Kawasaki Sportsbike Riders Club - Australia - Online Forum

Hi

Just wondering how i go about de-restricting my Balius ZR250. I heard that it was just restricted by a diaphragm in the carbies, is that correct? If you know how to de-restrict it i would like some help.

Cheers
Scott

Hi Scott welcome to the club
You will find that restrictors are generally a plate that reduces the size of the Inlet between the carb & inlet manifold... DO NOT head for the sensitive diaphragm in the carb I would talk to your local mechanic & if they are any good they can help with advice about how to de-restrict it properly.

robracer wrote:Hi Scott welcome to the club
You will find that restrictors are generally a plate that reduces the size of the Inlet between the carb & inlet manifold... DO NOT head for the sensitive diaphragm in the carb I would talk to your local mechanic & if they are any good they can help with advice about how to de-restrict it properly.

+1 Robs right on the money there.

Thanks for the replies, i will get a mechanic and see what advice they can give me in regards to it.

perhaps local Kawasaki salesman will help also

I was speaking to a mechanic and he reckons that if was to de-restrict it that i would loose bottom end power is that correct. Has anyone de-restricted one in the past.

srohara wrote:I was speaking to a mechanic and he reckons that if was to de-restrict it that i would loose bottom end power is that correct. Has anyone de-restricted one in the past.

thats standard with most bikes

can be fixed by droping a tooth from the front sprocket!!!!!

Firstly, the mod of removing the plates is likely reverse-able as they are likely to just be inserts that get slipped into the carb throat just before they are inserted into the carb boot on the engine. They would likely be retained by a small lip that goes around the edge of the carby and retained by being pressed against the boot.

Regarding the performance/behaviour change, they are spot on the money with the compromise between bottom end torque and top end power. Stock, my bike engine was designed as a bit of a mutant with the following long list of mods from the factory to take away from the top end but to give it a much fatter midrange to assist with the design parameters of a long range tourer.

* top end off a gixxer 750, and bottom end off a gsx1100,
* valves 2mm smaller than the ones within a gsxr750 of the era (even though my bikes engine comes in at about 937cc),
* 2mm smaller carbs to go with the smaller valves.
* slightly different grind on the cams,

All of which combined with the fact its a relative long stroker make It's top end no much to write home about (stock at the top end it has 12-15hp down on a zx9 from the same era, even with 30+cc more capacity) but the mid range torque curve is simply divine!! (and one of the reasons i bought it). My adding a straight through pipe didn't sacrifice much of the midrange due to the other factors mentioned above, but made it sound a lot nicer. Apparently a common mod for my bike which did give it a few hp at the top end (but sacrificing a little at the bottom) was to put a gsxr750 cam in)

Anyway, enough talk about mods to change the top vs mid range characteristics and onto your bike, Being a naked bike, they've likely tweaked the cam grind as well as possibly the valve size like they did to mine to give slightly less overlap and increase the midrange. But they may have stuck with a stock head and carb inserts to help with interchangeability & massive cost reduction.

I know that when i had an EL250 years and years ago that the gearing was a lot shorter, meaning great off the line, but it ran out of puff 20km/h or so lower than the gpx250 (same motor) as well as they ran a modified cam grind too.

Sorry about the blabber, but all things to consider if your desiring the elusive HP. But seriously, carb restrictors should be a relative piece of cake to remove.

If i was to de-restrict my bike, would it require new muffler and jets for the carbies also. I really want to de-restrict it but i still want to maintain the bottom end power and power curve. If you could tell me what the best things (mods) to do it would be a great help. I have spoken to 2 mechanics and got different advice. I not sure if they cant be bothered doing the job or what.

srohara wrote:If i was to de-restrict my bike, would it require new muffler and jets for the carbies also. I really want to de-restrict it but i still want to maintain the bottom end power and power curve. If you could tell me what the best things (mods) to do it would be a great help. I have spoken to 2 mechanics and got different advice. I not sure if they cant be bothered doing the job or what.

Personally I would leave it the way it is. Want more power.... learn to ride that bike to its fullest extent, then upgrade 2 a 600 or 1000.
When your licence says you can. Your not going to get that much of a difference with the mods. Just ride the wheels of it first, then buy a bigger cc machine.... then do mods. WOW.
You will only be chasing your tail with this adventure. Cost a lot for bugger all.
Believe me I know, just ask Frank.

Well here's an idea for you, if you still keen on trying this tweak and get around to feeling confident enough to remove the plates yourself. Remove them & take the bike straight down to a dyno that can do a/f measurement and see how the a/f mix works out.

Otherwise, don't worry about it

pilots on the money..............or saving there of..........ride it gain experience and confidence.......money saved goes to upgrade later........hmmmmmmmmm more experience more power

I wasn't aware that they were restricted by carby plates.

Claimed power for a ZXR250 C model is 45 hp. I've a feeling the Balius uses the A model ZXR donk and CDI, which means its claimed 40 hp with a different airbox and exhaust is pretty well right on the money.

Cams, ignition, carbs (if different size) and maybe even the head (can't remember if it was changed) from a C model ZXR would probably net a few horses. A decent exhaust and jetting might let loose a few more, but not many. Seriously not worth the bother or $$ in my opinion.

srohara wrote:I was speaking to a mechanic and he reckons that if was to de-restrict it that i would loose bottom end power is that correct. Has anyone de-restricted one in the past.

Mate, they have 0 bottom end anyways, just do it !

mike-s wrote:Well here's an idea for you, if you still keen on trying this tweak and get around to feeling confident enough to remove the plates yourself. Remove them & take the bike straight down to a dyno that can do a/f measurement and see how the a/f mix works out.

dude, thats what bum dyno is for, and its free