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Musings of a slightly smokey rear cylinder

2K views 2 replies 2 participants last post by  rhysmort 
#1 ·
Hope you're all keeping well.

Precursor to my query - the engine roughly has 1100 miles on it. Everything has been retorqued, no intake leaks, all buttoned up.

When riding for a period of time, at idle, the rear cylinder is giving off some white smoke, I thought first off maybe it's the rings?! but i've checked inside the head, the plug etc, no oil anywhere. Now there's a small amount of greasy residue in the exhaust, the carbon isn't 'dry' it's not thick greasy, just greasy? haha.

I thought it could be overfilled the oil bag. So, managed to drop the drainplug into the tundish. All the oil bag went over the garage floor. So new oil!.

Plugs are a light brown, both cylinders very close in colour. Kicks first kick hot or cold. Rides well.

Just strange, I'm hoping one of you fine people will be able to offer me insight. I can't imagine there can be oil coming from elsewhere. My friends 1950 panhead also does this on the reat cylinder, as I noticed today sat at lights!

cheers,

Rhys
 
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#2 ·
ok my guess your loosing the top end vacuum - what is that - that is -- the breather valve evacuates the oil from the spring bottoms - when this ( does not happens ) the valve guide gets flooded and this in turn allows the excess oil that has filled the valve cavity to be sucked into the exhaust port - your gooey oil deposit

question - does the cylinder heads top end seal area and or any of the gaskets seep NOT nessessary a real leak but seep oil < is it wet at all

the line that comes from the bottom of the spring pocket is it wet top or bottom - even if the top line that attaches to the rocker box is not wet it might be sucking air this will cause the oil to stay in the spring pocket and not be drawn up into the rocker box

fix for that is a drop of hydraulic Loctite sealant on the thread and the ball fitting end to insure its not loosing vacuum

picture up what your plugs actually look like - its a stretch but i might see something you dont -

knuckle oil return system is not a normal thing like other ( anything ) and it has its quarks
 
#3 ·
ok my guess your loosing the top end vacuum - what is that - that is -- the breather valve evacuates the oil from the spring bottoms - when this ( does not happens ) the valve guide gets flooded and this in turn allows the excess oil that has filled the valve cavity to be sucked into the exhaust port - your gooey oil deposit

question - does the cylinder heads top end seal area and or any of the gaskets seep NOT nessessary a real leak but seep oil < is it wet at all

the line that comes from the bottom of the spring pocket is it wet top or bottom - even if the top line that attaches to the rocker box is not wet it might be sucking air this will cause the oil to stay in the spring pocket and not be drawn up into the rocker box

fix for that is a drop of hydraulic Loctite sealant on the thread and the ball fitting end to insure its not loosing vacuum

picture up what your plugs actually look like - its a stretch but i might see something you dont -

knuckle oil return system is not a normal thing like other ( anything ) and it has its quarks
John,

thank you for your reply! From what I can garner from it the oil feeds to the rocker box you're suggesting can suck in air and thus force oil into the exhaust and thats' what the little smoke is when idling?

It only does it when the bikes been rode a long time too. Like if I go start it now warm it up for a few mins and ride for half hour it does it very little. It's longer riding.

I don't have any oil weeps than I can physically see, but a while back,my rear head exhaust wasn't fully pushed in and I had a small 'bubble' of oil come out. I didn't think anything of it. Plugs are a very light tan, it needs a little richer but still trying to find "optimum" but it's all bone dry in there. Glad I didn't fry the rings when I run it in!!

Rhys
 
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