Different carb "tunes" for winter and summer?

[Rusty Tinsnips 477]

Both my horses don't run like they did plowing snow this last winter. I haven't had time to tweak the carbs but I think that's what's is wrong with them. Nothing serious, just a little surge at full throttle on both that was not there in the winter. Do they need constant adjustments? Both carbs were rebuilt last year and ran great all winter.

[ebinmaine 67,678]

I was taught a good many years ago to make sure that the MAINTENANCE is done before you try doing DIAGNOSTICS.

 

So to that end,

 

A#1 question. Do you use ETHANOL gasoline?

Other than rebuilding the carb, what has been done recently?

Are the fuel lines new? If so, rubber or something else?

 

 

5 minutes ago, Rusty Tinsnips said:

Do they need constant adjustments?

 

So to go back to your original question.

Yes and no.

 

My experience has shown me over the years that carburetors can be a lot like people in that every single one of them has a different "personality."

 

[Rusty Tinsnips 477]

2 minutes ago, ebinmaine said:

Do you use ETHANOL gasoline?

No ethanol, and I am using seafoam.

 

7 minutes ago, ebinmaine said:

what has been done recently?

The usual, oil change, transmission oil change, new plug and points on the Kohler and lube everything that moves.

And new paint!

 

4 minutes ago, ebinmaine said:

Are the fuel lines new? If so, rubber or something else?

No not new and they are rubber, and one of them started leaking gas. I had a 5' piece of true blue line and replaced only the leaker. No crud showing in the clear fuel filters. Will replace all when I get some time.

[Maxwell-8 4,277]

Surging is almost always to lean, therefore maybe a jet is clogged up. 

Fuel shut-off completly open? 

Edited May 6, 2021 by Maxwell-8

[stevasaurus 22,765]

I have Kohler engines, and I have never had to re-adjust a carburetor because of a weather change.  The choke takes care of that when starting the engine.  

   The real answer is...try minor adjustments to see if the engine runs better.  The air / fuel mixture screw.

[Rusty Tinsnips 477]

Thanks all.

 

[Maxwell-8 4,277]

55 minutes ago, Rusty Tinsnips said:

seafoam.

You use seafoam all the time? In the oil or in the fuel?

[Rusty Tinsnips 477]

2 minutes ago, Maxwell-8 said:

In the oil or in the fuel

Just in the gas and "all the time" for me is about 10 hours runtime since last October.

[DennisThornton 4,769]

I'd suspect a spec of dirt or whatever in the carb.  Maybe the needle has a slight blockage.  Sometimes removing and replacing the needle fixes the issue.  Count the gentle turns in and then pull it out, if handy spray carb cleaner inside and the jet but I've had times when I didn't even need that.  Gently bottom out the needle and back it out to where it was, usually 1.5 turns to start with, note where screwing it in lowers the RPM and where backing it out drops the RPMs and set the needle in the middle of where it runs best.  I've had some luck just running the needle in and back to where it was.  Good luck. 

Edited May 6, 2021 by DennisThornton
low to lowers

[kpinnc 12,122]

I will add this- depending on how you store your tractors has alot to do with it, but; if you have plastic fuel tanks, they sweat quite a bit. Change in seasons can cause more condensation than otherwise. I dump the fuel bowl on my Kohlers every spring. A little water in the sediment bowl always makes my tractors sputter or fuss a bit. 

[Maxwell-8 4,277]

25 minutes ago, Rusty Tinsnips said:

Just in the gas and "all the time" for me is about 10 hours runtime since last October.

I personally wouldn't use it all the time, since you use ethanol free gas. 

But that is an other topic.

 

1 hour ago, Rusty Tinsnips said:

just a little surge at full throttle

Something is limiting the amount of fuel, that is clear. maybe try and pull out the choke every so slightly on full trottle and see (hear) if she stops surging.

[squonk 41,164]

Colder engines need more fuel. In winter they are sucking in cold air and maybe a bit of snow. A minor tweak (1/8) turn isn't unheard of as far as I am concerned. Had to do it many times.

[Stepney 2,325]

Mine always like a little tweak between the seasons including the truck.. just the nature of some engines. 

[EricF 589]

I'll add that if you do tweak or adjust the carb in the winter, you'll probably have to do it again in the spring. Temperature and varying gas blends for winter plus ethanol evaporation in different temperature/humidity ranges will affect how the carb responds when you set it.

 

I've seen service guides for carbs published since the 90s/2000s caution about this -- and recommend that when adjusting the carb in the winter, it should be done at an ambient temperature of 45-50 degrees Fahrenheit. (Which often means indoors in a heated shop...) It puts the evaporation rate of the ethanol more within expected tolerances. And winter blends of fuel often aggravate it. Ethanol just LOVES to either evaporate or pull moisture out of its surroundings and makes carb adjustments that much trickier.