# Carb adjustment for a Toro S-620



## jpjahn (Dec 7, 2008)

I have just put a carb kit in my Toro S-620 and now I need to adjust the carb. Can any one tell me the procedure? It is a Tecumseh diaphram carb with two needle valves.


----------



## paulr44 (Oct 14, 2008)

Pre-set idle screw to 3/4 turn out, high speed to 1 turn. You could probably leave it like that and it'd run fine.
Those engines have no ability to idle (via a control), although the idle and progression circuits are a part of the high-speed mixture. The best was to final adjust the high-speed is to load test it and listen to the engine. It should run rough until you apply a fair amount of load.
*DO THIS ON PAVEMENT - gravel is a no-no*, and make sure there are no people or windows etc. in your path.
Apply pressure to the front handlebar, and pull up and forward on the rear. You have to apply a good amount of down-force to load it up. I set-up all two-stroke snowblowers by ear, using a load test.
Two-strokes smooth out under load if set-up correctly, basically you want it smooth out with a fair load, but not a minimal load. So it's trial and error.
You could "balance" it. This is when you turn the screw in until it "four-strokes," which is when it leans out, runs smooth and races. Note the screw slot position, and back it out until it's running so rich, it starts to bog down. Note the screw position. It's usually about 1 turn between the two positions, and putting it halfway between the two is usually a good point, but usually can go a tad bit leaner for more power. Erring on the side of richness, is erring on the side of caution with a two-stroke, and best if not familiar with two-strokes. Plus, winter-use means more 0-2, which means more fuel is needed anyway.


----------



## jpjahn (Dec 7, 2008)

Ok Thanks, I will give it a try. How do tell which needle valve is the idle and which is the High rpm?


----------



## paulr44 (Oct 14, 2008)

Idle mixture screw is always the one closest to the manifold / engine.


----------



## pyro_maniac69 (Aug 12, 2007)

if yourlucky, just push it into some snow and see how well it does, I've gotten them little buggers to throw snow across a road before


----------



## joethefixitman (Mar 16, 2008)

heh heh thats cool i only got one to throw snow 6 feet but thats not bad, i like your way of adjusting the carb, but mine r funny, i only need to go 1/8 of a turn from closing on each needle i wonder if its from installing new o rings that did not fit right will that affect performance or not and how do i get the max speed out of these buggers, any i deas guys and thanks ahead of time.:wave::wave::wave:


----------



## paulr44 (Oct 14, 2008)

joethefixitman said:


> heh heh thats cool i only got one to throw snow 6 feet but thats not bad, i like your way of adjusting the carb, but mine r funny, i only need to go 1/8 of a turn from closing on each needle i wonder if its from installing new o rings that did not fit right will that affect performance or not and how do i get the max speed out of these buggers, any i deas guys and thanks ahead of time.:wave::wave::wave:


Either that, or the screws were bottomed with too much force, wallowing out the jet area and putting a depression in the screw taper.


----------



## joethefixitman (Mar 16, 2008)

that might be it i tend to put to much pressure when i screw them in, also i wonder if i need to put in new gaskets in where the carb mounts on, will that affect anything for the engine, also what can i do if i drilled to deep into a carb on the side where there are three holes for the fuel to jet into the carb and onto the engine that is under the welch plug. thanks for any thoughts.:thumbsup::thumbsup:


----------



## paulr44 (Oct 14, 2008)

Joe, buy yourself a very handy tool: Walbro 500-16 puch. Use it at a shallow angle to remove welch plugs. You usually don't have to pierce a plug to remove it, just bite into it enough and use the punch as a lever to pop it out. If you drill through a plug into the carb., you can damage the idle and/or progression ports, resulting in poor or no idle, and / or poor acceleration. Also, progression ports do factor in to full-speed mixture delivery. If you re-use intake or any gasket, you risk a leak. In most cases you can get away with re-use, but remember the gasket in place has been compressed, and has conformed to any deviations in mating surfaces. For the $1.50 or so a gasket costs, is it worth having to take something back apart for a simple leak? Intake leaks can cause poor idle, poor throttle response, surging, inability to achieve full RPM, stalling when hot, well you get the picture...


----------



## paulr44 (Oct 14, 2008)

Spelling: should be Walbro PUNCH (Oops)


----------



## joethefixitman (Mar 16, 2008)

thanks paul for the info looks like i need a new carb and that punch tool by the way where can i get one thanks paul.:thumbsup::thumbsup:


----------



## paulr44 (Oct 14, 2008)

Any local OPE shop can order one. Or, contact the Walbro distributor for the area:
Midwest Engine Warehouse
West Valley City, Utah
800-683-8484

Stens.com sells the walbro tool *kit*, but that's like $70.


----------

