New Build. 372xp case, an X-torq cylinder and a 575xp piston.

[Rich Fife]

i zoomed in i just looks more like a big gouge but i see water in the bottom. opticle illusion

If it was a gouge I wouldn't have wasted my time with this cylinder. It's bad enough that there is multiple vertical scoring. But, it's a junk saw and it's about testing the waters a little here and a little there.

 

[Rich Fife]

Sounds like a great video…

You can do it... I agree, it would make for a good video.

 

[Rich Fife]

Yep, I'm that guy... I mess with the stratos. Many have told me not to... but, I've played around and it works for what I need.

 

[Rich Fife]

Last pic... for now. I'm heading to the shop, I can't wait for the bearings, seals and gaskets to arrive... time to grab a junk powerhead that rotates smoothly.

 

[Ketchup]

Yep, I'm that guy... I mess with the stratos. Many have told me not to... but, I've played around and it works for what I need.

I mess with the stratos too. I live at elevation and I think advancing the cold air timing can help a bit.

So machining the base dropped the intake and the transfer uppers. Are you lowering the cold air ports further? Any mods planned for the piston windows? When talking strato intake, there are lots of openings: the mix port, the cold air ports and the piston windows at the transfer uppers. What does your timing look like on all three?

 

[Rich Fife]

I mess with the stratos too. I live at elevation and I think advancing the cold air timing can help a bit.

So machining the base dropped the intake and the transfer uppers. Are you lowering the cold air ports further? Any mods planned for the piston windows? When talking strato intake, there are lots of openings: the mix port, the cold air ports and the piston windows at the transfer uppers. What does your timing look like on all three?

I have 12* of opening difference between the stratos and Intake. I bump my intake duration a considerable amount on strato saws... if too much I go back in and create more volume... I probably do what most say not to. 🤷‍♂️
My though process is to open the stratos to slow the charge, and increase the intake duration to give it a richer charge... does it? Idk. But, some of the stratos I have worked on run strong. Im 100% certain they could run better, but, I'm a slow learner... you'd think after 1yr of messing with these things that I'd have a better grasp of things. 🤣
I typically also add a small charge to the strato ports... this tume I didn't as I want it to come.back down to idle a bit faster.

 

[Rich Fife]

I'm back with parts.

 

[huskihl]

I have 7* of opening difference between the stratos and Intake. I bump my intake duration a considerable amount on strato saws... if too much I go back in and create more volume... I probably do what most say not to. 🤷‍♂️
My though process is to open the stratos to slow the charge, and increase the intake duration to give it a richer charge... does it? Idk. But, some of the stratos I have worked on run strong. Im 100% certain they could run better, but, I'm a slow learner... you'd think after 1yr of messing with these things that I'd have a better grasp of things. 🤣
I typically also add a small charge to the strato ports... this tume I didn't as I want it to come.back down to idle a bit faster.

How do you tell when the stratos are opening?

 

[Rich Fife]

I didn't grab enough parts... this week I'll have to grab the follwing

Coil
Chain Brake bushing
Kill Switch
Exhaust bolts
Pull Handle
Bar Nuts
Cylinder mount spring

 

[Rich Fife]

How do you tell when the stratos are opening?

I probably shouldve worded that differently...
I can look into through the feeds and see When they open and close on the cutout on the piston...

 

[huskihl]

I probably shouldve worded that differently...
I can look into through the feeds and see When they open and close on the cutout on the piston...

Through the intake?

 

[Rich Fife]

There ya go.

 

[Ketchup]

I think @huskihl and I are getting at the same thing. Cold air can’t enter the transfer tunnels until the piston windows crack above the floor of the transfer uppers. The other cold air openings in the intake spigot must also be open, but can be ahead and often are. On an XT reading the uppers is easy because you can take the transfer covers off. There may be a trick on saws without covers, my way is a bit convoluted.

Anyway, when the mix port and the transfer uppers crack seem to matter most. Is yours opening mix 7degrees before the spigot ports or the piston windows? If you have been going off the spigot ports you may have several more degrees of separation.

