Cold Blooded Honda

NibbanaFarm · Dec 31, 2017

Went out to plow with the 739 this afternoon. It was 10 F. Had to pull the starter about 6-8 times to get the tractor started. Hadn't run it in about a month. Once running it seemed like it just never warmed up. Tended to stall when it came off idle from not being warm. If I ran it at higher rpm's for a while it warmed up a little and no problems. But if it idled for any time, it cooled off and tended to stall again. I'm using 5w-30 now. I wonder if I should switch to 0w-30 or 5w-20?

mddorange · Dec 31, 2017

When I go out to start my tractor, I have to warm the Glow plugs much longer that normal on the cold days down here, so I can only imagine what it takes up there.

MossRoad · Dec 31, 2017

Oil won't be the problem. As you mentioned, it got warmed up, but wouldn't idle well. That's not a 0W vs5W oil issue. It's a fuel/air ratio issue, or weak spark at idle issue.

I'd first change your fuel filter. It could be that at higher RPM its got the power to suck fuel, but at lower RPM, it doesn't. It's a cheap starting point.

MossRoad · Dec 31, 2017

Also, is that a manual choke engine or automatic choke?

MossRoad · Dec 31, 2017

Also check the air filter... sorry if this is obvious stuff, but gotta start at the beginning.

tomplum · Dec 31, 2017

Your engine oil weight could have an effect on your ability to crank it over, unsure any other effects on runability. So if that is the case, 0W30 would be the choice. Follow the rules on keeping fuel fresh, treat with an ounce of Seafoam plus occasionally use the bowl drain to get any condensation out would be a good idea too. Is icing a possibility? A typical snow thrower engine has no air filter for that reason. Other implements will sometimes have a baffle to flip to warm the intake air to lessen icing.

MossRoad · Dec 31, 2017

And make sure its fresh fuel if it sat for a year or so.

If that doesn't resolve it, get it running and spray a few shots of carb cleaner into it. Could just be a blob of gunk or dirt in there.

Then check your fuel line for cracks.

crmorse · Dec 31, 2017

If none of the above, check your thermostat. Might not be closing so at idle it's cooling the engine too much.

NibbanaFarm · Dec 31, 2017

I just did the annual maintenance so filters and fluids are new or cleaned. Fuel strainer in the carb was clean. Manual choke. When the choke is partially closed it runs good. The only thing I didn't do was change the spark plug. I treat all the fuel that goes in it and it only sat for less than a month. Very hard pulling that engine over. Will try some 0w-30 and a new spark plug.

Code54 · Dec 31, 2017

In the dead of winter around here my small engines are tough too pull. I switch to synthetic oil and it seems to help a bit in pull starting. On a cold night sit a few oz's of your conventional oil outside in a plastic cup and put a cup with some syn. oil next to it. In the morning see how each flows. It gives you a good idea of what is going on in the motor when you are trying to start it..

Code54 · Dec 31, 2017

This is a bit extreme but gives you the idea.
Cold Pour Test: AMSOIL Synthetic Oil versus Conventional Oil - YouTube

tomplum · Dec 31, 2017

I hope you see a difference with the 0 weight. That's about all you can do to help there besides warming the machine. With the choke helping the runability, it would sound like the main jet in carburetor should be cleaned. You can try running through a cleaner like Seafoam in the fuel. You probably have good access to the carburetor bowl nut. Shut off the fuel, remove the nut with a 10 mm wrench draining and cleaning the bowl. The main is straight up the stem of the carb. Most times all you need to do is give a few blasts of carb spray via the very center tube using the straw.

Code54 · Dec 31, 2017

Could put a stick on engine block heater on it. Ebay and Amazon both have a bunch of magnetic mount ones.

MossRoad · Jan 1, 2018

tomplum said:
I hope you see a difference with the 0 weight. That's about all you can do to help there besides warming the machine. With the choke helping the runability, it would sound like the main jet in carburetor should be cleaned. You can try running through a cleaner like Seafoam in the fuel. You probably have good access to the carburetor bowl nut. Shut off the fuel, remove the nut with a 10 mm wrench draining and cleaning the bowl. The main is straight up the stem of the carb. Most times all you need to do is give a few blasts of carb spray via the very center tube using the straw.

What he said...

MossRoad · Jan 1, 2018

crmorse said:
If none of the above, check your thermostat. Might not be closing so at idle it's cooling the engine too much.

Does a Honda air cooled engine have a thermostat? :confused3:

4get gto · Jan 1, 2018

Small engines are different animals when they run at 40 degree out verus 0. Once running readjust the carb a little and see what happens. I never had a small engine that started on 1- 2 pulls when its this cold out. Might be getting ice in the carb.

5 degrees this morning. High teens during the day. I'm not running right either.

crazyal · Jan 3, 2018

Code54 said:
Could put a stick on engine block heater on it. Ebay and Amazon both have a bunch of magnetic mount ones.

It's probably an aluminum block.

crmorse · Jan 3, 2018

MossRoad said:
Does a Honda air cooled engine have a thermostat? :confused3:

Doh! I missed that... that's what I get for feeling smart like I knew an answer.

Code54 · Jan 4, 2018

crazyal said:
It's probably an aluminum block.

We often use a strap to attach them to alum. blocks or tanks when needed. On some of the smaller machines we just lay them in position when needed. Works better than expected in most cases.

MossRoad · Jan 4, 2018

crmorse said:
Doh! I missed that... that's what I get for feeling smart like I knew an answer.

With all the electronic engine controls theses days, it wouldn't surprise me if a small air cooled engine had some sort of temp sensor and computer to adjust mixture, so that's why I asked. Thought maybe I needed some more education.