New chain set on a 450

[Posh Pete]

I just did this job on mine after nearly 10k miles in the last (nearly) 2 years. I decided to change the gearbox sprocket only this time. The rear wheel sprocket looked fine and I'll hang onto the new one until next change when both will be replaced.

If you're doing this job, be warned: it's a bugger! I eventually locked the front sprocket by removing the rear wheel, replacing the axle and locking the chain around it with a 16mm bolt and nut through the chain on one side of the axle and mole grips as a clamp on the other side. I then borrowed a friend's rattle gun and the nut came away in seconds. That was after several fruitless attempts with a big shifter, back brake, lumps of wood between the chain and back sprocket etc.

While in there, I removed the chain adjuster and screwed on a nyloc nut to the allen bolt. On a check ride today, I noticed the feckin thing had come loose again but the nyloc nut stopped it being lost. A wee tip : I had a package on the back to deliver the tool back to my pal. I could not be arsed removing it all to get at the tools under the seat. Then - inspiration! The ignition key is exactly the right size to tighten the allen bolt snug to the swinging arm! And it's still tight now!

 

[dommiek]

How do the RE mechanics get around this problem. Is there a special tool to lock the front sprocket to stop it turning?

 

[Posh Pete]

How do the RE mechanics get around this problem. Is there a special tool to lock the front sprocket to stop it turning?

Yes, there's a special tool although I doubt if many dealers actually have it. The method I used worked fine. I've also heard of someone using a long screwdriver through a gap in the brake disc.

 

[AdrianS]

Yes, there's a special tool although I doubt if many dealers actually have it. The method I used worked fine. I've also heard of someone using a long screwdriver through a gap in the brake disc.

It’s surprising how easily a good rattle gun will undo a very tight nut without having to lock the sprocket up.
I probably would have wedged a bit of wood between the chain and sprocket first, then used the rattle gun. That’s the way I’ve done it in the past.
Out of interest, what’s the recommended torque figure that Royal Enfield recommend the nut is tightened to?

 

[Greg Masters]

Is it not possible to remove said nut before you remove the chain?

 

[AdrianS]

Is it not possible to remove said nut before you remove the chain?

That’s what I always do. You need the chain to lock the sprocket.

 

[The Other PaulG]

Is it not possible to remove said nut before you remove the chain?

I assume that when he mentioned using the back brake unsuccessfully, the chain was still in place.

 

[sniper]

Same as every bike. Undo sprocket nut before chain with rattle gun.

 

[andysdad]

If you use a rattle gun, do not put the bike in gear and hope the motor will hold against the rattle gun’s torque.

Apparently you can damage the gearbox.

On my 411 I jammed the chain to the rear sprocket with a piece of wood, rear wheel on the ground, front in a chock.