RESOLVED - 2001 CG125W - "Clunk" coming from front

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

As the topic says, when I rotate the wheel in/out of gear, a loud intermittant rattling or knocking noise comes from the front sprocket.

Any ideas?

Thanks,

TobyR

ecclestone · L Plate Warrior Joined: 20 May 2006 Karma :

is it possible that the chain is so loose that it is hitting/around the front sprocket,,is the front sprocket loose,,is the chain very rusty and kinked,,is there something stuck by the front sprocket/??

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Being a Honda I would check that the little plate that holds the front sprocket on has not gone walkabout. They are held on with 2 small bolts (suggest you use thread lock on them).

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

Guest · Brolly Dolly Joined: 22 Apr 2004 Karma :

This is probably from a C90 but ...

https://www.vjmw.org/workshop/pics/68_cd175_sprocket_cover_paint.jpg

remove footrest and gear lever if they're in the way.

remove screws from sprocket cover.

pull sprocket cover off towards you.

re-assemble in reverse order.

jam125 · Borekit Bruiser Joined: 14 Jan 2006 Karma :

if its like mine the front sproket can twist a bit on the shaft and cause a clunk.
There are 3 bolts on the sproket cover one in hole that you will need a socket and extention to get at, one at the top of the cover and one just above the gear lever which is a pig to get out in a cramped shed. i dont know if it will be exactly the same beacase i have the cheapo hongdoo Embarassed

WavyGravy · Scooby Slapper Joined: 10 Mar 2006 Karma :

you'll probably need an impact driver to undo the screws.

dont be tempted to replace those grimy/oily/gunked up bolts holding the sproket locating ring on, theyre made from a high tensile strength steel and those shiny alloy ones they sell at B&Q could cause the nastiest accident and destroy your engine in a blink.
____________________
1975 CB125s, 1991 GN250, 1990 Ducati Paso 906
"Don't wake him up - He's got insomnia - He's trying to sleep it off"

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

Hi,

The noise is a deep clicking coming from this part of the bike when I rotate the back wheel in neutral with the engine off.

https://i66.photobucket.com/albums/h277/th0r0n/Arg.jpg

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

Opened her up,

The retaining clip is there, and there is no play on the sprocket, the clunk seems to be coming from 'within' the engine.

I gave it a clean
https://i66.photobucket.com/albums/h277/th0r0n/EngineCover.jpg

Sprocket = Ok
https://i66.photobucket.com/albums/h277/th0r0n/EngineCover1.jpg

It's really dirty
https://i66.photobucket.com/albums/h277/th0r0n/EngineCover2.jpg

Looks ok to me
https://i66.photobucket.com/albums/h277/th0r0n/EngineCover3.jpg

Oh fuck, I broke a gasket
https://i66.photobucket.com/albums/h277/th0r0n/EngineCover4.jpg[/b]

WavyGravy · Scooby Slapper Joined: 10 Mar 2006 Karma :

its a longshot but does your cg have a kickstart ? sometimes the return spring doesnt quite disengage the ratchet and it clicks when the engines turning over, am thinking if you removed the kickstart (if you have one) when you removed the exhaust did it go back exactly as it came off? can you press it forward a little more than the return spring takes it?
____________________
1975 CB125s, 1991 GN250, 1990 Ducati Paso 906
"Don't wake him up - He's got insomnia - He's trying to sleep it off"

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Counts that clip out.

Can you take another picture of the sprocket, with a more direct view point? Difficult to see, but it looks like the teeth are hooked in that picture. If so rotating the wheel backwards would give a click.

Beyond that I would be tempted to give the bike an oil change, and check the oil that comes out carefully.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

Here's a recording of the sound.

Disregard the file comments, I was bored.

WavyGravy · Scooby Slapper Joined: 10 Mar 2006 Karma :

I'm still leaning towards something to do with the kickstart,

i'd check your oil and your mesh filter as kickstart suggested, those dipstick bits must have gone somewhere.

when you spin the wheel have you tried putting your finger against the centre of the spindle and felt it 'bump' when the click happens (ignition off and keys out while you try this) .... or grab the kickstart and do the same thing, feel the bump?

Wouldnt worry too much about the gasket, its not to keep oil in but to keep water out, as long as theres no gap you'll be ok, if there is a gap be inventive.

Has the engine been split before you got it? (tell tale signs are the bolts that hold crankcases together)

I wouldnt worry about splitting the engine yourself other than for learning exercise, you can pick up second hand engines for less than the price a honda dealer will charge you for a few worn cogs if thats what it turns out to be, i still think its got something to do with the kickstart, especially if the engines been split in the past, theyre a real git when reassembling because the return spring pulls the assembly over to one side while youre trying to line up the gears and fit the 2 halves together, the slightest movement and something goes where it shouldnt
____________________
1975 CB125s, 1991 GN250, 1990 Ducati Paso 906
"Don't wake him up - He's got insomnia - He's trying to sleep it off"

WavyGravy · Scooby Slapper Joined: 10 Mar 2006 Karma :

This is your strife (groan)
____________________
1975 CB125s, 1991 GN250, 1990 Ducati Paso 906
"Don't wake him up - He's got insomnia - He's trying to sleep it off"

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

Good lord, that's a big mess of cogs right there :S

WavyGravy · Scooby Slapper Joined: 10 Mar 2006 Karma :

its just a process of elimination, as its happening with the engine off and in neutral its not a problem with the top half or with the crank. the fronthalf is connected to the back half via the clutch, assuming the kickstart is fully disengaging the clutch can be discounted because the noise is there in neutral.

That just leaves the gearshaft/layshaft assembly or something has fallen into the oil filler. unless hondas build quality has gone down the swannee i'd swear those gearboxes are the least stressed parts of the engine - unless someones been reading about clutchless shifting on a forum not a million miles from here Laughing

j/k

when you get a chance tomorrow mark one of the teeth on the final drive and see if the noise happens at the same place each time the things rotated, the shafts inside the engine spin at different rates, if it clunks in the same place it means the problems probably on that drive shaft
____________________
1975 CB125s, 1991 GN250, 1990 Ducati Paso 906
"Don't wake him up - He's got insomnia - He's trying to sleep it off"

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

I can't hear it when the bike is in gear, this might be because the engines quite loud tho Smile

But I'm pretty sure it doesn't make noise Smile

jam125 · Borekit Bruiser Joined: 14 Jan 2006 Karma :

yeah most tight bolts will crack when you un do them

Vin · World Chat Champion Joined: 02 Aug 2005 Karma :

veeeffarr · Super Spammer Joined: 22 Jul 2004 Karma :

Resolved:

This was due to tight spots in the chain.

I removed the chain and gave it a paraffin bath, left it to dry, and coated heavily in chain lube and refit.

The wheel spins freely now.