On Thursday night last week the bike was finished and we fired it up. The engine ran like a dream and all was poised for a first run this weekend.
On Friday evening I got home early and planned to spend an hour on the farm practising to get the carb and suspension set up and see how it felt compared to the previous frame.
I pulled it from the shed but try as I might, I just couldn't get it to start. All the usual checks gave no clues (big fat spark, fuel getting through, vales opening/closing correctly, clutch disengaging etc). The only thing that felt odd was that with the plug out just turning the engine over on the kickstart was quite hard and felt somehow a like there was a non metallic resistance of some type.
On Saturday morning I took it over to Dad's workshop and we pulled the engine back out of the frame and took the head and barrel off. By this time, we were unable to turn the engine over and could only just about move the piston back and forwards but not up and down.
Fearing a main bearing problem or similar I took the engine over to Pete Kirby and thankfully Pete dropped what he was doing and pulled the engine apart for me.
Whilst doing so, the engine was turned upside down and what I can only describe as oily gloop (about the same texture as snotty blancmange) ran out of the engine. This didn't look good at all!
As the engine came apart we found more and more of this oil that appeared to contain fibres in it that had clearly got into just about every part of the engine. As we got to the crank it became clear just what had happened.
When we bought the frame it was advised that a modification was required to the oil pump cover on the bottom of the engine where the scavenge pipe is cut short and the original cover is replaced with a flat plate that is milled out to allow the oil to pool and still be picked up by the shorter pipe. This mod allows a flat bash plate to be fitted as it does not protrude as far beneath the engine as the original cover.
It now appears that when the scavenge pipe was cut, a rag was put in the engine to ensure that no metal particles fell into the engine. We think that the subsequent fitting and milling of the new cover took place and it was fitted but the rag may have not been removed!
So, the engine ran when it was started but in the 5 mins or so that it was run, the rag was pulled up into the engine, wrapped itself around the big end and crank and the fibres from the cloth contaminated the oil and ran around the engine.
Quite fortunately, the engine refused to start and caused no damage to the engine apart from some slight scoring on the big end shells.
Pete has now been tasked with the job of completely flushing out the engine, removing any traces of the contaminated oil and we have decided to change the main bearing and big end shells as a precaution before a full rebuild.
It is a shame that it didn't go to plan this weekend but it could have been oh so worse and an engine rebuild and missed trial was the only real damage so not the end of the world. The pictures are of the engine as we found it when the cases were opened up......
I know I like to polish my bikes and keep them clean but I think a polishing rag in the engine whilst it was running might have been a little bit of over kill ;0)
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