Mysterious Stihl 064

[Sunterbach]

Well, its mysterious to me. I have an 064 that I've been rebuilding. Never seen it run correctly, given to me broken.
After a full rebuild, the saw runs decent without an air filter, but as soon as I put an air filter on, it riches out heavily and blubbers until it stalls.
Here's the build:
New bearings and seals
New meteor cylinder and piston
New crankshaft
All new gaskets and rubber (fuel line, impulse line, etc)
New WJ-76 to replace rebuilt WJ-48 (to rule out if WJ-48 was problem. No change)
The cover plate for the carb (air filter mount) seems like its for a bing carb maybe, cause it doesn't have the hole for the compensator... so I cut one into it

Saw holds pressure and vacuum perfectly and compression is 105 right now (New non broken in rings).

PLEASE let me know if yall have any ideas!

 

[funky sawman]

Compression is still too low, even non seated rings the comp should be 150+++

 

[Sunterbach]

Compression is still too low, even non seated rings the comp should be 150+++

Ok. New rotating assembly. No air leak. Where could the missing compression have gone?

 

[Totembear]

Does the meteor cylinder have a compression relief valve, and did you block it off?

 

[Totembear]

Its a wonder it even runs at 105 if that is the correct number, my guess is it isnt

 

[Gamma Woods]

105? Are you sure you put the rings on? What's the squish look like? And does your compression tester have the valve at the end (2 stroke specific)?

 

[glock37]

Check squish on piston too cylinder

What gasket you use ?


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[Sunterbach]

Does the meteor cylinder have a compression relief valve, and did you block it off?

No there's no hole there from factory on the one.

105? Are you sure you put the rings on? What's the squish look like? And does your compression tester have the valve at the end (2 stroke specific)?

I'll check squish tomorrow. And my tester does have a small needle check valve on the end of it, but I'm not sure if it's 2 stroke specific.

Check squish on piston too cylinder

What gasket you use ?


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I got an OEM .5mm base gasket on there

 

[Totembear]

Check squish on piston too cylinder

What gasket you use ?


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How ya been? Hopefully well!

 

[Gamma Woods]

"2 stroke specific" perhaps isn't the best way to word it, but testers for vehicles tend to give false readings on small engines. It all boils down to the location of the valve, needs to be at the end that screws into the plug hole; yours sounds right for the job. Wanted to rule out a false reading from the equation.

Did the piston and cylinder come together as a kit?

I have a feeling you'll be pulling that jug soon, should check ring gap when that time comes (and clearance while you're at it).

 

[Sunterbach]

"2 stroke specific" perhaps isn't the best way to word it, but testers for vehicles tend to give false readings on small engines. It all boils down to the location of the valve, needs to be at the end that screws into the plug hole; yours sounds right for the job. Wanted to rule out a false reading from the equation.

Did the piston and cylinder come together as a kit?

I have a feeling you'll be pulling that jug soon, should check ring gap when that time comes (and clearance while you're at it).

Ok ya ive got the right compression tester. And yep they came as a kit, snd they're "real meteor" (that feels like an oxymoron). What do you mean check ring gap?

 

[Sunterbach]

105? Are you sure you put the rings on? What's the squish look like? And does your compression tester have the valve at the end (2 stroke specific)?

Check squish on piston too cylinder

What gasket you use ?


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Squish is .0425 well shoot. Yall think they gave me the wrong piston or jug? I can pull it and measure it against the oem piston I pulled. I used the .5mm oem base gasket and didn't screw with anything else so I'm confused by this

 

[Sunterbach]

Now my compression is reading 85????? Brand new top end new rings. Holds air and vac on pressure test. WHY

 

[Gamma Woods]

It's a way to check ring wear. You put the piston ring (by itself, not attached to the piston) into the cylinder and use the top of the ringless piston to get it nice and even and measure the gap between the ends of the rings. Feeler gauges are needed.

I asked about the P&C coming as a kit to rule out the unlikely scenario they are mismatched. Stranger things have happened.

It's just unusual for a kit from a generally well respected AM company to have such low compression. Things might be way out of spec and need work out of the box, but that's not typical of Meteor.

 

[Gamma Woods]

Squish is .0425 well shoot

That could be tighter, but it's not horrible and wouldn't account for compression that low.

Are you giving the saw 6-7 good full, fast pulls when you do a compression test, or just one?

 

[glock37]

Delete gasket use some dirko or honda bond on base recheck after a day recheck compression


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[Sunterbach]

It's a way to check ring wear. You put the piston ring (by itself, not attached to the piston) into the cylinder and use the top of the ringless piston to get it nice and even and measure the gap between the ends of the rings. Feeler gauges are needed.

I asked about the P&C coming as a kit to rule out the unlikely scenario they are mismatched. Stranger things have happened.

It's just unusual for a kit from a generally well respected AM company to have such low compression. Things might be way out of spec and need work out of the box, but that's not typical of Meteor.

Ok. Ring gap is .80mm (.032in) seems big?

That could be tighter, but it's not horrible and wouldn't account for compression that low.

Are you giving the saw 6-7 good full, fast pulls when you do a compression test, or just one?

Lotsa pulls. It stopped moving after 6 but I did 12 for good measure. No change.

Delete gasket use some dirko or honda bond on base recheck after a day recheck compression


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Thats what I was thinking bout doing but seems like that shouldn't be necessary to make a saw run ya know? Feel like I have a bigger problem and that's just a bandaid.

 

[Sunterbach]

By the way just wanted to say thanks for everyone helping here. I've been an avid reader for years but this is my first real post. Yall awesome

Anyway I measured the meteor piston and jug against the oem. They are exact same dimensions. So that's not it

 

[Binthewoods]

What sort of compression reading are you getting from a known good running saw with the same tester?

 

[Sunterbach]

What sort of compression reading are you getting from a known good running saw with the same tester?

I pulled 155 with my 461 iirc last month


Also I have a new crank in here. It looked the same as the old one but I never measured. Could we be talking about a stroke issue?