Piston wash patterns

[Wilhelm]

This is "Piston wash patterns", not "Air filter pics".

Well, close enough, carry on . . .

 

[RI Chevy]

Every thread on this forum has a derail or 2 Wilhelm. Lol

 

[MG porting]

Nope, went to bed. Quite the interesting thread to scroll through during my morning constitutional though. Half way through I realized I was on my work phone... we'll see if I have to try to explain this, could be a good laugh with my boss if I do.

Or you're fired!!! Let's hope that doesn't happen.lol

 

[NightRogue]

372xp oe transfer wash from brand new never gassed saws

 

[NightRogue]

Ported 266 wash

 

[NightRogue]

Ported 090 wash

 

[justoldsaws]

Piston from my 288xp, I bought it off a commercial firewood seller a few years back, its done a lot of work, i pulled the top off to replace the ring which were very worn
Small damage on top of piston is from a piston stop.

 

[Maintenance Chief]

I feel like "wash patterns " are snake oil for porters who don't necessarily know what they're doing. I could be wrong but if a saw is running strong and a beast in the cut , am I supposed to pull the cylinder off to check the wash patterns?
Now I could see if someone hacked at the cylinder with a grinder and was held to the flame on why it ran like dump, "oh see the wash pattern is totally off" and so forth , this all sounds like whodo to me.

 

[huskyboy]

I feel like "wash patterns " are snake oil for porters who don't necessarily know what they're doing. I could be wrong but if a saw is running strong and a beast in the cut , am I supposed to pull the cylinder off to check the wash patterns?
Now I could see if someone hacked at the cylinder with a grinder and was held to the flame on why it ran like dump, "oh see the wash pattern is totally off" and so forth , this all sounds like whodo to me.

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.

 

[huskihl]

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.

Flatter will make more torque. It’s possible to point them up too much and it’ll blow out the exhaust

 

[Ketchup]

Stock 2511t with about 8 hours on it.

 

[huskyboy]

Flatter will make more torque. It’s possible to point them up too much and it’ll blow out the exhaust

I guess the dyno could tell us more than reading a piston top?

 

[NightRogue]

I guess the dyno could tell us more than reading a piston top?

We can make power by burning lotsa fuel and then we can make the same power with burning a little less fuel. Dyno will show the gains, piston wash will show if you're spitting gas outside a little or excessively. It also shows the accuracy of transfer opening on both sides, whether they're spot on or slightly off. I think studying piston wash is important

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[huskyboy]

I think studying piston wash is important

I agree with you. I think reading the piston top in conjunction with dynoing the saw and verifying results in the wood would be a interesting thing to see what kind of results there would be.

 

[huskyboy]

Stock 395 washstock 12mm 044 wash stock 7910 wash

 

[NightRogue]

Flatter will make more torque. It’s possible to point them up too much and it’ll blow out the exhaust

There's 2 different angle when comes to transfer, vertical and horizontal. Here's some read

Vertical flat angle should give more rpm and higher hp, slope should give more low end tq. On quad port, angled secondary and flat main should give best of both worlds

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[NightRogue]

More read......
Tongue wash is not really that good.... Its more of fuel economy setup

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[huskyboy]

More read......
Tongue wash is not really that good.... Its more of fuel economy setup

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So the shorter the “tongue” the better for overall power? They all seem to have a short tongue on the ones I looked at on saws. Haven’t seen one as long as the “bad” example yet on a saw piston. But I haven’t worked on as many saws as some of you guys. Seems like a result of a mistake that would be made on a ported cylinder?

 

[huskyboy]

I’ve seen interesting wash in the combustion chambers on a few saws too. Stock wash 395:

 

[NightRogue]

So the shorter the “tongue” the better for overall power? They all seem to have a short tongue on the ones I looked at on saws. Haven’t seen one as long as the “bad” example yet on a saw piston. But I haven’t worked on as many saws as some of you guys. Seems like a result of a mistake that would be made on a ported cylinder?

Shorter tongue = more fuel economy, less high rpm power. It can spin 12~13k max rpm but power rpm might be at below 8k

Tongue shows the scavenging loop ends near spark plug, a loop that goes over and reaches near exhaust port is desirable for high rpm power

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