NC30 misfiring?

[Stokeded]

Hi all.
Thanks for taking the time to read. New to the forums having picked up my first 400, actually downsizing for the fun and the beauty of it! Here is my issue.
First decent ride out tonight. Bike seems fine although I suspect extremely worn clutch as I cannot select N when the bike is running, I replaced the cable to prove it wasn't stretched and still at maximum amount of slack taken in it barely has any "pull" on it and the bike stalls at lights due to friction somewhere. Anyone violently disagree?
That aside the engine sounds lovely until. I encounter a driver with either a sense of humour or is blind. He makes an unexpected right 90 turn 100yds ahead and I hang off the front brake to stop it. After a suitable debriefing (directed expletives inside my helmet) I pull off. The bike sounds awful. No midrange pull, like fuel is running out/blocked induction. And I limp home running hot, with vibrations i reckon is one pot missing, puffing the odd cloud of smoke.
Any thoughts? Thanks again for your help in advance

[Morespeedvicar]

Hi, i'm guessing you've got an nc30? Alot of nc30 wont go into neutral easily, you have to have a good blip of the throttle and it'll go in, you may need to have a look at the clutch it shouldn't drag if its adjusted properley.
My only thought on the bad running is it may need a carb rebuild.
Cheers
Ian

[Neosophist]

Sounds like a normal neglected 400.

full service and

Follow cammos carb guide (sticky thread at the top) to get the carbs overhauled and sorted out

While your doing the carbs get the valve clearacnes checked and set.

Replace carbs and check fuel tap is ok then balance carbs.

bike should run like swiss watch.


it takes a few days (give yourself a weekend or two to mess about and DONT rush), its not difficult if you follow the guide just time consuming.

So many people dont do it, or try "go faster mods" and ruin the bike.

Once you have the carbs sorted check the electrical system too, often they fail and can cause running issues.

After this it should run great.

[iDemonix]

^ solid advice, exactly what I was going to say - sounds like your usual neglected V4.

Give it a good service, start Friday night, aim to finish Sunday night but if you can't then don't rush it. Give the carbs a proper scrub, new oil + filters + plugs. Don't forget you can adjust the clutch on the bracket that holds the cable to the engine too. Have a play with it.

As for neutral, these engines are notoriously tricky to get in to N at stand still - you need to blip the throttle. My old engine was a piece of piss to get in to N, but my new engine won't go in at all without a blip.

[Neosophist]

^ solid advice, exactly what I was going to say - sounds like your usual neglected V4.

Give it a good service, start Friday night, aim to finish Sunday night but if you can't then don't rush it. Give the carbs a proper scrub, new oil + filters + plugs. Don't forget you can adjust the clutch on the bracket that holds the cable to the engine too. Have a play with it.

As for neutral, these engines are notoriously tricky to get in to N at stand still - you need to blip the throttle. My old engine was a piece of piss to get in to N, but my new engine won't go in at all without a blip.

its usually worn fingers on the clutch basket, small grooves wear into them which stop the plates moving about as easily.

[iDemonix]

Nothing a quick file can't sort

[Stokeded]

Guys, thank you so much. Good advice! I have started a full service. And boy is it in a bad way. 3 of 4 plugs are good (carbs ok.) but one was covered in acrid stinking oil
Where has it come from? My thoughts and what I glean from other posts.

Best case, loose spark plug, a small engine leak of oil into the front left plug well and it got in there? However with a fair bit of oil residue on inside of exhaust manifold I fear far worse.

Worst case. Blown piston ring? Engine, out, overhaul etc.... (So much for summer) My questions would be: can I inspect the front piston head whilst the engine remains in the frame? Is it cheaper to get a second engine in the short term c£250 eBay?

I have read posts where dudes mention valve clearances getting oil into pistons?

I do not have a massive amount of experience and tools but keen as mustard!

[Neosophist]

Go slowly is the best advice.

Is the oil on the tip of the plug (electrode!?) or on the actual ceramic / threads of the plug.

Oil here is somewhat normal.

The plugs are deep recessed into the engine.. crap from the carbs and airbox can sometimes leak out and gets stuck on the plugs, the rubber seal from the rockerbox might be leaking a small amount of oil which will often end up in the plug hole (there is a drain hole too which elads down by the exahust).

Black plugs suggest bad running.. after sorting the carbs out to rule that out you can then see if they stay black after some long hot riding which should burn off any crap.

If they are not running a nice tan color you might be burning oil. This can be cuased by a few things.

Id focus on getting the carbs sorted now and seeing how it runs first.

If it turns out to be a worn engine contaminating the plugs with oil then its 99% of the time mch cheaper to get a new engine.

They are quite bullet proof so you must be unlucky to get a knackered one.

Most likely give it a good servie, strip and rebuild carbs and it will run ok.

[Stokeded]

Thanks for all your words guys,

The carbs are off and away for a balance and ultrasonic bath.

So i do some invest into the oil in piston problem and i find this little rubbber gem in the spark plug well. The spark plug was loose and how it was installed with this obstruction i will never know!

http://instagram.com/p/aX4dsjgerb/
http://instagram.com/p/aX4hELgerc/

Back to my original problem. The source of the oil in the cylinder. I would still like your experienced opinions.

Was is a product of a dodgy spark plug seal and the obstruction breaking the seal of the rocket cover gasket thus letting oil into the head?
Is it worth whipping off the valve stem and inspect the oil seal? (have no valve compression tool)
Or worst case; there is still oil weeping in the pot when i dry crank the engine, legacy oil or busted piston ring?
I am no mechanic but haynes book of fun is keeping me right at the moment!
Thanks Dudes!
Ed