RVF 400 won't rev past 12000 in 4th

gsxrchris · Post by **gsxrchris** » Wed Feb 15, 2012 5:15 pm

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Hi fellas.
I am in need of some ideas with my little RVF400.
she rides and accelerates what seems ok in the first 3 gears going all the way to 14500rpm red line, but as soon as she is in 4th and she creeps past 11500rpm to 12000rpm which is around 115 mph and won't go any more. My old vfr 400 NC30 went all the to the red line in every gear so i know how they should go.
I know about deresticting in the back of the speedo which is KPH clock and have fitted a MPH converter so the speed needle never gets round to the area of restriction plus the bike also has the derestrictor box fitted too for the electrics. I have had it on a dyno and the dyno sheet says 62 hp and fuelling is ok, but the guy did say he deals with more modern fuel injected bike with ECU's fitted so had no ideas. It has a after market exhaust system fitted but with the dyno readout it seems the fueling is ok.
So any ideas would be very much appreciated.

gsxrchris · Post by **gsxrchris** » Wed Feb 15, 2012 5:27 pm

A quick addition to the above, whilst on the dyno the fella said there is no problem seen like what I have just described and he has a brake dyno and he told me he put a brake load of around 15% to 20% so it seems to me that the problem is when being ridden with all that ram air???

Post by **thunderace** » Wed Feb 15, 2012 6:22 pm

gsxrchris wrote:as soon as she is in 4th and she creeps past 11500rpm to 12000rpm which is around 115 mph and won't go any more.

That's plenty more than fast enough for UK roads, I'd not worry about it

Post by **Drunkn Munky** » Wed Feb 15, 2012 6:32 pm

Isnt 115mph the usual jap restriction speed?? sounds like your derestriction box isnt working. Also i dont think RVF's are restricted behind the clocks like VFR's are, Just remove that derestriction box and connect the orange/blue wire from the CDI to +12v

Post by **kevprojex** » Wed Feb 15, 2012 9:34 pm

Drunkn Munky wrote:Isnt 115mph the usual jap restriction speed?? sounds like your derestriction box isnt working. Also i dont think RVF's are restricted behind the clocks like VFR's are, Just remove that derestriction box and connect the orange/blue wire from the CDI to +12v

Sounds like the restriction to me as well because 62bhp at the wheel will take it past that speed with ease.

arsey30 · Post by **arsey30** » Sat Feb 18, 2012 7:23 pm

I read on another forum that NC35s were never speed restricted, as the max power [54hp?] was within the Japanese speed/power limits at that time.
My nc35 has the 3 wire connector going into the speedo head, so what is it for.

I de restricted mine with a 2k ohm resistsor before riding it, so don't know if it needed it or not.

Post by **Speedy** » Sat Feb 18, 2012 9:00 pm

The NC35 is speed restricted, much like most (if not all) 400cc Japanese imports!
The restriction on the 35 works in the exact same way as the 30, though there are slight differences on the mechanisms found inside the speedo!
You can find an article I made quite some time ago, on how to de-restrict the NC35, on the link below:
http://www.veaminicori.talktalk.net/workshop.htm

gsxrchris, that sounds like the speed restriction (180Kph or 112Mph), but with the MPH converter it shouldn't be, so I'm stumped!

Also, you don't need the derestrictor box when you got the converter.

Post by **Neosophist** » Sun Feb 19, 2012 4:30 am

as above.. the NC35 is restricted to 180km/h as all Japanese vehicles are.

The 53hp was just a change in the legislation from 1992 onwareds I believe. It changed so that a 400cc couldn't produce more than 53hp (no % tolerance), the previous older legislation was no more than 53 +/- 10% (which is why all the JDM bikes produced 59ps)

It's scrapped all together now, but the 53ps is still enough to go over the speed limit hence the restriction.

For the OP.

It's interesting.. maybe it's all the bike has, is the gearing stock?

The restrictor shouldn't kick in if you have a delimiter box connected, if your box wasn't working the bike would misfire over 5500rpm.

Is the vaccum pipe ok? Sometimes at high speed it can collapse on itself shutting off the fuel, which gives you a misfire / running out of fuel like situation at high speed.

gsxrchris · Post by **gsxrchris** » Wed Feb 22, 2012 6:12 pm

Many thanks for the replies so far. Will hope to ae play with it at the weekend.
Will let you all know how I get on.

RVF 400 won't rev past 12000 in 4th

RVF 400 won't rev past 12000 in 4th

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Re: RVF 400 won't rev past 12000 in 4th

Re: RVF 400 won't rev past 12000 in 4th

Re: RVF 400 won't rev past 12000 in 4th

Re: RVF 400 won't rev past 12000 in 4th

Re: RVF 400 won't rev past 12000 in 4th

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