What oil is best? and what ratio?

[Keith Gandy]

Was the step in your saw added by porting it?

Yes sir.

 

[andyshine77]

I figured the slope was the same but just not as drastic of a pressure drop as the step. There is a pic somewhere here on the 390xp stepdown in mine. It worked well

It does seem to work, I've used it a few times.

 

[Keith Gandy]

So the pressure drop created by the step helps pull exhaust out which probably is helping pull fuel charge in.

Ive even added alil freeport on a ported 460 on the bottom exhaust port that helped with what u r describing I do believe. No way to prove it but sure seem to run well freeporting!!

 

[huskihl]

It does seem to work, I've used it a few times.

Yes sir.

I believe what you’re actually feeling is the increased volume in the flange.
I can see the idea of the lip helping ramp the gasses out, but the only way to confirm that would be to add the ramp without adding port volume.
I can also see leaving that ramp area there if there was enough material underneath it to carve out but you wanted to leave some material at the wall to prevent freeport

 

[andyshine77]

So the pressure drop created by the step helps pull exhaust out which probably is helping pull fuel charge in.

Speeds up transfer velocity a little bit, won't affect much if anything I the intake side, as it will be pretty much closed off by that time. Free porting will reduce case pressure a bit and actually slow down the transfer velocity and volume slightly. Generally free porting is considered a negative, though I've seem saws run fine with a slight free porting.

Poulan's are a good place to start.[emoji4]

 

[Keith Gandy]

I believe what you’re actually feeling is the increased volume in the flange.
I can see the idea of the lip helping ramp the gasses out, but the only way to confirm that would be to add the ramp without adding port volume.
I can also see leaving that ramp area there if there was enough material underneath it to carve out but you wanted to leave some material at the wall to prevent freeport

Yes I happen to wander up on the freeport on the 460 by accident!!!

 

[andyshine77]

I believe what you’re actually feeling is the increased volume in the flange.
I can see the idea of the lip helping ramp the gasses out, but the only way to confirm that would be to add the ramp without adding port volume.
I can also see leaving that ramp area there if there was enough material underneath it to carve out but you wanted to leave some material at the wall to prevent freeport

It's a step, you're not actually lowering the bottom of the port at the cylinder wall. Free porting is not a good idea in general.

 

[Keith Gandy]

066 stepdown I did

 

[andyshine77]

Hard to see with all the reflection[emoji6] I sometimes polished the exhaust port too, keeps carbon from sticking.

 

[Keith Gandy]

Hard to see with all the reflection[emoji6] I sometimes polished the exhaust port too, keeps carbon from sticking.

I had a well known porter on this site that told me once he liked a smooth layer of carbon on top of the piston and exhaust port. Philosophy was it prevents heat sinking the piston and cylinder

 

[huskihl]

It's a step, you're not actually lowering the bottom of the port at the cylinder wall. Free porting is not a good idea in general.

I understand that it’s step. But you can’t “create” the step, short of adding some type of material to that area. You can only remove material around it and “leave” the step. My point is, who’s to say that the perceived gains weren’t from adding volume to the exhaust flange Rather than leaving the step? You’d need to remove the step after initial testing and confirm that the saw ran better with it than without. I’ve just never heard of anyone doing that I guess

 

[andyshine77]

I understand that it’s step. But you can’t “create” the step, short of adding some type of material to that area. You can only remove material around it and “leave” the step. My point is, who’s to say that the perceived gains weren’t from adding volume to the exhaust flange Rather than leaving the step? You’d need to remove the step after initial testing and confirm that the saw ran better with it than without. I’ve just never heard of anyone doing that I guess

OK got it, I wasn't 100% clear on what you were saying. Some cylinders come with the step from the factory, the 346xp is a good example. It's also discussed in dome of the two cycle building literature I've gone through. It removes material, but doesn't affect actual port area, as you're not changing the are a at the cylinder wall. Does it work definitively? I cannot tell you one way or the other.

Hope I'm on the right track.[emoji111]

 

[andyshine77]

I had a well known porter on this site that told me once he liked a smooth layer of carbon on top of the piston and exhaust port. Philosophy was it prevents heat sinking the piston and cylinder

You're always doing to get some buildup, just hopefully not big crusty chunks.

 

[huskihl]

OK got it, I wasn't 100% clear on what you were saying. Some cylinders come with the step from the factory, the 346xp is a good example. It's also discussed in dome of the two cycle building literature I've gone through. It removes material, but doesn't affect actual port area, as you're not changing the are a at the cylinder wall. Does it work definitively? I cannot tell you one way or the other.

Hope I'm on the right track.[emoji111]

Yep that’s what I meant.

 

[Keith Gandy]

You're always doing to get some buildup, just hopefully not big crusty chunks.

Yes sir. I saw a 390 on Klotz that had hard smooth carbon on the piston top and was conformed to the shape of the combustion chamber. Almost look like a popup. Took a wire wheel to clean it was so hard

 

[huskihl]

The 5 series Huskies have a similar voodoo going on in the exhaust roof. I don’t know enough about it to recreate it after machine work to the cylinder. I usually end up coming straight out after I hit the number I want

 

[Keith Gandy]

The 5 series Huskies have a similar voodoo going on in the exhaust roof. I don’t know enough about it to recreate it after machine work to the cylinder. I usually end up coming straight out after I hit the number I want

Ive been out the loop for awhile! How does the 550xp mk ii run compared to a ported 346xp? Im still partial to my 346 OE

 

[huskihl]

Ive been out the loop for awhile! How does the 550xp mk ii run compared to a ported 346xp? Im still partial to my 346 OE

I’ve only done a few of the Mark 2’s. They run just like a Mark 1 after porting for me. The transfers are a bit more refined in the 2 and the exhaust is a bit higher, hence the added hp. But if you were making the Mark1 transfers look like the Mark2, and used the same numbers, they end up identical. In the end, my 346’s end up cutting the same speed as my 550’s, but I think there’s more room for improvement in my 550 recipe because I haven’t done as many

 

[lehman live edge slab]

Someone mentioned testing Castrol brand oil I’m not 100% sure if they make Stihl oils anymore or not but I know they used to make all of stihls oil back when they used to have the orange bottle, the white bottle semi synthetic and the silver bottle ultra. In fact I’ve seen Stihl oil bottles with Castrol right on front so you may have even done some testing of it by accident with the orange bottle. I think for the cheap oil tests later some of the alco no smoke two stroke should be included. 1.19$ a bottle for a gallon mix up here but maybe the poulan oil or some husky oil will work since I’ve heard they are the same oil but not sure if it’s true

 

[andyshine77]

Ive been out the loop for awhile! How does the 550xp mk ii run compared to a ported 346xp? Im still partial to my 346 OE

Only ported the first generation 550xp. In a woods port the 550xp will run right with a 346, now if you really push things "bigger carb and so on" the 346 will still be stronger, at least for me. I still prefer the 346 for a number of reasons, but I will say the 550 feels really nice in the woods.