[92xjunker]

If it's going to be a daily driver, flat slides will drive you nuts. You'll have to tune almost every time you take it out. 1 reason why I don't run mine daily. You may just have to use larger CV carbs. GSXFJim is designing a pre single exhaust header with 1 3/4 down tubes. Good luck with it, keep us informed.

[i3notsr]

Yeah...that is why I am going to do the exhaust first then carbs if needed. The more important factor is that as the bike is now the main choke point is the exhaust, open that up first then if needed probably going to a 38mm or 39mmo will be just fine. Right now i'm trying to see if yoshimura will do a custom exhaust seeing as they are only about 30 mins from me. If they wont then I will try 2 brothers (still being in socal). I know holeshot has a system that looks pretty good but it is tuned for stock so that might be a last resort. Buttonwillow is on the 15th of feb, i'll have video and let you guys know how it performs.

[92xjunker]

With better flow and better cams you should be able to run pods and be able to tune them for such. Bench flow numbers would show improvement in efficiency. The early GSXR bikes also ran cv carbs. All yoshi has to do is pull their old info and build one.... That would be awesome... I have a yoshi header on mine, it has 1 7/8 down tubes.

[i3notsr]

Pods are already on and running perfectly. Im hoping thats all yoshi has to do because i cant find an old full exhaust to save my life. I tried to get APE to flowbench the head but they said it didnt matter bla bla bla and i wanted the bike running so i skipped that step lol. The final step will be to fit a small intercooler of some sort along with emulators or a gsxr fork swap. Even leaving the carbs stock i think i should be able to hit about 110ish hp after figuring out how to cool down the intake temp. The bike hit somewhere between 45-50 mph at the top of first flat out and last time i took it to about 75% throttle and it was limited at 9.5k i hit around 40. I could leave the bike alone and be completely satisfied, but whats the fun in that? The goal was and is to see how close to a modern 750 i can get with a motor design from the late 80's.

[92xjunker]

I'll let you know what I can get when mine is ported with larger exhaust valves and a new designed ignition is installed. That's all I have left to do.

[i3notsr]

From what the guys at APE were saying the motor has what might be an 1100 head and larger valves would be perfect. I don't see why Suzuki would have changed the head from pre to post. Can't wait to see your numbers or any other numbers lol.

[92xjunker]

I believe the only change pre to post is the cams, they wanted to get the torque a little more into the usable range.

[i3notsr]

I just remembered that you wrote that you constantly need to mess with your flatslide's. Your issue with the carbs might actually be fixed after you do head work. So much of the mechanical things that people change are dependent on other things that people don't change. A better flowing head may improve the efficiency of your carbs and how often you need to mess with them. Fuel or in this case gas can only burn as long as there is enough air to allow the burn, and airflow is linear. If you are running larger mm carbs then that extra air is being limited by how well the head flows and the exhaust after that. Hence the carbs needing to be constantly re-adjusted.

[92xjunker]

Flat slides are a fixed metered mechanical carb, when the weather changes you need to retune the carbs for it, it's just part of using racing carbs. CV carbs are atmospherically controlled, they will pull fuel depending on air density.

[i3notsr]

Well there is another example of some bike components are different than the same thing on a car lol. I had no idea of that difference, I thought it was just the way the air and fuel were delivered (which I guess that still counts...), just a different way than I thought.

[92xjunker]

same as a car but, a car has variable timing to help compensate. Something bikes don't have so, they will feel the effects more.

[Kreylyn]

Pods are already on and running perfectly.

Flat slides are a fixed metered mechanical carb, when the weather changes you need to retune the carbs for it, it's just part of using racing carbs. CV carbs are atmospherically controlled, they will pull fuel depending on air density.

Well there is another example of some bike components are different than the same thing on a car lol. I had no idea of that difference, I thought it was just the way the air and fuel were delivered (which I guess that still counts...), just a different way than I thought.

IMHO, The biggest contributor to your flat spot is the pods. As 92 was saying, the CV carbs are very dependent upon the air pressures and flow. Pods do not provide enough restriction to give the proper pressures and flow for CV carbs.


Your other changes may decrease that flat spot by increasing flow and/or tuning for that will/may change the range of the flat spot. I don't believe you will ever get rid of it entirely using pods/cv carbs combo unless there are other mods done specifically to address all the problems pods alone cause.


Examples...


Improper shape and fitment that block the pilot and main jet air intakes.
Improper shape with no velocity stack
No pressure balance due to pods being individual instead of a single air source
No blocking/regulation of variable pressures and air flow when in real world enviroments.


and so on...


Krey

[i3notsr]

Hmmmmm...looks like I will be putting the stock box back on to see how that effects things. I understand that the dyno readings show a flat spot, but when riding I feel no lag or hesitation or even what could be described as feeling like a flat spot. I kept the stock specifically for this reason but as of yet it has not seemed like putting it back on was needed. I can't say that changing it out would really hurt anything so I may just throw it on and see what happens. The cool part is putting the old box back on might clean up how the bike looks a little lol, and I get a discount on K&N filters.


Yoshimura emailed me back and told me to go draw fire lol. Pretty much just told me they no longer make anything for any katana's and my best bet would be ebay or a local shop to fab something. Looks like i'm going to go visit Two Brothers and see if they can do it.


I really appreciate people's thoughts and chiming in on all this, it is proving very helpful.

[maniac1886]

If you put the stock airbox back in your wasting your time unless you use a paper filter. No K&N, no foam, no high flow.

[i3notsr]

So even with extra flow and pods working well enough for me not to even notice a flat spot the K&N still will be bad with the stock airbox? I thought that the reason to stay away from the K&N filters and stick to the OEM paper was because it acted like pods. I might try both the paper and the K&N when I throw the stock airbox back in just to see what's what. I'm all for trying different setups with this.