tabby59

All of the air/oil cooled motors have the same bore center dimensions, so head pipe fit into the ports are the same. Primary pipe length from the 750s to the 1100s may be different. The 750s in general will rev higher than the 1100s, so the primary pipes may be shorter. Add in that different the different strokes of the different motors will affect the cylinder height. Also, there may be some different oil pan dimensions that add or subtract material that can make a difference in fitment. I'm sorry if I am not giving you a fast and easy answer. I'm just giving you a handful of variables to ponder. If you are creative, you may be able fit something up that was unexpected. A small example of a non fit. I have a 1993 GSX1100G{1127 upper end}. I tried to fit a Bandit 1200 pipe to it, but the cases for the shafty were different enough from the Bandit, that there wasn't enough room for the primary pipes the clear the bottom of the cases. And this is BEFORE you consider possible clearance issues with the mid pipe to the frame, etc.

Thanks nelson! I'm not used to your dyno sheets. I was looking at the bottom graph. AFRs? The K&Ns on the 40s looked like it went lean up top. The Pipers went rich? I can't read the graphs very well. I don't know if you pay as big a "penalty" for being too big with CV carbs. I would imagine that if an engine couldn't quite pull enough air through one, the vacuum slide just wouldn't retract all the way?? Might it still maintain a constant velocity? So much I don't know about fuel mixers.

Wow,,,,,, you weren't messing around notching the K&Ns. Something to consider. I have RS38s, which both the Piper and the K&N don't really fit. I had to make aluminum sleeves that I shrunk fit onto the RSs,,,,, with some additional "adapting" shall we say. The Pipers definitely have more room. You are right about a direct comparison. Too bad you didn't try the Pipers on the 40s. My engine is a hot rodded 750/907. It made 142 rwhp without filters, 138 with individual K&N pods. My engine builder said to run the duals to get the 4 hp back. If you are curious, you can see my dyno sheets in one of my Facebook albums. Just look up Tab Burgess

Hi folks. I'm just checking in to see if any of you have used these filters on your A/O motors and what are your thoughts. I'd especially be interested in how they compare to the K&N RU-2922. The K&Ns push against the frame of my Slabby enough to push them down some, while the MPX 1004 looks to be tapered a bit and might fit in there better. Dyno comparisons would be greatly appreciated if you have them. If the Pipers flow as well, great, I might give them a try. If not, well, I'll be less inclined.

If everything is indeed DynoJet Stg3, I would see if you can get a copy of the initial setup sheet or instructions. I've installed several DynoJet kits and have had few, if any problems, with the initial setup. It always helps to go back to basics and baselines, then make one change at a time. Typically, I'll install the smallest main jets that came with the kit, set the fuel screws at the recommended settings, install the jet needles at the baseline setting. I'll start tuning by dropping the needles until drivability suffers. If it is already being fussy, I'll still drop the needles to confirm whether it is indeed lean or rich. If it gets worse, it is already lean. If it gets better, then it was too rich. I always shoot for just enough needle height above being too lean. Once that is settled, then I'll start to see how little fuel screw I'll need to maintain a smooth idle. On my 86 GSXR750, using 87 34mm carbs, it would idle fine and carburate with as little as a 1/2 turn of screw. I save the main jet for last, and usually will make that decision with the help of the drag strip.

OK, next question, what jets, needle, fuel screw settings are you using? The more you give us, the better we can diagnose what your bike is doing.

What bike/year/carbs do you have?

I'd do either a Factory Pro or Dynojet kit and some quality time on a dyno measuring the AFR, with the K&Ns. Just throwing main jets at it isn't going to be very successful. A good jet kit will help improve the lift rates of the CV slides and supply jet needles to match the lift rates.

Have you even taken the valve cover off to see what is going on in there? It could just be loose valve clearances, maybe a cam lobe gone to crap, and yeah, you can see if the springs are up to snuff.

I'm here in the US. Over here I would look up a company like Sudco and see what specific FCR there was for your GSXR. I have Mikuni RS38s on my 86 750/907, and Sudco has the specific RS carb set and jetting specs online. I'm sure with enough digging you can find that kind of info.

I dug around the net to find the "left side bell crank" shaft part number, Mikuni # 700-17012. For those of you considering the swap. http://www.dynoman.net/carb/pdf/mikRS-access.pdf

I don't have the part number handy, but all you have to do is order the shaft made to do that,,,, that's it. All the parts swap over. You have to have some patience doing the swap. Some of the parts are a bit tiny{spring pins!} so you have to be careful not to lose any. You don't have to break the carbs off the rack either. The carbs will have to be re-synched afterwards. It helps if you do a crude manual synch of the slides. I used a small drill bit on carb #3, adjusted the idle screw to get a very light drag on the bit, under the slide, then adjusted the other 3 to match that drag. Then I got out my Morgan Carbtune.

Foz, I know what you mean on the "heavy throttle". I converted my RS38s to a side pull and when I did, I ditched the second return spring, and put the first one on the least preload peg. Works just fine on the street

I have RS38s on my modded 750/907 and they work just fine on the street. My last tank of gas, on a memorial ride, I got 52 mpg {US gallon}. I'm using 16/40 sprockets and can short shift into 6th by 35 mph. So yeah, RS38s on your motor ought to work real well. I'd still look into getting those FCRs dialed in. Spend some money with a good dyno shop to get the jetting just right.

91 will be fine with that bike. OEM compression on that motor is 10.6:1 if I remember correctly. Using a higher octane will just empty your wallet quicker. There are no ill effects to using the higher octane, it doesn't "burn hotter". Higher octane fuels have a higher "latent heat of combustion" point, or the temperature where it will self ignite. That is so when used in higher CR motors it will help prevent pinging or knocking.