This has probably been covered many times but after a while searching I'm struggling to find the info

So I bought my road fzr the other day.. noticed after first ride that it doesn't want to rev above 9500 rpm

I've checked the following
Exup working
new fuel filter
carbs clean - even swapped the ones off my race 3tj
swapped the cdi off my race bike too ( same code but it's been sorted by bdk)

There is a green/ red wire that is out of a 3 pin block connecter that's just taped up

I've tried to compare to my race bike but it has a race loom and so minimal

anyway after changing it all it still wont rev any higher

I'm not the best with electrics lol

Um ... that's odd. It's not the restriction that's causing it.

The restriction is
If the bike doesn't get a 0 kmh signal when the ignition comes on it restricts to 12.5k rpm in all gears. Otherwise it restricts to 180kmh (112mph) in top gear only.
It hits a soft limiter cutting a cylinder and then cutting a second one.

Check the carb jets are in the right places, if the idle jets are swapped with the mains it won't rev clean past 8k

Thanks for the reply .. I'm going down the wrong route then

The only other thing I noticed was that the tank was pressurised after a ride ( hissing as the air/ gas trying to escape) - I used compressed air on the tank vent to try and clear it

I now wonder if the pressure is not letting the fuel feed enough at high rpm

I would have said carbs myself bit ruled it out by swapping them

Also the BDK TCI would eliminate the restriction.

You are correct in the green/red is part of the restriction circuit.


Boris' suggestion on transposed jets is normally a goer . Starters and mains. BUT in this case you swapped carbs so NO.


Swap complete coils from your race bike.


A duff plug , even from new is not unheard of.

After that its a leakdown and compression test.

Edit; I composed this after you just replied to Evil;

Sort the tank cap any how.

Try swapping your End Can and Full Pipe to eliminate that part of the equation.

The tank vents through the filler cap take it apart from the underside.
Could be a coil breakdown

Right I'm working on it now ... left the cap unlocked and went up the road

It is slightly better that I can get to 9500 rpm.. roll off the throttle a little and it will get to 10 k

Just taking the plugs out and I guess it's worth swapping the coils

Oh and in neutral sat still it wil rev beyond with no hint of a flat spot or miss fire so it's linked with it being under load I guess


Bloody bikes lol

Fuel pump/fuel pump relay? restrictive fuel filter? is there a filter in the end of the fuel line (where it joins the carbs), my exup had a wee plastic sock type filter that pushed inside the red fuel hose. could have some debris in it.....

Arrrggghhhh

I've lock wired the exup open to just make sure it's having no impact on things ( it does rattle )

Changed the fuel pump to a spare one ( I convinced myself the old one seemed lazy as it was only having the odd click even though I could see there was no fuel in the new filter)
Changed the plugs

Checked them chris .. flowing fuel from the tank and no sock filter pal


Still no joy - as mentioned above I should swap the header pipes