DR650 carby leaking into piston
 

I am getting a friends DR650 going. He did a trip across Australia and back before he left he put a new carby in the bike a Mikuni T 40 6 / HS40 did the trip about a year ago he left fuel in the carby and the bike sitting there.
We could just get the bike started with throttle open but would not idle. I removed the carby cleaned it out checked the float bowl height. After putting together using 1 lt fuel tank we found fuel would fload into the piston. If I hold the 1 lt fuel tank at the same height as the float bowl the bike will run higher than the carby the bike will die. I suspect the float bowel needle that I cleaned. Any ideas or help would be great.
Nick

If fuel is leaking into the piston/head/valve area ...
DO NOT START UP THE BIKE! :nono:
Could be a LOT of fuel is in the crankcase. Not good.

You can get Hydrolock and bend a rod if you try to crank the motor over when it's full of fuel.
So, do nothing until:

1. Drain Oil (fuel will come out too).
2. Remove spark plugs to aid in drainage of fuel.
3. The float needle valve (little rubber tipped pointy thing) has crud stuck in there and is not fully seating ... this is what is causing the fuel to continue to flow ... and end up in the combustion chamber. Once crud is cleaned out, float needle valve should STOP fuel flow once float bowl is full.

4. Clean the whole area below the needle valve. High pressure air is good. Careful not to damage float or float carriage or other parts. Float needle valve is located below float at bottom of float bowl.
(wear eye protection when using high pressure air)

5. Add in line fuel filter.
6. Flush out fuel tank if bike has sat a year or more.

Hi Mollydog
 

Thanks for your help. Can I test the carby for not leaking while out of the bike? I was going to remove the carby again clean and look at the float needle under magnifier then put back together before installing in motorcycle hook up 1 lt fuel bottle to see if carby is still leaking rather than install only to pull out of bike again. The carby is only about 1 1/2 years old so I am hoping it is just dirt. If still leaking new float needle.
Many thanks
Nick

Yes, you can test it off the bike, you can even use WATER to test, just make sure ALL WATER is OUT before re-installing.

If it leaks, it will piss out the little fuel overflow tube somewhere at bottom of Carb. I've seen the TM40, but don't have one on my bike.

Check the rubber tip of float needle, make sure there is no wear gruve on it where it seats. If so, replace it.

bier

Thanks Mollydog
 

Just got it going I cleaned the float valve seat with a cotton bud drill and metal polish. I was also wondering why the fuel went into the engine and not out the vent overflow pipe I found that all the breather hoses were blocked with wasp nests. I live in Cairns Australia so needs some fine tunning but getting there.
Thanks Nick