airbox mods

[blackwolf]

I would like to cut my airbox inhalf, but I'm wondering if it would be to much air and lean the fuel out to much. Idid change the pilot jets andthey are no. 40s it had 35s in it but I had to change them because I put a pair of accel coils on.So what does anybody think of that Idea of cutting the airbox good idea or bad and why .

[Deesel]

Putting extra holes in your airbox will definately lean it out. I opened up my airbox (installed a K&N filter and removed the steel mesh under the filter) on my 82 850L and had to drastically increase the jetting (needles and mains).
I also put on a V&H pipe and made a dramatic performance improvement, both drivability and acceleration without a loss in fuel economy.
It took a little persistance to get it right but I am glad I made the changes.

[brveagle]

Why are you doing it? It's only gonna make your bike run worse.

[Deesel]

Yes if you dont rejet- it will definately run worse.
Modifying my air box and rejetting gave my motorcycle a substancial improvement in performance.

[christopher_2]

I had 29mm smooth bore carbs that were running so rich the bike was cutting out and running rough. I cut the air cleaner back out and put a K & N filter in and it ran much better. It had leaned out enough it stopped cutting out and I actually had to use the choke to start the bike.

[lhanscom]

Why are you doing it? It's only gonna make your bike run worse.

Do you really think the aftermarket would thrive like it does if all it did was make your bike run worse? You may like your bike just as it is, great, but blanket statements discouraging modification because they're going to screw something up is how we breed fear and ignorance of how the mechanics of these bikes work. I apoligize for the soap box episode.

If you're going to do it, have a plan, and have patience, getting it tuned right takes time, and you must be willing to take that time. There are compromises that you will make too, volume goes up, often gas mileage is effected some, though this may have more to do with the rider then the mods, and depending on the bike, rain performance may decline. Making these mods you will probably lose hp in the low rpm range, and gain hp in the high rpms. Usually the engine feels like it will rev quicker too.

[oldschoolGS]

Generally speaking, hacking the airbox is usually a bad idea. Try just removing the lid or snorkle and see how it runs.

The airbox is designed as a plenium to provide even flow to all carbs. Cutting holes or removing pieces is pure trial and mostly error, you will wind up pulling your hair out and become an expert at carb removal/reinstallation. Been there myself.

Now ditching the airbox for pods is a different matter. A specific jet kit and pods is the way to go for performance on GS bikes. The only airbox I would keep installed is that on a FI bike.

Good Luck, Ed.
1983 GS750ED
2005 GSF1200SZ
1992 Ducati 900SS

[Deesel]

oh yeah, the airbox (PLENUM) on my "L" is one sophisticated piece!!!
dont mess with such highly scientific technology like an airbox on a vintage Suzuki GS.
In reality there is nothing that special about these motors.The gs engines are common "well designed" motorcycle engines. They respond great to all the common hot rodding tricks and good tuning.
Its not black magic to find a couple extra horsepower from the factory setup.
Keep in mind, the factory setup is designed to be user friendly so gramma can ride, have good emmissions AND still have some horsepower. This leaves some opportunity for higher performance.

My gramma doesnt ride my bike much anymore and who needs the ozone layer! (just kiddin)

[Nerobro]

On the GS550's the airbox is REALLY important. A lot of strange tricks were pulled to make the BS32SS's work on such a small motor. The manifold from the airbox to the carburators has restrictors in it so each carburator will breathe the same.

I could probally encourage removing the airbox but continuing to use the manifold. However my experiments with removing the airbox were futile untill I went out and got a stage 3 jet kit from dynojet. it turns out that the stock needles taper is WAY off for using the carbs in any way but with the airbox.

Just to add to the confusion, the bike is severely over carburated. They use the same carbs on the GS550, 650, and 850. While that may mean the 850 is a little under carburated both it and the 650 are supposed to make 70 something horsepower. This means the 49hp the 550 puts out is a rediculously small number for the size carbs it's got.

Potentailly the needles from a GS850 might make the 550 carbs run right without the airbox.... I should try that one of these days.

It does sound like you're a little confused. Changing the coils shouldn't require any change of jetting. I still run the stock pilots on my bikes... none have needed any changes in that realm.

[oldschoolGS]

oh yeah, the airbox (PLENUM) on my "L" is one sophisticated piece!!!
dont mess with such highly scientific technology like an airbox on a vintage Suzuki GS.
In reality there is nothing that special about these motors.The gs engines are common "well designed" motorcycle engines. They respond great to all the common hot rodding tricks and good tuning.

You are exactly right, except my definition of "good tuning" does not involve experimental cutting up of the airbox and trying to develop your own jet kit. I was that much of a novice 20 years ago, but have learned from my past mistakes. Since new, my '83 GS750E has run the full spectrum of mods from 747cc to 802cc with several different engine/intake setups. My last setup was GSXR 34CV flatslides with pods and DJ stage 3 kit.

The folks at Dyno Jet and K+N are in business for a reason.

Not one of my three current bikes listed below have stock intake systems with the Bandit and Duc sporting full aftermarket Minuni RS and Keihn FCR carbs respectively.

Tune On, Ed.
1983 GS750ED
2005 GSF1200SZ
1992 900SS