Too much compression?

[Cj genever]

Ok, I just finished a jug drop and mm on a 262xp. Squish is .0195. End gap is .008. Pressure cold is 215 psi. I expect more once it is broken in. Will the bottom end take it? What octane? I have been filtering out the ethanol from 93, leaving me with 90. I suspect I would need to keep it at 93

 

[Big_Wood]

heck man, you'll be fine with regular 87

 

[Cj genever]

Really? Why would it be ok for my chainsaw, but not my bikes?

 

[Stihlbillie]

Dieseling?

 

[Frank Savage]

Because saw crank is cheaper Sorry, couldn´t resist

Edit:
I think you will be right at the edge of what the crank can handle regularly with good oil, work habits etc.

 

[jmssaws]

066 never bn started piston and rings, it's broke in now and settled at 240

 

[MillerModSaws]

Op of it worries you open up your squish a little. You would be suprised at how much it'll drop if you open it up to .025.

 

[jmssaws]

Short stroke evidently. I've run 87 with saws at 235 lbs of compression even on a mill.

I've cn one saw that was detonating and it was a stock ms 460.
235lb is where they start to run good ain't it mike.

 

[awol]

This one runs good on 87 octane. The reading was taken after a brief warm up and cool down, it will likely climb some more.

 

[redfin]

Op, Im a tad suspious of your comp reading. I recently finished a 262. Iirc i sanded .008" out of the squish and ended up with a .018" clearance. That was with a made base gasket.

Im at 2100' at it is blowin 185 after 5 or 6 tanks.

 

[jmssaws]

This one runs good on 87 octane. The reading was taken after a brief warm up and cool down, it will likely climb some more.

View attachment 464300

I bet that's not 90cc.

 

[jmssaws]

Must be where the stihls like to run.

It seems so, wonder how 250lb runs?

 

[Cj genever]

I got 185 and was pleased, then I realized the de-comp was in. I re checked with it out and got 215. Why did you sand down the jug to add a gasket? Seems redundant

 

[Cj genever]

Op, Im a tad suspious of your comp reading. I recently finished a 262. Iirc i sanded .008" out of the squish and ended up with a .018" clearance. That was with a made base gasket.

Im at 2100' at it is blowin 185 after 5 or 6 tanks.

What is your end gap? Your air density is about 78kPa, while mine is about 100kPa

 

[drf255]

Ok, I just finished a jug drop and mm on a 262xp. Squish is .0195. End gap is .008. Pressure cold is 215 psi. I expect more once it is broken in. Will the bottom end take it? What octane? I have been filtering out the ethanol from 93, leaving me with 90. I suspect I would need to keep it at 93

Did you run the saw at all before the reading, or was it just with oiled rings?

Op, Im a tad suspious of your comp reading. I recently finished a 262. Iirc i sanded .008" out of the squish and ended up with a .018" clearance. That was with a made base gasket.

Im at 2100' at it is blowin 185 after 5 or 6 tanks.

I think his ring end gap was .008. I think he took more than that from the band.

 

[jmssaws]

Ring gap 008? Are they file fit or something?

 

[redfin]

What is your end gap? Your air density is about 78kPa, while mine is about 100kPa

This was with a new Meteor and Caber. My gap was .008"

 

[awol]

I bet that's not 90cc.

Nope, but this one is!

 

[jmssaws]

Nope, but this one is!
View attachment 464318

Now that's compression, small cc compression is easy big cc compression isnt.

 

[redfin]

I got 185 and was pleased, then I realized the de-comp was in. I re checked with it out and got 215. Why did you sand down the jug to add a gasket? Seems redundant

The stock gasket was to big for the number I was aiming for. I probably could have found the correct size material to get my number but I wanted to flatten the squish band.