Ported 390xp vs. Ported MS460

[Moparmyway]

So Sorry,Oh yea I have never done one of those.

If you ported it, I don't intend to bash, but having smoothe, symmetrical port openings into the cylinder is important for piston/ring life as well as keeping stress risers from forming cracks in the metal. The plating can also flake off between those divots.

 

[Chainsaw Jim]

I'm almost done with it. I just need to finish the upper transfers and then chamfer the chit out of everything.
These things like having gorilla nostrils.

 

[jmssaws]

I'm almost done with it. I just need to finish the upper transfers and then chamfer the chit out of everything.
These things like having gorilla nostrils.
View attachment 23965

Intake free ported?

 

[jmssaws]

Full circle piston?

 

[jmssaws]

By the way, nice clean grinding.

 

[jacob j.]

That doesn't look very good to be polite.

The original porter hogged the lower transfers out a lot- it'll be interesting to see how much torque the motor has.

 

[mdavlee]

The original porter hogged the lower transfers out a lot- it'll be interesting to see how much torque the motor has.

Hopefully there's still 35-38 degrees of case compression

 

[jacob j.]

Hopefully there's still 35-38 degrees of case compression

The first 385 I ported I pretty well ruined- I hogged out the lowers and gave it too much intake timing. It revved up nicely but fell on its' face in the wood.

 

[mdavlee]

The first 385 I ported I pretty well ruined- I hogged out the lowers and gave it too much intake timing. It revved up nicely but fell on its' face in the wood.

That would do it.

 

[jmssaws]

It takes time to learn to put the grinder down.

 

[MustangMike]

OK, Hopefully this works, it is the first time I have attempted to post a video from youtube.

I'm bucking some Chestnut Oak with the MS460 ported by Dr. Al: (fingers crossed)

 

[Canadian farm boy]

OK, Hopefully this works, it is the first time I have attempted to post a video from youtube.

I'm bucking some Chestnut Oak with the MS460 ported by Dr. Al: (fingers crossed)

Video worked for me

Saw looks great Mike. Sounds really healthy.
Really throwing some chips there. Good stuff

 

[MustangMike]

Thanks Mike, and I really liked your 066 in the Video thread!

 

[Chainsaw Jim]

No free porting. I didn't lower the intake or the exhaust any. I thought the op went below the floor on the intake but I was pleased to see there was factory bevel left in the lowest part of the center. I just squared it up and chamfered it.
I'm thinking the case pressure has zero effect once throttled up. I believe it's the necessary pressure for the choke to pull the fuel from the tank to get it started. I didn't design these things so that's pure speculation on my part. Here's some pics of a 372 I built that's a runnin bastard and its freeported (unintentionally) on the exhaust by a full 1/8th inch.

 

[Chainsaw Jim]

The squish band in this cylinder was not very even from the factory. Without the gasket it was running .012 on one side and .020 on the other. Now it is a nice .020 all the way around.
Here it is all finished up. That tool mark next to the port won't be a problem. It looks like the rings have been nice on it up to this point.

 

[jmssaws]

I thought since the intake was so wide it would free port on the side of the piston but it's a full circle piston,I forgot about that.

 

[Chainsaw Jim]

I see what you mean.
That piston with its thickness and weight reminds me of an old 056 piston.

 

[blackjack99574]

Nice work! How's it run?

 

[Chainsaw Jim]

I didn't think I'd get it going before dark. The combination of a broken clutch spring and the starter pawls grabbing the knot and twisting the rope to death had me scrambling to get it back together and tuned.
But here are the first few cuts. I'm sure it'll get a little stronger after the rings set.

 

[angelo c]

I didn't think I'd get it going before dark. The combination of a broken clutch spring and the starter pawls grabbing the knot and twisting the rope to death had me scrambling to get it back together and tuned.
But here are the first few cuts. I'm sure it'll get a little stronger after the rings set.

Nice job.
Saw screams " I need a few more inches on the chain"
Handles the load real well.


Let's limit the wife jokes about needing a few more inches too please...