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Just to put another idea, if the oil was a modern synthetic,maybe the rings haven't bedded in? have you ridden it to gently? I believe you have to get pressure behind the rings ,to force them against the cylinder wall to bed them in, ideally firm acceleration to 6k revs,then shut the throttle, I think the idea is to pressure the rings on acceleration,then with a shut throttle it sucks oil mist up the bores to lubricate them,.I have heard of modern engines using lots of oil because the new owner drives them to sedately to run them in.you have well over 500 miles on the clock,with the mineral oil,start to work it? try running it up to 8k in 3rd then slamming the throttle shut, it can't hurt
Quote from: Johnwebley on September 25, 2022, 02:34:35 PM Just to put another idea, if the oil was a modern synthetic,maybe the rings haven't bedded in? have you ridden it to gently? I believe you have to get pressure behind the rings ,to force them against the cylinder wall to bed them in, ideally firm acceleration to 6k revs,then shut the throttle, I think the idea is to pressure the rings on acceleration,then with a shut throttle it sucks oil mist up the bores to lubricate them,.I have heard of modern engines using lots of oil because the new owner drives them to sedately to run them in.you have well over 500 miles on the clock,with the mineral oil,start to work it? try running it up to 8k in 3rd then slamming the throttle shut, it can't hurt Totally correct there John. At over 500 miles there should be no pussy footing around at that mileage. You stand more chance of polishing the bores, which will make it smoke, if the engine isn't put under load.
K2-K6, I don’t intend to get into ‘Oil Wars’ but simply put old engines use thicker oil, if you wish to use synthetics designed for modern engines in old classics, it’s your call.
Was following a Triumph 900 the other week coming back from an oil meet. It started to smoke, I could smell oil being burnt. I signaled him to pull over and his left leg up to the knee was saturated in oil, it was pouring out of the engine and forming a pool on the floor. He'd only had the bike a month so he was understandably a little upset. Turns out one of the half moon shaped rubbers sealing the camcover to the head, where the cams would be, had popped out. We managed to force it back in enough that he could get home.The next week he turns up and explains the breather pipe had been fitted wrong by the PO and instead of being fed to the bottom of the airbox they'd fitted it to a blank on the airbox. This compressed the cases so much the seal popped out.This got me wondering, could the engine be forcing oil back into the airfilter via the recycling system fitted to the 400, this causes the smoke from the exhaust. Which leads you to think it must be head related when in fact it could be something else, like a failed ring allowing compression into the crankcase. Have you checked the airfilter to see if it looks really wet with oil?