Trying to determine oil ratio on 5.5hp Tecumseh 643-20B engine

[dboyce02]

Hello,
I just picked up a outboard Tecumseh 5.5hp and I can not seem to find the oil ratio listed anywhere on the engine or online. Can someone please help?

Engine Plate Reads:
? 643-20B
TECUMSEH
7540445

It has a sticker on on the case stating 5.5hp 95cc with a twist grip throttle idle fuel mixture adjustment and pull out choke. Please post if you know anything about this engine, from my digging around it appears to be air cooled with an impeller to cool down the mid exhaust.

Thanks in advance!
Dan

 

[mrcrabs]

Re: Trying to determine oil ratio on 5.5hp Tecumseh 643-20B engine

Welcome to Iboats Dan,

your oil ratio is 32:1
http://home.earthlink.net/~brixent/Model1723-1905.htm

from my digging around it appears to be air cooled with an impeller to cool down the mid exhaust.

Actually the impeller cools the lower crank bearing and sinks heat away from the exhaust port, the only real benefit the lower leg gets is it helps keep the grease in the swivel and keeps the paint from peeling