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Discussion Starter · #1 ·
Does anyone have experience running Keihin 41mm flatslides on the ZX11? I've read that they are worth a significant power gain. I'm wondering how true this is. Right now my stock carbs have aftermarket jets and needles and are tuned pretty much perfect. I don't want to start a nightmare of tuning if its not going to be worth a reasonable HP gain. I also don't want to sacrifice any drivability / reliability. Right now my ZX is a turnkey machine. Starts right up every time, no stumbles or problems or issues of any kind. Any info on these carbs will be greatly appreciated.
Thanks.
T
 

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I got 93 zx11c came with flat sides , at high speed they ran great but low speed I could load up a set of plug in a heart beat . The was set up to race so I put a set off a zx11d 40mm now I can run on the street but they were fun . Dan
 

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Discussion Starter · #5 ·
You say you have your 11 carbs dialed in perfectly...
I'm curious what main jet size you are using (Dynojet or Keihin jet size since the scales are different), what pipe, air filter and number of turns out on the mixture screws.
Thanks.
I'm not really sure. I know the pipe is a stainless Muzzy 4 into 1. I think its a race pipe because its loud as hell. Its not a pipe that somebody gutted the baffle out. The guy I bought it from (a good friend of mine) paid for the bike to be pro tuned. The guy who did the work put the pipe on, put adjustable cam sprockets on, and did the carbs. I always think its a great idea to do the carbs, cams, and exhaust all at the same time and tune them to each other. Not sure about the air filter, there may not even be one in there (the original owner was that kind of guy). In the next few days I'm going to open it up and look. I have a brand new K&N to put in if the box is empty. I've never had any reason to play with the tune at all. It starts perfect, idles great, and pulls smooth and strong all the way to redline. If I crack it wide open in first it pulls the wheel up easily. I ran low 11's at the strip last summer. A good rider could have gone much quicker, but I'm a novice and really stink off the line. 130 mph trap speeds prove that the HP is there.
 

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I have a set of 41mm FCR carbs on my zx11. I originally purchased the carbs after putting on a SS2R pipe and carbon fiber can, Dyno coils, Vance and hines power pack. The bike pulled harder and longer through ever gear but the low end left alot to be desired. It gives the bike a totally different sound as well. I ended up installing a 1mm over higher compression Muzzy piston kit and what a hugh difference low, mid and top end pull harder than anything I have felt. 2nd gear roll ons at 55 to 60 with no double clutching. I am pretty satisfied, but always want to go fast and pull harder
 

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I think that SwalkerZX11 has hit on something here. The carbs may be too much for a stock engine. The stock carbs are easy to tune and there is a lot to be had in them by tuning to a variety of mods. But the 41 FS's may be overkill without supporting mods. 39's may be be a better choice for a stock motor... just my .02 worth
 

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Do you run the stock airbox with the 41s? I would assume that the airbox is tuned for the 40mm carbs and you would be bottle-necking with the 41s. (especially at low speeds without the help of the ram air)
 
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