Rvf400 restriction kit ???

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Rushvf1
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Rvf400 restriction kit ???

Post by Rushvf1 » Thu Oct 25, 2018 12:53 pm

Hey all. First question, my rvf400 is a Australian grey import. Just starting to look at info and found a bit about restriction kit. I'm assuming it would have one in it. If so can anyone provide more info? Cheers

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NGneer
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Re: Rvf400 restriction kit ???

Post by NGneer » Thu Oct 25, 2018 6:03 pm

Due to rules at the time the 400cc bikes in the Japanese market were 'speed' restricted to a top Speed of 180kmh (110mph).

The restriction is by means of an optical sensor inside the speedometer, and a black sector attached to the indicator needle shaft. When the needle swings round to 180 km/h (110 mph) the sector starts to block the sensor, ignition is then cut to the front two cylinders thereby reducing power such that the motorcycle can not accelerate further.

The good News is these restrictions can be removed through various means.
1. You can split your clocks and remove part of the sensor.
2. Buy a KMH to MPH converter that goes between the speedo cable and the speedo istelf so the clock actuall reads in MPH and you will never reach 180mph so no Problem.
3. Buy a plug and play "black box" which plugs into the existing loom and effectivly blocks the signal to cut the ignition to the front two cyliders. cheap as chips and widely avaiable.
4. Buy yourself some resistors and build your own (see http://www.400greybike.com/files/NC35%20Res%20Mod.pdf) - which effectivly does the same as the pulg and Play derestrictor boxes.

Hope that helps :peace:

P.S. The NC30/35 could also be 'power' restricted to 33HP by the use of a restriction washer in each of the rubber sections between the carbs and cylinder inlet.

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Re: Rvf400 restriction kit ???

Post by Rushvf1 » Thu Oct 25, 2018 9:34 pm

Hey thanks. I'm building a track bike so no real need for a Speedo. If I just disconnect from then sprocket drive I'm assuming that will work first up? Also doing pipe, dyno playing with jetting at some point. So I'll be looking for inlet restriction. Thanks NGneer

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NGneer
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Re: Rvf400 restriction kit ???

Post by NGneer » Thu Oct 25, 2018 10:46 pm

Rushvf1 wrote:
Thu Oct 25, 2018 9:34 pm
Hey thanks. I'm building a track bike so no real need for a Speedo. If I just disconnect from then sprocket drive I'm assuming that will work first up? Also doing pipe, dyno playing with jetting at some point. So I'll be looking for inlet restriction. Thanks NGneer
If you disconect the speedo drive cable then yes i guess that would work. HOWEVER - Honda must have thought about People simply unpluging the speedo to prevent it sending the "I am doing 180kmh" Signal to the ECU and if you just unplug the electrical plug from the speedo it will go into "limp home mode" and won't rev much above 5000RPM.

The simplist way to negate the upper Speed limiter really is one of the plug in boxes (just 6 quid from Rick Oliver), but if you are building a real track toy it could be worth considering one of the programable Ignitech CDI Units which help overcome the midrange flatspot and also remove the Speed Limitation.

Have a look in the V4 section and the sticky post at the top of the V4 General page for Rick Olivers current list ;)

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Re: Rvf400 restriction kit ???

Post by Rushvf1 » Fri Oct 26, 2018 8:34 am

Cheers mate 😁


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