Anyone know the New Compression on a ms361 or ms290?

[Burntime]

I bought a 361 and want to test my old one to check it. Is it just remove the plug, screw in the gauge, and pull like crazy?

 

[Anthony_Va.]

I don't think you need to pull too hard. Just pull.

The 361 I just bought was said to have 165lbs compression. Thats bone stack with no mods.

 

[mtngun]

Is it just remove the plug, screw in the gauge, and pull like crazy?

Choke off, throttle wide open while you are pulling.

 

[Burntime]

Thanks, I figured it was the same as a regular 4 stroke but wanted to make sure...

 

[spudulike]

expect 100psi on the first pull and 150 - 175psi after 5 pulls - nearer the latter on a newer machine.

Spud

 

[Burntime]

At what point is it "used up?" Basically what is bad compression?

 

[blsnelling]

At what point is it "used up?" Basically what is bad compression?

I don't want to see anything less than 140 in a modern saw. Some Husky 372s are an exception to the rule. Some of them don't have as high of compression, even when new. That's just how they are.

 

[Burntime]

Thanks, so basically if my ms361 is less then 140 its getting tired... That helps a lot!!!

 

[blsnelling]

Thanks, so basically if my ms361 is less then 140 its getting tired... That helps a lot!!!

A 361 will often have 160-170 PSI. They tend to run on the high side.

 

[Burntime]

Any specifics on my 029 farm bosses? Any real world experiences with the upper and lower numbers?

 

[blsnelling]

Any specifics on my 029 farm bosses? Any real world experiences with the upper and lower numbers?

I'd expect 145-160 on that one. It's pretty typical.

 

[adam32]

I don't want to see anything less than 140 in a modern saw. Some Husky 372s are an exception to the rule. Some of them don't have as high of compression, even when new. That's just how they are.

Whats common for a 372? Mines right about 125...pretty new saw, not used much at all...

 

[Burntime]

Something is up. I get 120-130 on a like new ms361. It cuts hands down quicker then my 290 farm boss. I even used some teflon tape to seal the compression guage better and still only get the 120-130. I did it yesterday and was worried the guy straight gassed it and today cut with it. My guage has to be fubar...

 

[albert]

I rather pull the muffler and look. I have seen alot of saws with scored pistons l blow over 140 on a good guage.

 

[mdavlee]

Whats common for a 372? Mines right about 125...pretty new saw, not used much at all...

The 372xpw I had was 135 lbs broke in and 155 with no base gasket and squish down around .020. Differences in gauges and elevation will also change readings.

 

[Burntime]

But mine is the other way...it reads low but cuts like new? Thats why I think its the gauge.

 

[gink595]

Whats common for a 372? Mines right about 125...pretty new saw, not used much at all...

Wow that does seem low, I dont' feel so bad now for my 066 that is blowing 90-100 on a new piston and rings

 

[blsnelling]

Something is up. I get 120-130 on a like new ms361. It cuts hands down quicker then my 290 farm boss. I even used some teflon tape to seal the compression guage better and still only get the 120-130. I did it yesterday and was worried the guy straight gassed it and today cut with it. My guage has to be fubar...

This might be your problem, LINK.

The 372xpw I had was 135 lbs broke in and 155 with no base gasket and squish down around .020. Differences in gauges and elevation will also change readings.

That's not uncommon on that model.

 

[Anthony_Va.]

mY 660 blows around 155. I hear that is on the top end for them, which is good for me.

My 260 hits around 150.

My old 066 is 15 yrs old and was blowing 150 before I sold it. Original jug/slug. Wish I would have kept it, but at least I kept it in the family.

 

[mdavlee]

The 660 I had was around 160 or so.