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Been out on bike to day and when got to 90 it just didn't want t go any faster throttle was fully open . Plus the bike don't seem quick enough for a 400 . Any ideas ppm? Cheers

fuel > Air mixture is well off. mine done the same until i covered up 1/3 of the snorkel

So I'm gathering that's on the carbs. Another thing it does is when stop at lights revs stay pretty high for a few mins then calm down around 3k does this when warm

I have put this post on here as I didn't know if the bike was restricted or not !

it doesnt sound like its restricted, sound like you have an air leak going by the hanging revs when you pull up to a stop. The inlet rubbers are usually the cause for that, a bit of sealant between the inlet and the engine block usually cures it, or if you really fussy new o'rings. Might also want to check the carb clamps are done up tightly too, no going any faster than 90 suggests its more than a small air leak. Also check the airbox is sitting flush on top of the carbs.

The hanging revs do suggest an air leak, but i wouldn't have thought that would account for it not going over 90.... This does sound like it could be a 33hp restriction, although even then they tend to be able to go more than 90. With a strong tail wind my old vfr would just about do 90 restricted AND running on 3 cyclinders.

Check all ure downpipes are getting hot to make sure it is running 4...

sounds like to me it is restricted.........does it rev out fully in the lower gears?? as the restrictor plates can also cause air leaks causing the hanging revs and lower top end.

Whats it rev to off load 10k or 12.5K ?

It revs to around 12 . Checked the Cdi unit and it's blue with an m on so won't be that. And it's a uk bike. It seems to struggle after 70. Really jerky. Will have to try some were on Monday to have a look at the carbs . 1&2 nd all seem good and no limitnon that.

agree with cansa. Sounds like it needs a Dynojet kit or similar. Does full throttle work at all?

How long have you had the bike & has it always been like it ?

has it got uk carbs on it?they havent been replaced for 30mm ones have they??
mine is a uk spec bike and revs to 14k......
start with all the basics though.......check fuel pump, air leaks, spark plugs etc