Author Topic: Smoking Dragonfly  (Read 270 times)

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Offline Roys rider

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Smoking Dragonfly
« on: 24 Mar 2020 at 22:15 »
Hi All,
When I first started this NOS engine last year, the left cylinder smoked and dripped oil from the exhaust. I had a feeling that maybe I had broken the oil ring when fitting the cylinder and this proved to be correct when I took the cylinder off a couple of months back. I bought and fitted a new one (split serrated) and I don't think I broke this one (and I put the gap at the top).
Yesterday was warm enough to take the bike out and start it. Exactly the same smokey oily problem. Any ideas?
Cheers
Peter

Offline graeme

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Re: Smoking Dragonfly
« Reply #1 on: 24 Mar 2020 at 23:54 »
Hi Peter
I think you will have to pull the cylinder off again to be sure you didn't break the ring. Symptoms sound exactly the same as before. Have you ridden the bike at all to see if the smoke clears?

Offline eddie

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Re: Smoking Dragonfly
« Reply #2 on: 25 Mar 2020 at 07:24 »
Peter,
           A question - have you still got the original Dragonfly split skirt pistons? If so, check them out carefully to make sure the rings are free in the grooves - they were renowned for collapsing above the split - this results in the ring grooves having a wavy form, and poor seating of the rings. Swapping to Mark type solid skirt pistons usually effects a cure.

  Regards,
                  Eddie.

Offline Aero

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Re: Smoking Dragonfly
« Reply #3 on: 25 Mar 2020 at 18:45 »
Maybe put some miles on the bike before condemning it, as you may be lucky enough to find its just the old oil burning off inside the exhaust from the last issue

Offline Roys rider

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Re: Smoking Dragonfly
« Reply #4 on: 25 Mar 2020 at 22:25 »
Thank you for your usual excellent advice.
I am assuming these are D/f pistons as that was what it said on the box. I have seen the advice to fit Mk ones but these are the only ones I have. I will check if/when I take the cylinder off. They are brand new so shouldn't have distorted yet or is that in the manufacturing. As I can't do much else I might as well take it apart again.
I like the idea of putting a few miles on it, however at the moment I might have flashing blue lights appearing through the blue smoke. Honest officer I'm going to the chemist.
Stay safe.
Peter

Offline Doug

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Re: Smoking Dragonfly
« Reply #5 on: 26 Mar 2020 at 16:54 »
I though oily exhaust killed the COVID-19 bug? If so, maybe we should all switch to Scotts!   :)

-Doug