How to fix snowblower surging

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I've posted about this before, the last time I think was last winter. We have a 2008 M/Y Craftsman 26" with a Chonda 208CC OHV engine. The engine has great power, and runs pretty smooth overall. The one problem I have with it is that at high throttle, it surges very badly, especially under load. I honestly don't know what to do about it. I've run Techron through it, it has a new spark plug... Do any of you have any suggestions on how to fix this? Adjust the mixture or something maybe?
 
I would vote for the fuel mixture adjustment also. I had this problem on a portable generator.
turn the adjustment screw clockwise, if this starts to shut down the engine, turn it ccw till the surging stops. I also poured in 2 oz of stabil fuel stabilizer should there be any water in the tank. Ethanol attracks water. I got rid of the surging with the adjustment screw setting .
 
Nick, I vaguely recall your issue with this last winter. Did you change out to a quality spark plug? These engines can be set to run lean right from the factory, which is what this sounds like. Does it have a choke? Does it settle out if you choke it a bit? The carb probably doens't have much if any adjustability, but if it did, I'd try to give it a tweak. Could be crud in the carb jetting as well. I've seen that on brand-new stuff.

Joel
 
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Yeah I replaced it with an NGK plug, I posted a thread about it a week or two ago. And yes, it does smooth out if I turn the choke on a little bit.
 
Worst case, I wonder if you could swap the carb out for a generic 6.5hp carb. They can be had for under $30.
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http://cgi.ebay.com/HONDA-CARBURETOR-GX2...=item41535507b6

Joel
 
Wow that honda carb looks identical to the one that is on the snowblower... Chinese honda clone no lie. Though I would wonder if a 6.5HP carb would be big enough for this engine, which I would think is more than that.
 
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Did it ever run good at high speed?

My 6.5hp Honda had a bad surging problem that was caused by a cracked intake gasket.

Lean causes the surging because as the engine accelerates to top speed the carb's main (high speed) circuit mix goes lean. Unable to sustain full speed because of the lean mix, the rpm drop down until the mix gets rich again from the idle (slow speed) circuit. because the rpm has dropped the governor pulls the throttle wide open and it's then able to accelerate again, due to a better mixture, until it gets to high speed and the cycle starts over.

If it has an automatic choke it also plays into the cycle of lean/rich surging.
 
Well, since it is a honda engine, made in china... I'll look into that, maybe that is the problem. And no, it's done this from the first time we used it.
 
Before you buy a new carb, remove the nut on the bottom of the float bowl and clean the main jet (it's proberbly the nut itself)
 
From reading your posts sounds like high speed adjustment is needed, most snowblower carbs come with adjustment screws to adjust the blower under load.
 
Has the carb ever been removed and disassembled for cleaning? If the jets or fine passages are occluded with crud it can easily lead to surging. Running Techron isn't necessarily enough to rule cleanliness out as the problem.
 
"I believe it needs to be cleaned well, then adjusted correctly..."

Unless I'm wrong, from the illustration, that looks like it has a fixed jet. No adjustment is possible.
 
Sorry for the old thread...I just found this after searching the forum.
I have a 208cc Craftsman snowblower I bought last winter. Although I added gas treatment/stabilizer last winter The Engine will only run with the choke on now. So I tried taking the carb bowl off to clean the jets, but I'm not sure where the jets are? The bolt does not have any holes in it , like some tutorials show. Do I need to turn the machine upside down and tear it completely apart ?
Also, now there's a small gas drip from the carb after putting it back together, do I need to replace the o-ring/gasket now too? Thanks for any help and Happy New year !
Dean
 
A picture of the carb will help.

On most carbs I've worked on, the main jet is located in a protrusion coming down from the carb body into the float bowl. Look inside the protrusion and see if you find a small brass fitting with a tiny hole in the center and a slot across the surface. If you do, that's the main jet. You need a proper size screwdriver to get it out. If you use one that's too small, you'll end up with a damaged slot and possibly not being able to remove the jet.

You can try leaving the jet in and running a very thin piece of wire through it. I like to use trash bag ties with the plastic or paper removed from the wire. That's thin and flexible enough to get into just about every orifice on the carb.

When you put the float bowl back on, it seems you didn't have the gasket properly mounted. They're pretty thin and tend to twist a bit. Take the float bowl off, straighten out the gasket then put a smear of grease around the carb body where the float bowl gasket sits. Gently push the gasket onto the greased surface and ensure that it's laying flat. The grease should hold it in position while you carefully install the float bowl.

Certainly you jest that the gas treatment/stabilizer didn't work!

Blasphemy!!!

Stop using that junk and drain your fuel tank and carb at the end of each season. It will go a long way to prevent carb problems. If you're using last years fuel and it doesn't smell like fresh gasoline, siphon the fuel from the tank and put in some new gas.
 
Thanks for that great reply !
I will take a pic asap. The Brass jet that protrudes down that you describe sounds correct. Is The flat screw your talking about up inside? There is a hole on both sides , but I assume you are talking about looking up inside from the underneath? And useing the proper sized flat screwdriver to remove the jet, corrrect?
Yes I will drain this time !!
 
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