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atlas righthand smoking

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hi. I have had problems with righthand smoking after rebuild the crank was balanced and has seven 10m holes and one 5m hole more on the right side, I wonder if its throwing up to much oil under the piston ? thanks bryan.

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 Atlas engines  can have high pressure feed to the head  which can build up oil by the inlets, combine this with  the effect of the 6 start pump overworking the pressure control device  on the timing side and it can make for an oily engine if there is anything less than  perfect  piston ring sealing.  Is it run in yet?.Which way do the rocker shaft oilways face?.

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One of the issues with Atlas motors is the valve guides are not  machined to have valve seals .You can fit Commando  valve guides and seals . If you go this route  check compatibilty  of your valves /new guides , some combinations  cause bad  stem wear. Our Atlas was also smoking on the right side . Fitted better oil rings and Commando inlet guides with seals , All good now.  Except for the Vibration,    ,whats your advice ? !.

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I was hoping Bryan would give us some  more  script  on the  re-balanced Atlas ,  can't see myself adding 2 more cylinders , but  a  dynamic  balance job   is not beyond  the  bounds of possibility.

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hi. smoking was soon after first startup did not run bike for very long it was very bad, it was re-bored to+60 with nos 7-5 to 1 pistons and the spigot removed and spacer rings fitted. sorry for not getting back on sooner internet problems. bryan.

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Vibration-having used a Commando F/bed for many miles, vibration was an issue for several miles, cures -going from points to electronic ignition. A magneto can have a significant timing error between cylinders. Superblend bearings. Making sure the head steady was correctly bolted tight. Dynamic balancing did help but not as much as I hoped.

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Ignoring balance factors and suchlike. If an engine smokes on one side after a rebuild, the first thing I would check is the piston rings. Oh so easy to break a ring as the barrels are lowered onto the crankcase. No indication that anything is amiss until you find that it smokes on one side.

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When I replaced our atlas rings I did not have  ring compressors  and with the oil rings having 5 components each I was a bit nervous. So I installed the pistons  carefully with the cylinders upside down on the bench and  then fitted the pins and  last 2 circlips with the barrels propped up on the cases. Bit fidley  but it worked.

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Are your ring gaps equally spaced at 120 degree to each other, easy to move them when dropping the barrels on. Also did you check the skirt clearance each side? I always measure the barrels carefully after a rebore, as not all machinists can measure these days.

I have a standard barrel wants a hone on the fridge, its there to annoy my wife, the bike has been sitting behind the settee for two years looking neglected. She never goes out now because I need to use her lovely new computerised oven to heat crankcases up to fit new bearings in. Last time I used the oven the cakes tasted oily, she was not amused.

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Almost sounds like grounds for divorce.  But there is the possibility that a new wife might be more reasonable. !!.

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I remember reading somewhere that when a bike is parked up on a sidestand the tilt of the engine will let oil accumulate to one side of the head and then run down the guide(s).

Just a thought.

Mike

 


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