Uh......there's more.

That hack works better on a 394. They have a block instead of a boot and use longer bolts, so the carb will rotate further.
Your fix is a popular one as well

 

Why is this happening in the first place though? Seems like the trigger assembly is working normal after popping that clip back in and no signs of damage internally.

 

I believe there’s something going on in the trigger. Or the white plastic carb pulley is worn or cracked

 

Stihl MS660 re-rebuild.

Got a new Meteor piston and cylinder kit on Friday. Put it in and cleaned up the saw prior in the parts washer.

Went dry with the base gasket this time.

Started up fine and on the high side was maxing out at 14,500 with the H screw turned all the way out! Limiters on the carb.

Whipped out the sheet of EPDM I just got and blocked off the muffler-cylinder port as well as between the intake boot and the carb.

Pressure tested and was leaking out of........wait for it.......the friggin spark plug hole. Wtf.

Had used the Oregon spark plug that had come with the P/C kit. Took out a brand new NGK spark plug. Same thing. Bubbles everywhere.

Shout out to Ryan at WolfCreekSawShop.com. I sent him an email with a video and he suggested I just try and clean up the surface of the cylinder where the crush washer of the spark plug goes. There was indeed a bit of a hump/bump whatever there and it actually worked.

Held pressure at 7psi for over 5 min with no drop at all. Held vacuum at 10inHg and that held for over 5 minutes with no drop either.

I don't know for sure but it is most likely that I forgot to crank down on the cylinder bolts. That's my best guess. If it was a straight gas situation other saws would have blown up I imagine. But who knows.

Here's a quick video showing the leak and then after the fix.

 

14,500 rpm’s sounded high to me so I looked up specs. It shows a max rpm of 13,5, but maybe you meant to type 13,500

 

I should clarify. It was hitting 14,500 with the air leak........that I didn't know about....but I figured there had to be one....with the new p/c because I had the H jet opened up all the way.

So you are correct - should be 13,500. And I will test it out as soon as I get a new oil pickup line for it. It's puking out oil after use so I'll confirm it's the line before ordering......

And then I'll test it out and see where I'm at. If I have to remove the limiter on the carb screws I will.

 

Crapcan that Tygon (or imitation) line. I don’t even use it for tank vents these days.

 

While most carbs will tune within the range of the limiters, I still pull them on older saws so I can really see/feel what the saw needs for fuel.

On a 92cc saw with an aftermarket top end, a history of scorched pistons, and in the hands of groundies, tune that sucker rich at 12,900 or so and listen to it in and out of big wood to confirm tune.

 

Roger that on both accounts.

 

Just ordered this:

OEM STIHL TS420 ,TS400 , TS410 FUEL LINE HOSE ( 39 in ) 0000 930 2803 764560409887 | eBay

39" of fuel line. Proper part number according to the parts diagram. #20. Part #0000 930 2803.

 

OEM fuel line is the only way to go. Husqvarna, Echo, Stihl… all very good.