SICK NC30

[sAsLEX]

ok, on our coro loop ride on Sunday the bike had a little hissy and decided it would like to not run on all four cylinders at low revs, when you opened her up she would cough and splutter sounding more like an xr than a V4 then all of a sudden come back on song at the most innapproprite times, ie mid corner.

Now it has done this before and some carb cleaner in the fuel "seemed" to fix it, so i chucked some in at Tairua and again it seemed to clear up, kinda still running rough at low revs

Today I went in to uni, roughly 20 k, and she decided to run on less than four most of the way.

Was thinking it was dirty carbs not feeding the cylinders properly, but going along the motorway it gave a couple of pops and fart like backfires, unburnt gases??

Does anyone have any ideas where I should start?? was going to attemt to drain the carbs this afternoon.

[Pwalo]

I think you've got two potential sources of trouble. Carbs, or "Honda" electrics. Could be as simple as rust in your petrol tank, or worn needles.Unfortunately the NC isn't the easiest of bikes to work on so your best bet is probably to take to your trusty bike mechanic.

At least have a chat to him/her and see what they think. They could also give you an idea of the likely costs involved. Good luck.

[MSTRS:Me]

Could also try the next level up in the bike's spark plug heat range

[vifferman]

Was thinking it was dirty carbs not feeding the cylinders properly, but going along the motorway it gave a couple of pops and fart like backfires, unburnt gases??

"Pops and fart like backfires" are from lean running.
Given that you reckoned carb cleaner helped, I'd look at fueling issues: faulty/blocked fuel tap, crap in the carb bowls, etc.
Could also be an air leak, or electrical (cracked plug boot, etc), but this sounds more like somehting that's affecting more than one cyclinder, so that points to interrupted fuel delivery.

[Motu]

You've got 3 more cyls and carbs than you need - get rid of them and your problems will be solved.

[sAsLEX]

in reply to a sugesstion from someone on another forum
http://www.400greybike.co.uk/Forum/t...TOPIC_ID=26314

ok had a look at the vacuum line and it looks fine, not too perished or anything, and when the bike is running I chucked my finger on it and it seemed to suck a fair bit.

of note though is with the tank away from the bike, petrol come out when i turn the tap on, i though the vacuum was meant to stop all fuel unless there was negative pressure in the vacuum line

could this be flooding the carbs?? I dont think this is too likely but....

[sAsLEX]

another bump as bike is now in bits outside, going to clean out the carbs.

Someone said plug boot, this the bit that covers the plug in its recess??

ps real loud when you have head near carb without aircleaner to muffle and then you run it to check if the vacuum hose is vacuuming!

ok now carbs are off the bike and ready to be dissassembled.

[sAsLEX]

ok carbs taken off and cleaned, a couple of the jets/holey pole things were quite badly gunked, crosses fingers that this was the problem.

Next hurdle is to get the carbs back on as putting the four connected carb back into 4 not moving holes is very difficult, just tried outside with moon and torch but had to call it a day on lack of light, wil be up with the sun to get it going before riding time tomorrow!!!

[Gixxer 4 ever]

ok carbs taken off and cleaned, a couple of the jets/holey pole things were quite badly gunked, crosses fingers that this was the problem.

Next hurdle is to get the carbs back on as putting the four connected carb back into 4 not moving holes is very difficult, just tried outside with moon and torch but had to call it a day on lack of light, wil be up with the sun to get it going before riding time tomorrow!!!

Cool good on you. Yep they are hard to put in and I can say it is time to give it up. I have pushed on late in the night with poor light and regretted it. I split a carb mount when applying to much pressure to it and ended up with an air leak. Should have gone to bed and done it in the morning. Good choice. I am no mechanic but I used CRC on both the carbs and the mounting blocks the second time around and it made the job of fitting them one inside the other 100% easier. Good luck tomorrow.

[sAsLEX]

yeah got them on in the morning with a bit of brute force!


Took the bike for a quick test run autobahn, kopu, whangamata, whitianga, coromandel, kopu and then back home.


Started to run a bit rough coming over the hills out of tairua, and again coming down into coromandel and then all the way to kopu. Was running real rough at low revs until about 10.5k and then it would come on song and run fine.

Also ran fine once at open road speeds and filtering on the motorway so maybe the raised heat of twisties is causing something to go amiss?? The temp on the gauge never got much above 90 though

[sAsLEX]

prob mooring at a "i have no fuckin clue" guess as there is quite a few ships due in for NAVY DAY on sat 5th march.

oh and they would shoot your shady lookin ass



hides from hitcher for improper arse spelling

[Motu]

Hmm I had a simalar problem on the ol GPX600 one time.
It turned out to be water in the fuel (rusty as tank).
When the bike was run at reasonable speeds the fuel in the float bowls went down and the water floating on top got sucked into carbs... engines dont run on water!!
I would slow down/pull over.. fuel level went back up..bike run again.
Problem solved after I tipped the contaminated fuel out and repaired hole in tank.
Water will stay in the tank every time you fill up cause it floats on top.. have to tip it all out.
Come to think of it this sounds nothing like your problem... as you were.

ps Whats with the orange buoys around your ships at the naval base at the moment???What happens if i take a boat inside there perimtere?
Is this something to do with the aussies/submarine being there?

It's the water that's heavy,the fuel is on top.

[Blakamin]

"Sick NC30"...???? problly a hangover...

nuthin wont fix!!!



(sorry, been away )

[Gixxer 4 ever]

Started to run a bit rough coming over the hills out of tairua, and again coming down into coromandel and then all the way to kopu. Was running real rough at low revs until about 10.5k and then it would come on song and run fine.

Sounds like an air leak to me. Did you have a good look at the carb mounting blocks? They can crack or perish and suck air. That gives you the sort of problem you described.

[sAsLEX]

Sounds like an air leak to me. Did you have a good look at the carb mounting blocks? They can crack or perish and suck air. That gives you the sort of problem you described.

ok cleaned the carbs out agian as it has been running rough for the last week or so after running fine for ages, it could be the air leak, but after runing carb cleaner in it after it buggered up after the last time i cleaned the carbs it came right.


So me is thinking that it could be this air leak thing, kinda due to the fact it is damn hard to get the carbs to seat correctly (did it at night again after riding down to taupo), the rubber things appeared in ok condition though but might take it round to the master of NC30's some time to get his opinion

or it is sparkplugs/lead problem as it has had one or more of the leads replaced in the past, according to the master, and they are different colours.

ps its a pain in the arse trying to pass vehicles with bugger all power!!!