Can a mk1 B12 run well without the airbox ?

[PaintItBlack]

I’m modifying a B12, which has included making up a new subframe, my plan had always been to run a couple of K+n pod filters,

after reading through a few threads it seems the carbs can be very difficult to setup with pods, and some guys have given up and refitted the airbox,

begining to wonder if my plan to fit pods is such a good idea, thing is with the new subframe the airbox isn’t going back in unless I fabricate a new lid to fit between the frame rails, is that a better route than trying to get pods to work,

ive rejetted a few carbs before, but not cv type carbs, and I’ve got an innovate air/fuel gauge which would take a lot of guesswork out of the job,

I do prefer the idea of pods, but can they be made to work well, or should I start making up a new airbox lid ?

thanks for any replies 

[fatblokeonbandit]

Can a mk1 B12 run well without the airbox ?

Yes

 

[PaintItBlack]

13 minutes ago, fatblokeonbandit said:

Can a mk1 B12 run well without the airbox ?

Yes

 

Thanks, nice looking bike you got there 

was it a real pain to jet correctly?

did you have to use a dynojet kit ?

edit: just spotted your not not using stock carbs

Edited October 18, 2023 by PaintItBlack

[Gixer1460]

Dual pods - yes, Individual pods - no! And with stock carbs - usually a DJ kit (or others are available but i've not used them) works mint!

Don't ask me why, its just fact. Many have tried 4 singles with varying results usually unsatisfactory!

[fatblokeonbandit]

was it a pain to jet?? no i took it to a dyno and had it set up properely, that was about 8 years ago, all ive done since is clean them once and balance the cabrs every year.. works a treat, pulls well..

 

many years ago i spent 2 days with a big box of jets and a dyno jet kit, got it running well, or so I thought, had it dynoed later and the improvment wass amazing.. 

[PaintItBlack]

Thank you chaps that’s very helpful, and the answer I was hoping for

I’ll not waste anymore time trying to shoehorn the airbox into a space that it don’t want to go 

[TonyGee]

my setup on my zed project.

B12 engine and carbs.

ive used the airbox rubbers (of the airbox) and 4 ramair sponge filters. 

150 main jets

needles in the highest position ( clip in the lowest position ) 

mixture screws 3 1/2 turns out  (you might have to tweak them slightly) 

exhaust, black widow  headers and link pipe, cheap Chinese end can.  

bike runs great right up to 7000rpm. haven't had it any higher than that as run out of road where I live, but I think it will pull up to the limiter no problem.  plugs look good after a plug chop. 

[PaintItBlack]

12 minutes ago, TonyGee said:

my setup on my zed project.

B12 engine and carbs.

ive used the airbox rubbers (of the airbox) and 4 ramair sponge filters. 

150 main jets

needles in the highest position ( clip in the lowest position ) 

mixture screws 3 1/2 turns out  (you might have to tweak them slightly) 

exhaust, black widow  headers and link pipe, cheap Chinese end can.  

bike runs great right up to 7000rpm. haven't had it any higher than that as run out of road where I live, but I think it will pull up to the limiter no problem.  plugs look good after a plug chop. 

Thanks, I’ll give that a go before splashing out on a dynojet kit,

I’ve got a similar exhaust setup to you, so could be pretty close,

long way off setting up the carbs yet though, but knowing it should run well without the airbox is a big help 

[TonyGee]

9 minutes ago, PaintItBlack said:

Thanks, I’ll give that a go before splashing out on a dynojet kit,

I’ve got a similar exhaust setup to you, so could be pretty close,

long way off setting up the carbs yet though, but knowing it should run well without the airbox is a big help 

one of the lads on here give me the settings but for the life of me I can't remember who  but I was happy as the bike runs great, just cost me the price of the main jets and filters.  

[Upshotknothole]

I've been seeing an uptick in people on the internet claiming that you need an air box to get maximum HP out of these old GSXR engines lately, especially over on facebook. If that was true, all of the old racers would have kept the air boxes. Fuel injected bikes, thumpers, bikes with ram air and down draft carbs, yeah they need air boxes. Bandits and GSXRs are mostly fine without them.

You want the dual pod filters, don't use the singles. Explanation I heard years ago was the dual pods give more standing air for the carbs to draw from, lets them breath a little better. Whether that's actually true or not, who knows, it's just what I was told and has been my experience with individual pods ever since.

Most of the stock bandit/gsxr carbs work great without an airbox, the BST40s being the exception. Just extremely hard to tune with pods.

A jet kit from DynoJet or FactoryPro will get you pretty close to where you want to be, a dyno will always get it the rest of the way.

