I know the bikes are limited to 180kph/110mph, but my bike seems to stop pulling when it's reaching about 90mph.

I've ordered an de-restricting CDI, but is there any reason you can think of why my bike is stopping 20mph slower than it should be?

Thanks in advance.

Perhaps clean the carbs ? And of course thats 90mph on a private road ?? Lol

Clutch slipping perhaps? Do the revs keep rising but the speedo doesn't?

No, the bikehits about 90 on the clocks, and then the revs stay more or less the same. Going from 5 to 6th is the same problem, but the revs just get a bit lower.

Not had that problem but it does sound as though you have 33bhp restrictors in the carb inlets as that sort of speed is right with them installed.

Brilliant... How the hell do you get them out?

I'm awaiting a Haynes manual for the bike soon, and will be stripping it apart as soon as the time allows.

Take your carbs off, and they will be in the rubber inlets. No need to remove cables. Just loosen the clamps and pull the carbs out. Just make sure you push them back square. A long screw driver will be needed as the inner rubber clamps are hard to get too. And if they are not there, well its good practice!

I didn't get around to taking the carbs themselves off, light wasn't permitting but I did remove the airbox. I found four metal trumpets which sit on top of the carbs, two small, two large. Any idea what they do, and (as I have't got my Haynes yet) which cylinders each size goes back on!

They all have the bellmouths, they speed up the air going into the carbs ! Early ones had two tall two short .
Later ones had 4 short ones . They're not restrictions.

Is it worth having a look down the bellmouths if you have the airbox off? With the bike not running, open the throttle fully, then lift up the vacuum operated bits that i cant remember the name of. you should then be able to see straight down to the valves. I would have thought that you would see the restriction washers if they are in there.