Parksy's single cylinder four stroke

[Parksy]

Couple of questions. The engine has a lot of kick. I have a quick video of myself holding the engine while running.
https://youtu.be/mSJpisyhHuQ
Will lowering compression help reduce this?

The carby doesn't appear to draw fuel and requires the fuel tank to sit higher than the carby inlet. It's a very basic carby with a Venturi and metering valve. Is this a normal thing?

Cheers

Andy

 

[Brian Rupnow]

Couple of questions. The engine has a lot of kick. I have a quick video of myself holding the engine while running.
https://youtu.be/mSJpisyhHuQ
Will lowering compression help reduce this?

The carby doesn't appear to draw fuel and requires the fuel tank to sit higher than the carby inlet. It's a very basic carby with a Venturi and metering valve. Is this a normal thing?

Cheers

Andy

Compression should be about 5 or 6 to 1 Carb should suck fuel up at least 3/4" if it is working right. tank above carb is a no-no--causes flooding and potential fires.

 

[Parksy]

Thank you Brian. Turns out the carb works just fine, I just needed to play around with it. It even self primes itself. I will change the fuel tank mounts and set it lower. For some reason I was under the impression that the tank needed gravity to assist.
Runs better with the tank sitting lower also.

Cheers

 

[Brian Rupnow]

You asked the other day about hand starting your engine. If the engine sets for a while, gravity will make the fuel flow back into the tank, and your wrist will fall off before you get it to hand start. To prevent the fuel flowing back into the tank, a great solution is a little ball valve setting vertically in the gas line. Something about 5/32" diameter. The suction caused by venturi effect in your carb will lift the ball off it's seat and suck the gas up to the carburetor, but when the engine is not on the intake stroke or is setting idle, gravity pulls the valve back into it's seat and prevents the gas from backflowing into the tank. This makes hand starting (or any kind of starting) much easier.
http://www.homemodelenginemachinist.com/showthread.php?t=24778&highlight=ball+valve

 

[Parksy]

Thank you again Brian! That is perfect!!