# HS621 only runs on choke



## Buschy2586 (Nov 12, 2018)

Hi all,
Just picked up an HS621 and am having some trouble getting it running. I've taken the carb off twice now and ran a whole can of carb cleaner through it. Looks to be totally clear, but it will only run with the choke on. I've gotten it to run for short bursts with the choke off but it surges hard backfires and then normally dies out. 

I've drained out all the old gas and replaced it with new gas with stabilizer added. I've cleaned out the carb twice, changed the spark plug, put on a new drive belt, have new rubber for the auger and blade on the way, and changed the oil.

What else should I be checking?? Should I look into a knock off carb replacement or spend the money on a Honda carb? Should I replace the fuel lines? I don't have much experience on small engines so any guidance would be greatly appreciated. 

Thanks in advance!

Scott


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## vinnycom (Nov 6, 2017)

its running lean. u gotta make sure the main jet is clear, use small wire to get into all the small holes with carb cleaner.
took me a few times to figure it out. if carbs been neglected it needs more attention then just spraying carb cleaner into it.
or u got a vacuum intake leak, spraying carb cleaner along the intake path while engine is running will give u an answer.


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## Jackmels (Feb 18, 2013)

Carb is Clogged. There are some holes in the front of the Carb Throat. Using a Blowgun, hit all the holes with compressed air until gas flows out of the front. Problem Solved. Or if You want to go new, repops are $10 https://www.ebay.com/itm/Carburetor...=item21287c8fa6:g:cIgAAOSw0bxZte-Z:rk:20:pf:0


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## dadnjesse (Nov 24, 2015)

Just went through same thing with my 621, needed a little choke to stay running. I bought the Honda oem carb from boats.net for $45.59. runs perfect now, I didn't even want to bother trying to clean it. Just make sure you take pictures as your taking it apart. And get new gaskets.


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## Freezn (Mar 1, 2014)

dadnjesse said:


> Just went through same thing with my 621, needed a little choke to stay running. I bought the Honda oem carb from boats.net for $45.59. runs perfect now, I didn't even want to bother trying to clean it. Just make sure you take pictures as your taking it apart. And get new gaskets.


+1 Buy a new Honda OEM carb with twist spout fuel drain (not the cheap knock-off with bolt drain) and replace. Then take your old carb, pull the main jet and clean the tube holes with a wire. Probably very tiny piece of crud or varnish in one of the holes. If you have access to an ultrasonic cleaner, have the old carb dipped once or twice for a final cleaning. Then you can either keep the old carb as a back-up or sell on Ebay for $25 - $30.


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## Buschy2586 (Nov 12, 2018)

Alright,

New season, same old problem.

Last season, i bought the OEM carb and swapped them out. Ran well for the season.

Started her up this season and got the same surging problem, dieing off choke. Got cheap and bought a knock off carb, just swapped it and still same problem. Starts right up on choke, starts surging at half choke and dies with the choke off. 

I'm using fuel from my mower with stahbil in it, probably a few months old....would that be an issue? it smells fine. Should i replace the fuel line? 

What else can I check on this guy before I need to drag this thing to a small engine repair show with my tail between my legs....

Thanks in advance,
Scott


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## AriensProMike (Dec 2, 2014)

I would try fuel lines first. Also clean the carb and rinse the fuel tank and let it all dry out. 

Might be an air leak. Check gaskets and make sure everything was put in the correct orientation. Possible valve adjustment or if it's an ohc engine. It could have jumped timing. 

Good luck and welcome to the forum.


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## lmichael (Nov 5, 2019)

I'd be looking for an air leak (bad gasket perhaps)


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## Snowbelt_subie (Dec 20, 2016)

Buschy2586 said:


> Alright,
> 
> 
> 
> ...


That's pretty odd.


#1 Have you made sure that gas is getting to the carb from the tank line? I had something like this before it was something in the tank blocking fuel from filling up the bowl fast enough.

#2 the fuel shut off make sure when you are turning from off to on fuel is coming out the other end.


If not either of those ? I'm stumped it's a lean condition for sure. And I'f you said it ran well for a season that doesnt seem like an air leak.



Sent from my SM-G950U using Tapatalk


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## HondaPowerBro (Oct 10, 2021)

Hi, sorry to revive a dead post, but I tried removing the jet of my HS621 and couldn't find a screwdriver wide or narrow enough. *What is the size of screwdriver needed?*
I also tried to kind of clear the blockage with a tiny screwdriver in the jet, and also heard a noise like a part falling out when spraying with carb cleaner.

