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Messages - PJM47

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31
CB750 / Re: Engine full of fuel and seized up
« on: October 14, 2020, 03:44:39 PM »
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?







32
CB750 / Re: Engine full of fuel and seized up
« on: October 14, 2020, 01:19:33 PM »
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

33
CB750 / Re: Engine full of fuel and seized up
« on: October 13, 2020, 08:31:07 PM »
Yes flywheel next. Doesn’t that need a special tool though? Any recommendations?

The wear on the shells is fairly even.

The flywheel gear is so close I can’t get my smallest feeler in between it and the case, that doesn’t sound right, and there are marks on the case where it looks to have rubbed.

34
CB750 / Re: Engine full of fuel and seized up
« on: October 13, 2020, 05:27:51 PM »
Just try oiling the shells they won't turn bone dry.

Yes they are all fully oiled

35
CB750 / Re: Engine full of fuel and seized up
« on: October 13, 2020, 05:18:06 PM »
OK so hope you are all still interested in this the one folks. Think we are getting to the end. Not sure who is on for winning the sweepstake.

So I removed one rod at a time as suggested thinking at some point it would free up, but got to the last one and guess what, it is still exactly the same, it turns a bit then gets stuck. As everything is loose it now actually lifts the crank out of the case / bearings if I try to turn it more. The primary chain is off at this point and there is nothing left connected just the crank sat in its slot, it won't rotate freely.

It looks like the big gear behind the alternator is right up against the case and maybe getting stuck in places, its very close anyway. So bent crank or maybe just that gear is bent? Should it be so close to the case?


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36
CB750 / Re: Engine full of fuel and seized up
« on: October 12, 2020, 08:35:51 PM »
Yes I think it probably would have turned if I tried hard enough but i didn’t want to go mad and break something else when it obviously wasn’t happy. it really really didn’t want to turn on the kick. It’s possible there’s more thank one problem of course but hopefully not. Also it is freeing up a bit from where this started when it wouldn,t turn on the crank either. Should find out soon enough thanks to all the encouragement to get on with it.

37
CB750 / Re: Engine full of fuel and seized up
« on: October 12, 2020, 07:00:58 PM »
Not necessarily, it may just be completely lacking in lubrication.

Ok sound like a plan, will do this next.

38
CB750 / Re: Engine full of fuel and seized up
« on: October 12, 2020, 06:24:30 PM »
So head off today. All went well, quite easy really. Barrels are all looking good, no marks or scoring.

Indeed this engine is beautifully designed, unlike the British ones from the same era I've worked on.

Still very hard and uneven to turn over as we would expect. So I guess fairly conclusive big end / conrod damage now as there's not much else left.


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39
CB750 / Re: Engine full of fuel and seized up
« on: October 11, 2020, 07:25:31 PM »
Yeah sorry I may have got carried way, I guess I thought as it felt the same with the cam off completely it wasn’t a cam problem.

40
CB750 / Re: Engine full of fuel and seized up
« on: October 11, 2020, 06:47:36 PM »
Yeah I took it off, and the cam out after that pic. We’re only left with the con rods or piston rings. I guess.



41
CB750 / Re: Engine full of fuel and seized up
« on: October 11, 2020, 04:52:38 PM »
OK so rockers off, no change.
Cam out, no change.

Still very stiff to move in places.

Everything looks ok with the cam though.

Head coming off next then.

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42
CB750 / Re: Engine full of fuel and seized up
« on: October 11, 2020, 04:45:44 PM »
This thread started in August and it's now October and not a lot seems to have changed. WTF???? ::)

I've only just started stripping it down last week as I've been busy with other projects.

43
CB750 / Re: Engine full of fuel and seized up
« on: October 11, 2020, 09:33:16 AM »
All looks ok under the rocker cover.

Cam out and head off next then. I'll read the manual, but any top tips I should be aware of?

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44
CB750 / Re: Engine full of fuel and seized up
« on: October 10, 2020, 07:57:54 PM »
Ok will have a look at that next.

45
CB750 / Re: Engine full of fuel and seized up
« on: October 10, 2020, 06:12:39 PM »
Yes absolutely, but do we know there actually is a problem now?

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