 

[huskihl]

I think @huskihl and I are getting at the same thing. Cold air can’t enter the transfer tunnels until the piston windows crack above the floor of the transfer uppers. The other cold air openings in the intake spigot must also be open, but can be ahead and often are. On an XT reading the uppers is easy because you can take the transfer covers off. There may be a trick on saws without covers, my way is a bit convoluted.

Anyway, when the mix port and the transfer uppers crack seem to matter most. Is yours opening mix 7degrees before the spigot ports or the piston windows? If you have been going off the spigot ports you may have several more degrees of separation.

I was just thinking that it’s kinda important-ish that they open at similar times. A big delay would max out one and barely flow any through the other. But I believe they actually open on the way up when the piston cutout cracks open in the bottom of the upper transfers. So there’s still a chance they are timed a little more closely

 

[Ketchup]

I was just thinking that it’s kinda important-ish that they open at similar times. A big delay would max out one and barely flow any through the other. But I believe they actually open on the way up when the piston cutout cracks open in the bottom of the upper transfers. So there’s still a chance they are timed a little more closely

We’re thinking the same.

But it’s possible setting the intakes far apart can work. I haven’t done it. @Rich Fife have you done an XT without the separation? It would be interesting to see the difference.

 

[Rich Fife]

Gotcha... I've only checked the stratos from the intake side... and made the degree adjustments via intake duration. I should pull the cylinder off and detail those numbers.

Wait a minute... I need to go back and double check 7*...
Lmao

 

[Ketchup]

Gotcha... I've only checked the stratos from the intake side... and made the degree adjustments via intake duration. I should pull the cylinder off and detail those numbers.

🤔🤔🤔 what a minute... I need to go back and double check 7*...
Lmao

Copy. Read the cold air with the transfer covers off. As the piston comes up the windows will crack at the bottom of the transfer upper. Timing should be pretty close to where your intake landed after you set squish.

 

[Rich Fife]

At BDC the fresh air ports are closed, as the piston pockets aren't exposed. As the saw sits now after machine work and porting, @ 100* BTDC the fresh air ports open and stay open until 105* ATDC... so the fresh air ports keep a constant charge on the piston pockets and after 105* ATDC the trapped fresh air is pumped into the case. I'm not too sure id be able to see when that fresh air is released... I guess if its not visible, simple measurements paired with the degrees would give me those details. But, I never worried about that... I just added intake duration and either drilled a couple holes to add fuel to the fresh air charge and/or modified the elbow and boot....

I can say that If you're too aggressive with adding fuel to the fresh air charge the saw will be slow to return to idle... maybe by a second or 2....

 

[Rich Fife]

"Rich Fife have you done an XT without the separation?"

I have removed the dividers in the elbow, boot and swapped carbs, epoxied the stratos and then ported the intake to make it operate like a normal saw... that was done on a 2172... at the same time I did a 372xt where I added the holes, more intake timing and the mods with the boot and elbow but kept the carb... the XT was a screamer... the 2172 had a deeper tone and was slower on throttle response but it had more torque. I'll see if I still have any videos on the laptop. if so, I'll post them back onto YT and copy the link. I deleted over 150 videos of the saws I built over a years time.

 

[drf256]

Interesting stuff for sure. A few questions.

What did you hone that cylinder with? Looks kinda rough. Have you had success with it?

Probably an illusion, but do those pistons have the same size wrist pin?

Im assuming you already turned the 51mm piston down to 50mm? If not, how are you timing it?

Does your distance from crown to top ring land exceed .100? Will any portion of the top ring hit the space between the top of the plating and the squish band (aka ring of death)?

About the ring pins. Pistons usually have a cast in boss to retain more of the pin than the piston thickness ordinarily could. You’re already making the piston 20 thou thinner on each side. How will you safely retain the pin?

Ive heard of people pinning the top pin only through the crown. You can use interference fit or a good meturllagy threaded screw through the crown. Sink it in and use a dab of tig aluminum on top of it and machine the crown.