When I tried to turn it on again, gas leaked everywhere. What did I do wrong? Did I scratch up the jet by jiggling a screwdriver in there?
Do I need to replace the carb? How can I source a new pilot jet in Canada for HS621?

Sorry and Thanks


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## contender (Jan 18, 2018)

I see you are in Canada, but where, I'M on the outskirts of Kitchener/Waterloo....

Lots of experts on here......I'm not one of them but going to pickup my 5th HS621 in the morning, I'm pushing for 7, one for each day........just kidding

Offer some more facts, is this machine new to you, worked great last year etc etc....

The part you may have heard falling out, might have been the float jet if it happened to be jarred, which could also now explain the leak you have.

Because you couldn't get the jet out i know you had the carb bowl off, did you mark its orientation, before you removed it??? Very Very important to get back in the correct position. Get your self a service manual if you don't have one...

I source some of my parts from boats.not, i will let you try to find that...one of the forums i frequent won't allow an actually link, and some stuff at my local Honda Dealer. In Canada most if not all Honda Dealers sell at suggested retail....

Also good idea to start a new thread, for a new problem.....

BTW, IMO, best single stage unit offered, but I do like my HS928 track machine......


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## orangputeh (Nov 24, 2016)

Honda_Power_Lover said:


> Hi, sorry to revive a dead post, but I tried removing the jet of my HS621 and couldn't find a screwdriver wide or narrow enough. *What is the size of screwdriver needed?*
> I also tried to kind of clear the blockage with a tiny screwdriver in the jet, and also heard a noise like a part falling out when spraying with carb cleaner.
> 
> When I tried to turn it on again, gas leaked everywhere. What did I do wrong? Did I scratch up the jet by jiggling a screwdriver in there?
> ...


That main jet is BRASS so unless you have the proper carb cleaning wires you probably screwed it up. I make my own carb screwdrivers by finding the exact size width and then grinding down sides so it will fit in pick up tube.

The reason it is leaking gas is probably what the other poster mentioned. 1. the catb bowl O ring has to be on coreectly. 2. the bowl has to be put on correctly in most Honda models. I have to redo the O ring from time to time so don't feel bad. 

BTW you have a great Honda in the 621. If you have to just buy a new OEM Honda carb and throw it on. Reasonable price and will last. Use Ethanol free gas if you can find it or premium gas treated with a gas stabilizer. 

good luck.


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## CarlB (Jan 2, 2011)

if your sure you got the carb clean i would be looking at a vacuume leak.


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## HondaPowerBro (Oct 10, 2021)

Hi everyone, thanks for you speedy and knowledgable replies. 
I opened up the carb again this morning and the sound I heard was the float cup's pin going into the abyss.
So I either need to source a new pin and main jet or a new carb and probably get someone to do a house visit to help me take the jet out.
I tried taking the jet out again but no screwdriver gave me the confidence to begin....
Would replacing the carb be difficult? Anyone can point to a video tutorial? I'm afraid of messing up more of the snowblower.....


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## tabora (Mar 1, 2017)

HondaPowerBro said:


> I tried taking the jet out again but no screwdriver gave me the confidence to begin...


As others said above, take a 5/16" flat blade screwdriver and grind off the sides until it's no wider than the jet tube threads = about 6mm, or use a 8-10 flat long hex bit. A 1/4" hex bit is 0.2887" across the points = 7.333mm so will also need grinding if not already relieved. The jet thread OD is 7mm. Soak the jet thoroughly with carb cleaner before you try to remove it. Also clean the emulsion tube above the jet and note which way is up for reassembly.


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## HondaPowerBro (Oct 10, 2021)

tabora said:


> As others said above, take a 5/16" flat blade screwdriver and grind off the sides until it's no wider than the jet tube threads = about 6mm, or use a 8-10 flat long hex bit. A 1/4" hex bit is 0.2887" across the points = 7.333mm so will also need grinding if not already relieved. The jet thread OD is 7mm. Soak the jet thoroughly with carb cleaner before you try to remove it. Also clean the emulsion tube above the jet and note which way is up for reassembly.


I don't have a grinder, thanks for replying on my other post too tabora.
However, seems like the direction is gunsmith tools:



https://www.garagejournal.com/forum/threads/carburetor-screwdrivers-for-jets-they-must-be-out-there-somewhere.229925/


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## contender (Jan 18, 2018)

Hondapowerbro, what province are you in?? Lots of Canadians on here, so you never know, I could be the guy next door??

