Hi,
I picked up my new NC23 today (1989) and it isnt running properly, I realise it could be a number of things but wondered if the symptoms are typical of a particular problem. Symptoms : Stalls sometimes when pulling up, frequent backfires when coming off the gas, uneven running at low revs, runs better at high revs, speedo seems to be reading too low for road speed, doesnt seem able to reach top speed. I am not mechanically gifted to say the least, but would like some idea of the problem before I take it to a mechanic. By the way, does anyone know of a good mechanic in Suffolk/Norfolk area ? thanks

Hi first of all get some picks up....
secondly what makes you feel the speedo is out? by how many miles?
where abouts are you located in the norfolk suffolk area? im in lowestoft. perhaps if you're nearby i could take a look at it for you.

Adam.

Congrats on the purchase.. get some pics up!

By the backfiring, not reaching full speed and cutting out it sounds like its not running properly..

Do you know if the bike is standard?

Yep its not running properly The speedo is reading low, it felt like I was going faster than speedo said, so today I checked it against my sat nav, it varies according to how fast you go, but 55 on speedo is about 67 mph. The speedo looks like a km/hr one to me but there is a sticker saying MPH and 30 on the clock is closer to 30 mph than it would be to 45 km/hr if it was a km clock (if that makes sense).

I dont know about any mods except that the exhaust is unbaffled although not marked ` not for road use`. Road legal replacement in the post.

I live in Brandon which is right on the border between Suffolk and Norfolk. I believe these should be able to do 120, this one wouldnt atm.

Will post some pics , but it could be the dark blue all over respray that is making it run rough and slowing it down !! I am sure it would go faster in red/white/blue

My nc23 had similar symptoms to this when it had been sitting a while. Couldbe gummed up carbs so try cleaning them

Hi All,

Have fitted new exhaust (old one was loud, looked illegal/unbaffled) this has stopped the backfiring and improved running. Have also adjusted tick over and the stalling is now rectified. Bike is running much smoother better, but would probably still benefit from carbs being cleaned as suggested. BUT, the bike will not go over 85 mph (tested on private land) regardless of whether it is in 3rd gear or above, when it gets to this speed it sort of misses and has no acceleration. The bike will rev up to near the red line in lower gears. It feels like it is limited/restricted in some way. I believe these were limited in Japan to around 100 mph.

As I havent any experience of these bikes or limiters I do not know if this is the problem or not. Any advice/help would be appreciated Cheers

Speed restriction kicks in at about 118mph I think. As suggested, strip and clean your carbs, and check your jet sizes while you're there. Any performance mods? Is the new exhaust standard?

Hi Wozza,

The exhaust is an aftermarket `Fuel` exhaust, road legal with baffle. As far as I know no mods fitted. Will have to get carbs done but it seems strange it will not go past the 85 mph as it accelerates well up to there.

Sounds like carbs to me. Have had the same probs in one of mine. rrj. have now bought new carbs.
Cant exactly remember but have a feeling the carbs may be slightly different . The airbox DEFINATELY is. You cant swap the airbox from an rrj to an rrk., though you can swap the carbs and air box.

I know jets at least are different between J and K.