first build with what I have...

[XP_Slinger]

If you are really at .024 squish, that part is done for you. The carbon may have made that measure slightly lower than it is. You really can’t do much about it anyway.

Unless you wanna degree it, I’m not so sure you should mess with the transfers.

The intake port is slippery slope on strato saws. There is deliberate restriction there so that the negative case pressure will pull air into the transfers via the strato port-personally I wouldn’t play with it.

I’d widen the exhaust port to 65% and keep a good arch on the roof. Open muff, advance timing and call it a day.

My seed to this addiction was a clam shell, an MS250. My grinding has come a long way, I’m not even sure how I didn’t catch a ring on that saw. We all start somewhere, so don’t be discouraged.

Look at how pretty I made this ex port 5 years ago.

View attachment 219983

Flatter than Roseanne singing the anthem. Cool to see where you started Al.

 

[sonoransaw]

Thanks for the porting advice, Terry!

Drf256, I was thinking about the carbon interference too. Probably should redo squish. And thanks for those porting tips! I’ll be happy if my job looks as good as yours….

Appreciating all the tips and feedback....I'm probably (definitely) going to need things clarified and re-explained. Might be slow on the uptake, but once I get it, I get it...

Cleaned the chassis as well as piston assembly and mounted the engine back on it. Printed a degree wheel and got that set up to learn this part of the process. (I know I need to grind the teeth off the saw blade. It's a junk blade so there are no sharp points, and I'm working with extremely limited time, so the finer details will have to wait.) The arbor hole on the saw blade somehow fit perfectly over the chuck arbor mount.

Reading and watching vids now on how to use the wheel to get timing info.

 

[XP_Slinger]

Thanks for the porting advice, Terry!

Drf256, I was thinking about the carbon interference too. Probably should redo squish. And thanks for those porting tips! I’ll be happy if my job looks as good as yours….

Appreciating all the tips and feedback....I'm probably (definitely) going to need things clarified and re-explained. Might be slow on the uptake, but once I get it, I get it...

Cleaned the chassis as well as piston assembly and mounted the engine back on it. Printed a degree wheel and got that set up to learn this part of the process. (I know I need to grind the teeth off the saw blade. It's a junk blade so there are no sharp points, and I'm working with extremely limited time, so the finer details will have to wait.) The arbor hole on the saw blade somehow fit perfectly over the chuck arbor mount.

Reading and watching vids now on how to use the wheel to get timing info.

That’s a mans degree wheel right there. This is where Tim Allen starts grunting on tool time. Lol.

you’re gonna do fine man

 

[5000+]

Is that a chrome piston and non plated bore?

 

[sonoransaw]

@XP_Slinger......

Is that a chrome piston and non plated bore?

Was reading about the chrome plated pistons on Poulans, but I don't know if mine is one. Seems like it might be. Almost certain the bore is non-plated. I'll get more pics later that may help show that....

 

[XP_Slinger]

@XP_Slinger......



Was reading about the chrome plated pistons on Poulans, but I don't know if mine is one. Seems like it might be. Almost certain the bore is non-plated. I'll get more pics later that may help show that....

Lol! Well played. Chuck would definitely give a thumbs up

 

[MG porting]

If you are really at .024 squish, that part is done for you. The carbon may have made that measure slightly lower than it is. You really can’t do much about it anyway.

Unless you wanna degree it, I’m not so sure you should mess with the transfers.

The intake port is slippery slope on strato saws. There is deliberate restriction there so that the negative case pressure will pull air into the transfers via the strato port-personally I wouldn’t play with it.

I’d widen the exhaust port to 65% and keep a good arch on the roof. Open muff, advance timing and call it a day.

My seed to this addiction was a clam shell, an MS250. My grinding has come a long way, I’m not even sure how I didn’t catch a ring on that saw. We all start somewhere, so don’t be discouraged.

Look at how pretty I made this ex port 5 years ago.

View attachment 219983

I bet it still ran good.

 

[sonoransaw]

Set up a little wire pointer and figured out TDC.

From there I figured exhaust timing and duration and intake timing. I couldn't figure out anything to do with transfers, maybe because this is a strato engine??? (Update: found the transfer ports. They were just hard to see in there at first. So I'll work on getting timing for them.) (Update: transfer timing measured and added below.)

Anyway, these are my figures so far....
101 exhaust
137 exhaust duration
64 intake
129 transfer

Lovin this process.....life is good....thanks for all the help!

 

[XP_Slinger]

Set up a little wire pointer and figured out TDC.

From there I figured exhaust timing and duration and intake timing. I couldn't figure out anything to do with transfers, maybe because this is a strato engine??? (Update: found the transfer ports. They were just hard to see in there at first. So I'll work on getting timing for them.) (Update: transfer timing measured and added below.)