Not asking for an address just city....etc


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## HondaPowerBro (Oct 10, 2021)

Hi Contender, lol was just reading your reply re: Honda dealers. Did you mean the Honda car dealers or just the outdoor products stores that sell snowblowers?
I was going to call the car dealer tomorrow but realized you might have been talking about the snowblower stores. 
I live in Richmond Hill, Ontario  

Ya, I realize the grinding of the screwdriver is the best bet, but I've never done that before and I'm scared to use a grinder.
lol


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## orangputeh (Nov 24, 2016)

HondaPowerBro said:


> Hi Contender, lol was just reading your reply re: Honda dealers. Did you mean the Honda car dealers or just the outdoor products stores that sell snowblowers?
> I was going to call the car dealer tomorrow but realized you might have been talking about the snowblower stores.
> I live in Richmond Hill, Ontario
> 
> ...


I can slip you a file in a cake.....


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## contender (Jan 18, 2018)

HondaPowerBro said:


> Hi Contender, lol was just reading your reply re: Honda dealers. Did you mean the Honda car dealers or just the outdoor products stores that sell snowblowers?
> I was going to call the car dealer tomorrow but realized you might have been talking about the snowblower stores.
> I live in Richmond Hill, Ontario
> 
> ...


Nope, any shop that is an authorized honda dealer for power equip, maybe one of the local guys on this forum in your area will chime in, if not maybe better to get a professional to look at...


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## tabora (Mar 1, 2017)

HondaPowerBro said:


> Does my family just not have the right tools that everyone else has?





HondaPowerBro said:


> I'm scared to use a grinder.


I don't know what I'd do without a grinder... I have 4 bench/pedestal grinders with different wheel grits and wire brush types and 4 handheld ones. Plus lathes, milling machines, drill presses, etc. But the grinders are SO useful; I make/modify tools all the time.


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## HondaPowerBro (Oct 10, 2021)

So... somehow I got my HS621 to work with the choke pressed all the way down.
I lost the carb pin and it leaked gas everywhere, then I gave up for that night.
The next day I found the pin on the ground, and reinstalled it, but didn't start it
The next weekend I followed some advice to get the main jet out by filing down a screwdriver, but that didn't work because the handle was too long
But I tried to start it to test if the pin fixed the leaking gas problem.
I forgot to pull the choke up to start and it rough started and then quit on me. 
I saw the choke was down and then pulled it up and it started, then I was able to put the choke down all the way without it dying on me.

Is it possible that the start with the choke down somehow 'cleared' the carb???? what the heck?
Haven't started it again to see if it was a lucky break or if it can actually run with choke down normally in repeated uses.... 
Anyone experience this?


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## WrenchIt (Dec 6, 2020)

Anything is possible, but you should let it run for several minutes to be sure you are past the initial carb bowl fill of gas. If nothing else, yanking the needle (aka float pin) could have let some dirt wash free when you were leaking gas.

Add some Sea Foam to your gas for several tanks to help dissolve gas deposits in the carb. I'm not a believer in Sea Foam but enough guys swear by it that I use the stuff now and then even though I think its a waste of money. It can't hurt (I hope) and might do some good.


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## Oneacer (Jan 3, 2011)

I have been using Stabil and SeaFoam for many years in all my gas .... 2oz of each in every 5 gallon can when I fill them up. (1 oz of each in 2 1/2 gallons). ..... Never had a carb issue ...... Just about every single unit that comes my way has carb issues from not using treated fuel, ..... as well as other operator neglect issues of course ....


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## orangputeh (Nov 24, 2016)

WrenchIt said:


> Anything is possible, but you should let it run for several minutes to be sure you are past the initial carb bowl fill of gas. If nothing else, yanking the needle (aka float pin) could have let some dirt wash free when you were leaking gas.
> 
> Add some Sea Foam to your gas for several tanks to help dissolve gas deposits in the carb. I'm not a believer in Sea Foam but enough guys swear by it that I use the stuff now and then even though I think its a waste of money. It can't hurt (I hope) and might do some good.


trouble with seafoam is that people thinks more is better which can cause more problems. i agree with oneacer's use of this stuff. it's not a miracle fix in my experience.


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## WrenchIt (Dec 6, 2020)

orangputeh said:


> trouble with seafoam is that people thinks more is better which can cause more problems. i agree with oneacer's use of this stuff. it's not a miracle fix in my experience.


Trouble with most people's thinking is more of ANYTHING is better. Sex, drugs, rock n roll, you name it. Ever watch Amish carpenters go at any poor stud or joist while framing a structure? If they made fully automatic nail guns, those guys would have one. If one nail is good, 100 should be that much better. (Except it's not.)


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