White limiter cap mayhem MS391

[Bally1020]

Hello all!
Working on buddies/ customer saw. Took apart carb cleaned replaced gaskets fuel strainer etc.
Put back on to setup and have white limiter caps to play with.
At first i thought they were all plastic like others i have encountered but nooooo.
They require that small left hand thread bolt i cant find on any site online to purchase.
The guy wants his saw back. So i got a dremel clamped to a chair and attempted to cut my own tool.
It almost worked, it bit,i turn the cap until it feels loose but they just wouldnt come out.
My question is , can they be drilled out? I have spent too long trying to get these out now and coming to bug you guys is my last resort!
I read that the stihl dealers may have the tool but our dealers are booked solid for a month or more.
Probably full of saws with scored pistons from being set lean and run at our higher than 1000ft above sea level altitude. Any help greatly appreciated as always.
Cheers

 

[HarleyT]

Here is what it looks like. Looks like the limiter cap tool would be the same as the ms290 one.

 

[HarleyT]

Here is a snip of the manual.

 

[HarleyT]

Here is the pic of the tool.

 

[HarleyT]

Once they are even slightly boogered up, that tool won't work, and I usually pluck/cut them out.
I have tried drilling them out, but if the bit hits the adjuster screw, then damage occurs.

 

[Mad Professor]

Here is the pic of the tool.
View attachment 889083

Any idea what the thread is? I wonder if fastener supply stores might have a screw with the same...........

 

[HarleyT]

Any idea what the thread is? I wonder if fastener supply stores might have a screw with the same...........

No, doesn't look like anything regular,

hell, just grind the tip off of a pointy screw, and thread it in a hair, and yank. Just take care not to mess up the needle underneath.

 

[Jasent]

I removed mine with drywall screw. Just plastic caps that cover the normal slotted jet screw.

 

[Mad Professor]

I bet the diameter/pitch for the tool threads is common metric, but the EPA made it lefty so people couldn't just buy a screw, and easily to make a tool.

 

[Bally1020]

All very helpful! i was going off the MS391 workshop manual and it doesnt show the same pictures. My eyes must be bad i couldnt even see the tabs to line it up ! Mind you i had left the carb on for this round. Good to know they are just caps. I will take the carb back off and try and use a right handed screw. Left hand easy outs dont bite deep enough, my failed left hand screw attempts were a partial success. Time for some righty screwin' and if not I will break out the big guns and dremel the $hit out! Thanks for all support !!!!

 

[kevin j]

It’s a left-hand thread so that as you tighten it into the plastic it doesn’t tighten the needle and jam it into the seat and damage both. I have the tool, purchased many years ago while they were still available on eBay. I’ve been told a fine thread drywall screws works. just be careful not to tighten the needle into the seat

 

[HarleyT]

It’s a left-hand thread so that as you tighten it into the plastic it doesn’t tighten the needle and jam it into the seat and damage both. I have the tool, purchased many years ago while they were still available on eBay. I’ve been told a fine thread drywall screws works. just be careful not to tighten the needle into the seat

Yeah, I have ground the tapered point off of a screw to remove the length of taper, and it bites into the plastic right off the bat, so you don't have to worry about hitting the mixture screw.

 

[SteveSr]

If t his cap is like the earlier ones... Grind the tip off of a fine drywall screw... Screw the screw into the limiter cap to get a good bite... Rotate the screw AND cap CCW to where the slot in the carb lines up with the fin on the cap... Pull the screw and cap straight out. The cap will NOT come out unless the slot and fin line up.

 

[stihl86]

I've used drywall screws to get them out after I destroyed them with the proper tools, technic and a complete lack of patience.
Why there's so many different styles I don't know.
Engineers justifying there existence.

 

[HarleyT]

Us rednecks here in Ky. do almost everything with duct tape and drywall screws.

 

[HarleyT]

But gorilla glue is closing in fast.

Haven't tried it in my hair yet.

 

[Woodslasher]

But gorilla glue is closing in fast.

Haven't tried it in my hair yet.

Have you tried sniffing it yet? How does it compare to the potency of pipe glues?

 

[Bally1020]

It's about four a.m. I think. My determination to get his saw returned has taken many hours. I do have a legit question. But first, a big up yours to the regulating body of people who thought it would be the brightest idea to regulate such a small engine that gets run less than once a month for a short time only. Bravo, the caps were a lot of fun. You owe me some hair! Here's a couple pics. I used a lighter to hot glue a small lense to this tablet to get a closer picture!
My question is now.... Can i use this spring that i just cut in half that i had set aside for just this occassion? Can anyone see why it would not work? I could just put it together and test it, but those tiny wires can only be bent around tight curves so many times, so I thought I would put the question out there to potentially save another dismantling + wire splicing session!
Pic 1 - one side out
Pic 2 - other side out and first screw in with spring half. Turned to the stop carefully
Pic 3 - spring and screw
Pic 4 - spring with screw on, or vice versa, it's late.... Or early. I don't know anymore ! lol

thank you.

 

[Vintage Engine Repairs]

Picked one up for a fellow member @trains, he maybe able to give some advice on how to do without the proper tool?

 

[SteveSr]

It's about four a.m. I think. My determination to get his saw returned has taken many hours. I do have a legit question. But first, a big up yours to the regulating body of people who thought it would be the brightest idea to regulate such a small engine that gets run less than once a month for a short time only. Bravo, the caps were a lot of fun. You owe me some hair! Here's a couple pics. I used a lighter to hot glue a small lense to this tablet to get a closer picture!
My question is now.... Can i use this spring that i just cut in half that i had set aside for just this occassion? Can anyone see why it would not work? I could just put it together and test it, but those tiny wires can only be bent around tight curves so many times, so I thought I would put the question out there to potentially save another dismantling + wire splicing session!
Pic 1 - one side out
Pic 2 - other side out and first screw in with spring half. Turned to the stop carefully
Pic 3 - spring and screw
Pic 4 - spring with screw on, or vice versa, it's late.... Or early. I don't know anymore ! lol

thank you.

What, exactly are you trying to do? Add a spring that was never there or replace one that got mangled/destroyed on disassembly? That white nylon seal/gasket in the needle bore is designed to hold the screw and prevent air leaks through the screw threads. Also make sure that no crud from the disassembly process gets into the needle bore as it WILL clog passageways in the carb. Had old welch plug sealant cause similar issues.