[TonyGee]

24 minutes ago, Upshotknothole said:

ou want the dual pod filters, don't use the singles. Explanation I heard years ago was the dual pods give more standing air for the carbs to draw from, lets them breath a little better. Whether that's actually true or not, who knows, it's just what I was told and has been my experience with individual pods ever since.

yeah thats what I heard, but my thinking was using single sponge filters on each of the airbox rubbers would seal better than one sponge filter across  2  airbox rubbers and leaving a gap between them, if that makes sense !!!!!!   

saying that it seems to work. 

Edited October 18, 2023 by TonyGee

[Upshotknothole]

27 minutes ago, TonyGee said:

yeah thats what I heard, but my thinking was using single sponge filters on each of the airbox rubbers would seal better than one sponge filter across  2  airbox rubbers and leaving a gap between them, if that makes sense !!!!!!   

saying that it seems to work. 

The ram air filters flow a lot better than the K&Ns and the airbox rubbers probably help too. I still use K&Ns with CV carbs, but I use dual ram air with velocity stacks on flat slides.

[PaintItBlack]

57 minutes ago, Upshotknothole said:

I've been seeing an uptick in people on the internet claiming that you need an air box to get maximum HP out of these old GSXR engines lately, especially over on facebook. If that was true, all of the old racers would have kept the air boxes. Fuel injected bikes, thumpers, bikes with ram air and down draft carbs, yeah they need air boxes. Bandits and GSXRs are mostly fine without them.

You want the dual pod filters, don't use the singles. Explanation I heard years ago was the dual pods give more standing air for the carbs to draw from, lets them breath a little better. Whether that's actually true or not, who knows, it's just what I was told and has been my experience with individual pods ever since.

Most of the stock bandit/gsxr carbs work great without an airbox, the BST40s being the exception. Just extremely hard to tune with pods.

A jet kit from DynoJet or FactoryPro will get you pretty close to where you want to be, a dyno will always get it the rest of the way.

Thanks, feeling a lot more confident about not using the airbox, 

Twin pods had been my plan from the start ,but a few threads from guys that couldn’t sort their jetting had me questioning that decision 

[TonyGee]

2 minutes ago, PaintItBlack said:

Thanks, feeling a lot more confident about not using the airbox, 

Twin pods had been my plan from the start ,but a few threads from guys that couldn’t sort their jetting had me questioning that decision 

the settings i posted will work on some bikes but might not on others, they where base settings but worked great on my bike. its all trial and error with jetting. 

[clivegto]

Tony is pretty close to the mark in my experience. 

[Joseph]

7 hours ago, TonyGee said:

my setup on my zed project.

B12 engine and carbs.

ive used the airbox rubbers (of the airbox) and 4 ramair sponge filters. 

150 main jets

needles in the highest position ( clip in the lowest position ) 

mixture screws 3 1/2 turns out  (you might have to tweak them slightly) 

exhaust, black widow  headers and link pipe, cheap Chinese end can.  

bike runs great right up to 7000rpm. haven't had it any higher than that as run out of road where I live, but I think it will pull up to the limiter no problem.  plugs look good after a plug chop. 

Currently trying to set up my 1127R engine with BST34

I have KN single pods and the exact same exhaust as you, currently on 140 mains, 3 turns and middle notch needles, it's sluggish when you try to give it beans, so sounds like i need to up the game ?

[Upshotknothole]

9 minutes ago, Joseph said:

Currently trying to set up my 1127R engine with BST34

I have KN single pods and the exact same exhaust as you, currently on 140 mains, 3 turns and middle notch needles, it's sluggish when you try to give it beans, so sounds like i need to up the game ?

Dual pods will make it run a lot better.

[TonyGee]

36 minutes ago, clivegto said:

Tony is pretty close to the mark in my experience. 

was it you who give me the settings Clive ? 

[Joseph]

7 minutes ago, Upshotknothole said:

Dual pods will make it run a lot better.

I saw that you wrote that but unfortunately i'm going to have to stick with the singles on this bike

[Upshotknothole]

4 minutes ago, Joseph said:

I saw that you wrote that but unfortunately i'm going to have to stick with the singles on this bike

If you have to use singles, it seems like the foam filters with the air box rubbers works better. Either way it'll probably need an afternoon on the dyno to get sorted.

[Joseph]

Can't do dyno either. Nobody offers dyno carburetor set up in the country i live in 

[Upshotknothole]

2 hours ago, Joseph said:

Can't do dyno either. Nobody offers dyno carburetor set up in the country i live in 

I've got the same problem where I'm at. Hand full of shops around with dynos, but if they can't tune your bike with a computer, they don't even want to talk to you.

[2scars]

In my area most won’t run it unless they did the work to the engine.  Drives me crazy.