Rough running NC30 - help!

[DoktorMandrake]

Thanks chaps.

I did disturb the exhaust. Originally I was going to take it off but only dislodged the rear pipes from the manifold as it was stuck fast at the join under the sump.

I never renewed gaskets, just bolted it up. However if I seal the end can with my hand, the bike dies quickly, so I'd discounted a leak. Might have another look.

Will also try to find source of noise tomorrow.


Arsey: clutch freed itself over night. I just re-seated the rocker cover as it was leaking, will check the tank etc. See if I can get to the bottom of it.

[arsey30]

If exhaust was unbolted that check that first.

[DoktorMandrake]

It was the crank bearings. Drained oil earlier and it was full of metal. So I need a new engine

[GeeTee]

it's running on all four but that didn't sound right. Thought knocking sounded mechanical to me - like a worn bearing somewhere. Did you refill it with the right level of oil after changing it?

[DoktorMandrake]

Yeah I did it by the book. Measured the oil.

[arsey30]

Never heard of oil/filter change stopping oil circulation before, apart from forgetting to fill up with new oil, are you sure.
Sounded too loud and slow for crank bearings, did the red oil pressure light go out?

Why measure the oil?
I take note of roughly how much is going in by the marking in the can, but then run the motor up to fill the filter, leave to settle for 10 mins then check and top up.

[DoktorMandrake]

I usually do it using the can but there were no markings so I measured it. Oil pressure light was out. I filled her up and then checked on dipstick after running and letting her settle for a bit. Oil level was fine.

I dunno what exactly it was, except a lot of metal came out when I drained the oil the second time.

[arsey30]

Did you ride the bike at all?

Makes no sense, if oil light was out then pressure was at least minimum required to feed the crank, probably more.
Running for a short time would not produce much swarf, when oil or pressure is low when riding, the rod may seize on the crank and the shell turn within the rod, then a lot of swarf will get into the oil, but most will be trapped in the filter anyway.

Cutting a filter in half is a way of checking for wear/swarf.

[DoktorMandrake]

When I changed the original oil, I did not notice anything, but I was not really looking. It had a magnetic sump plug, so I stupidly thought, oh the sump plug is clear, so it must be alright. I also naively believe Hondas to be indestructible, so did not scrutinise the oil as I might have done if I had suspected something was up. The work I did was all minimal, methodical and done in a clean environment. I had wondered if I left her without oil in for too long, given that it was a couple of weeks between draining her and getting the oil, but I have had engines in the past that have been dry for a long time and never had any problems.

I will have a look at the filter. I threw the original filter away so only have the one that I put on. I still have the original oil that came in the bike, so may drop a magnet in there and see if there are any particles.

She sounded fine when I picked her up, but then she did not rev very high through the range or very cleanly, as she had been stood for a year and the carbs needed cleaning. Maybe that masked the noises? I dunno. Bit of a bugger but all is not lost yet. Well, except the engine. The rest of the bike is ok.

[Neosophist]

Im with arsey30 on this one.

it sounds a little strange.. not denying having metal in your oil is a very very bad sign, but it could just be co-incidental.

crank bearings usually make same kind of nice as engine speed, that sounds like a very specific vibration.

It sounds like your looking at 2 separate issues.

I wouldnt worry about leaving it a long time. I pressure washed the insides of a vfr engine once with about 5 litres of parrafin after leaving it with no carbs on caused it to fill with water.. took the sump / clutch / genny and rocker cases off and got the gun in there everywhere..

cranked it for a couple of 30 seconds blasts with the kill switch on to bring oil all aroudn as i was lazy and dint re-oil the camshafts and its still running now.

certainly still a bit of a mystery, if what you did somehow caused the bearings to fail i think your very unlucky.

nothing dropped int eh rocker box did it? you havent popped a shim out and its gotten chewed up in the cam-gears?

At the very least id be tempted to throw in some clean oil and run it for a bit longer and see if any more metal comes out of it..