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My buddy brought me his old Simplicity blower last week (really a little beauty, I'll post pics later!) with an HS50 Tecumseh. He got it from the original owner, it had sat for years, needed tank flushed and carb rebuilt - you know the drill. He cleaned it, surges like crazy, he brought it to me. It was a snowy day, put it through it's paces - amazing little machine! Throws better than my big Drift Breaker, looks like it has an impeller kit, threw snow like a fountain! Under load, it ran pretty near very well - shut of the auger, surges. I gave it a real thorough cleaning, poked all the little bleed holes, the whole works - still surges. So I bought an Ebay carb - not an OEM, they're over 60 bucks, but a decent Chinese Oregon carb. Replaced the carb gasket, checked the intake-to-head gasket, installed new carb. Re-flushed the tank, good new fuel, fired right up - you guessed it. Surges and hunts. If I hold the governor rod steady, it smooths out and runs pretty good. My Tecumseh manual tells me that if you can do that, it's probably in the gov adjustment. In my experience, it's hardly ever the gov, and usually a carb issue. But I'm starting to wonder, after all the cleaning, flushing, and replacement. I'm including pics - the first two are in the slow position, the last two are at WOT. My buddy didn't play with the governor, but did he put something together wrong? I put it back the way I found it. The speed is controlled by a remote cable and lever on the dash. The #s are - HS50-67166C, SER 9071B (I think, lots of surface rust around the numbers). I'm not familiar with adjusting govs on this style of Tecumseh - the manual says something about gov follower arms and a gov spool - ? Anybody make that a little easier? In other words - help! Any help adjusting the governor, or troubleshooting the wild surging - also, what year this engine might be? I appreciate the help in advance!
 

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Discussion Starter #2
A couple of quick follow-ups - the linkage doesn't bind, and moves freely. The spring has a good tension, but not too tight, from what I can tell. The surging goes from almost stalling to pretty #$%@ high, and a good, consistent surge every second - you could practically use it as a stopwatch! I've worked with small engines for more years than I want to remember (!), and I'm familiar with your typical Tecumseh sputter and flutter, but this one is pretty bad. Also, wanted to post a pic - it's a cute little critter, and throws the **** out of some snow - now if I could just get it to smooth out and run...
 

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I don't know how a new carb could get crud in it; but the symptoms (surging at idle but running well under load) are identical to when the Idle Restrictor Screw/Valve becomes clogged.

Do I see one of those under a black plastic cap in the first picture ?

If so, it has three (3) "tiny" orifices that may need to be cleared of crud.
 

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On my Tec the governor linkage connects to the hole shown with the arrow:



I've tried both on mine and the one I've pointed to seemed more stable.

Surprised you're still seeing surging with an adjustable carb. How are you making the adjustments?

Are you sure there's no air leaks past, say, the carb to manifold gasket?
 

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On my Tec the governor linkage connects to the hole shown with the arrow:

I've tried both on mine and the one I've pointed to seemed more stable.

Surprised you're still seeing surging with an adjustable carb. How are you making the adjustments?

Are you sure there's no air leaks past, say, the carb to manifold gasket?
When messing with my OHSK100 governor last year, I could make it surge if I connected the governor rod to the wrong hole. I'd simply increased the "gain" on the governor too much, I suspect, causing it to make excessive throttle changes, which put it into a loop of surging.

So maybe I misunderstood, but it doesn't seem strange to me that you could get surging on a carb that's running right, but has the governor connected wrong.

I'm glad you like the machine, wildbill59! I had either the same machine, or one very close to it, as my first blower (bought it 2001, not new).

Mine was tired. The auger drive chain was worn, so it kept coming off until I replaced it. The impeller bearing was shot, but I had a hard time finding a replacement. That "impeller kit" is stock, mine had thick rubber paddles on the tips of the impeller. But, due to age, they were cracking and getting close to breaking.

My favorite part of it was the drive system. Having an apparently geared transmission (not friction disk), with chains on the solid tires, made it unstoppable. Sadly, it didn't have the guts to really take advantage of that. The used 8hp 26" MTD that I bought as a replacement worked far better than my particular Simplicity.
 

