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NC35 Restriction (or not)

Posted: Sat Sep 14, 2019 7:15 pm
by bluetinfloor
Hello

I have done various searches, both on this forum and generally but wonder if there is a simple way of establishing if my import 1994 NC35 has the top end restriction still in place.

I don't think I have seen greater than 110 ish on the speedo and at 15 stone that takes a bit getting to, plus the bike has a MPH speedo overlay and I am 1 tooth down on the front so its all a bit mysterious to me. Had the bike on track, but just at 3 sisters, but that is nowhere allowing any 6th flat out scenario.

Had read something about removing the light/indicator fuse and some behaviour would confirm one way or the other, but seeking some expert guidance.

The true restriction is losing about 3 stone, but any other pointers as to whether its in place or not appreciated.

Thanks

Re: NC35 Restriction (or not)

Posted: Sun Sep 15, 2019 5:20 am
by magg
110mph is 180kph and is the speed limit restriction. If the instrument light/indicator fuse is removed and the engine will not rev above 5000rpm then the speed limited is fitted.

Re: NC35 Restriction (or not)

Posted: Sun Sep 15, 2019 6:59 pm
by bluetinfloor
Thanks - will check that out.

What do you think derestricted top speed will be?

Re: NC35 Restriction (or not)

Posted: Fri Sep 20, 2019 10:26 am
by bluetinfloor
Revs fine with this fuse out so the bike has been derestricted in the past. Thanks for your advice

Memo to self - lose that 2 or 3 stones before next Spring..

magg wrote:
Sun Sep 15, 2019 5:20 am
110mph is 180kph and is the speed limit restriction. If the instrument light/indicator fuse is removed and the engine will not rev above 5000rpm then the speed limited is fitted.

Re: NC35 Restriction (or not)

Posted: Fri Sep 20, 2019 1:06 pm
by magg
What rpm do you see at 110 mph.

Re: NC35 Restriction (or not)

Posted: Fri Sep 20, 2019 1:08 pm
by magg
Just to clarify, the fuse must be removed before you started the engine.

Re: NC35 Restriction (or not)

Posted: Sat Sep 21, 2019 12:13 pm
by bluetinfloor
magg wrote:
Fri Sep 20, 2019 1:08 pm
Just to clarify, the fuse must be removed before you started the engine.
Oopps....without thinking did the test stationary in neutral with the bike warm and revs cleanly with and without fuse (ignition off and on for each)

Tried again riding the bike today without fuse and it’s restricted, won’t rev beyond 5kish

A task to add to winter list...

Re: NC35 Restriction (or not)

Posted: Wed Nov 20, 2019 9:21 am
by unkul79
Hi. I've a cb400 sf 1992. It's been fiddled with by someone and I'm new to bikes. Any chance you could point me in the right direction regarding the fuse I need to test with. My bike fuse box only has four fuses. Is this correct or does it sound wrong. Essentially the.bike wont go past 60mph. I tend to thing that there is a rev lmiter in place as I'm shifting up through the gears very quickly. Unfortunately the previous owner removed the dash for and ebay special that doesn't have a tachometer. So really I'm.goin off the sound of the engine. Any advice would be really helpful. Thanks

Re: NC35 Restriction (or not)

Posted: Wed Nov 20, 2019 10:25 am
by magg
Although I have no direct experience with the 1992 CB400, I suspect that there would be an OEM speed limiter function, and unless the limiter circuit has been bypassed when the OEM speedometer was removed, the engine will not rev much above 5000rpm, which is probably around 60mph.

Re: NC35 Restriction (or not)

Posted: Wed Nov 20, 2019 8:47 pm
by unkul79
Thanks for the reply. Any ideas as to how to bypass this. Or is there somewhere you would recommend for further research. Cheers