Primary Drive Gear Bolt Tightening, how w/o moving crank?

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#1
I am putting my bike back together for the 1st time, :) I am at a point where I am to put the primary drive gear back on the crank shaft and I have everything ready and waiting, but I'm not sure how to tackle the problem of torquing the bolt to 50ft/lbs without spinning the crank around..

I'm sure there is a tool to buy to do it, but it'd be nice to be able to without spending more for a one time thing

I tried a strap wrench on the gear as I tightened the bolt and it worked until I had to actually put a lot of pressure, then the rubber strap just kept moving/falling off the gear. I dont even think I made it to 30ft/lbs.
Any tricks?

Thank You!
 
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#2
If the strap wrench is all you have to work with you may try holding the opposite side by the fly wheel. Not sure on that bike but might be worth looking at.
 

darringer

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#3
Wedge a penny between the primary gear and the clutch basket gear to lock the crankshaft to get the correct torque. The penny is softer than either gear, and will deform long before damaging the gears. Used this trick forever with zero problems.
 

IndyMX

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#4
if you have the cylinder and head back on already, you can use a piece of nylon rope in the spark plug hole... run enough down in so that when the piston comes up to the top, it stops... make sure you leave enough out so that you can remove it.
 
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#5
You could use an air impact and been done!I have done all the tricks,except the rope and have decided not to be putting all that stress on my crank,rod and basket!
 
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#6
whenfoxforks-ruled said:
You could use an air impact and been done!I have done all the tricks,except the rope and have decided not to be putting all that stress on my crank,rod and basket!
It'd be nice to do that, but my impact I dont really have an idea of how much torque it is putting out. Its a cheaper one w/ 250ft lbs max, and 4 settings, but they dont give you a est of the torque on each setting.

Maybe the penny will work... Sounds scary but ive done worse when assembling things lol. Cause I dont have the top end on yet.
 

darringer

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#7
There's alot more load on those gears while you're hammering the throttle than from the wedged, soft penny. Done it more times than I can recall without incident.
 
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#8
another trick is to wedge a grease rag or a wadded paper towel in the gears. works every time.
 
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#9
i use an old primary drive gear or as everyone else said a penny or a piece of brass. any thing softer than the gears