Bike is not sounding at all good (video attached)

[Whosthedaddy]

Riding at a healthy pace on the way home, had a thought that the wind noise in my helmet was affecting the music, pulled over and nope, a horrid knocking noise.

https://www.youtube.com/watch?v=eJ97WXXMfe4

I then spent the remaining 17 odd miles almost coasting home fearing it would stutter and cut out.

It did cross my mind that I had dropped a cylinder as sounded like a big single but no, both exhausts are working fine and feeling powerful when the throttle is blipped.

I haven't noticed anything wrong or to worry about, a real bolt out of the blue!


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Current : MSX 125 Past : CBR 900RR Monkeybike : c50 LAC : ZXR750 H2 : FZR600 : ZX7R P3 : YW100 : TRX850: Trophy 900 T309 : GSXR 600 L0: Monkeybike : XJ6S Whosthedaddy

[27cows]

Sounds unpleasantly like it could be a big end.
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[Whosthedaddy]

[ms51ves3]

That sounds awful.

Cam chain tensioner become loose, maybe? I have no idea what I'm talking about though.

[cb1rocket]

it could be anything, but first check the basics, could be cam chain tensioner, but as the knocking is so consistant, it could well be the big end.

Looks like an engine out job to inspect unfortunatly.

Could just be better off buying a new engine perhaps from a breaker? or get a smashed up donar off ebay

[Whosthedaddy]

[Bru]

Sounds too deep in tone to be chain. In fact, sounds almost exactly like my engine (also a twin), when one of the big ends failed. Did your temp rise (on the bike)?

Best bet - drain the oil into a shallow pan, and then pour it slowly out into another container. If you spot glittery flakes at the bottom of the first container, then you know it's a bearing.

Avoid riding the bike, as you could still get away with just bearings, rather than losing the crank.

[stinkwheel]

Use a screwdriver/bit of broom handle pressed against your ear and strategic parts of the engine as a sounding rod to localise where the noise is coming from. You'll be surprised at what you can hear.

Two, left of field suggestions.

1) Loose spark plug.

2) Balancer chain (I assume it must have a balancer in there given the firing order).
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[mr.kris]

TRX850s are known for crank problems id say thats what it sounds like sorry! Xxx
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[Whosthedaddy]

Thanks guys.

Easiest thing would be to change the oil tomorrow and look for any debris as will be making sure that the plugs are snug.

I've heard about the screwdriver to the ear listening for the knocking but to be honest it'll mean nothing to me other than top or bottom, front or back.

A loose crank actually knackered the engine in my old Impreza, I believe it to have been due to Halfords not tightening a pulley properly after they changed the cambelt.

What could cause a crank to go? No work has been done on it or is it just a design or V twin problem?
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Current : MSX 125 Past : CBR 900RR Monkeybike : c50 LAC : ZXR750 H2 : FZR600 : ZX7R P3 : YW100 : TRX850: Trophy 900 T309 : GSXR 600 L0: Monkeybike : XJ6S Whosthedaddy

[Pete.]

Drop the oil - if you have golden/bronze coloured flakes of metal fall out or what looks like silver paint floating on the oil then your ends have had it - which will mean the crank is shot and probably the rod too. If it's really bad you might even have kissed the valves.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[WD Forte]

My guess is not big ends but main bearings
ends usually clatter when you rev up while this noise is
constant at tick over
OR
generator rotor come adrift maybe?

Just guesses of course, as said you need to open her up and
have a look

[Phoenix]

Doesn't sound good, sounds like my first Fireblade years ago before the engine ate itself, it'd had a crank regrind previously and always had a tapping noise but very quickly over the course of a day it got worse and worse until it sounded like a tractor with the exhaust manifold off and then just died completely.

Best bet is as stinkwheel says though, drain oil and check balancer chain and camchain, if they're all ok then the engine has to come apart anyway so you've just made a start.

[instigator]

G knows about the TRX's, I'd PM him for a response.

Its one of the reasons why I never got a TRX - I think they were known for having shit top ends. Quite what goes wrong with them, I don't know...something about their valves....well that was fucking useful, eh?

[hmmmnz]

this is sounding very much like a cagiva ive been working on,
the starter clutch bolts attached to the flywheel/generator have loosened up, and are knocking on the engine block as they spin past.

what i would do is
1. check the timing chain, tensionor, and timing,
2, dump the oil, pull the left cover, and see if there is any play in the crank.
3, pull off the flywheel, and check the balance shaft chain/gear and see if thats sweet,
check the starter clutch bolts, and preen them if need be,

if all of that looks good,
then i would drop the engine, and dissasemble the top end , and check the piston, valves and bore,

if they all look good, then i would pull the barrel, and see if you have any play in the piston and on the conrod,

if you have got that far and still not found anything.... well
i'd be looking for a new engine

good luck, shouldnt be too hard to find the cause,,,.... fixing it may be an arse though
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[MaybeGuy]

could be one of the exhausts blowing at the head.

observe

https://www.youtube.com/watch?v=JinH0XtN0mw
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[Whosthedaddy]

[hmmmnz]

man that sucks,
tedium engine
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the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches