Engine full of fuel and seized up

[MrDavo]

That gear wheel that is fouling the case took all the torque from the starter motor, trying to turn a crank that was locked solid. Is it possible that it is just now on the p*ss somehow, and the crank isn’t bent? The way it is fouling and leaving a witness mark makes me wonder, the main bearing hasn’t moved laterally looking at the picture. I can’t see the gear wheel bending, but nothing is impossible.

Possibly the starter clutch arrangement is damaged or bent instead, that would be a far better outcome than the crank. I had a tool to get the alternator off but nothing would budge, I ended up going to a local engineering shop. Trigger’s yer man there, however if it is now on skewiff then things may not be straightforward.

[K2-K6]

Still something odd there as the crankshaft should rotate forward while leaving the starter gear stationary via it's sprag clutch.

It may prevent the starter motor from operating,  if it were damaged.  But the kickstart doesn't go through that way,  it's via the primary drive direct to crank and avoiding the starter gear.
You'd have imagined that the kick would still work in the above scenario.

Also if main bearings where dry,  it's likely that it would be consistent in resistance for whole rotations,  and not more pulse like.

[McCabe-Thiele (Ted)]

That gear does look very close I'm not familiar with your engine but how is the gear & flywheel located on the crankshaft is it a woodruff key & taper fitting ?
Is there any kind of spacer or thrust washer between the gaer and the crankcase any end float control?

[Bryanj]

Generator is on a taper and there are no thrusts as there is no sideways force on the crank, unless you throw it down the road

[McCabe-Thiele (Ted)]

I'm thinking the woodruff key has moved as part of your troubles - I can't see the crank being bent given the circumstances. It's definitely a mystery it will be very interesting when you finally locate the cause.

[Trigger]

I'm thinking the woodruff key has moved as part of your troubles - I can't see the crank being bent given the circumstances. It's definitely a mystery it will be very interesting when you finally locate the cause.

No woodruff key on a 750 SOHC 

[MrDavo]

If the gear is on a taper then it could have shifted to 'cockeyed' under a twisting stress, especially if there is any scope to move sideways, even by a fraction.If it is now fouling the case then it would still be hard to turn even from the kickstart.

Whatever I am glad you are getting to the bottom  of it, as the suspense is killing us.

This reminds me of when, as a teenager, I worked some evenings and weekends at a garage in Lancaster - even at school I had a Moggie Minor and a Triumph T100 to support. One day the boss asked me to come with him to help tow in a Mini estate that had clanked to a sudden halt in Galgate. We spoke to the lady driver, who told us that she had just topped the water up at a petrol station, and how it had taken ever such a lot to fill it right to the top. My boss asked her to show him where she had put this water, and she pointed to the oil filler cap on top of the rocker cover. 

[PJM47]

Thanks for your continuing support on this one people.

After lifting the crank in an out a few times the large starter gear has come loose and is now free to move on the taper shaft, I can move it latterly by 5mm or so, it spins freely (independently of the shaft) clockwise but not anticlockwise. Not sure what is going on there.

But with the starter gear now floating loose on the shaft and the crank back in the case, the crank now rotates freely and smoothly, phew, so I believe somehow that gear had got jammed against the case causing the problem.

I need to get the special generator puller tool before I can look any further, and how to fix it is not yet clear but I'm thinking we are pretty close now...

Cheers
Paul

[Trigger]

On the inside of the starter cog is a bronze bush, it is easy to see it that is damaged 

You have done this a little arse about face as, you should of taken the fly wheel off before splitting the engine 

[philward]

No problem with the starter riing only turning one way as that's what it should do - so one thing less to worry about

Sent from my moto g(7) power using Tapatalk

[K2-K6]

"After lifting the crank in an out a few times the large starter gear has come loose and is now free to move on the taper shaft, I can move it latterly by 5mm or so, it spins freely (independently of the shaft) clockwise but not anticlockwise. Not sure what is going on there."

That's the correct operation of it,  a very clever "sprag" clutch that will spin the crank in one direction when actioned by the starter motor, but be completely free in rotation in the opposite direction.  It stays still while the motor runs and is virtually frictionless.

It means the starter doesn't have to be engaged/disengaged unlike a car system.

[philward]

On the inside of the starter cog is a bronze bush, it is easy to see it that is damaged 

You have done this a little arse about face as, you should of taken the fly wheel off before splitting the engine 

Will be difficult to get it off now even with the tool due to holding the crank - should be doable but more difficult

Sent from my moto g(7) power using Tapatalk

[PJM47]

Ok learning a lot here.

Managed to get the generator nut off, just waiting for the puller tool now.

Although the starter gear is now behaving more correctly (it didn't spin any direction before, only just realised that wasn't normal!) I assume there is still something wrong? In normal operation is that cog free to move a bit latterly. I assume it's not meant to be able to rub the case if it wants?

[Bryanj]

Still doubt the starter gear caused the problem

[K2-K6]

Ok learning a lot here.

Managed to get the generator nut off, just waiting for the puller tool now.

Although the starter gear is now behaving more correctly (it didn't spin any direction before, only just realised that wasn't normal!) I assume there is still something wrong? In normal operation is that cog free to move a bit latterly. I assume it's not meant to be able to rub the case if it wants?

There's a sectioned schematic of it in the original 750 manual (doesn't appear in last one) that may help, check Ash's dropbox stash for a look.  If not there I can photo and post from mine.