Piston wash patterns

[Ronie]

Yea looks black and cooked to me.

What do you think would cause that, running lean?

 

[MustangMike]

Often it is the oil.

 

[Ronie]

Often it is the oil.

Thanks!

 

[huskyboy]

What do you think would cause that, running lean?

I agree with Mike. 50:1 with crappy quality oil/gas and a dull chain.

 

[Lightning Performance]

View attachment 299876

Retard the timing a bit to eliminate that hot spot in the middle.

 

[Ronie]

Retard the timing a bit to eliminate that hot spot in the middle.

I've never heard of the 550 needing to be retarded, is that something you have had to do to them?

 

[Lightning Performance]

The theory many porters have is that a flatter transfer roof... charge washes the piston top. Usually makes more power than sloped roofs. How true is this? Idk. I’m no pro porter.

Think about that statement some more.
Flatter how?
Roof angle during exit or roof height across the area?
Decisions decisions...
What did it do?
And what does it allow you to do?

I've heard of the 550 needing to be retarded, is that something you have had to do to them?

Just based on the coke forming on the bottom of the piston dome. You have a hot spot there. The carbon is dry looking on top. The bottom has carbon coking from boiling the oil inside the case. Heavy deposits are sticking to it.

Clean it and see if it returns with good oil

 

[Ronie]

Think about that statement some more.
Flatter how?
Roof angle during exit or roof height across the area?
Decisions decisions...
What did it do?
And what does it allow you to do?

Just based in the coke forming on the bottom of the piston dome. You have a hot spot there. The carbon is dry looking on top. The bottom has carbon coking from boiling the oil inside the case. Heavy deposits are sticking to it.

Clean it and see if it returns with good oil

Ok, thanks.

 

[Lightning Performance]

Ok, thanks.

If you can keep that from happening it's possible to run a bit leaner and burn less gas.

 

[Ronie]

If you can keep that from happening it's possible to run a bit leaner and burn less gas.

It's a Husqvarna 550 with auto tune so I got to take the tune it gives me.

 

[Lightning Performance]

It's a Husqvarna 550 with auto tune so I got to take the tune it gives me.

You have no way to move the flywheel?

 

[RI Chevy]

Kenny hasn't touched a 550. LOL

 

[huskyboy]

I've heard of the 550 needing to be retarded, is that something you have had to do to them?

No need to retard it. But I don’t do any timing advance to them or 572’s and 562’s anymore. You can only go roughly a 1/4 off the key before they start to pop. It also tends to just make them run hotter with minimal gains for the effort of doing it. Widening the exhaust, tightening the squish and doing a muffler mod is all they really need for a reliable “woods” port with a decent little gain. Just my opinion.

 

[Lightning Performance]

No need to retard it. But I don’t do any timing advance to them or 572’s and 562’s anymore. You can only go roughly a 1/4 off the key before they start to pop. It also tends to just make them run hotter with minimal gains for the effort of doing it. Widening the exhaust, tightening the squish and doing a muffler mod is all they really need for a reliable woods port with a decent little gain.

You made my case.

They all tend to be a little different. Trying never hurt anything. You can move things around a bit on Mtronic.

 

[huskyboy]

You made my case.

They all tend to be a little different. Trying never hurt anything. You can move things around a bit on Mtronic.

Good point. I guess you don’t know until you actually test and try it firsthand?

 

[Lightning Performance]

Kenny hasn't touched a 550. LOL

Nope never had an auto tune saw. Still does not dismiss a hot spot. He should not have a hot spot under the piston with carbon coating the top. That wasn't a stretch or have anything to do with Mtronic, Autotune or being out of tune. It could simply be too much ignition advance. Are you still laughing? Just curious...

 

[RI Chevy]

LMFAO.
Nah. Not laughing anymore.

 

[Nutball]

I didn't know I was supposed to laugh, or what to laugh about.

 

[huskihl]

Nope never had an auto tune saw. Still does not dismiss a hot spot. He should not have a hot spot under the piston with carbon coating the top. That wasn't a stretch or have anything to do with Mtronic, Autotune or being out of tune. It could simply be too much ignition advance. Are you still laughing? Just curious...

Most saws I see with cooked piston undersides were ran lean or with shît oil. When 2 of 4 of the same model were run on cheap oil and were cooked, and the other 2 were run on H1r and Red Armor are fine, should I only advance the last 2? Or recommend a better oil to the first 2?

 

[RI Chevy]

Yes Kevin.