Hi all, hoping for a bit of advice....

I recently had the carbs off my nc35 to remove the 33bhp restrictor washers that were fitted.

Everything went fairly smoothly and when back together I took the bike for a test ride. Rode about 15 miles and everything seemed good until I stopped at a petrol station.

When I re started the bike it was running rough and making a mechanical rattle noise. I limped home and have since had the carbs back off to check I hadn't done anything obvious but everything looks present.

I'm not greatly experienced mechanically so I wanted to see if anyone who knows these V4s well can give me any pointers before I go any further?

Here is a recording : http://youtu.be/uZFizO88RoQ


Cheers,

I presume you did re-tune the carbs after taking the restrictors off?

I tried the links, and they didnt work.

Thanks, i fixed that.

Woah! I would not be running that thing until you get that fixed.

Have you checked your oil level? And oil quality?
Could be the valve train being starved of oil, could be a loose oil pump.
Worst case scenario.

Can you kinda guess where the noise was coming from?

That sounds fucked

Stop running it til you can check that it has not got somethign totally easy and obvious wrong with it like a loose exhaust or something along those lines.

A tractor sounding moto = a big end failure.

Get the oil out of it into a clean tray and see if you can spy any brass/bronze coloured bit of shit in it.

Thanks for the replies guys.

The oil was less than 6 months old, and the level was fine. I've drained it this afternoon and it looked fine, nothing "extra" visible in there.

I did not re-tune the carbs - I put the tank back on to give it a test and see how it was running first.... I did get a bit carried away and went farther than intended.

I thought if the carb settings had been a big problem I would have noticed it straight away... unless running lean for a few miles has damaged the cylinders?

Another possibility (I've done some searching since my OP, and something came up which i had forgotten.) Shortly after I had first started it the throttle cable stuck open on a blip and it revved up to the limiter in neutral before I could react and hit the kill switch. I freed up the throttle and it seemed fine afterwards so I dismissed this, but I understand something could have been bent through over revving...

...although I would have thought this would have made itself apparent immediately?

CMSMJ1 wrote: A tractor sounding moto = a big end failure.

Get the oil out of it into a clean tray and see if you can spy any brass/bronze coloured bit of shit in it.

Big end failure doesn't usually sound tractor until the engine is loaded - it will quite happily sit there revving away cleanly in neutral. Put it in gear and try to ride it, that's when the noise comes.

I'd be guessing after everything you describe something somewhere has gotten loose/not tightened properly. Strip it down again to recheck everything.

You don't mention the most important bit- where is the sound coming from exactly?

It sounds like it idles fine... was it actually running rough and down on power etc? If not then probably is something minor that's loose.

It’s definitely not running right, won’t idle properly and was struggling up through the revs under load when I limped back.

I was hoping it would be something simple, but the exhaust seems solid and there isn’t anything else I’ve taken off that could be loose and clattering around. I guess I don’t have the ear for it, but I just couldn’t work out exactly where it’s coming from, other than it seems to be inside the engine.

I’ll take the top end apart and have a look for anything damaged next..