Engine full of fuel and seized up

[bobv7]

This thread started in August and it's now October and not a lot seems to have changed. WTF?

[Johnwebley]

Just take the cam out and see what happens.


It should be fairly easy to turn over.

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[Trigger]

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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I see a lot of damage were people put the wrong length bolts in the wrong place when putting the cam towers back on. There are 4 bolts that have number 7 on the head, make sure these go back were you took them from as, they are a tad longer than the other bolts and if in the wrong place will punch the bottom of the thread holes out and will leak.

What you need to do is remove the rockers and get the cam chain off. Leaving the cam towers on the head, place the cam shaft back in the towers and put the cam caps back on. Bolt it down and see if the cam rotates easy in the towers. This will rule out it the cam shaft is bent or not.

I still have not seen anything untowards from the pictures. Have you assembled the gear box in the lower casing and with the clutch basket on, tried the kick start ?

[K2-K6]

Once you've removed the rocker shafts (and rockers) you can still turn the engine to see what it feels like ae all the valves are just left closed, as long as the plugs are out you'll not have any resistance from valve springs.

It obviously won't check the cam as trigger has indicated above though.

[PJM47]

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.

[PJM47]

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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[Trigger]

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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The cam chain is still on in your picture

[PJM47]

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.

[Trigger]

Did you test the cam in the towers with the chain off ?  You are jumping too far ahead with pictures so, if i can't see the stages then, i will miss things that maybe important to advise on this problem .

[PJM47]

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.

[K2-K6]

If it's tweaked the rods such that the big end sits out of plane with it's journal,  then that pinching would give sporadic resistance.

You'd expect to find witness marks on the big end shells as they would effectively try to wear "diagonally "  which if wearing away would slowly allow you to turn it as the shell material wears off.  Potentially 

PJM47, notice, from dismantling, how you can set the cam timing with absolutely no risk when you come to reassemble as nothing interfears while rotating/ checking until you put the rockers in.  It's a very clever design like that.

[PJM47]

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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[royhall]

Not necessarily, it may just be completely lacking in lubrication.

[philward]

So final check is undo con rod main bearing and try manually moving piston up and down - if moves freely, then must be a tweaked rod. Logically, if you disconnect one at a time, and turn crank you will be able to identify which rod (rods) thats tweaked?

[PJM47]

Not necessarily, it may just be completely lacking in lubrication.

Ok sound like a plan, will do this next.