Another Stihl 460 build

[Rich Fife]

I'm sure with enough run time, type of oil/fuel used, Temps, burn quality or lack of... anything will be coated.
Don't mind my ignorance, but, how many 2 stroke oils are detergent based? I'm assuming they would yield a lesser build up?

 

[Powerstroke Cowboy]

I’m going to reference back to my days building racing high performance V8’s again here, BUT: flame propagation across the piston top was a hot topic about 15 years ago. What was found, based on dyno results, was that controlling the burn across the piston top made the engine easier to tune. Shiny new pistons made less power than taking those same pistons and bead blasting them, leaving the surface roughed a bit…

Also, as far as coatings go, back again about 15 years, they were already coating combustion chambers and piston tops with heat resistant coating to contain the heat in the combustion chamber, with good results. May not be cost effective in a small engine like a chainsaw, but on top fuel dragsters it made a difference in power, as well as part longevity.

That's a interesting observation on the lightly roughed surface being easier to tune. I wonder if it has something to do with keeping the air/fuel mixture suspended better? The air/fuel mixture seems to stick/cling to a polished surface.

Yes, coating combustion chambers is nothing new, that's for sure. Guy's I know we're dabbling in it back in 2010 (maybe earlier?) in diesels. The problem they were having is it would not last long. But a diesel used for sled pulling and drag racing can see 1800 and higher EGTs. They even had trouble in DD rigs burning the coating off.

I did coat the exhaust port and piston top recently on a chainsaw. Time will tell if it lasts or not. The coating I used needed baked on. There's a lot better coatings out there than I used though.

 

[Powerstroke Cowboy]

I'm sure with enough run time, type of oil/fuel used, Temps, burn quality or lack of... anything will be coated.
Don't mind my ignorance, but, how many 2 stroke oils are detergent based? I'm assuming they would yield a lesser build up?

In theory they should. But, it might be more dependent on how well the fresh air/fuel mixture sweeps the piston top as it enters the combustion chamber.

Likewise, don't mind my ignorance. But feel free to call me out on it! I want to learn all I can!

 

[Rich Fife]

In theory they should. But, it might be more dependent on how well the fresh air/fuel mixture sweeps the piston top as it enters the combustion chamber.

Right. So IF the dimpleshelp to keep the fuel-air charge suspended/agitated as well as helps to direct the flame front, one should see less carbon deposits... in theory...

Likewise, don't mind my ignorance. But feel free to call me out on it! I want to learn all I can!

I'm hit and miss, absolutely call me on *s-word that doesn't sound right... like I mentioned before, in my head... things sound legit and make sense... sometimes when I write it out it contradicts what I want to say or it's like "wtf... this dude is retarded!" Ahahaha
GUILTY

 

[Powerstroke Cowboy]

Right. So IF the dimpleshelp to keep the fuel-air charge suspended/agitated as well as helps to direct the flame front, one should see less carbon deposits... in theory...

I'm hit and miss, absolutely call me on *s-word that doesn't sound right... like I mentioned before, in my head... things sound legit and make sense... sometimes when I write it out it contradicts what I want to say or it's like "wtf... this dude is retarded!" Ahahaha
GUILTY

Time will tell what the dimples do, or don't do.

I to, have a hard time putting thoughts to paper. So I can understand that.

 

[Rich Fife]

Such a beautiful weekend, high 70's low 80's with a breeze... not much saw work got done.

The little bit of saw work that I did... well, I put a decent amount of heat into it...

Tonight I'll drill and tap for the sparkplug... do a sweep on the bore and if all is good, I'll skim the squish .002".

 

[srcarr52]

Such a beautiful weekend, high 70's low 80's with a breeze... not much saw work got done.

The little bit of saw work that I did... well, I put a decent amount of heat into it...

Tonight I'll drill and tap for the sparkplug... do a sweep on the bore and if all is good, I'll skim the squish .002".

It will be fine, I do this type of repair a lot.

 

[Rich Fife]

It will be fine, I do this type of repair a lot.

I was too sure... but, I guess I should've figured it would've been fine due to the distance from the wall.

Here in a minute or two, I'll spot face the cylinder to get the plug depth correct as well as indexed "properly" where the strap is away from the piston...

 

[Rich Fife]

It's not the quality of repair that I would like.... but, this is my saw so blemishes 'can' be overlooked... A year from now, I won't even remember. Lol

 

[srcarr52]

Well, that didn't go according to plan. What happened?

 

[Rich Fife]

Well, that didn't go according to plan. What happened?

No, it went as planned.... the plug hole got filled, drilled and threaded. The sparkplug is tight. Lmao

As for inside, I didn't clean/prep the area... I just turned the heat up... and said "nope". ... I figured, its my saw, I have a new OEM cylinder on the shelf... if I junk this old worn out cylinder, I'm not too worried about it.

Side note: the black anodized knurled aluminum finally came it. This weekend I'll be making some more contra style tools. (Black, Gold, Silver)... I might engrave a logo on them and fill it in with red epoxy... should look sweet... and be very quiet... these new bearings are like glass.

 

[srcarr52]

No, it went as planned.... the plug hole got filled, drilled and threaded. The sparkplug is tight. Lmao

As for inside, I didn't clean/prep the area... I just turned the heat up... and said "nope". ... I figured, its my saw, I have a new OEM cylinder on the shelf... if I junk this old worn out cylinder, I'm not too worried about it.

Side note: the black anodized knurled aluminum finally came it. This weekend I'll be making some more contra style tools. (Black, Gold, Silver)... I might engrave a logo on them and fill it in with red epoxy... should look sweet... and be very quiet... these new bearings are like glass.

Oh, the plug looked off center and angled.

 

[Rich Fife]

Oh, the plug looked off center

Yes. The plug hole was moved closer to the coil.

and angled.

In person It didn't look angled... but, the picture says otherwise. I LOVE IT.
Betcha it'll run just fine... ahahaha

 

[Rich Fife]

Yep, it's definitely angled... guess I better do some more whacky stuff to the piston.

 

[Rich Fife]

The only thing I can think of is... I ran the tap down crooked.
Meh, I ain't too worried about it... it's a fawking chainsaw built from junk... soooo its Fiiiiinnnnnne!

 

[Rich Fife]

Picked up both of these for $80. One had a tank that was smashed the other had low compression. Check out that piston. But the cylinders are mint.

 

[Rich Fife]

1st heat cycle... runs pretty good. Even with all of the blemishes.

 

[Powerstroke Cowboy]

Nice find.

 

[Rich Fife]

Nice find.

I thought it was a good deal. They also have a bunch of 461s too. I'll be heading back to see what I can get all of them for.

 

[Rich Fife]

This weekend the dimpled, crooked, offset 460 will be tossed into some wood sporting this 32"...