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110mph restriction issue

Posted: Sun Jan 06, 2013 9:17 am
by Joezxr
hello, i own a 1992 zxr 400L model and im having a few problems with the top speed brick walling at 110mph

iv looked around lots of forums and i know about all the restrictions but my problem doesnt really match any of the restrictions that i have been told it could be.

basically my bike revs to 14k in every gear and absolutely flies to 110mph but then stops and is trying to pull further buy really struggles as if its being held back, i have a yoshimura exhaust silencer with the normal manifold but with no restriction plates on the manifold, i have english mph clocks and an UK blue sticker "M" CDI.

i have replaced and maintained everything on my bike that could be effecting this problem but i cannot figure out what is wrong, i have changed all the spark plugs, checked all the HT leads, cleaned my carbs, sealed my airbox and inlet rubbers, replaced all of my fuel lines and made sure they are all clear and my carbs are set to 2 1/4 turns out each, i balanced them the other day and my airbox snorkel/hole bit currently is half taped over to balance out the mixture of air and fuel.

like i said this current set up runs great, the whole rev range is smooth as anything and the plugs are a lovley coffee brown colour! the confusing part is i have had 130mph out of the bike previoulsy with the same engine but im beggining to believe the clocks were lying and i was just sat at 110mph the whole time! the previous owner of the bike who is a friend of mine also said he had around 140mph out of the SP engine he used to have in the bike but also came across this problem eventually and cant remember how he fixed it.

i would just like some advice on what it could possibly be? i have no more ideas... :(

Re: 110mph restriction issue

Posted: Sun Jan 06, 2013 12:16 pm
by CMSMJ1
|Jap bikes have a restriction to 112mph (180kmh)

Feck knows where the restriction is on the ZXR... without getting you to do top speed runs on the HM the Queen's highway it is hard to find it out eh?

I'd guess that the CDI is taking a signal from the clocks - so try unplugging the clocks/speedo drive. then test it ona private road with an assistant..or see if it revs out.

Re: 110mph restriction issue

Posted: Sun Jan 06, 2013 9:56 pm
by thunderace
Unless you're on the race track why is it an issue?

Re: 110mph restriction issue

Posted: Sun Jan 13, 2013 9:24 am
by dobbslc
It's something to do with the pink wire in the speedo, it either needs grounding or a resister putting in it.
For track use only,,,,,,,, :whistle: