I have just about replaced everything on the bike. Exup is free to operate, carbs cleaned and balanced, fuel pump squirts fuel across room when disconnected from the carb feed, all carb slides rise at same rate when throttle opened. On the stand the bike revs in what appears to be a good way. As soon as I drop in gear it loses power and dies. I have ordered a new CDI box and a pair of used coils although not yet installed. Is there something I am missing as it is driving me crazy. I have checked the carbs refil with fuel, I know it fuels and sparks because it runs so well on the stand. Just no power under load. Please help?

Have you tried disconecting the exup ?

Yes disconnected servo cables and ran the bike with valve open? It displays same symptoms albeit sounding much 'throatier'

I have to say I'm a bit stumped, but breaking down under load sounds electrical. Other than swapping stuff out and hoping the only thing I could suggest is a dyno run ... but then it's not going to pull a gear to do that.

You haven't tried to derestrict it, or fiddled with the wires behind the clocks ??? It could be a dodgy earth on the restriction or low fuel circuit somehow causing the cdi run the restriction (cutting two cylinders) but that's just a stab in the dark.

The bike has replacement clocks in km.

I will fit coils and CDI unit. I'll see how that goes. All cylinders have similar compression and it runs in what appears to be good order on the stand. Starts first time without choke. After I have changed coils and CDI it will narrow down the problem I guess.

The speedo has wires coming out the back that go into the loom ???

3TJ's have a top speed restriction, if you try to remove it then the cdi will restrict in all gears, it shouldn't affect the bike below 12,500 rpm though.

The revs dontt get any where near that range? The power is cut almost immediately

holland389 wrote: The power is cut almost immediately

another shot in the dark
is this when you pull the clutch in, put it in gear, or let the clutch out
as this does sound electrical, and could be as simple as a faulty neutral or clutch switch
will it run ok if you go up through the gears on a paddock stand, if so none of the above

EDIT just re-read this thread
is the bike an fzr400rr 3tj or the fzr400rr 4dx, the later being the english model
(1993 don't mean diddle, if that's what the log book says, mine says 1992 and it's a 1989)
easiest way to tell is the rear light, the 3tj is sexy ( 2 horizontal lights one above the other and quite small)
the 4dx has, what can only be described as, a caravan rear light ( big and ugly), MPH clocks and an oil cooler etc

if so the replacement clocks (in KPH) could be the problem