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View Full Version : RS50 MY06 jet / carb set up help!!! Very smokey and bogs down.



C13Johnson
10-01-2015, 05:33 AM
Hi guys, I'm totally new to this thread so have no idea if even anyone reads these. I recently purchased a non running MY06 RS50 off gumtree. Since I have put a new cylinder, piston, rings and gaskets on (standard 50cc cylinder). It has a cheap looking 21mm carb (with hand operated choke) with a 92 main jet and not sure on the others as there's no markings on them. Also has one of those cone air filters on it. Looks like the previous owner did everything they could to try get a couple more mph. So possibly even had a 70cc kit on but not sure.

Run down:
RS50 my06 2008
50cc barrel
Full arrow exhaust
Cheap chinese 21mm carb
92 main jet unsure on others
Polini air filter (cone)

The bike starts fine and runs just pours out white smoke and bogs down loads. Won't go up hills and don't want to keep running it unless it could be bad for it. I have tried adjusting the ratio on the carb as believe it's burning too much oil but still nothing's making a difference. Also have checked the oil pump and that's set correct and pumping fine. Also sometimes it revs up randomly without even pulling the throttle.

Could this be the cheap carb or wrong jets? What carb or jets would I need taking into account all the above?
Sorry about the essay just thought as much detail as possible would help!

Will attach pictures when I get to a computer.

290498290499

Please help!!

Chris

Sketchytom
10-01-2015, 11:56 AM
Now is it white smoke because of it burning water.

Because 2 stroke smoke usually has a slight bluey tinge to it.

Check the radiator isn't loosing fluid.

If it's not loosing fluid.

Then it is probably running crazy rich, the colour of the spark plug will tell you that.

Also check the oil pump is set up correctly.

emX50
10-03-2015, 07:00 AM
Now is it white smoke because of it burning water.

Because 2 stroke smoke usually has a slight bluey tinge to it.

Check the radiator isn't loosing fluid.

If it's not loosing fluid.

Then it is probably running crazy rich, the colour of the spark plug will tell you that.

Also check the oil pump is set up correctly.

This is a good assessment.

Testing for rich mix:
As Tom stated..... check the spark plug.
If rich it will be sooty black..... possibly even wet black and stinking of petrol.

If the plug is wet with droplets..... it will be water.
It could be from a wet cone air-filter, but that should clear after a few minutes running.
(If you had an airbox, then you'd open it and drain the rain water)

If it is wet and shiny..... then it will be over-oiling.

I have experienced all these conditions with my AM6.

Testing for over-oiling:
You could disconnect the oil pipe, and block it.
Then drain the tank, and test with a pre-mix of oil and fuel.

If the smoking continues, then 'over-oiling' is eliminated.

Testing for water leak:
If the radiator needs topping up..... it is a sign that water is being lost somewhere.
At that point I'd whip the head off and check the gasket.

You could drain the water from the system at the water pump, and run the engine at standstill till warm (be careful not to overheat the engine).
If the white smoke clears, then you know, that the head gasket has failed.

However note: it may take time to clear, as the crank case may be full of water.
Therefore, checking the head gasket first, is the safest way forward.
You can also loosen the exhaust expansion pipe flange, to see water pour out.

If it was a water leak, you can either run the engine until the crankcase is clear.
Or, remove the engine and cylinder, block the gearbox breather, and up-end the motor to drain it.

If it is not a water or oil problem, the fuel mix must be way too rich.