Started the engine build yesterday, got some of the studs out of the old cases and installed in the cleaned ones, fitted the ball bearing on the drive side, swapped the scavenge pipes over, everything going along fine. Fitted the new -0.010" big end shells into the timing side con rod and torqued it up to 10 lb-ft no problems, the rod spins on the crank as smooth as silk. Fitted up the drive side the same and it's tight, checked and cleaned everything again, still tight. Removed the assembly from the timing side and fitted it to the drive side and it's fine, so the journal is OK, the problem must be in the rod itself or the cap. 5 hours spent trying to find the reason, and still not there. Start again this morning, if we can't find it then the rods and end caps will have to be ground on the mating faces and re-honed to size I reckon.
Still, if it was easy they'd let women and kids do it.
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Actually had this exact (I think if I understand you) problem on a build I did for a customer 3 or 4 years ago: an A10 super rocket.
ReplyDeleteThe guy had been experiencing cold siezes on this bike for a while - it was all together - he'd go to start it and it'd just sieze cold as he tried to kick it over.. I think it happened 3 times and every time he sent it to a different shop - I believe SRM was the last to poke around in his motor.
Anyways I got my hands on it and sent the crank and rods to an engineering 'shop in Northampton who measured it somehow whilst together I think; they found OVALITY in the rod(s) at the big end.. Re-machining the rods sorted the problem. The soft-ish shells simply took the shape of the rod big ends when tightened up causing the problem. He never had the problem again I heard recently. :)