Saving Old Seagulls

Kia ora,
have just changed my needle to a 25:1 and am having
difficulties.
When I run the motor in a drum without prop at full revs petrol begins
running out of the fuel bowl indicator hole afterabout 40 seconds.! The
motor runs evenly with the needle flush with the top at half revs but oh
boy what an environmental disaster in our little Bay when the fuel spills.

Would having the prop on make a difference?

Please help.

Chris,
From Governors Bay in The South Island of New Zealand.

Nothing to do with props or mixture needles. Simply put your float chamber needle valve is not seating properly and shutting off the supply of fuel from the tank. Assuming there IS a float and a needle in there the next 99 out of 100 possibilities are that there is dirt or other foreign body in there.... time to strip and 100% clean it out. And to be sure also consider the filter on the carb banjo bolt , the fuel pipe, the filter in the tank and also the tank itself.....


Peter

If by full revs, you mean full throttle, you stand a good chance of grenading your engine. With no prop to provide load, the engine will easily overspeed without judicious throttle control. Additionally, the excessive vibration may be unseating the float valve, causing the overflow problem. Put the propeller back on and try it, keeping an eye on the cooling water flow, as that is sometimes affected by turbulence in a test barrel. If it continues to leak fuel at even normal rpms ckeck the float valve for proper set-up and for a bit of crud on the needle seat. Search the S.O.S. site for carb diagrams and specs if you're unsure.

Todd On Stillwater

Thanks Peter and Todd.
Will try all of these things but will run with prop on first.

Chris.

Putting the prop back on and engine on boat works better than ever before now.

Thanks all - no boating today - Tsunami watch!

Chris.