uh oh, LOUD knocking noise from engine

subway

bit freaked out,
theres an extremely loud knocking noise from my bike.
sounds like something is whacking about inside the engine,
feels like its constantly jumping a tooth on the front sprocket due to the chatter coming up from the bottom of the bike.

not sure how else to describe, bike fels light and underpowered and noise is unbearble.

does anyone have any ideas?
she was just serviced and dyno'ed last week and everything came up all clear,
bike is a '91 honda bros with 15km on the clock.
local bike shop is closed today so cant do anything until tomorrow -
anyone want to reassure me.................

Pigeon Reaper

Afriad I can't reassure oyu. Just don't ride her until it's checked out, hopefully it's something simple.

Garibaldi

I had something, that at least sounds similar to what you describe, happen to me a few years back. Picked the bike up from a service and, later that day, there was an incredible amount of noise and banging coming from the engine. I still find it hard to believe to this day, but they had "forgotten" to put the engine oil in after the initial drain. Needless to say, I never went back to them, after they'd repaired the damage. Don't think they're in business anymore either.

subway

hmm,
theyres definitely oil in there.
tbh, i have no choice but to ride it, im in work now and have no way of getting home or back here tomorrow

hopefully it all be ok.
thansk for the replies

Pigeon Reaper

Be very careful and keep the clutch close to hand. If the bike vibrates pull in. Last thing you need is the engine to seize and throw you off which is the worse case scenario.

subway

cheers,
ill be taking it handy all the way.

hopefully its something simple as it nothing showed up at the service last week and with the low mileage and all that ...

cheers again,
al

subway

could it be some kind of clutch issue?
the chatter is definitely coming from the bottom of the engine and doesnt seem to be one of the cylinders acting up

Elfish

Is the noise happening when in neutral?

Does it get worse as you rev the engine in neutral?

Hoping it only happens when in gear and you give it power......then it might be a knackered front sprocket and drive chain clunking over it(should have been picked up in service ...)

Have a look at clutch plates ... maybe one has broken. Not unknown.

Did you recently have a slight knocking at low revs in high gears as you give it throttle?

Your idea of bad knocking is probably different to mine, but there is hope, it may not be bad engine trouble yet.

Let us know how you get on. I'd very strongly advise against driving until you get someone that knows bikes to listen to it.

bushy...

Probably too late ,but get someone with a van/trailer to move it , do not drive it, it may be crank/rod problems.

subway

front sprocket is only about 6 months / 5000 km old so dont think its that.
not sure how to look at the clutch plates so dont want to try.

Did you recently have a slight knocking at low revs in high gears as you give it throttle?{/quote]
nothing recently but that would describe the knocking as it developed this mroning.
nothing when i pulled off,
getting worse as i was accelretaing through second and third.
bike was shaking at 60km/h in 3rd
then when dropping back to first at the lights etc. the knocking remained, even in neutral
theres also a faint rattle at the end of each knoc [ could be constant but cant make it out]
ended up keeping it at about 45 - 50 km/h and 3,5 / 4000rpm all the way to work.
shop opens at 10 so ill be off down in a little while.

subway

well the owrst has been confirmed
its the big end bearing and the engine is knackered.

anyone know the parts value of a mint bros?
anyone got a bike to sell me?

Pigeon Reaper

Try get a new engine for the bike before you scrap it. you were lucky that the engine didn't seize.

subway

engine + fitting = 700eu
ive put about 600 into it in the past 2 months between tyres and servicing.

at this point im going to cut my losses and move on to a 600

ANTO D10 DUB

http://www.cheshiremotorcyclesalvage.com/acatalog/ the only thing with this lot is you'll have to pick it up at hollyhead . theres a 650 for 250 sterling and a 400 for 195 stering worth considering if you want to do the swap yourself.
heard someone got a african twin 750 squeezed into one of them?

Pigeon Reaper

If you were brave or know someone whos good with bikes they could swap the engine for you. There's a couple of people in some other forums who would be able to advise you on the job. It sounds more difficult than it is.