Predator Engine Surging (hunting)

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  #1  
Old 01-03-12, 08:55 AM
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Predator Engine Surging (hunting)

Just joined after reading a few posts. Looks like there are some very knowledgable folks on here. My problem is this. I am just completing a project where I adapted a Craftsman lawn tractor snowblower to mount on front of my ATV. I purchased a Predator 420cc engine from (yes) Harbor Freight. I know it's Chineese, but they've been making engines for years so I thought that since it was what I could afford, I'd try it. The issue is that when the blower comes under full load, the engine surges (hunts as some put it) untill the load comes off and it idles great. I know that it has to do with the govourner, but I also susspect bad gas. The gas I used is about two years old, but it works fine in the ATV. This is a new engine with less that 10 hours time on it. Any thoughts (other than that I souldn't have bought a Chineese engine) would be appreciated. Thanks.
 
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Old 01-03-12, 11:24 AM
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You knowingly put two year old gas into a new engine? I suppose there are also people that drink milk that's two weeks out of date. Feel free to open a new thread if your ATV starts acting up.

My first suspicion is the carburetor and not the governor especially since you used old gas. All it takes is a speck of dirt or varnish to clog a tiny passage or jet. I have also seen some very poor quality carburetors on no name Chinese engines that just cannot be made to work but if the engine has run under load OK before then it's probably dirt in the carb somewhere.

Here is a link to Briggs & Stratton's trouble shooting chart which may help. For a surging engine the first three possibles are in the carburetor while the 4th on the list is the governor.
 
  #3  
Old 01-03-12, 11:48 AM
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Well I guess I'll have to take the heat for being so dumb. I drained all that old gas out and went out and got some fresh 94+ and it seems to run better, in fact the more I ran it the better it seems to run. Any idea where the jets are on this unit? All the info I've found is for US stuff.
 
  #4  
Old 01-03-12, 12:45 PM
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Documentation and replacement parts are some of the main problems with those clone engines. They are imported under many different names and almost always with no documentation. The best you can do is try and figure out what engine they were copying. Without having ever actually seen one of the Predator's like you have I'd say look at documentation on a Honda GX390 or GX440.

Here's the owners manual for a GX390. It's a popular racing go kart engine so there are a lot of videos online how to work on the carb but you have to pick through which are modified for racing and which are more stock.
 
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