This is sort of three queries in one, and i'm sorry if it's bad forum etiquette to do that, but i've had a search for similar things on here and am not sure that other threads fit my query, so here goes.... After buying my NC30 a few weeks ago I've only just had my first decent ride in the dry, everytime i've junmped on it recently at the weekend it's ended up being torrential rain, and i don't use it for commuting as i live close to where i work and it doesn't have the chance to get warm on the trip so i tend to walk. On this good ride yesterday i discovered a few things about my bike and would love some advice please Greybikers -

1 - occasionally when accelerating it felt hesitant, like i opened the throttle and there was a delay in between me winding it on and actually speeding up, or it would accelerate but feel like the engine was 'chugging', almost like it wasn't revving cleanly. This happened three times during a 60 mile ride, and only for a few seconds but it was pretty annoying and since this was the first proper chance i've had to wring it's neck a little, i'm surprised becasue on all my other rides this hasn't happened. My bike has a full system and can, and has suppsedly been setup with a dynojet kit but now i'm not so sure. It feels like a fuelling problem - can anyone shed some light on this before i take it to my local dyno for a closer inspection?

2 - I was told that the bike has been derestricted - it's still got a kph clock face but has had a conversion which i thought would remove the 112 mph (i think that's the correct figure) rstriction. Going down a road i'm familiar with and that has no speed cameras i was nailing it and it refused to go past 110. Am i correct in thinking that my biike is infact still restricted? And if so, how do i remove the restrictions - i thought it was the clocks, is there some other restrictive factor on the import NC30s?

3 - I gave it a service and oil change last week, and took the tank off to access the airbox and clean it. I put the tank back on, bolted it up etc and sat it back so it was resting on the rubbers. I've now noticed that the tank has a bit too much movement for my liking, more than i tihnk it should have. The rubbers should be in one position but they seems to move around a lot under the tank. There are two rubbers on each side of the frame, up near the headstock, but none further down - although it looks like there was once something there as there are old sticky marking on the frame near the back of the tank. What could be causing the tank to be loose? It's bolted on properly etc - is it worth me getting more rubbers etc to stabilise it?

Sorry for the really long post , and thank you.

Si

1- It does sound like a fuelling problem but see point 2; I'd start by checking the vaccum hose which goes from the fuel tap to number 3 cylinder (seating on the bike it's the right rear); it could be kinking and that stops it sucking the diaphram open in the tap. If that's ok, short of pulling off the carbs and cleaning them (also making sure the re-jetting was actually done), a trip to the dyno is a good idea!

2- What conversion was it done? Motrax gearbox (blue thing) that connects the speedo cable to the speedo? If that's the case, the reading is now in MPH so what you saw was actually 110mph. It may have had a resistor soldered to the wiring (either behind the clocks or at the CDI) and if that wasn't done properly it may not be doing what's suppose to and in fact, it may even be causing the slow throttle response? Get the top fairing off and have a good look at the wiring behind the clocks.
Import 400's all came speed restricted to 112mph (180kph) as you correctly said and yes, they are inside the speedo; all it needs is a small (normaly black) 'half-moon' shaped tab removed or bent back so it doesn't pass between two 'hall' sensors which are attached to a PCB (a circuit board) inside the speedo.

3- The tank should have 4 bits of rubber: 2x small(ish) square ones, one either side of it supporting it to the frame spars, 1x big one at the front which hooks under it and to the frame and 1x at the back where the bolt that secures the tank to the frame goes through.
Edit: where does it have too much movement now, front or rear? Did you notice any rubbers at the places I mentioned above? Maybe one has fallen off when you removed the tank?

Have a look a this parts manual to see them:
http://www.akhara.com/nc30/nc30parts/files/33.htm

Edit: Some photos of the inside of my old NC30's speedo:

Remove or bend back that tab and you're done!

