Need advice loosening a front sprocket nut - why you should keep the chain tensioned

[motorbyclist]

went on a 60km trail ride the other week, and by the last few km, if the weight of the bike wasn't all on the rear wheel, giving the throttle a squirt just made lots of chain noise and not much forward motion

safe to say i neglected to check the chain tension before beginning the ride

could've done with some more lube too


anyway, i've been trying for an hour now to get the front sprocket off. i've got the right size socket, covered the nut with crc and i'm turning it the right way, but sofar all i've managed to do is turn the engine over and bend a screwdriver i used to try to lock the rear wheel (put shaft in hole in rear sprocket, jamming against swingarm)

tried tightening it to hopefully crack any corrosion, tried using a hammer (of course) for a similar reason...

any hints/tips/advice/solutions?

(the bike is a '98 yamaha yz400f - and yes i know it needs a clean)

[The Pastor]

use a bigger power bar

[Disco Dan]

ya tried putting the bike in gear?

[Subike]

have you got access to an air powered rattle gun
if not
An impact screwdriver with a 1/2 drive head and a brass hammer
and be sure its not a left hand thread

Failing the access to those tools, take it to a person who has,
trying to lock the crank from turning to force the nut free could result in damage you just dont want to know about.

The right tool for the right job will always get you there faster.
The wrong tool will always wear out the soles of your feet

[motorbyclist]

ya tried putting the bike in gear?

yes, that's what i meant by "sofar all i've managed to do is turn the engine over"

tried jamming it at the rear wheel with a scredriver, but still no luck, just a bent screwdriver

have you got access to an air powered rattle gun
if not
An impact screwdriver with a 1/2 drive head and a brass hammer
and be sure its not a left hand thread

Failing the access to those tools, take it to a person who has,
trying to lock the crank from turning to force the nut free could result in damage you just dont want to know about.

The right tool for the right job will always get you there faster.
The wrong tool will always wear out the soles of your feet

i was worried about that

i'm sure about the thread - i can see a bit of it, and a left hand thread would be "wrong" for this application

i've got an impact driver, but it's got a 1/4" head, and i believe it may be broken anyway

[FJRider]

have you got access to an air powered rattle gun
if not
An impact screwdriver with a 1/2 drive head and a brass hammer
and be sure its not a left hand thread

Failing the access to those tools, take it to a person who has,
trying to lock the crank from turning to force the nut free could result in damage you just dont want to know about.

The right tool for the right job will always get you there faster.
The wrong tool will always wear out the soles of your feet

what he said

[Buddha#81:Me]

Put the bike in 1st and get someone to sit on the bike whith their foot on the rear brake put a bit of pipe over the handle of your power bar and swing on it......tention the chain fairly tight first or it will just jump over the front sprocket.

Also make sure it doesn't have a lock tab stopping the nut from turning.

Good luck.........

[boomer]

i think you've got the wrong bit of ya bike.. those pics aren't of a sprocket!!! far out... maintenance hasn't been high on the agenda huh!?



get a socket set then get a hollow metal bar and use teh bar as an extension to put the force on the sprocket... maybe a couple of taps on the extension with a rubber mallet will 'help'

alternatively take it to the shop and ask for a FULL service ya tight arse

[Subike]

Put the bike in 1st and get someone to sit on the bike whith their foot on the rear brake put a bit of pipe over the handle of your power bar and swing on it......tention the chain fairly tight first or it will just jump over the front sprocket.

Also make sure it doesn't have a lock tab stopping the nut from turning.

Good luck.........

Have a good look at the pic,
Doing what you suggest would have no effect what so ever
there is no teeth left on the front sprocket to lock on to

[motorbyclist]

Put the bike in 1st and get someone to sit on the bike whith their foot on the rear brake put a bit of pipe over the handle of your power bar and swing on it......tention the chain fairly tight first or it will just jump over the front sprocket.

Also make sure it doesn't have a lock tab stopping the nut from turning.

Good luck.........

Have a good look at the pic,
Doing what you suggest would have no effect what so ever
there is no teeth left on the front sprocket to lock on to

that, and i've tried it already


but what is this lock tab of which you speak?

[FROSTY:Me]

Dude--the sprockets ferked right?--if yer gonna replace chain and sprockets why not tighten the chain till its bar tight -Then jam something into the sprocket/chain.
Wouldnt normally suggest it

[motorbyclist]

get a socket set then get a hollow metal bar and use teh bar as an extension to put the force on the sprocket... maybe a couple of taps on the extension with a rubber mallet will 'help'

alternatively take it to the shop and ask for a FULL service ya tight arse

done the first bit, and that bike has never seen a mechanic since i bought it a few years ago

if i ever scrounge enough money together for a rebuild, i'll be doing myself anyway

good ol' YZFs just dont die

[motorbyclist]

Dude--the sprockets ferked right?--if yer gonna replace chain and sprockets why not tighten the chain till its bar tight -Then jam something into the sprocket/chain.
Wouldnt normally suggest it

how exactly do you mean? already jammed everything at the rear wheel....

and the rear sprocket is surprisingly intact, but i'll be replacing it anyway - along with the plastic bit on the swingarm... chain has made it's own grooves in the metal

[Ixion]

They tighten the damn thing ultra tight and then put high strength loctite on as well.

What Mr Frosty means , is tighten the chain as tight as it will go, then shove something like a tommy bar in between the chain and the sprocket just at the bit that the chain goes onto the sprocket (the front one ). So that when you turn the sheel, the tommy bar will be drawn into the sprocket so it ends up (or tries ot end up) jammed between the sprocket and the chain . Since the chain is tight, theres no room for the tommy bar, and it will lock the sproket.

It'll likely bugger the sprocket and the chain , but as Mr Frosty says, in your case, so what.

That'll lock it for certain. Only way the thing will turn then is to break the chain.

[motorbyclist]

They tighten the damn thing ultra tight and then put high strength loctite on as well.

What Mr Frosty means , is tighten the chain as tight as it will go, then shove something like a tommy bar in between the chain and the sprocket just at the bit that the chain goes onto the sprocket (the front one ). So that when you turn the sheel, the tommy bar will be drawn into the sprocket so it ends up (or tries ot end up) jammed between the sprocket and the chain . Since the chain is tight, theres no room for the tommy bar, and it will lock the sproket.

It'll likely bugger the sprocket and the chain , but as Mr Frosty says, in your case, so what.

That'll lock it for certain. Only way the thing will turn then is to break the chain.

right, i see both why it's do damn tight and how you mean to jam it

i'll give it a go tomorrow after work and get back to you


do you reckon it would've tightened at all during use? i can't tell if there's a spline on the shaft or not from where i'm sitting - all my past bikes had splines and a locker thing bolted on to the sprocket so it was pretty obvious