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[B10BLT]

Hi All. Out yesterday with my 2003 sixty five with 535 Hitchcocks conversion. ( and newly fitted sidecar!). Previously very reliable. No tappet noise, though had not checked recently. Going uphill with engine under load, smoke accompanied by clattering and engine failed. No compression at all.. Removed tappet cover. Inlet pushrod would not move at all. Light failing, so called the breakdown truck. Any ideas please before starting to dismantle?

[Beezabryan]

Strip the head & you may well find the reason for your woes.

[Thack]

I'm not sure what you are expecting people to say. Nobody can diagnose an engine failure like this from a paragraph on a discussion board.



All I would suggest is what Beezabryan said: start at the top of the engine.



HOWEVER, I would warn you of one thing. I made a massive mistake once by doing that. My Matchless 250 seized up one day, so I took the top end off. The bottom end seemed fine and rotated freely with no play, so I had the barrel rebored and got a new piston. Put it back together.



What a fool. The reason the engine had seized in the first place is because the oil pump drive had failed. Yes, I was young and naive back then, which is why I didn't check it properly.



The lesson? Even though you should start at the top and find a fault, check everything else THOROUGHLY.

[papasmurf]

Perhaps the pushrod has jumped off and jammed. (It does happed apparentlt.)

[Gwilly]

Its the smoke bit that worries me. Was this from the head gasket area or from the exhaust?..

Was the conversion fully run in before the sidecar addition..?

[jefrs]

Many many reasons. What springs to mind is jammed valve and hence seals gone but could easily be something else. Valve jammed open gives no compression, seals shot produces smoky oil, and the pushrod won't move.



Strip the top out. Good luck.

[B10BLT]

Thanks all. As suggested, stripped down head.. Had hoped jammed valve but actually We think the Amal carb must be under jetted. Beware all fitters of big bore.. Expensive mistake.. Engine had been very carefully run in.. However Piston melted... Ever onward...

[sofiaspin]

Does the kit include a pre-jetted Amal Mk 1, or advice on jetting? Did you not upgrade the jetting at all? Useful information to know hope the rebuild is not too costly.

[jefrs]

Oh dear. New piston and re-bore? A series of plug chops may help gauge the mix but really only to select the right grade of plug for your load usage. Without an O2 sensor showing the air/fuel ratio one listens to the engine, which is why it is called tuning - like a piano. Those little sounds tell us what is going on inside, tinkling pinking sounds not being very good at all. Other senses like smells of petrol and oh my gosh this engine is hot are useful too.

[Tim NZ]

Either a pic, or an accurate and detailed description of the piston (top, bottom, underneath, and sides) and the location of the seizure damage and the cause can be confirmed...


Not identifying the cause, then prospects of an encore appearance are likely ?