any supersport high-performance muffler will do. This combo, when used with the MAC header I have, should prove to be right in the ballpark for the Dynojet Stage-3 recommended settings. (According to others who have used this rare setup)

Man, I wish I had a garage...

Dm of mD

 

[Detman101]

Harrison,

Before I take you up on your offer I'm going to pull the baffle out of the MAC canister and see how the bike runs and sounds. I know it's gonna be loud but if the carbs balance out I may just leave it that way for a week or two until I can get good weather and time to test other mufflers.


Dm of mD

 

[kkesler]

I started by getting a mid-pipe and stock can off Ebay for ~10 bucks. Nobody wants that stuff, so you can pick it up cheap. Just don't try to get your jetting right until you change from the stock 1k can to the aftermarket, as it made much more difference than I expected (even on the little 450). The late model (01 up IIRC) gixxers use a 4 bolt mount, which is what I went with. Hayabusas use a three bolt mount, and it can be difficult to find single aftermarket cans since the bike uses 2.

To make sure it would work, I bought a rashed Yosh can off a racebike pretty cheap. Now that I know it works, I can look for a nicer one.

Kurt

 

[kkesler]

I lost the baffle out of my Mac, which is what started this whole experiment. Loud does not begin to define the racket coming out of that motorcycle. I made cruiser guys with their straight pipes cry, shook squirrels out of the trees and shattered windows in police cruisers.

Give it try, by all means, as it must be experienced. Once.

8O

Kurt

 

[Detman101]

Uh oh, now I'm worried.... :lol:

do you think that the baffle removed is as loud or louder than running just the headers?

Cause i've run the headers bare before I put the bike up for this repair and MAN was it loud. I would think that the slight megaphone shape of the canister housing will amplify this ruckus?

Lordy...Better get the earplugs ready.

:? 8O
Dm of mD

 

[Detman101]

I started by getting a mid-pipe and stock can off Ebay for ~10 bucks. Nobody wants that stuff, so you can pick it up cheap. Just don't try to get your jetting right until you change from the stock 1k can to the aftermarket, as it made much more difference than I expected (even on the little 450). The late model (01 up IIRC) gixxers use a 4 bolt mount, which is what I went with. Hayabusas use a three bolt mount, and it can be difficult to find single aftermarket cans since the bike uses 2.

To make sure it would work, I bought a rashed Yosh can off a racebike pretty cheap. Now that I know it works, I can look for a nicer one.

Kurt

Woooowee!! Stock cans must be in demand. I haven't seen one cheaper than 50 bucks on Ebay. I'll keep looking for a Gixxer 1000 stock mid-pipe and can though. Thanks again for the lead!!! I feel as though i'm almost there already!!


Dm of mD

 

[Anonymous]

Here's the link you need for the jet sizes from different manufacturers. http://www.vmaxoutlaw.com/tech/dyno-mikuni.htm

 

[kkesler]

That list starts high, as a 140 mikuni is the smallest they list. Still a nice list, though.

Kurt

 

[Detman101]

Whoa!! Thanks for the list GSTaylor!!

With that information I will stick to Dynojet jets in my carbs.
Their way of measuring the hole makes a lot more sense to me
compared to mikuni's measurement number being how much fuel the jet flows per minute.

WINNER: DYNOJET!!!



Dm of mD

 

[Anonymous]

That sounds like a fascinating seup for your 450, I'm thinking about doing that myself. However, when I check Ebay for the mid pipe, the ones listed have a "servo" in them. I'm guessing this is for adjusting back pressure and power at different revs. What did you do with this?

Sam

No way to know how your jetting will work out until you do the work, as this type of setup is pretty rare. I am using a Yoshimura RS3 canister, a Mac header, and a GSXR1K midpipe and K&N cone filters on my GS450S. The stage three kit was still too rich, so I have gone to a smaller main (125 instead of 135) with the needles at middle-slot and it seems to be pretty close now.

You can look forward to lots of testing.


Kurt

 

[kkesler]

We cut the mid-pipe off right after the valve. Cut the Mac megaphone a few inches into the flare, then cut a slot in the back of what was left. Folded that up around the midpipe and welded it all together. Then we cut a stainless bracket to go from the old footpeg mount to the muffler bolts, plus a piece of 1/4 inch aluminum bar stock to go to the muffler mount.

The valve? It went in that trash

I can post some pics if you like. If what you have is a GS450E or S, one of the best changes I made was to put some stock rear shocks from a GS850 on it. Much stiffer and better damped.

Kurt

 

[Detman101]

Ah crud, you had to weld?! 8O
If i can't find anything that will fit on the mac header without welding I'm just going to use the stock mac canister without the baffle.
I'll order the competition baffle on monday.

:?
Dm of mD

 

[kkesler]

Yes, welding required. If you do most of the cutting, you should be able to get an independant muffler shop or a metal fabrication shop to weld it up for you for a nominal charge. Or maybe some kind soul here on the gsresources that lives near you would volunteer to do it.

Lots of mods require welding. If you can't weld it yourself, you should cultivate a relationship with a local fabrication shop.

Kurt

 

[Anonymous]

If you check out the chart you will notice that the jet size between the 2 are a difference of 10. If you have a Dyno jet subtract 10 to get the Mikuni of the same/close to the same size jet. If you have Mikuni do the opposite and add 10 to the jet size to get a Dyno jet of simular size.

 

[Detman101]

If you check out the chart you will notice that the jet size between the 2 are a difference of 10. If you have a Dyno jet subtract 10 to get the Mikuni of the same/close to the same size jet. If you have Mikuni do the opposite and add 10 to the jet size to get a Dyno jet of simular size.

AWESOME!!

Thanks!!!
I believe that may have been the "Rosetta stone" to figuring out how these mains work!!


Dm of mD