# Why is my hs50 popping a little at high throttle?



## orangputeh (Nov 24, 2016)

Recently serviced my hs 50. new plug ( same gap as old ) cleaned out carb best i could, new gas treated.

starts first pull . runs well at idle ( does not hunt or surge ) but when I raise the throttle from midway to full it starts popping a little. runs good but something not right as it pops every couple seconds. pop pop..........pop....poppop. like that. it was running like this also before the service.

does this point to carb or maybe the valves? this is a 34 year old machine.

I let it run for 20-30 minutes and nothing changed.

oh, ya....also adjusted the air fuel screw according to shop manual and nothing changed.

thanks.


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## nwcove (Mar 2, 2015)

open up the fuel needle a bit to see if its running lean. ( or add some choke)


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## DriverRider (Nov 20, 2016)

nwcove said:


> ( or add some choke)


Yup, while it is popping add choke and see if it smooths out.


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## jtclays (Sep 24, 2010)

Wha


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## orangputeh (Nov 24, 2016)

jtclays said:


> What's the old plug look like? Brownish tan is good. Grey to whitish is lean. Did you have the carb completely off? Replace gaskets? Sometimes those Honda insulators warp or degrade over time and they'll start sucking some extra air there. Make sure the studs are snug into the block, sometimes they want to wonder out with the nuts being removed.


the old plug looked good, perfect brownish tan. I'll try some choke and see if it evens out and check studs.

thanks everyone.


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## JnC (Feb 21, 2014)

I am actually having a similar issue with one of my work neighbor's HS828. It pops at high RPM but smooths out if you kick a choke in a bit. I changed the carb last year to one from another machine, both carbs were fully cleaned/serviced prior to install, yet the same thing is happening again with the new set up.


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## jtclays (Sep 24, 2010)

Orangputeh, 34 years may be the Honda service interval for adjusting the valves:grin:
If it were a Briggs OHV, you'd already have done it 12 -15 times and had 5 head gaskets:wavetowel2:
34 years and still starts right up even with a little pop is not too darn bad.


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## JnC (Feb 21, 2014)

jtclays said:


> Orangputeh, 34 years may be the Honda service interval for adjusting the valves:grin:
> If it were a Briggs OHV, you'd already have done it 12 -15 times and had 5 head gaskets:wavetowel2:
> 34 years and still starts right up even with a little pop is not too darn bad.



Funny you say that as someone else suggested to adjust the valves as well. 

I am pretty sure that will solve the issue for me as well as i changed the carb on the machine and still had the same issue where as I have never had a cleaned carb show any signs of popping in the past.


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## 43128 (Feb 14, 2014)

any chance you have one of the h50s with a cdi module?


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## orangputeh (Nov 24, 2016)

jtclays said:


> Orangputeh, 34 years may be the Honda service interval for adjusting the valves:grin:
> If it were a Briggs OHV, you'd already have done it 12 -15 times and had 5 head gaskets:wavetowel2:
> 34 years and still starts right up even with a little pop is not too darn bad.


i agree. the honda shop manual shows how to check the valve lash but does not have an adjustment procedure. it suggest new valves .

i don't think it is a backfire. it's just little pops .not constantly. a few seconds of good running , then a couple pops.

i'll try applying a little choke.

and what about the air/fuel mixture screw? I'll play with that too and check back here.


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## orangputeh (Nov 24, 2016)

43128 said:


> any chance you have one of the h50s with a cdi module?


sorry, but what is that? where is it? what does it do?


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## NeoGP (Jun 21, 2017)

orangputeh said:


> sorry, but what is that? where is it? what does it do?


Capacitor discharge ignition (CDI) or thyristor ignition is a type of automotive electronic ignition system which is widely used in outboard motors, motorcycles, lawn mowers, chainsaws, small engines, turbine-powered aircraft, and some cars. It was originally developed to overcome the long charging times associated with high inductance coils used in inductive discharge ignition (IDI) systems, making the ignition system more suitable for high engine speeds (for small engines, racing engines and rotary engines). The capacitive-discharge ignition uses capacitor discharge current to the coil to fire the spark plugs.


Do you have a box like this on the machine??


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## orangputeh (Nov 24, 2016)

NeoGP said:


> Capacitor discharge ignition (CDI) or thyristor ignition is a type of automotive electronic ignition system which is widely used in outboard motors, motorcycles, lawn mowers, chainsaws, small engines, turbine-powered aircraft, and some cars. It was originally developed to overcome the long charging times associated with high inductance coils used in inductive discharge ignition (IDI) systems, making the ignition system more suitable for high engine speeds (for small engines, racing engines and rotary engines). The capacitive-discharge ignition uses capacitor discharge current to the coil to fire the spark plugs.
> 
> 
> Do you have a box like this on the machine??


not that i can see. thank you.


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## orangputeh (Nov 24, 2016)

i checke d the studs. they are tight.

tried the choke in different positions and it did not change anything.


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## jtclays (Sep 24, 2010)

Kin


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## alphaboy123 (Oct 27, 2016)

jtclays said:


> Kind of having brain fart here. Is that machine old enough to be a G series like the old HS35? Flat head? The couple HS35's I worked on had points. Intermittent spark could be bad or dirty points.


So my wonderful hs55 had this issue last season. I ran seafoam in the gas tank and it sputtered more than stopped and has been fine since then.









Sent from my SM-T820 using Tapatalk


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## 10953 (Sep 4, 2017)

sounds a lot like a valve not seating properly, adjust the valves and run some fuel system cleaner through it to try and clean carbon off the valve faces and stem, if not i personally would be pulling them out trying to lap them back into the seats.

34 years on a small engine is a long time, 200 hours most get the valves adjusted, by 500 if not sooner a valve job.


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## ChubRub (Sep 28, 2017)

Whats up everyone! This is my first post on this forum. I finally got the balls to sign up not to long ago after checking out this site on and off for the last 2 or 3 years after aquiring my first snowblower. 
Anyways I have two tillers a FR500 and an FR700 with these G series engines that I have completely broken down cleaned up and rebuilt. As mentioned previously I would check the valve clearances at TDC they tend to stretch overtime especially the exhaust valve I'm guessing from the heat. Also you can look up the serial number stamped on the engine and see if it has a cam chain. I think it does and they can and will stretch. It's an easy fix for about 20 bucks if you do it yourself just make sure you put the two dots stamped on the the camshaft sprocket and the crankshaft sprocket facing each other. I learned that the hard way.


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