Bungartz K5

[charlie]

I have made some progress with the K5. Prop to stand machine on whilst changing implements now works. Handlebars now swing left and right. Unfortunately I did not take any photos of this work only this close up of the swivel mechanism before freeing off.

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[charlie]

The major issue with this machine is an unknown engine problem that caused it to stop/seize up, the previous owner suspected a bearing in the engine.
So I set about stripping the engine.
First task was to remove cowling, exhaust and inlet etc.

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[charlie]

The engine has an aluminium cylinder head and the previous owner had told me when he had previously removed cylinder he did not risk removing head due to head bolts corroded into cylinder head. I followed the same course of action and removed barrel and head together to reveal piston etc.

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[charlie]

Inspection of the piston revealed one piston ring was rotating in groove due to broken lock pin. This will need repairing before reassembly. Luckily piston ring had not suffered serious damage. The engine is a two stroke and ring could have caught in one of the ports. There was excessive movement of piston on connecting rod, so gudgeon pin was removed, this showed wear in pin and bush; this will need attention before reassembly.

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[charlie]

Now on to the task of removing the crankshaft. First the clutch withdrawl mechanism, clutch assembly and fywheel had to be removed. The taper pins holding clutch fork to shaft required a lot of heat to free them. Heat and pullers were also needed to remove clutch and flywheel, luckily tapped holes are provided for attaching a puller.

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[charlie]

With flywheel and clutch removed it was just a simple case of splitting the crankcase to remove crankshaft.

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[charlie]

Now the problem could be seen.
Front bearing rusty and very dry, rear bearing cage had broken up allowing rollers to fall out when crank was removed. Both bearings will need replacing, so I will be taking the crank and bearings along with piston to Cox and Turner Engineering to see what can be done.

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[trusty220]

That’s a really well engineered engine by the look of it. I should say, over-engineered, but you should be able to overcome the problems without too much trouble. The little end bush will probably be the most difficult one to replace.
Good luck with it, Charlie. It will be good to see it working at the events this year.

[charlie]

I sent an e mail to Cox and Turner and hope to visit them Friday morning, Ian did say ‘just don’t be in a hurry to get it back’. I have a feeling they are very busy. So may not be out until next year.

[hortiman]

It would be good to hear it running again Charlie, as I remember hearing it grind to a halt in a little puff of blue smoke at GDSF.

Good luck
Chris

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