Anyway, these are my figures so far....
101 exhaust
137 exhaust duration
64 intake
129 transfer

Lovin this process.....life is good....thanks for all the help!

Your exhaust duration is actually 158. Multiply opening by 2 then subtract from 360. Make sense???

What method did you use to find TDC?

 

[sonoransaw]

Your exhaust duration is actually 158. Multiply opening by 2 then subtract from 360. Make sense???

What method did you use to find TDC?

Thanks for that! Learning all the time....

For TDC I put a stop in the spark plug hole and adjusted the wheel so it stopped at equal degrees on both sides of TDC... Sound right?

 

[XP_Slinger]

Thanks for that! Learning all the time....

For TDC I put a stop in the spark plug hole and adjusted the wheel so it stopped at equal degrees on both sides of TDC... Sound right?

Yup that will do. I do the same thing by rotating forward til the piston is on the stop, set degree wheel to zero. Then Rotate crank backwards til piston hits the stop, divided what ever the pointer lands on by two then rotate the wheel to that degree mark.

 

[Terry Syd]

That intake timing looks rather short. 128 degrees of intake duration? Generally, on a modded saw guys are looking for 155-160 duration on the intake.

You may want to check that intake timing again. - Can you see when the strato is opening? It may be that the manufacturer biased the strato to open well before the intake. On my Husky 450 the stock strato timing opened 10 degrees before the intake. I increased the intake timing to match the strato.

 

[sonoransaw]

Thanks, XP_Slinger and Terry Syd. I appreciate the question, Terry. I don't trust myself with this stuff yet....I went back and set everything up again from scratch. I measured and took numbers again and again. This is what I came up with...Some of the numbers are the same, but the exhaust is quite a bit different. I had gotten this exhaust number before, but then got a different number, now I'm back to this number.
113 exhaust
64 intake
128 transfer
I also took numbers for the strato ports.
There are two levels of strato ports (upper and lower) in the piston.
I got 75 for the lower strato and 156 for the upper. Not sure if those numbers are good for anything...
It doesn't look like I can match the intake to the stratos like you mentioned, Terry, because of how things are located. The strato is quite a bit above the intake.

Anyway, I'm not rushing into anything here. Watched a bunch of videos and read a lot more over the weekend. And will continue to do so. I feel like there is a little light on the horizon. When I take tools to the ports I need to feel good about what I'm doing.

It's been quite interesting to read the vastly different opinions on things, like how to port the exhaust....Navigating through all this is a bit daunting for the novice.

 

[Terry Syd]

Helping over the internet has its' limitations.

I got 75 for the lower strato

I suspect that is the opening of the strato port, but you will have to confirm it. If it is, then the strato is opening 11 degrees before the intake. If that is the case, then if you open the intake at 75 degrees then the strato and intake will be matched.

 

[sonoransaw]

Little video showing the numbers from the degree wheel....Still reading and trying to figure this stuff out. Dang, my brain hurts....port duration, converting from degrees to inches....Hopefully I'll start to pick it up soon...

 

[drf256]

You did the intake correctly.

The others really can’t be confirmed without a ring and pick. I know you have the issue with a clamshell which makes popping a ring in and out laborious. The ex roof is much more accurate if you face the ex port towards a lit area, look through the plug hole, and see where the ambient light starts to peak through.

Visually looking at the transfer opening through the ex port is extremely unreliable. I’ve been off 15+ degrees doing it that way. Viewing the ex closing via outside vs through plug hole (and confirmed with ring later) is usually off by up to 6* for me.

I bet your exhaust roof is much higher than you are measuring. Try through plug hole and report back.

 

[XP_Slinger]

Little video showing the numbers from the degree wheel....Still reading and trying to figure this stuff out. Dang, my brain hurts....port duration, converting from degrees to inches....Hopefully I'll start to pick it up soon...

You’ve got the hang of it. Would recommend shining a bright flashlight in the spark plug hole when checking exhaust timing.

 

[sonoransaw]

Thanks guys....should have mentioned I did the light through the spark plug hole to measure exhaust multiple times before the video....Came up 113 to 114, so I'm good with that....I've measured these ports a bunch in every way with the degree wheel now, so if you guys approve, which you seem to, I'm solid on those numbers.

 

[MG porting]

Do what drf256 said and shine a light through the exhaust port and look through the spark plug hole to confirm when it starts to open your doing good it just seems like the exhaust roof is pretty low but other than that good job and keep it up that's how you learn.

 

[sonoransaw]

Do what drf256 said and shine a light through the exhaust port

Thanks, MG....I used the flashlight through the SPH to confirm my numbers multiple times....Why it seems low, I don't know....just the design of this particular saw???