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Okay - this is what was hoping for! Yanmar Robin and Blackfin, I was thinking one of the rods or springs might have been in the wrong hole, that's why I included the pics. The gov linkage is tricky to remove without pulling the whole carb/intake deal, that's why I didn't just start swapping springs and rods around. It's family day today (what - my snowblower isn't part of the family?!), so I won't get to try until tomorrow. Vermont, didn't pull the fixed jet yet - I know it's not impossible for crud to be in new carbs, just seemed that it acted exactly the same after swapping carbs. I'm going to pull it just for good measure when I get a chance. blackfin, the old carb was adjustable, but the new one has fixed jets. I started at the intial settings on the old one, it would smooth a bid after fiddling around, but always came back to the surge. It was never perfect under load, but still ran better than no-load. Also, added sealant to the intake-to-head gasket, replaced the carb-to-intake gasket. RedOctobyr - yep, I like it a lot, might try to buy it from him (not like I need more snow blowers!). I suspected that the kit was factory, but this is the first time I'd every seen rubber on impeller that was stock. And right, mine are pretty busted up too, although the rest of the machine is great - obviously low hours, so no issue with worn chains, bearings, etc. Real strong gearbox drive, they just don't build 'em like that anymore! And Scutflut - thanks, I have the same manual. It was confusing me a little with spools and follower arms, but I might have it figured out now. Thank you, one and all, for your help and advice! I'll post a follow-up as soon as I get a chance to play with it (that's what she said!).:biggrin:
 

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Hey wildbill if you start to close the choke butterfly and it begins to smooth out its most likely still lean and wants more fuel. I have seen many of those carbs do that right out of the box. I find it best to try and repair the original adjustable carb if it can be saved or buy an oem that is also adjustable. we have also used micro drills to open the small holes in both jets to try and flow more fuel to stop the surging. Hope this helps.
 

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Okay, another bad week - didn't get to work on this until Wednesday, didn't get any forum time until tonight! Tried all of the advice - switched the gov rod and spring, and checked the idle restrictor screw. Steves602, might have to look into those micro bits - seemed like the main inlet in the screw was really small. But I tried all of the above, no luck, exactly the same. We're catching the 'Polar Vortex' here in Pittsburgh, supposed to be wind chills way below zero for a couple of days. Should be better by mid-week, think I'll try giving the old carb another soaking and going over. I've also been thinking about trying a different OEM Tecumseh carb - it's a series 3, for late model push mowers. I bought a handful of them on Ebay, NOS. They have a primer bulb, and don't have provisions for the airbox and choke. But it should at least bolt up - I'm thinking that if it runs smooth, at least I know it's a carb problem. Anyone know if that should work?
 

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Could it be an oil weight problem?

It seems as though this is the only thing that you have not investigated. And sorry if this this another squirrel chase.
 

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On the Idle Restrictor Screw/Valve, you cleaned all three (3) tiny openings, the one running lengthwise down the tube, and the one that runs perpendicular through the tube, intersecting the first one. You should be able to see your wire coming up from the bottom or center one, right through the holes of the second one.

They are tiny. I've used the wire found in a "Twist'um" like what you'd find being used to seal a loaf of bread, after the paper or plastic has been stripped off the wire. That wire is smaller than what you'd find in a Pipe Cleaner, and is now a part of my Tool Box.

Just checking.
 

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Or a single wire brush hair.
 

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Thanks guys - interesting, never gave much thought to the oil - gotta look into what he was using. Don't be sorry - always willing to take a shot if it means fixing a problem! And yep, Vermont007 - gave all three the poke - the two bigger ones that are across from each other, and the narrower one that runs lengthwise. Bread twisties (used to grab a bunch in the produce section, the long green ones for tying vegetable bags!), wire brush hairs (thanks, db9938 - been there, done that for many years - I have an old one that I keep just to pull wires out of!), old pieces of electric guitar and bass strings. Also, a torch tip cleaning tool - 5 bucks on ebay, works great! Think I'm gonna try switching carbs and checking oil weight. Thanks again!
 
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