1970's Sears 5hp GAS MIX HELP

[Chrisravosa36]

Hi, I just bought a 1970's Sears 5hp, I know some people dont like the sears model, but I thought for the pice id try it. Not going to be biase with a brand ive never had experinse with. plus its simple. My friend offered me the motor for 25$, he said he winterized it a few years ago (2008) and left it in a heat garage. His father was the original owner, under 50 hours he claims. So anyways, Im looking to find the correct fuel mixture for this motor, I am going to try 40:1. People say 40:1 or 50:1 but I play it safe at 40:1. I just refilled the lower unit with oil, I have not tried to start it yet, just need water. Im hoping it will start with a little time and starting fluid. I took off the fuel filter on the side, put some seafoam in the carb through there and am letting it sit overnight, hopefully breaking anything up in there. Il drain the bowl in the morning, put some gas in her and see if she fires. Might just have to use a drill starter if it wont start.... Also I sprayed some penetrating oil in the tank, cleaned it out with water 2 times then filled with baking soda and vinger, it got that thing nice and clean!!


Let me know what you think, I think for 25$ It isn't a bad project.

 

[F_R]

I can't comment on the specific model, but I'll agree that for $25 it's worth a shot. At least you got one with a real carburetor. Next thing is spark. Have you checked it? Let's just hope it isn't one of those with non-working electronic ignition. Otherwise you probably can get it going. You know that thing has a water pump, right? Don't run it out of the water. Personally, I don't understand how they got those things to run on so little oil. The engine began it's history as a 16:1 chainsaw engine. I guess they don't need as much oil as they once thought they did.

 

[Chrisravosa36]

I checked spark the old fashion way, put my finger on the plug, had my buddy pull the cord a bit. Its got spark. I knew it had some sort of pump, I think it has a exhaust cooler pump I think.

 

[Chrisravosa36]

Found out its a 1971, it recommends 24:1 but Im not sure if this is the old oil mix, not sure how much this would be with the current oils..


If you look on this chart, count 8 down from the top, number 58991, thats my motor, 5hp.

http://home.earthlink.net/~brixent/Model21758890-59900.htm

 

[jbcurt00]

Its 44yrs old, use the recommended amount of oil. 24 to 1 is already less oil then FR said the same motor used when used as a chainsaw, 16 to 1.

 

[Chrisravosa36]

Ok, thanks I did use 24:1, It started, ran rough, died, continued to play with the idle adjustment on the bottom of the float bow and the adjustment screw next to the choke. started to run better. I did not see any water coming out of the exhaust hole, this concerns me, so I am back here now. I cant figure out how to take the lower unit off to go check the water impeller.


Here is a video of her running: https://www.youtube.com/watch?v=oPXOJEs21To

 

[F_R]

The rear gearcase retaining screw is shown in your close-up picture of the propeller. It is inside the exhaust outlet. The front retaining nut is behind a clip on the forward edge of the gearcase.

 

[Chrisravosa36]

Just removed it, need a new impeller, found one on ebay. I looked and there is alot of carbon build up on the cylinder head, going to remove the head and decarb it today.