Well thanks to all who contributed over the past year to the woes which was a basket case.

Finally budget and circumstance has seen another nc23 saved from the scrappers or eBay...



MOT has been passed and first ride of her at all took place the other night. And that is where the saga continues.

So it pulls a lot harder than I was expecting for a 400. At first I had an issue where I’d screwed up the de restriction but sorted that. Bike now will rev through the range however, above 8k it’s really laboured and will hardly pull through.

Drop down a gear and it’ll shoot trough to huger revs but then not pull any further.

Roll off the throttle and pause a little and it’ll recover but not with power to match the bottom end.

Headers all getting hot but number two cylinders header doesn’t seem as hot as the other two.

Thoughts are as follows...


Blocked main jets
Air leak somewhere, carb rubbers or box mounting
Fuel starvation from other means than jets.
Poss reg rec issue


It was a basket case and I’m pretty sure on rebuilding the carbs it was 110 mains and looking at a J carb sizing I think these should be bigger at 116.

Anyone any thoughts on diagnosing??

Thanks again to all. Couldn’t have got this far without the forum!!!


Matt


Sent from my iPhone using Tapatalk

Blocked jets or float valves sticking . Coil breaking down when warm ? Worn O-rings on the mixture jets?

Thanks dunkenb...


Mixture o-rings were new when overhauled the carbs so highly unlikely on that one.

As for could breaking down is there anyway to test such a theory or is it swap the set over to a known working set and see?

Cheers for the help so far. The jet size is concerning me... if the right size for the RRJ is 116’s would having 110’s give the lack of power at top end?

Should have mentioned before... stock exhaust and end can to try get the base setting right before the winter upgrade plan comes to life.

Again cheers for the thoughts dunkenb, all considerations welcome, dying to get some full power fun before the winter sets in!


Sent from my iPhone using Tapatalk

Feul tap or diaphragm. I had the same problem with my nc24.


Sent from my SM-J120F using Tapatalk

Thanks for the suggestion stood RuanJK...


Weirdly timed but I wanted to update the chain anyway for anyone else who may have come across the same issue but...


SOLVED!!

So ordered some new carb rubbers as one was a bit cruddy when I put them on. That all came couple of days ago and so a day off work saw me in the garage, freezing as it was.

So today she had new rubber mounts installed. Took the time with the carbs off to have a good inspection of diaphragms. Turned out they were all good so nothing on that front.

Went back to my original suspicion of the jetting.

Bowls off and low and behold, number 4 carb had the main jet sitting loose in the bowl. [emoji849]. Had a quick look as was indeed a 110 as my suspicions.

Quick trip to the lovely folks at Allen’s Carb shop for a set of 115’s.

Installed, rebuilt and just got back from test ride when I saw your post.

She’s now pulling hard all the way through and power was more than I was expecting to be honest (fair while on 600/750’s)

Thanks to all for the help.


Cheers Matt


Sent from my iPhone using Tapatalk

That is great to hear. Enjoy it buddy

Sent from my SM-J120F using Tapatalk

Thanks for updating your post with a happy ending then anyone in the future knows what to look for if they have the same issue