390xp

[jropo]

Nice tester, not cheap though. Nothing Snap-On is cheap.

I duno about the comp, I'm gona run some tanks through it and take it back apart. Maybe something happened to the rings? Maybe there was a burr on one of the ports and hurt the rings? Who knows.

No they are not cheap. The Snap-on guy used to come to the shop, went in the truck once, saw the prices, walked back out.
I did end up getting a Blue Point D/A, nice.

Looked like you had nice chamfers, and I think you'd notice a burr.
Ring of death?
Exh?
Lets just hope that them rings need to see some run time, and your decomp. was leaking a little.:msp_thumbup:
Hope she's ok.

 

[blsnelling]

It's something besides run in time. A saw will have good compression from the time it's put together. This one is quite odd, don't know what to thing.

 

[parrisw]

It's something besides run in time. A saw will have good compression from the time it's put together. This one is quite odd, don't know what to thing.

I'm thinking the same Brad???? Maybe an anomaly with this piston and cylinder? I really don't know. But my well run in 372 with popup is only 160psi, and it runs dam good.

 

[blsnelling]

I'm thinking the same Brad???? Maybe an anomaly with this piston and cylinder? I really don't know. But my well run in 372 with popup is only 160psi, and it runs dam good.

What's your elevation?

 

[parrisw]

[video]http://s155.photobucket.com/albums/s294/scottk66/?action=view&current=MVI_0053.mp4[/video]
385 with 205lbs

Nice, 385's also have lower EX ports.

 

[parrisw]

What's your elevation?

Sea level.

 

[tree monkey]

did you run the saw or check comp before porting?

 

[tlandrum]

i just did an xpw with combustion chamber cut and dropped the cylinder .065 and after porting it only has 150 psi. but i did not replace the rings. the rings had been run in this saw at a saw mill operation ,bucking stacks of lumber. id say the compression would come up a bit if i had replaced the rings. i will be replacing them in the near future but the saws runs like a stiped asss ape so no real need for it yet.

 

[parrisw]

did you run the saw or check comp before porting?

No I did not.

 

[jropo]

Whats the difference between a 385/390 top end?
1mm?

 

[parrisw]

Whats the difference between a 385/390 top end?
1mm?

Yes. 1mm or 3cc's

 

[jropo]

1mm is not alot.
Might be a possablity.
385 slug 390 jug?
What was your ring gap?
Don't know if 1mm would even make the skirt slap.
Call me crazy.

 

[tree monkey]

1mm is not alot.
Might be a possablity.
385 slug 390 jug?
What was your ring gap?
Don't know if 1mm would even make the skirt slap.
Call me crazy.

390 would not run with a 385 piston in it

 

[parrisw]

1mm is not alot.
Might be a possablity.
385 slug 390 jug?
What was your ring gap?
Don't know if 1mm would even make the skirt slap.
Call me crazy.

You're crazy.

 

[jropo]

You're crazy.

Just an idea.

 

[deye223]

opcorn:

 

[Mastermind]

opcorn:

Pass the popcorn.......

I think you just didn't cut enough from the band to make up for raising the exhaust. You just took .025 out right? If that's the case it should still run real strong.

 

[parrisw]

Pass the popcorn.......

I think you just didn't cut enough from the band to make up for raising the exhaust. You just took .025 out right? If that's the case it should still run real strong.

I hope your right. I didn't raise the ex though Randy. These 390 come with pretty high exhaust from factory. Ya I only took out .025. and since then, reading how much other people take out of the chambers, I didn't take out enough. It's just wierd that some people say with just reduced squish theirs is pulling over 175psi, unless their gauges are overcompensating for something.

Regardless, its coming apart again, I want more intake duration, I never lowered the intake, since I was thinking I was going to machine more from the cylinder.

 

[blsnelling]

I only took .035" out of mine and it's nearly 200 PSI. .010" isn't going to make up that much difference. Additionally, I did raise my exhaust. Something is definately amiss.

 

[parrisw]

I only took .035" out of mine and it's nearly 200 PSI. .010" isn't going to make up that much difference. Additionally, I did raise my exhaust. Something is definately amiss.

Yes, .010 won't make much diff at all. Maybe I farked up a measurement? I don't know. I'll recheck squish when I take it apart, maybe its way out.