Strter freewheel key

S

sergio750sf

New member
Location
France
Hello

Yesterday I tried to start the engine of my new rebuilt 750 sf and the starter freewheel key broked !
Need your help to find the reason of this problem and fix it.

Have a good day 


 
Loose nut.

The woodruff key is not meant to tarnsmit any movement, the (tight) taper does that.  The key is for positioning only.

piet 
 
sfcpiet said:
Loose nut.

The woodruff key is not meant to tarnsmit any movement, the (tight) taper does that.  The key is for positioning only.

piet
Click to expand...
Ditto the taper carries all the load.
A lot of manufactures these days have done away with the key all together ( cheaper not to have to machine a slot ) and rely solely on the bolts being torqued up correctly. Amazing how many so called mechanic's dont even own a torque wrench let alone use one.
 
If the mating surfaces of the taper are damaged (scratched, scoured) it will affect the strength of the fit. Can be lapped using valve grinding paste between the freewheel and the crank taper, hand-turning back-and-forward. Easy enuff to make a new key as well - and then tighten securely!
 
Many thanks for your answers
I noticed some scratches on the crank taper and the free wheel as well.
Before install  a new key on I will try the valve grinding past method.
Is there any product I can use to increass the torque capacity of the taper?

Many
 
If tightened to the correct torque, the nut and taper are more than adequate to transmit any movement applied.  Introducing a friction-enhancing medium may result in a permanant fitting... :D

Just make sure both the internal and external tapers are clean and in good condition and do up the nut nice and tight.  Reckon applicable torque would be around 90-110Nm, I hit it with a rattle gun at the lowest setting for a second or 2, never had an issue with that method.  Also puts far less strain on the crank assembly than blocking it from the LH side and applying torque from the RH side.

piet
 
sergio750sf said:
Hi

The " left" Grower washers seem not to exist nowadays.
What kind of locking washer do you use to secure the starter freewheel nut ?

Serge
Click to expand...

In stock at OCT, just need to ask...  octeam@gmx.de

piet
 
you should also check (say) lower points are firing the left cylinder through the correct coil and not vice versa.
Easily fixed if only temporarily (due to lead lengths)  just swap left plug lead for right.

the backfire resulting from this may have shown up the problem with the loose taper, better now than later (no kickstart)
Clem
 
sergio750sf said:
Yes Piet but I am in France and the postage fees are 10 times the price of the washers !!
Click to expand...

Huh??

Price of the special washer about ?3, postage in letter approx. ?1,50.  Cheaper than walking...

piet
 
Hi

I ordered from OCT  a lot of parts and two washers (priced 1?19)

Reinstalled the free wheel and torqued the nut to 12 danm and it works !
The engine runs and needs some adjustements but I am confident.

Viva Laverda
 
D?sol? pour ta SFC et ta TT2 et les autres machines
Quel genre de  types ont  pu faire une chose pareille ?

Sorry for your SFC and your TT2 and the other bikes
What kind of people are able to do such a thing ?
 
Merci Sergio. Je suis convaincu qu'il s'agit d'ados vers?s dans les mauvais coups.
La TT2 est ? la maison mais d'autres priorit?s pour l'instant.

Thanks Sergio. I'm convinced that it's kids out for a few thrills.
The TT2 is at home but I have other priorities for the moment.

Paul
 
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