Ht-131 Flooding?

[Aggie 2012]

Howdy gents

I know this is technically more of a weedeater but I've got a pole saw that I found in the ditch.
It's a ht 131 stihl.

First one I've seen that has Stihl's so called 4 mix engine which is kinda confusing.

Wouldn't run for more than a few seconds. Tore the carb apart to find all the gaskets to be stiff so I put a carb kit in it. What bothers me is I dont understand this spring loaded button and extra tube that runs to the bottom of the crank case. I have to assume this is the impulse line because it ties in to the pump side of the carb?
What's that spring for?

I removed the limiters from the high and low settings because that's what I do with all my two strokes

The saw started and runs decent on the high side (limited coil b/c leaning up the high did nothing) gonna have to tune it in the wood.
Problem is as soon as I let off the throttle from starting it would die. I played with the low and idle but no such luck because it never restarted for me.
I wrote down the base settings before tearing the carb apart

The high was 3 turns out (seems very rich but I know nothing on these 4 mixers)

Low was 1 3/4 turns out

I cannot get the saw to restart but I noticed after cranking on the pull rope for a while I had gas in the air filter box. Is the carb flooding or would this be a tank vent issue?
(Separate hose running from fuel tank to the filter housing)

Thanks
-Travis

 

[CR888]

They flood really easily with fuel even soaking the air filter. If this is the case remove air filter and ring it out. Remove spark plug and turn upside down and pull over engine to clear excess gas. Dry spark plug and restart without air filter in place. 1-2 pulls on choke then switch too fast idle. Often you will NOT hear a pop on choke and if you keep pulling it floods fast. They can be tricky until you work out how sensitive they are to flooding and the problem with the air filter getting soaked means you have no hope clearing fuel and restarting. Remove air filter until its running and don't wait to hear a 'pop' before switching to fast idle. Even holding throttle wide open while starting helps after flooding, its tricky but helps.

 

[Aggie 2012]

They flood really easily with fuel even soaking the air filter. If this is the case remove air filter and ring it out. Remove spark plug and turn upside down and pull over engine to clear excess gas. Dry spark plug and restart without air filter in place. 1-2 pulls on choke then switch too fast idle. Often you will NOT hear a pop on choke and if you keep pulling it floods fast. They can be tricky until you work out how sensitive they are to flooding and the problem with the air filter getting soaked means you have no hope clearing fuel and restarting. Remove air filter until its running and don't wait to hear a 'pop' before switching to fast idle. Even holding throttle wide open while starting helps after flooding, its tricky but helps.

Thanks CR for the advice. It sounds like you've learned this through experience. I appreciate you saving me several hours of head scratching.


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[Rockjock]

Depending on which carb you have the H can be as much as 4 1/2 turns out. Did you just replace the gaskets or did you replace and USC clean the carb? I have found my HT 131 to be very easy to start. Checking the valve clearances would be in order as well. Good luck.

 

[rynosawr]

Great advice from CR888, as I would say the exact same thing about the 4 mixes I have messed with, they are super easy to flood.

Also, the plug can get fuel fouled and not come back after getting so soaked.... I ruined one and it would never restart even after cleaning and drying out.

So, what I am saying is go ahead and put a new plug in it as well..... and keep one handy in case you flood it accidentally.

I never hear one of these engines pop or try to run when on choke when starting, like a 2 stroke does when it is ready to start.... so I went through the same learning curve as you Aggie.


Congrats on your find!

 

[Aggie 2012]

Ryno, Rockjock,

Thank you guys for weighing in here. I will heed your advice and +1 on this thing not "popping off" with the choke on. I'm thinking that may be where I ran into problems here to begin with.
I'll make sure that the high side is out at a min of 3 turns.





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[DND 9000]

What bothers me is I dont understand this spring loaded button and extra tube that runs to the bottom of the crank case. I have to assume this is the impulse line because it ties in to the pump side of the carb?
What's that spring for?

The 4 stroke or 4Mix engines don`t have a strong impulse signal as a regular 2 stroke engine has. That`s why they have this spring and a larger diameter impulse hose and 2 diaphragms on the fuel pump side. These parts act as a type of booster to create a stronger impulse signal that enough fuel is delivered into the carburetor.

 

[Martin Irving]

Howdy gents

I know this is technically more of a weedeater but I've got a pole saw that I found in the ditch.
It's a ht 131 stihl.

First one I've seen that has Stihl's so called 4 mix engine which is kinda confusing.

Wouldn't run for more than a few seconds. Tore the carb apart to find all the gaskets to be stiff so I put a carb kit in it. What bothers me is I dont understand this spring loaded button and extra tube that runs to the bottom of the crank case. I have to assume this is the impulse line because it ties in to the pump side of the carb?
What's that spring for?