Hi Speedy - thanks for your excellant help. I took it out after work last night to see how it was running (and it was a really nice evening, that was the only excuse i needed really) and fuelling-wise it was still playing up. It seems to happen at any speed, anywhere in the rev range, but only if the revs are constant for a while. It tends to splutter, like it's being choked, and the only way of getting the fuelling back to normal is to open the throttle and the bike clears its throat and fuels properly again. I think the carbs may be blocked, so i'm going to strip them down and give them a clean and see if that sorts the problem.

I saw your reply to another thread about derestricting the VFR and I think i might get a resistor ket and fiit that, i'm not sure i'm confident taking the speedo apart - after doing a bit more reading i think the Motrax converter is only converting, not derestricting, like i've been lead to believe it does do, although obviously not.

In terms of tank rubbers, it's got two either side of the tank up the front, then the rubber under the seat cowel that the bolt goes through. There are no small ones at at the back though or one right at the front, so i'm missing rubbers. I didn't notice until after i'd had the the tank off for the first time, but im guessing it's been like it since i bought it. Oh, and it has too much movement generally, i know that doesn't sound that helpful, but it's mostly side to side movement. I don't suppose you know anywhere i can get hold of some replacement tank rubbers? I've had a look on Google but can't find anything.

Thank you!

NC30 tank rubbers try Graeme France 07778628448, he should be able to get hold of you some.

Clean the carbs, do them one at a time as the jets are different, while there out check nobody else has mixed them up.. the emulsion tubes the jets go in are also different between front and rear carbs.

Record the jet size and report back.. also do you have std exhuast or aftermarket system? Airbox standard with standard filter?

The NC's have a notorious 'flatspot' around 5-7k.. some dyno time with an experienced V4 tuner might benefit if the carb cleaning is no avail...

There are other carb mods such as drilling the slider hole, washers under the needles etc etc. (search the forum)

Hope thats a start...

re- the tank rubbers if the rubber on the front of the tank is fitted wrong way it will allow movement ?

Neosophist wrote:Clean the carbs, do them one at a time as the jets are different, while there out check nobody else has mixed them up.. the emulsion tubes the jets go in are also different between front and rear carbs.

Record the jet size and report back.. also do you have std exhuast or aftermarket system? Airbox standard with standard filter?

The NC's have a notorious 'flatspot' around 5-7k.. some dyno time with an experienced V4 tuner might benefit if the carb cleaning is no avail...

There are other carb mods such as drilling the slider hole, washers under the needles etc etc. (search the forum)

Hope thats a start...

Ok, i'll make sure to clean each one seperately and check the jet size. I've got an aftermarket system by Beowulf, which i don't like too much. The guy i got the bike from told me that it's a full system, downpipes and all, but i can't be sure becasue my downpipes look the same as the standard ones, although i reckon it's reasonable to assume that aftermarket ones would be similar. I was told that the carbs have been set up to suit the exhaust - i think this is the case becasue when it runs nicely, it runs very nicely. If the fuelling was upset by the exhaust, wouldn't it fuel badly all through the rev range and continually? The airbox and filter are standard. I'm hoping to get the carbs out and will report back on my progress... hope fully it will go well. It all hinges on whether i er...screw it up or not. Hopefuly not though!

I'll also call Graeme France tomorrow and enquire about some tank rubbers. Thank you so much for your adive and input by the way.

Ref your carb problems - does your bike still have the original `heat guard` fitted to the front of the frame? It`s a little plastic deflector which sits over the top of the top radiator and has two rubber flaps attached which go over/under the cross tube behind the headstock. It doesn`t look like it does much but you do get the kind of carburetion glitches you describe if it is missing...

I've done some investigation into the tank rubbers and worked out what one is missing, so i'll be getting it replaced.

With regards to the carbs... i'm starting to think it might be a pilot jet - the problem mostly happens at low revs, either after shutting the throttle off then opening it again or when pulling away, or it cuts out at junctions. Sometimes it may happen if the bike is at a constant speed and the same revs for a while. I'm going to strip and clean the carbs on Sunday and will report my findings! What size should the jets be as standard?

Rick - I'm not sure if i still have the original heat guard - i'll have a check and see about replacing it if i find it's not there - thanks for the tip

was it the pilot jet ??

i think i have the same issue wity my bakie at the moment,