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moderate knocking on engine.
Posted: Sun Feb 20, 2011 2:52 am
by niteblade
helping a friend post his question.
"my nc35 bike was in idling mode and i over-rev it till red-line and there has been some knocking sound ever since and moderate vibrations felt on tank, so do anybody know what happen to my bike(pls let me know what is wrong)?"
any kind soul would like to help him point of potential problems?
Re: moderate knocking on engine.
Posted: Sun Feb 20, 2011 4:25 am
by superlite
This is a wind-up right
Sounds like a bent valve or two I reckon.
Re: moderate knocking on engine.
Posted: Sun Feb 20, 2011 6:12 am
by amaechizzle
I would be doing a compression test asap!
Re: moderate knocking on engine.
Posted: Sun Feb 20, 2011 10:19 am
by thunderace
Doh!

Re: moderate knocking on engine.
Posted: Sun Feb 20, 2011 10:34 am
by trademe900
How did you over rev it, they have a limiter.
Did you downshift too many gears?
Re: moderate knocking on engine.
Posted: Sun Feb 20, 2011 5:10 pm
by Neosophist
People don't realise that when the bike is in neutral you shouldn't rev it past 10,000rpm.
There is no load on the engine and it can damage parts, it says this in the Honda Manual too somewhere.. race warmup procedure is 2-4ktpm, 5-8k and 8-10k rpm if i remember properly.
id do what has been said and check compressions to make sure valves are not bent, use a screwdriver or engine stethoscope to locate the source of the noise.. it could be something silly like loose bolts
Re: moderate knocking on engine.
Posted: Fri Mar 11, 2011 6:49 pm
by Bill
i did not realise this, makes sence really when you think about it, i never rev it anywere near than in neuatral anyway (why would you need to) but what about when its in gear but the clutch is pulled in? i dont do this either but just woundering?
cheers
Bill,
Re: moderate knocking on engine.
Posted: Fri Mar 11, 2011 8:23 pm
by skinnydog0_0
Neosophist wrote:People don't realise that when the bike is in neutral you shouldn't rev it past 10,000rpm.
There is no load on the engine and it can damage parts, it says this in the Honda Manual too somewhere.. race warmup procedure is 2-4ktpm, 5-8k and 8-10k rpm if i remember properly.
id do what has been said and check compressions to make sure valves are not bent, use a screwdriver or engine stethoscope to locate the source of the noise.. it could be something silly like loose bolts
Mr Honda says, when warming NO GOING OVER 10K
You might be lucky and just dislodged a shim, but the valves can bend quite easily. Can you check the the valves and shims?