Piston wash patterns

[drf256]

I know that every tool is useful in this game, but I’ve got a question.

Seems like every saw I take apart has more carbon on the piston crown on the PTO side than on the flywheel side.

Seen it here on many other’s saws as well.

It can’t be that every saw flows better on the flywheel side, and hotter can burn carbon off the crown.

Does the charge cooling the crown cause more carbon or less?

Will carbon wash off of flow is good in every case?

Does indexing a plug really make a difference?

 

[Simondo]

You say the larger amount of carbon is on the PTO side ? ....ergo, most likely the hotter side. The reverse of higher temp burning off carbon one would think.

 

[drf256]

Just spoke to a buddy that knows his stuff.

Being I’ve been using Motul800 at 32:1 and did some milling with the saw, he feels wash cant be read at all, accurately.

 

[Sty57]

Hooray Oil thread.

 

[drf256]

Hooray Oil thread.

Awe Sheet

 

[huskyboy]

Doc, echo powerblend leaves a beautiful light thin carbon on inside of exhaust tuned properly. I bet it leaves a nice wash on the piston from what I can see. Leaves a nice coating of oil in bottom end too at 40:1 for me. It’s reasonably priced too. Maybe give it a go just for testing? (Not trying to start a oil thread guys... Lol just one oil out of a few that I noticed works well).

 

[Duane(Pa)]

Very interesting thread, mostly because someone hooked you up on piston wash between 4:59 and 5:47AM

 

[Wolverine]

Here's an old pic of my stock 394 piston (after a decent amount of milling). I asked about the wash pattern and was told it looked nice and even. The trusted builder who told me that also said if it was uneven it could indicate tansfers on one side opening a tad before the other.


This was with Husky XP if we are going down the erl path..

 

[Fruecrue]

Cylinder cooling from the flywheel fan certainly can’t be symmetrical, could that effect internal temps enough to affect wash pattern?

 

[srcarr52]

Cylinder cooling from the flywheel fan certainly can’t be symmetrical, could that effect internal temps enough to affect wash pattern?

Bingo!

 

[bwalker]

As it pertains to piston wash more carbon =hot, less carbon equals rich..
Its a useful tool for telling the overal tuning of the saw over time in a coarse sense. It cant be used to tune a saw per se, but does confirm your saw is tuned properly once you believe you have it set right.

 

[bwalker]

Indexing your plug doesnt effect wash or anything else tuning related.
However, indexing the plug can keep the plug cleaner if your using something like castor that is dirty.
Personally I have never worried about it.

 

[smokey7]

On our fan/air cooled motors its very hard to get a even wash. That 394 that wolverine posted is the most symmetrical pattern ive ever seen on a motor like ours. Water cooled motors and free air motors seem to give consistant patterns. Fan cooled motors not so much. @drf256 did your buddy say that the oil or the milling made it where it couldnt be read accurately? Lets see a pic of the saw you have questions about. Also indexing the plug will make a very small impact in wash and a very small impact on throttle response and tuning changes very slight

 

[Steve]

Here is a pic of the piston wash from my 6421 with a bbk. I've done nothing but milling with it.

 

[paragonbuilder]

Cylinder cooling from the flywheel fan certainly can’t be symmetrical, could that effect internal temps enough to affect wash pattern?

Bingo!

So should the wash pattern be uneven then? To some extent. Perhaps angle of the wash the same but pto side being “dirtier” is ok?

 

[drf256]

Here is a pic of the piston wash from my 6421 with a bbk. I've done nothing but milling with it.View attachment 139734

Exactly

See how the PTO side seems to be flowing less?

 

[Duane(Pa)]

Here is a pic of the piston wash from my 6421 with a bbk. I've done nothing but milling with it.View attachment 139734

I'm thinking that crank and rod look awfully dry. Is that the way you found it?

 

[Steve]

I'm thinking that crank and rod look awfully dry. Is that the way you found it?

It had quite a bit of oil in the case and on the bearings. I ran husky xp 32:1. It was well lubricated!

 

[huskyboy]

It had quite a bit of oil in the case and on the bearings. I ran husky xp 32:1. It was well lubricated!

It’s hard to capture the reflection of oil in pictures

 

[smokey7]

I agree @Steve that poor pod and crank throws look as dry as a popcorn fart. But if you saw it has residual oil in the case then maybe it is ok. Ive never ran hp at 32:1 but dad ran a ton of it at 50:1. Only lost 1 crank in a very high hour jonny 630.