Locking The Crank

[squirrel_hunter]

Need to tighten the primary drive gear on my engine, 65nm according to Yamaha. Trouble is, how do I stop the crank from rotating?

When I disassembled it I used a rattle gun, but that wont work for tightening it to an accurate setting. Yamaha say to use a rag between the primary drive and the clutch drive gears. But I tried that on disassembly. All that happened was the rag got mangled through the gears and was a pain to remove the remains. So ideas?

[EEKNOWS]

A bit of 3mm aluminium flat bar jammed in between the gears works fine, much tougher than a rag 

[Edd]

Jip that should do the trick. The web will not turn at 65 nm, or just grab the web closest to the shaft it in a vice between two aluminium plates so as to not scratch and dent the web and torque away

Edd

[teezer250]

You could also try a 1p or 2p copper coin or flatten a piece of copper tubing (plumbing pipe) jammed in the gears.

[squirrel_hunter]

There is something about jamming some metal between gears that I really don't like the idea of. Don't know why but I just fear it jamming in there and damaging something.

What I have seen before is a sort of flat plate with a fork like cut out that sits over the crank with the conrod in the cut out. Stick a bar through the small end and rotate round until it locks. A sort of universal locking tool. But no matter what I search for I cant find anything like that?

[EEKNOWS]

so long as the "jammy" is softer than the gears no problems. Pit Posse sell the fork your looking for, they are a good idea but not as good as the jammy  when putting the engine back together

http://pitposse.com/stenloupto.html

http://pitposse.com/pibaho1.html

[teezer250]

You could make your own locking tool with a bit of flat aluminium plate and cut a slot that fits snugly UNDER the BOTTOM of the little end of the conrod with a bit of careful measuring.DO NOT PUT A BAR THROUGH THE LITTLE END EYE TO JAM THE CRANK AS THIS CAN ELONGATE THE HOLE.

A soft metal(copper coin) will not harm the gears and i have used this method to do mine a few years ago.

[squirrel_hunter]

http://pitposse.com/pibaho1.html

That's what I've been looking for, shame they are not UK based.

they are a good idea but not as good as the jammy  when putting the engine back together

Why is that?

DO NOT PUT A BAR THROUGH THE LITTLE END EYE TO JAM THE CRANK AS THIS CAN ELONGATE THE HOLE.

I wouldn't have thought that would happen as I've used this method before without issue. If I were to put a piston on there and lock it against the base of the piston, would that be better at spreading the load on the small end?

I think I might pop into my local shop and see what they use. But using a 2p to lock it is something I can do. I just don't want it to jam the crank and then jam in there.

[squirrel_hunter]

Well had a chat with my local bike shop and they would use any variety of technique to lock the crank, from official Honda tools, nuts, screwdrivers, and locking plates. So thanks all for the advice here, I decided to go with the 2p method.



And jobs a good un. Primary drive and alternator fully torqued up.

I took the clutch out to check after the first torqueing and there was some copper on one of the teeth, but only superficial, no damage. I will remember this for the next time I need to build an engine...

[Mick]

Bit late but the way I was told by Terry Becketts engine builder was if you intended to remove crank strip and reassemble,take the crank and fit the very right hand web in a vice,fit the bearing,seal,primary gear,nut and tighten.Because the the web is secure in vice there's no chance of you knocking crank out of true.