I removed the limiters from the high and low settings because that's what I do with all my two strokes

The saw started and runs decent on the high side (limited coil b/c leaning up the high did nothing) gonna have to tune it in the wood.
Problem is as soon as I let off the throttle from starting it would die. I played with the low and idle but no such luck because it never restarted for me.
I wrote down the base settings before tearing the carb apart

The high was 3 turns out (seems very rich but I know nothing on these 4 mixers)

Low was 1 3/4 turns out

I cannot get the saw to restart but I noticed after cranking on the pull rope for a while I had gas in the air filter box. Is the carb flooding or would this be a tank vent issue?
(Separate hose running from fuel tank to the filter housing)

Thanks
-Travis

Your settings are well out, could be build up of oxide coating in jets. You can soak in carb cleaner then blast with airline, this may shift it but I have seen carbs needing to be replaced. But a good soak and blast should help, next check your breather, if blocked over pressure will lead to flooding especially with a weakened spring due to sitting, check breather by using mouth to ensure slight pressure but air still passing and perhaps replace spring, as far as memory serves the line from crankcase takes blow by fuel mix and reintroduces it into carb despite where it looks like it's attached. once this is all done you should have no flooding unless you have a weak spark, it should run on correct setting, check your idle screw contact is not bent and will increase or decrease revs as you turn. And if exhaust has an anti spark clean this. And I won't insult your intelligence but some air filters must be replaced and not cleaned.

 

[1Alpha1]

My HT-131 is one of the easiest to start pieces of O P E that I own. I haven't used it a lot mind you, so it's still rather new to me.

I bought it for it's specific use only. That is to say, feet on the ground and the bar up in the tree. My days of ladders and saws are over.

 

[CR888]

+1 on cleaning spark arrestor screen, it may have nothing to do with your starting issues but its good practice to keep them clean by torching the with a propane torch which burns off all the carbon crud. I'd restore H&L needles to factory spec remove soggy air filter and start it with 1 pull on choke then straight to fast idle or hold the throttle open and pin the unit down with ya foot while starting. Once you get to know the 4mix's flooding sensitivity you will find it easy to start. I went through this issue when I got mine. Its just how they are...

 

[Aggie 2012]

Thanks Fellas. I took yalls advice and had her running but can't seem to adjust the carb correctly without the chain spinning.


On all my two strokes I try to lean out the low jet To a higher but steady rpm then bring it down with the idle screw and repeat the process one more time which usually yields good throttle response but the chain on this pole saw continues to spin and it wants to die out if I close the butterfly too much.

I guess I will disassemble the carb once again and do a better job of cleaning and compressed air?

I will look at maybe getting a new air filter along with cleaning the spark arrestor of carbon buildup (didn't really spend much time looking at this screen so thanks for the reminder)

No intelligence to insult here by the way.
I am up for any kind of criticism. I feel like half the issues I run into turn out to be the simple things that get over looked.


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[rynosawr]

Check the clutch Spring, as I have had 2 of these 4 mixes that the clutch spring was "sprung out" and holding the clutch tight to the drum instead of pulling the clutch shoes in and only letting them out at a higher RPM than idle, which would cause it to always be turning the shaft, no matter the RPM.

Also, since you found it in a ditch, it could just be really dirty in the clutch drum and need a good cleaning.... 120 grit on the clutch drum after scraping the crud out of it, then clean with some type of drying cleaner (brake parts cleaner, etc.) so there is no residue. Make sure the Clutch friction surfaces don't have abnormally deep wear areas and are even and half round. If anything is rusty, just buff it with 120 grit until it is smoothed down some. Don't replace unless it is really worn with a much thicker metal lip at the edge of the Clutch drum bell. There is a spec for this, but I don't have it handy.... needless to say, the metal lip can be pretty thick and they still work fine (it just means the clutch drum is getting very thin and could shatter), so you might need to replace it for safety's sake.

You will have to pull the engine off the forward housing to check it all out

 

[Aggie 2012]

Check the clutch Spring, as I have had 2 of these 4 mixes that the clutch spring was "sprung out" and holding the clutch tight to the drum instead of pulling the clutch shoes in and only letting them out at a higher RPM than idle, which would cause it to always be turning the shaft, no matter the RPM.

Also, since you found it in a ditch, it could just be really dirty in the clutch drum and need a good cleaning.... 120 grit on the clutch drum after scraping the crud out of it, then clean with some type of drying cleaner (brake parts cleaner, etc.) so there is no residue. Make sure the Clutch friction surfaces don't have abnormally deep wear areas and are even and half round. If anything is rusty, just buff it with 120 grit until it is smoothed down some. Don't replace unless it is really worn with a much thicker metal lip at the edge of the Clutch drum bell. There is a spec for this, but I don't have it handy.... needless to say, the metal lip can be pretty thick and they still work fine (it just means the clutch drum is getting very thin and could shatter), so you might need to replace it for safety's sake.

You will have to pull the engine off the forward housing to check it all out

Thanks Ryno

After inspecting it does look quite dirty and I can see some rust on the outer part of the drum. I might just pull it apart and see. (Good learning opportunity for me here)

I appreciate your input sir


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