It runs…well sort of

The nice weather and a free morning brought Graham over on Saturday and we decided to have a look at the Cota 123.

I’d spent some time on the Montesa Cota 123 over the last couple of months which basically involved working out why there was no spark, despite a new condensor and a set of points. In the end the stator went of to West Country Windings (who are now in Essex ?) and they changed the energy transfer coil. Not cheap, but there was now a heatlhy spark coming from the bike.

It looks better than it runs (at the moment)

We spent some time trying to kick it over, then stripped the carb (an Amal Concentric) as potentially there was no fuel getting through. The using the Clymer manual reset the ignition timing and the points gap. More kicking and bump-starting still didn’t manage to get it to fire up, so we reset the timing. There was fuel and a spark, so it must be that they weren’t doing it at the right time.

There seemingly was compression, but how good is a bit of an unknown. Anyway on the fourth bump-start attempt, she fired up and I shot off down the road (well sort of)

Getting the barrel off

Pulled ok in 4th (I think) and managed to get it back to the house before it cut out. No idle and difficult to keep running, but it sounded good and the engine seemed to pull well. After more checking, we eventually got it running again for a couple of more laps up and down the road.

Leaking base gasket

It could be compression, and the crankcase seals or barrel/head gasket being possible favourites. Getting the head and the barrel off the bike, showed there had been some seepage across the gasket and a potential cause of the problem. The barrel nuts are 7mm hex bolts and I needed to cut an allen key and fit a 7mm socket to drive it, to get them off.

Will look at the crankcase seals next, though I did change one of them last year in the earlier attempt of getting it to run. Will see what happens

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