shop-talk
[Top] [All Lists]

Re: weedwhacker style carbs...

To: Mark Andy <mark@sccaprepared.com>
Subject: Re: weedwhacker style carbs...
From: Trevor Boicey <tboicey@brit.ca>
Date: Tue, 09 Aug 2005 17:00:23 -0400
Mark Andy wrote:
> Interesting... I didn't know there was a difference in two stroke oil 
> between air & water cooled motors.  Which is designed to run hotter... 
> The Air cooled stuff? 

   Yes.

   The water cooled oil is primarily for outboard motors, which are 
water cooled except for a few tiny ones.

   Because of how much oil a big 200hp outboard can drink, many times 
the wall of oil in the store will be all outboard motor oil except for a 
tiny strip of air cooled bottles.

   These things sip oil.

   When we bought our first house a while ago, my wife bought me a small 
gas weedwhipper as a birthday gift. It remains the only brand-new gas 
powered anything I've ever owned.

   Anyways, it came with a tiny bottle of oil and said something like 
"mix with 4L of gas".

   So I dutifully bought 4L of gas, and poured it in. Then after using 
the thing for a month, I realized that 4L of mixed gas is a lifetime 
supply of fuel for a weedwhipper.

   I used that fuel can for about 6 years, and each year the weedwhipper 
ran progressively worse. I knew it was the bad fuel but it still ran so 
I figured I would just try to use it up.

   Finally it just got that it was so hard to keep running that I poured 
the remainder in my big boat tank. Now I mix gas for it in a juice jar 
about two cups at a time. That can last me a whole year of just 
weedwhipping my suburban house.

> What symptoms will using water cooled oil in an 
> air cooled motor have?

   I've done it in a pinch, but it's probably akin to running too-thin 
oil in your car. At high temperatures it's probably very thin and not 
very protective. It pours like water even from the bottle.

> The fuel pump is in the carb or separate?

   As already mentioned, it's usually part of the carb. (not just small 
engines do this, my 16hp lawn tractor has a combined pump/carb and 
combined rebuild kit)

   My tiny weedwhipper has the entire carb and pump machined out of a 1" 
cube of aluminum. Looks like a borg ship. Amazingly integrated and very 
impressive that they managed to make a carb and a fuel pump with only a 
few drilled holes, some gaskets, and one plate that covers one side and 
provides other half of the fuel pump.

-- 
Trevor Boicey, P. Eng.
Ottawa, Canada, tboicey@brit.ca
ICQ #17432933 http://www.brit.ca/~tboicey/






<Prev in Thread] Current Thread [Next in Thread>