Derestriction... - GSX-R 400 RR SP?

On most Japanese bikes like the RGV or GSXR 400's you have to remove the speed restrictors built into the speedometer or the gearbox. I will find out through my contact in Japan what needs to be done to get full power from it. I do know the M-Max box will remove the speed restriction but will not make the motor produce full power. Give me a few days to discuss what needs to be done with the bike through my contact in Japan.

I asked him and he was not 100% positive so he is looking into. I will contact him again today and see what he found out. Sorry it is taking so long.

Both units you linked to are only removing the Speed Restriction (112mph) and not the Bhp restriction that is imposed on Domestic Japanese models.

If I can get 63.6 HP from my 2 stroke RGV250 (stock derestricted is 55 HP) and some others get over 70 HP I am confident that with some minor mods your 4 stroke 400 can get up into the 70's with out much problems. I know the guys racing in the formula 400 class in the UK are in the high 80's and low 90's in HP.

As soon as Johji finds out I will pass it on to you.

In most cases all of the restriction methods used are in the eletrical , exhaust and carbs so dont worry.

Sorry for the long wait...My PC Crashed!

Look into the exhaust header and remove the welded in collars or better yet purchase a Yosh system for it.

You will need a set of UK spec Carbs from what Johji said the Jap spec carbs are smaller.

the only thing that is in question is whether you will need to change the CDI to a UK spec one......We couldn't get any answers on that. It seems the CDI will not let the bike rev past 11,500 rpm's.

Hope this helps.