also how are the 3tj's top speed restricted?

The top speed is restricted by the CDI. It recieves a signal from the speedo at 0kmh to reset it or it will restrict the engine in all gears, and 180kmh where it cuts the spark to the engine.

Hi guys,

I have a 4dx (3TJ), will this be restricted or full power? What mph top speed should I achieve as stock, any ideas?

The 4DX (European model) is not resricted. Expect about 125mph ... I think. It depends on the speedo a bit too.

I was pulling around 115mph at Cadwell before running out of straight! So that sounds about right as there were still revs to spare. Once my valve clearances are sorted and the carbs balanced 125mph should be achievable easy enough.

just had cdi derestricded wow what a bike now bendy is a star man it has transformed the bike no end made an old man very happy bendy been a realy good lad helped me a lot with jetting ect and by the way he can ride a bike to saw him at oulton well sortted bike well ridden 10 out of 10

Thanks Alfie.

I have a 3TJ track bike that I had some trouble with (it could have been the CDI restricting but the water pump was damaged, so not really sure yet) but am intererested in doing this if it makes sense.

Now as far as I know the engine is stock, so is giving it the increased RPM safe for the einge or are there mods required.

I have a M-max box too so may just put that on and leave it at that.

The CDI puts a speed restriction on the bike, it cuts the spark to one or two cylinders to do it.
Not sure how it cuts when it doesn't get the 0 khm / mph signal but I'd imagine it's the same and it should come in around 12500rpm.

So deresticting the CDI shouldn't change how it makes it's power just add to the top end in all / or top gear. The M-Max box should do the same thing.
I don't know if either of these takes out the rev-limiter at 15500rpm

Dont know about m-max box but de-restricting takes the rev limit higher, I've reved mine to 15k+ on track but not recomended, Generally 14k max.

thanks for the cdi stuart, worked just the same as my other race one before it went pop. may send you my broken one to see if its repairable...!