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Hey everybody, got my restrictor kit in as of a few days ago and had my first day riding yestarday (it was awesome). I found that to hit the higher speeds the bike requires you to go OVER the restriction wich cuts in at around 8k? So its essentially running up to around 10k but im assuming its not recieiving the correct mixture at those revs (hence the restriction). I wander if this might damage the bike in any way? Any help on this matter would be great, cheers guys.

Assuming that the restrictor kit you have fitted is the washers with holes in.................these do NOT restrict revs at all

I see! So when it reaches the point where the restrictor is effecting performance, (i.e anything over 8k) what acctually happens that stops the power? I like to understand how things work so if you dont mind explaining a little that would be much appreciated !!

I'd guess you have a restricted Jap market bike and its not been properly de restricted. And it has good to the 10K default set limit

when my bike was restricted it did redline when in manuel but when underload in the gears it wouldnt well 1st and 2nd it would but after that it wouldnt because it takes too long for the bike to redline in thsese gears through only having 33bhp it has got te power to redline but will take a long time hence why i only took it over 10,000rpm in 1st and 2nd ......does this help???

It you can red-line it then i'm assuming the JDM (Japanese 180km/h speedo restriction or rev limiter if it's removed isn't coming into play)

So as for your 33bhp restriction.

They are washers fitted into the carb inlet rubbers... these create a smaller intake port so the engine cannot receive as much fuel / air as it would without them.

Think of it like the water saves you can get that screw onto taps that just restrict the flow.

This is all they do.

You should be able to rev it to whatever, the only difference is at WOT (Wide open throttle) your maximum power will be limited as your engine can't take in as much fuel air mix as it otherwise would.

These are some very good replies thanks guys. When i say restricted i mean iv fitted the 33bhp washers! Im just trying to understand how to get the best acceleration out of the bike out of curiosity! I.E Is it still best to run it up to 12k or more before switching up a gear? To me it still feels like its pulling a lot in these higher revs, im doing 90 in 3rd etc. Should i be changing gears earlier? I was under the impression the bike created 33bhp at around 8k hence i assumed your sposed to change gear at 8k with the restrictor in! Id really like to work this out so keep it coming guys!!!

Crustis1 wrote: im doing 90 in 3rd etc.

mines much the same lol and magic things happen when it hits 10k revs aswell

Is yours restricted too?

no,
u tested urs to see if its actually restricted?

I put all four washers in myself LOL .

yeh but did u make em or did u buy em and if u bought/made them are they specific to the zxr400? slightly off and it wont restrict properly lol

Get it on a dyno and see how many bhp it's making.

You can rev it as much as you want... if you've made the inlets smaller then it won't be able to produce as much power.

How much power it's actually making now is anyones guess! If there ZXR 33bhp washers it wont' be far of.. so no matter how much you rev it you won't get more than 33bhp.

This still doesn't mean you can't go fast.. it's a lightweight bike compared to a car.

An average family car will make around 120bhp and weigh maybe 2000kg?

even 33bhp with a sub 200kg bike and you can see...

10 x ligher but only 4 x less power

Thankyou for the responses!! x

Take the f@&kin washers out and let the engine breath mate and have fun.