NC30 won't rev past 10k

Jarlly · Post by **Jarlly** » Sat Oct 12, 2013 3:23 pm

Hi Guys :) Story so far is I bought an NC30, love it. Last week she stopped revving past 12.5k (a nice gentle 'no more power available' kind of won't rev any further). Now she won't rev past 10k (harsh backfire, bike bucks around a bit). Same in 1st, 2nd and 3rd gear. Haven't tried any higher gears because of public roads, etc. It's the same when revving in neutral/ clutch in. Bike has a km/h speedo.

Any ideas?! The rest of the rev range is unchanged from when she revved all the way to 14.5k. Being limited to 10k isn't awful for the short term, but I'm more than slightly worried about the rev ceiling dropping further!

Yeah, she's a beauty :)

Post by **VFRkieran** » Sat Oct 12, 2013 6:27 pm

Sounds a bit like fuel starvation to me, I'd bet your vaccine hose has started to deteriorate and at high rpm the extra suction is causing it to close up until the revs drop back down.

Easy fix though, get in contact with Rick o the hoses you need are under a tenner.

Post by **dobbslc** » Sat Oct 12, 2013 7:03 pm

Did you buy that from an English man in Wales?
It looks familiar.

Jarlly · Post by **Jarlly** » Sun Oct 13, 2013 12:37 am

I've already had fuel starvation issues due to a kinked vac hose (all fine now, examination showed the hose to be fairly recent). One thing I noticed is that on my old bike (03 transalp) I could suck the vac hose and feel the fuel valve click open (and then if I blocked off the end to trap the vacuum it would remain open), on this one I have to suck and remain sucking quite hard to get fuel to flow out at a 'rapid trickle'. Is that normal?

Post by **VFRkieran** » Sun Oct 13, 2013 8:05 am

Unsure exactly how easy it is to get the fuel flowing, how could you tell the hose had been replaced not long ago? Whilst cold they can look fine but as soon as the engine is running and it warms up you will be surprised how easily the vacume hose closes up.

For the sake of 10 quid I'd replace them, start from the cheapest simple solution to your problem and work your way up is my advice.

Jarlly · Post by **Jarlly** » Tue Oct 15, 2013 7:14 pm

So, today the plot thickens! Whilst leaving work I had the poor fuelling issue I've had for a while but thought I'd solved by re-routing the vacuum hose, so will be getting another vac hose (plus a couple of other bits and bobs RickOliver sells, very useful :) ). Thankfully today I got through the fuelling issue without too much stress, just significant loss of power and spluttering for ~10 seconds whilst pulling away from some lights. A bit later on the dual carriageway I was able to rev back to 14.5k. Not 100% smooth at the top but better than it was. New vacuum hose on order (along with a few other toys :D). Fingers crossed, etc!

I bought it from a girl near chippenham, 66k on the clock, and fairly neglected mechanically. But it looks amazing and was only a grand, and since spending a bit of time bringing her back to full health she's great to ride :)

Jarlly · Post by **Jarlly** » Sat Oct 19, 2013 7:41 pm

Today I replaced the vac hose and opened up the fuel tap to see if there were any obvious issues. The screws holding the fuel tap together were obviously new (or amazingly shiny for a 20 year old bike!) and the diaphram looked in excellent condition. I greased the areas where the diaphram rubber seals against the metal, put it back together and tried sucking on it- much better results, only requiring a gentle suck for immediate delivery of fuel, and I was able to feel the valve opening as I sucked the hose. Still required continual vacuum to open the valve, but much less forcefully than last time. Only issue was that when I cracked the throttle it only made it to 13k, at which point she was still obviously unhappy. What are people's opinions on the issue?

NC30 won't rev past 10k

NC30 won't rev past 10k

Re: NC30 won't rev past 10k

Re: NC30 won't rev past 10k

Re: NC30 won't rev past 10k

Re: NC30 won't rev past 10k

Re: NC30 won't rev past 10k

Re: NC30 won't rev past 10k