Fantic 300 1984 woodruff key searing

[benborisjamimajess]

Hi, so my fantic 300 1984 has been shearing woodruff keys not that often but a couple of times?? I used to have a 200 that did it a few times over a few years. Is this just a fantic thing of is there something else going on?? Thanks 

[kurtas]

Theoretically the woodruff key should not take any load from the engine at all, it only locates the flywheel correctly for timing purposes.
I would be investigating the torque you are using to retain the flywheel onto the tapered fit.
Also worth checking the tapered fit itself and maybe lapping it to correct if the fit/surface is poor.

[lsv]

8 hours ago, kurtas said:

Theoretically the woodruff key should not take any load from the engine at all, it only locates the flywheel correctly for timing purposes.
I would be investigating the torque you are using to retain the flywheel onto the tapered fit.
Also worth checking the tapered fit itself and maybe lapping it to correct if the fit/surface is poor.

Hooray, for once a correct and sensible answer on here! Take note especially of the last sentence.

[b40rt]

9 hours ago, benborisjamimajess said:

Hi, so my fantic 300 1984 has been shearing woodruff keys not that often but a couple of times?? I used to have a 200 that did it a few times over a few years. Is this just a fantic thing of is there something else going on?? Thanks 

 Make sure you give it the answer its hoping for, otherwise it has a hissie fit. 

[hero]

My 1986 241 has sheared its woodruff key and the flywheel is now jammed on the shaft

Ive broken a puller trying to remove it

Any ideas on getting the flywheel off?

 

[benborisjamimajess]

On 5/15/2023 at 11:39 PM, kurtas said:

Theoretically the woodruff key should not take any load from the engine at all, it only locates the flywheel correctly for timing purposes.
I would be investigating the torque you are using to retain the flywheel onto the tapered fit.
Also worth checking the tapered fit itself and maybe lapping it to correct if the fit/surface is poor

Any idea what sort of torque on flywheel nut?? 

[benborisjamimajess]

1 hour ago, hero said:

My 1986 241 has sheared its woodruff key and the flywheel is now jammed on the shaft

Ive broken a puller trying to remove it

Any ideas on getting the flywheel off?

 

Tighten up the puller until it's tight then give the end of the puller a sharp but not to hevey hit with a hammer, may as well put a little bit of heat on flywheel near to shaft aswell

[hero]

I've tried both those methods... a bit wary of too much heat with the electrics so close behind the flywheel

I'm assuming the key sheared and the flywheel continued moved round the shaft dragging what's left of the key with it.

The bike was running  (after 20+ years in a shed) then suddenly stopped

Now it just kicks back through the kickstart

So i'm left with maybe a makeshift attachment for a half shaft puller?

Or cut the flywheel off - if thats possible?

But i'm open to other suggestions

[fourex]

10 hours ago, benborisjamimajess said:

Any idea what sort of torque on flywheel nut?? 

65-70Nm according to my Fantic 300 manual.

[benborisjamimajess]

43 minutes ago, fourex said:

65-70Nm according to my Fantic 300 manual.

Thanks very much 

[hero]

As no-one came forward with a reply to my question above of how to remove a flywheel with a sheared key from the 241 engine that will not come off the shaft, I had to suppose that ( most fortunately ) it has'nt happened to anyone else. However, I was still stuck with what was probably a "write off" engine. If the flywheel wont come off then its not even possible to split the cases or remove the crank etc rendering it no more use as an engine. Even more difficult than getting the flywheel off is getting a replacement engine. I did get the flywheel off and (completely open to critisism of my method), here is how I did it;  I took a 41mm holesaw and cut completely through the centre of the flywheel. This actually ruined 2 cutters and, of course, the flywheel. The outer part of the severed flywheel came off and I could see the coils. I was then left with the remainder of the flywheel on the shaft. I was now able to use a hacksaw blade along the remaining part, in line with the crank although I did have to shape the end of the blade in order not to damage the coils. The blade had to be hand-held and wrapped in a cloth to protect my fingers. I made 4 cuts very carefully at what I thought was the right angle of the taper and every now and then, refitted the puller to try. The puller eventually pulled it off the shaft. There is a graze or 2 along the shaft but it cleaned up well enough. Another bit that took some effort was getting the remaining part of the woodruff key out of the shaft slot. The story is quite short really in comparison to how long the job took but I can now move on, tear the motor apart and replace any parts that are worn. Pictures were taken and they're not very pretty.

[hero]

Cut off f;ywheel and remainder still on shaft. All removed now though. A new flywheel should be easier to find than a new engine I hope.