wasn't doing this last time I started the bike. Concentric Mk1 on a B40 Star . No choke or choke slide.
There was fuel left in over the winter. The fuel in the float bowl was disconcertingly orangy brown, but from the tank yellow... slightly darker than fresh unleaded, but is had millers VSPE additive so I presume that's why. I have no idea why the fuel in the float bowl was that colour. The stay up float should be fine with ethanol. I did change the fuel pipe in the autumn, but it was sold as a ethanol safe by draganfly..
So I drained carb and tank and cleaned the carb. I changed the 140 main jet to a 160 and put a new screw in 20 pilot jet at the same time.( same size as before)
I set the valves and the timing. auto advance comes out gets cleaned a bit and oiled in the process. same springs. not damage in process I believe.
It fires up easy, but is lumpy. Stop after a minute. Leave it 3 days. Come back start it up easy:lumpy but loads of white smoke. keep it running for a couple of minutes. needs a bit of extra throttle to stop it cutting out but I think all below 1/4 turn.smoke seems to stop if throttle down, but cuts out or runs lumpily with smoke. So I go and have a cup of tea ( before a new Pope is installed)
Now as far as I can see it wasn't at enough throttle that the increased main jet would be the cause.
After that I'm confused. I had finally sorted the timing and Thought it might run a bit better !
I forgot to put the Millers additive in so was straight but new unleaded. But it didn't smoke the first time. so not that and nothing to do with the fuel going orange as far as I can see.
The lumpiness may well be completely unrelated to the smoke, as the last time I had it running last year was after putting in a 25 pilot jet to see if it made the slightly uneven idle better. But instead it was worse, lumpy and hunting ...to use a newly learnt word) , but I suspected a possible air leak at the float bowl...... the bowl faces seems fractionally out of true. Used a new proper amal gasket which is thicker and hoped this was enough, as the out of trueness is on the body not the bowl.
I guess I'm going to strip the carb again and check the timing again.
Any other suggestions. Could the autoadvance function also be a cause ? I don't think anything significant changed by just cleaning & very lightly oiling it, but wasn't sure how tight to do the cam nut, so I opted for not too much , but some feeling of seating in !
Suggestions welcome....and I'll add them to the list of things to test/do.
Have you or did you have tank liner. This happened to my M33 when the liner dissolved into the fuel.
Dissolving tank liner also happened to me a few years back.
It was very noticable that the throttle slide gummed up with a varnish like coating.
Is the bike wet sumping?
Hi
2 yr old POR15 liner. Looked intact when I took the tank off and trained.
Don't think it's wet dumping.
Bit of a mystery as you say. White smoke, if not oil -you'd smell it, is usually associated with water vapour/condensation. From my days in the foundry I know cast iron absorbs water quite easily and recall when baking dies to remove the moisture, the water would sweat out unbelievably.
Could it simply have absorbed moisture as it's been laid up for a while? Have you tried to keep it running or even go for a ride to see if you can burn/clear it out? I imagine after running like that the plug would need a good clean.
Sorry can't be much more help at present.
I'm pretty sure it was unburnt fuel rather than water vapour. I do get a bit of water vapour if it's been standing for a good while, but it's never lasted more than say 20 seconds. It didn't happen 3 days before.
Definitely not burning oil to any great degree.
:) :) :)
Fuel going a yucky orangy brown is usually a sign of water in the fuel. :) Do you also find some little rubbery globules in the float chamber.
Mike 8) 8) 8) 8)