Should mower engine need to always use choke to start?

[E150GT]

I have my new to me Honda HRC216 with GXV160 engine. It was abused but not used commercially so it's still in pretty good shape. It starts and runs and will cut the grass. Great. I wouldn't think there's a problem if it didn't pop out the exhaust or what sounds like a misfire. Recording it with my phone won't pick it up but it's definitely there. Add to that if you slow the engine to idle and then back up to full speed it will will blow black smoke. The black smoke wouldn't alarm me too much but my HRX217 does not exhibit any of these thing when I do the same. I really cannot tell if there is a problem with it running too rich or not.
What I have done so far:
New OE air filter
New spark plug correctly gapped
New OE carburetor. Yes I have screwed with the adjustments. I set the idle with the little black screw and when I think it's good and I let it run it starts to go up to past 2000 rpm on its own. I'm not sure why.
Cleaned rust off coil and magnet on flywheel. I regapped with a business card. It was touching the flywheel on one side. I didn't clean surface rust off rest of the flywheel.
Adjusted valves. Intake was ok but exhaust was pretty tight. I had to wedge the feeler gauge in there and it left little scrape marks on the feeler. It was my first time ever doing valves.
One thing I have noticed is the engine does not need choke to start. Just stick it up the rabbit and pull the cord. It starts easier than my GCV200. I don't know if this is indication of too much fuel or not. It's not cold here in south texas. If I apply choke to a warm motor it will stumble and blow black smoke which I would think is normal.
Gas cap on or off makes no difference.
I'm thinking I might take this in to a shop but that's a big hassle and something I only want to do if I have to. What do you guys think ?

 

[JohnnyG]

Yes, it's running too rich.

 

[Hall]

How old is this Honda ? They have used "automatic" chokes for a long time.

 

[E150GT]

How old is this Honda ? They have used "automatic" chokes for a long time.

It's a 2019. Because it's a commercial mower that used a standard manual choke. My HRX has auto choke so I can't really compare and see if what I am experiencing is normal. My only other Honda was manual on auto off choke that I never tried to start without using it

 

[oldcodger]

My mowers have always needed choke when engine is cold. No choke required when even slightly warm or hot.

 

[The_Eric]

How rapid and consistent is the popping?


Do you have a spark tester and/or a leak down tester? Compressed air? Test the spark and see if it correlates to the miss/pop and/or fill the cylinder with compressed air while at TDC and see if it's leaking past a valve.

 

[E150GT]

I can probably do the compressed air test.
I just took a multimeter to the coil. The service manual says both primary and secondary resistance should be .8 to 1 ohm resistance. The primary side shows 2.3 or so ohms and the secondary side shows something crazy like 16k ohms. It's hard to know if that's right though because the numbers fluctuate all over the place while testing depending on how you hold the leads.

 

[The_Eric]

Well I'd say that you very likely found the issue.

 

[nbpt100]

Well I'd say that you very likely found the issue.

If you are testing it right , that may be the problem or one of your problems. When setting the air gap you said you used a business card. That is ok as long as it is one of the thinner traditional cards. They are .010 thick. Many today are now thicker. If you can measure it with a caliper/micrometer then do so and confirm it. I set the gaps to .010-.012 inches. Cleaning off the rust allows you to get it closer. The smaller the gap, the stronger the spark. I always clean rust off of both the magneto and the flywheel. It allows you to get the most accurate gap. Why did you change the carb instead of cleaning the original? I now almost always clean the original because there are so many mistakes made and generally poor quality with new Carbs. Especially aftermarket. Since you got OEM I assume it is of the best quality but is it the correct one? It may look similar but if one jet is off a hair it can run rich. If you have the old carb still, put the old jets in. Both the pilot and main jets. See if that changes anything.

Did you look at the new plug after running for a while. Is is black and carboned up? Suggesting it is too rich. Are you using a NGK BPR5ES?

The_Eric has excellent suggestions if the problems still persists. A leak down test can tell you a lot about the overall health of the engine and where you may be loosing compression.

