New MAC 2-1 exhaust

[Guest]

Hello, I just ordered a new MAC 2-1 exhaust for my '82 GS450L.

I know it'll force me to change something with the carbs, but what, and how?

I tried searching this section of the forum for these keywords: 'exhaust carbs', 'new exhaust carb', 'carb sync exhaust', and 'new exhaust carb sync' and nothing showed up.

Are there any threads\topics that already talk about this? If so where, and if not how should I go about doing this?

Will I actually need to do anything if I replace the stock 1-1 with a MAC 2-1?

Thanks in advance, and here's the one I purchased:

http://www.ebay.com/itm/161063713084?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

[earlfor]

The Mac exhaust is sold as not requiring rejetting.

[incarceration]

Really? That's awesome news!
I thought it may cause it seemed to change a lot, and the listing also mentioned it.

thanks for the great news! lol

[tkent02]

Really? That's awesome news!
I thought it may cause it seemed to change a lot, and the listing also mentioned it.

thanks for the great news! lol

Well, it might. check it out when you first start running it. These bikes are lean anyway, if it goes a little leaner with the pipe that might be bad.

[pete]

Hmmm... the description indicates otherwise...

Suzuki GS400/425/450 2-1 Black

Description:

Improves performance by increasing power, along with decreasing weight
Increased ground clearance
Does not block center stand, oil filter or drain plug access
Removable all steel, mechanical baffle
NOTE: Exhaust gaskets are not included, but may be purchased separately if required..
NOTE: Carburetor re-jetting may be desired for best performance.
Please Note: Installation of an aftermarket, performance exhaust system may change your motorcycles air-to-fuel requirements.

Exhaust discoloration (Blueing) is caused by engine conditions such as cam timing, fuel-to-air mixture, operating temperature, etc. It is not a result of defective manufacturing, therefore it is not covered by any warranty.


Having a hard time finding exactly what you need? Let us know. We are here to help!

It doesn't say you *have* to, but says you may need to... so best to do some plug chops after installation to check things out.

Do a search here on "tuning and jetting 450" and you should find my thread on the topic, may or may not help... I'm feeling a little too lazy to go find it myself and post it

[incarceration]

Well, it might. check it out when you first start running it. These bikes are lean anyway, if it goes a little leaner with the pipe that might be bad.

Will it be easy to tell?

... so best to do some plug chops after installation to check things out.

I'm sorry, but what are "plug chops"? I'm assuming looking at the spark plug ends after running it for X amount of time?

[cowboyup3371]

From Basscliff's site - http://members.dslextreme.com/users/...plug_chop.html

[incarceration]

Lol thanks.

I was just reading this, but doesn't seem to be one for a novice in the terminology.

http://www.snowvalley.20m.com/bikes/jets.htm

[tkent02]

Considering running too lean can be very expensive, I wouldn't take the chance.

It can't make more power without flowing more air. If it flows more air it will probably be leaner.

They were on the edge of being too lean from the factory. A lot of GSes benefit from a little richening of the mixtures even without any pipe change.

Just make sure.

[incarceration]

Considering running too lean can be very expensive, I wouldn't take the chance.

It can't make more power without flowing more air. If it flows more air it will probably be leaner.

They were on the edge of being too lean from the factory. A lot of GSes benefit from a little richening of the mixtures even without any pipe change.

Just make sure.

So I'll more than likely need to adjust the screw between the 2 carbs, right?
I don't really know any other adjustments that can be made without taking the carbs off again (really don't wanna have to do that again, that was a nightmare!)

[tkent02]

So I'll more than likely need to adjust the screw between the 2 carbs, right?
I don't really know any other adjustments that can be made without taking the carbs off again (really don't wanna have to do that again, that was a nightmare!)

No, if it's running lean you need to do more. Jet changes, needle positions, stuff like that.

If you think pulling the carbs is a nightmare, you should try replacing burnt valves.

[derwood]

pulling the carbs isn't to tough on a twin,
there are "jet kits around that will help a lot with getting it dialled in....

http://www.ebay.com/sch/i.html?_trksid=p2047675.m570.l1313.TR0.TRC0.X+Suzuki+GS450+GS+450+S+T+L+E+6+Sigma+Custom+Carburetor+Carb+Stage+1-3+Jet+Kit&_nkw=+Suzuki+GS450+GS+450+S+T+L+E+6+Sigma+Custom+Carburetor+Carb+Stage+1-3+Jet+Kit&_sacat=0&_from=R40

http://www.starcycle-usa.com/servlet/the-68812/83_Suzuki_GS450_Standard_Float_Dynojet_Motorcycle_Carburetor_Jet_Kit_-dsh-_Stage_1_%26_3-83-Suzuki-GS450/Detail

[pete]

Pull the carbs one more time, but replace all the philips head screws with allen heads.

Get a small allen key and you can do all your jetting changes without having to remove the carbs any more.

I can do main and pilot jets (both are in the float bowls) and adjust the needle without removing the carbs.

I did my slide and slide spring modifications also without removing the carbs.

Nice and easy on our 450's!

[incarceration]

Pull the carbs one more time, but replace all the philips head screws with allen heads.

Get a small allen key and you can do all your jetting changes without having to remove the carbs any more.

I can do main and pilot jets (both are in the float bowls) and adjust the needle without removing the carbs.

I did my slide and slide spring modifications also without removing the carbs.

Nice and easy on our 450's!

When I did my last pull and cleaning I did just that; I replaced all screws with allen keyed screws (which btw are fu*king rusting already!)

So how do I rejet without repulling?

[pete]

With the right sized allen key (mine's about two inches long or shorter), you can remove the float bowls with the carbs in place.

That allows you to swap the pilot and main jets out.

With the tank off and a longer allen key (I have one about 4 inches long or so), you can get the diaphragm covers off and carefully lift the slides up and out from under the frame top tubes again with the carbs in place.

I was sure I had a photo of taking the float bowls out but can't find it, however here's one showing the slides fit out under the frame rails: