Surging Predator Engine. Governor?

chas045(7b)March 14, 2013

I have a Predator engine that I put on my Horse Tiller. It surges dramatically at full throttle and it stops surging if I choke it half way or so, but the speed also decreases. I am aware that I could exchange it at Harbor Freight at least for another month. From here and some go kart sites, I have heard that a surging engine can be caused by a too small main jet in the carb. I got another jet so that I could bore it out a little although it turns out my littlest bit is probably larger than I would want. The range seems to be ~.070-.095".

However, I am now thinking that the surge is just totally due to the governor attempting to slow the engine down. The engine actually seems to run great. It doesn't stumble or anything. If I block the governor rod from retarding the throttle, the engine runs steady and smooth. I would guess that it would require shortening the governor rod by almost a quarter inch (it is not adjustable of course) to allow a non fluctuating effect. I could bend it of course, but that doesn't seem appropriate. If I can figure out how to easily slip the carb. off, I could reattach the rod to a 1/8" further away hole where the spring that attaches to the throttle handle is hooked. That spring moves the governor around a little for speed control.

I don't actually know how to check speed on a little engine. I do have an old auto tack, if I knew where to hook it up. I wouldn't want to over rev this engine, but it sounds like other engines I use even when I block the governor. I have heard that the go kart guys just take the governors off. Of course, these are the geniouses who increase valve springs, rejet everything, and replace flywheels so they don't blow up their keesters.

Anyway, does any one have any thoughts. I know a couple of you have several of these engines.

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rcmoser

I don't have predator and this probably won't help but my two cents anyway? I have honda GX. Once it surged due to the carb. too lean it would set there and hunt up and down and I could see the same thing the governor moving eraticlly.

IF your new engine it has any adjustments to the carb. I would first mark them to know where you started. Then try turn it counterclockwise 1/16 to 1/8 turn max to richen up the mixture... Heck maybe the EPA has restricted any adjustments on new engines. I Don't know just figure new engine don't have dirty carb. and probably adjusted or jetted lean to pass emmisions----Just guessing...

    Bookmark   March 14, 2013 at 5:39PM
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snuffyinatl

I have a Predator also, and it doesn't do this. Instead of attempting to fix it and possibly voiding your warranty, I would just exchange it. There are 2 versions of this engine, the regular EPA and the California emissions version, which will be jetted much leaner. You may want to make sure you don't have the California version. There are no adjustments on either engine. I have been pleasantly surprised with mine, I was expecting a bad running weak engine. Boy was I surprised...just hope the durability is as good as everyone elses. So far it has been a reliable powerhouse!

    Bookmark   March 14, 2013 at 7:00PM
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chas045(7b)

I'm in North Carolina Snuffy, so I doubt I got a Ca model. rcmoser, I should have mentioned that the predator is a knock off of the gx200 but it doesn't have Any adjustments. But again, as I said, it runs completely fine if the governor is blocked.

I suppose it is the obvious thing to trade it in, but I am just afraid that the new one will act identically.

    Bookmark   March 14, 2013 at 11:06PM
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gator_rider2(z8 Ga.)

I have Greyhound, Predator and Matador engines they came on market in that order. Greyhound came to HF for market year 2009 so few was sold in last Quarter 2008. With 2 other name changes the main jets where down sized to meet regulations each of these engine had to different model number ones California and one for rest country the California having smallest jetting in each model.Named. The rest of Country Models came in to Lean as well so backing out adjustment screw done real well on Greyhound about 2 rounds the Predator 4 Rounds done fairly well. Any film that coats jet from Corn oil cause 10% lean to engine only product out there that I have found that work to prevent this coating is Star-tron
additive are none deluded Gasoline High test gas helps as well if do use diluted gas.

    Bookmark   March 15, 2013 at 8:10AM
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snuffyinatl

North Carolina....are you in the mountains by any chance? You may need a high altitude kit...

    Bookmark   March 15, 2013 at 4:04PM
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chas045(7b)

Nice thought snuffy, but no I'm in the center of the state near Raleigh and Durham at about 400 feet. Anyway, since no one has had anything to say about the action of the governor I am going to do the exchange thing. I have removed the engine from my Horse Tiller and will haul it back the next time I go up to Durham.

    Bookmark   March 15, 2013 at 4:59PM
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snuffyinatl

Only thing I can figure is the governor just isn't set right. Mine runs flawlessly.

    Bookmark   March 15, 2013 at 5:19PM
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chas045(7b)

Hi snuffy, yes that is what I think as well, although I can't really figure out what that would mean. I would think if the governor shaft is round with no flat, and it became loose, then it would be like disconnecting it and obviously that isn't the case. I don't recall thinking that the engine surged dramatically when I originally got it 11 months ago.

Anyway: it doesn't matter for that engine anymore because it is back at HF and I have its replacement installed. The new engine runs well. It doesn't surge at all at low or medium speeds and only shows a perceptable (not audible) visual surge at full throttle. I haven't run it under load, other than to determine that I had my tiller belt and pulleys set properly, because the instructions say to give the engine a couple of hours break in at lower speeds. I did the same with the first engine.

    Bookmark   March 17, 2013 at 1:13PM
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chas045(7b)

Semi-Final Report on new engine.
I took my horse tiller out for a spin and it runs fine with no surging and it does the job without stalling like the other engine would do when it was tipped back too deeply. The soil is soft and I can till deeply and it still didn't stall. I didn't take the oil cutoff wire off. It just ran fine as is.

I suspect that the problem with the old surging engine may have been in the emulsion tube. It wouldn't fall out when I removed the main jet even though I banged on it a bit. Perhaps it was partially plugged.

    Bookmark   March 22, 2013 at 3:18PM
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snuffyinatl

Glad you got it taken care of! Those are great little engines...

    Bookmark   March 22, 2013 at 3:58PM
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