Honda engines are well made and I have seen abused Honda engines last a very long time. As you run it the problem may get worse and that will help you troubleshoot it better. Or it may never change and be a decent performing mower engine for a long time.

 

[E150GT]

If you are testing it right , that may be the problem or one of your problems. When setting the air gap you said you used a business card. That is ok as long as it is one of the thinner traditional cards. They are .010 thick. Many today are now thicker. If you can measure it with a caliper/micrometer then do so and confirm it. I set the gaps to .010-.012 inches. Cleaning off the rust allows you to get it closer. The smaller the gap, the stronger the spark. I always clean rust off of both the magneto and the flywheel. It allows you to get the most accurate gap. Why did you change the carb instead of cleaning the original? I now almost always clean the original because there are so many mistakes made and generally poor quality with new Carbs. Especially aftermarket. Since you got OEM I assume it is of the best quality but is it the correct one? It may look similar but if one jet is off a hair it can run rich. If you have the old carb still, put the old jets in. Both the pilot and main jets. See if that changes anything.

Did you look at the new plug after running for a while. Is is black and carboned up? Suggesting it is too rich. Are you using a NGK BPR5ES?

The_Eric has excellent suggestions if the problems still persists. A leak down test can tell you a lot about the overall health of the engine and where you may be loosing compression.

Honda engines are well made and I have seen abused Honda engines last a very long time. As you run it the problem may get worse and that will help you troubleshoot it better. Or it may never change and be a decent performing mower engine for a long time.

Well. I did clean the carb originally but it didn't change the behaviour of the engine. I thought maybe something was amiss with it so I got a new OE replacement. It's not cheap but I don't mind having a spare in inventory for the long haul.
I did order a new coil but it's not here yet. I am hopeful but not sure if the old one is bad or not. I tested according to the service manual but the readings are very inconsistent but only rarely can I get it to read close to what it specs out in the manual but I also read that with new transistorized magnetos they are hard to test with an ohm meter. When I put the new coil on I will use a feeler gauge as outlined in the manual. The manual has a typo on the testing procedure by the way. It lists the secondary ohm spec the same as the primary and it's not. The correct spec is at the front of the book under the specs section.
The spark plug is pretty new so it doesn't show anything bad on it. Not sure how long it takes to foul it out. It is a BPR5ES that I got from partspak.
The original plug was black and disgusting. I wish I saved it. The engine was burning some oil when I first got it and I assume some got in the intake when transporting it and it cleared up and stopped burning. I don't know if that plug was nasty from the oil or from running rich.
Honestly probably the majority of people would have just run it as is but I'm obsessive about this and I want it to run perfect. Not sure if that will happen or not but I'm gonna try. This coming week when they coil comes in we shall see.

 

[jhellwig]

Is the choke a separate lever or is it the style where you push the throttle past full speed? If it is part of the throttle it might need adjusted. The choke could be on at fill throttle.

 

[E150GT]

Is the choke a separate lever or is it the style where you push the throttle past full speed? If it is part of the throttle it might need adjusted. The choke could be on at fill throttle.

It's the one with the throttle. I have verified corrected function of the choke

 

[Oliveoil2]

Always at altitude, 5000ft and higher.

 

[oil pan 4]

If the engine is properly jetted it will need to be choked, even after it's running for a few seconds.
If it's a Honda or has a Honda clone carb I tune them so they don't run right with e10 gas, they have to have ethanol free.
I've got an MTD that runs so rich it won't start if I choke it. Stupid MTD doesn't offer sn altitude kit for it.
I may need to see if I can swap a Nikki carb like whats on my Craftsman riding mower. They're both 540ish cc.
I put the high altitude kit on my Craftsman riding mower, got more power and better fuel economy. After the high altitude kit I need a refuel before the mower does.

 

[Lubener]

If it starts easy and runs well, I wouldn't worry about it as long as the plug burns cleanly.

 

[E150GT]

New coil. No difference. I give up