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Discussion Starter #1 (Edited)
Last year, I installed a Honda GX390 on my Ariens. I had problems with snow coming on the carburator governor linkage. I made a carburator shield to protect it against this problem. Normally, sbowblower motors (I think) use heated air coming in the carburator. I thought doing something for my GX390, Here is what I thought to do.



- Install a shield between the air box and the muffler
- Making air inlet holes in the top of the air box cover on the muffler side

- Blocking the standard air inlet duct on air box so warmer air will come from top holes made in the air box cover on muffler side.

Here is a picture of the shield I will install. I use an air filter cage without air filter paper element but I use the foam filter around the cage inside the air filter box.

Finally, is it a good idea to heat the air or best is having cold air coming in the carburator ?


Thanks
 

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Finally, is it a good idea to heat the air or best is having cold air coming in the carburator ?
Sounds like you put a summer engine on it... The winterized GX390 has a number of shields to warm the carb bowl, but not necessarily the air intake. I think you want nice, dense cold air entering the carb, but want the fuel bowl and linkages kept warm and free of ice buildup. I'd just add the equivalent of the standard Honda HSS1332 shielding (or purchase the parts; most of them are not too expensive). See the Air Guide page here:
http://peparts.honda.com/powerequipment#/browse/sb/hss/hss1332/HSS1332A-ATD
and @ partspak: https://oemparts.partspak.com/oemparts/a/hpe/55bfa17b87a8661afc0babd5/air-guide

You don't want an air filter on a snowblower engine. It can ice up from ingesting snow powder and vapor. It's completely unnecessary for winter engines.
 

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Sounds like you put a summer engine on it... The winterized GX390 has a number of shields to warm the carb bowl, but not necessarily the air intake. I think you want nice, dense cold air entering the carb,

You don't want an air filter on a snowblower engine. It can ice up from ingesting snow powder and vapor. It's completely unnecessary for winter engines.
I was going to advise him to lose the air filter.
 

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Discussion Starter #4
As written


The paper filter element is not there. I simply use the foam filter. Last winter, I never had any ice clogging with the foam. I use it because they use a lot of sand on the road.
 

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Finally, is it a good idea to heat the air or best is having cold air coming in the carburator ?
Thanks
I think making sure the linkage is covered is a good idea as would capturing some heat if possible to melt any snow that might get in there so it's more likely not to stick and freeze something.

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As written

The paper filter element is not there. I simply use the foam filter. Last winter, I never had any ice clogging with the foam. I use it because they use a lot of sand on the road.
Again, strongly recommend against the foam filter.

Intake air temperature directly effects power. Cool air is denser so more air (oxygen) actually enters the engine. A 7.2 degree increase in air temperature causes a 1% decrease in horsepower. Ducting cooler air to your air cleaner inlet can give your engine a significant power boost.
 

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Ideally you want cold air to the intake, as long as you're not having carb icing problems. Warmer intake air will reduce carb icing, but will also reduce engine power. As far as that goes, a summer engine being used in the winter without feeding warm air to the carb might need to be jetted a little richer than stock for optimal power.

Running an air filter should be fine, provided the intake is placed in a way where it won't suck up snow and such that's flying around the machine. If the filter hasn't been icing up, I see no benefit to removing it.

Keeping the governor linkage warm and protected to avoid icing is definitely important.
 

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Running an air filter should be fine, provided the intake is placed in a way where it won't suck up snow and such that's flying around the machine. If the filter hasn't been icing up, I see no benefit to removing it.

Keeping the governor linkage warm and protected to avoid icing is definitely important.
Keeping the filter isn't that much of an issue as long as it's easily removable should it freeze up. For all the times I've been hit in the face with the discharge when I thought I had the wind direction figured out I'd rather run without a filter just so I don't freeze a filter but I agree it's a very unlikely thing to have happen. +1 on keeping the linkage warm and protected.

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This will be a little off the wall, but from experience playing with carburetor problems.
#1. Lose the air filter. Winter air is not as dirty as summer air. The sand on your road will not create dust.
#2. All horsepower formulations with air temps go out the door when you are using a carb as efficient as Honda.
Allow the intake air to be heated. Cold air rushing through the venturi of an efficient carburetor will turn it into a popsicle and the venturi size will be severely reduced.
Carbureted airplanes have the same issue and use heated air boxes that they can control for the humidity problems at different elevations.
Car engines are no different, they have heated intakes that keep the carbs warm. I have had straight sixes turn into popsicles without a heater plate under the carb.
In short, I would keep it simple and keep all the formulations out of it.
 

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As a point on the carb icing thing, if you really wanted to get fancy and try to strike the best balance between avoiding carb ice and best power, you could make an adjustable hot air feed from the engine cooling air to the intake.
 
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