Porting an 045 Super for a Longer Bar?

[Entisol]

I've got an 045 Super that's running well, but I want some more grunt to pull a 36" bar in softwood. The factory numbers are below.

Factory:
Squish .045"
Intake 72
Exhaust 106
Transfers 128

When I got the saw, I tore it down and went through everything. It had seen a lot of use, but was well cared for and in generally good condition. It needed a new piston, so I bought one from Sawzilla (Proline). The aftermarket piston is lighter and has windows, but it is about .020" shorter from wrist pin to top of piston, so port timing was almost exactly the same as factory with the aftermarket piston and base gasket removed. I took .020" off the base to get squish down to .025", removed a burr from the bottom of the intake port (that was worth 2 degrees, I might regret removing it), and widened the exhaust. I accidentally flattened the exhaust roof when widening (this port is deceiving, steep exit angle), so I raised the exhaust some to round it back out. The saw was sluggish when I first reassembled, but I advanced timing as far as the slots on the stator plate would allow, and it ran better.

Proline on left, original piston on right

Current numbers with Proline piston, gasket delete, .020" off base, intake deburred, exhaust widened/slightly raised:
Squish .025"
Intake 77
Exhaust 104-105
Transfers 131

It does not have the grunt that I think the saw is capable of. It bogs more than I think it should, given the displacement. It is cutting around 10,000rpm.

With the aftermarket piston, the compression is not as high as I'd like. There's tons of blowdown since I haven't touched the upper transfers yet. I'm going to tear back into it, but I'm looking for some advice from you guys.
- Stick with the proline piston, or try another? I want the compression back that I lost with the aftermarket piston. The factory piston is 54mm, domed, with 13mm wrist pin. Another member mentioned a 288 piston might work.
- Regardless, I'm thinking about taking another .020" off the base. This would allow me to cut squish and reduce the size of the combustion chamber, even if I use the same piston.
-Where would you go with the upper transfers? I want this saw to pull hard in a good usable range, high RPM is not the goal
-What about the exhaust? When I take it back apart, I'll make sure the exhaust is as wide as the piston will allow. I'm hesitant to raise the exhaust (even if I take more off the base) because I want torque/compression, and it already revs ~13,000k unloaded.

I'm interested in your thoughts! There's a lot of smart guys in this forum. I'll try to post a video of the saw running. Have a good one!

 

[Entisol]

Here's a video of the saw running a 36" Full Skip Oregon EXJ in a 27" Ponderosa. It's tuned a little lean in this video, but it gets the point across. I think I'll be able to push this saw a little harder once I get it right. You can hear it bog a couple times, and there's not much pressure. This was a new chain, didn't touch the rakers etc.

 

[Woodwackr]

Here's a video of the saw running a 36" Full Skip Oregon EXJ in a 27" Ponderosa. It's tuned a little lean in this video, but it gets the point across. I think I'll be able to push this saw a little harder once I get it right. You can hear it bog a couple times, and there's not much pressure. This was a new chain, didn't touch the rakers etc.

Seems to do just fine as is. A 28 will get you through 50” wood with less time and stress on the saw, however.

 

[jacob j.]

I'd be careful with taking material off the base of the cylinder - The flange on some of those cylinders is quite thin.

Check your ring end gap - some of the aftermarket pistons come with pretty crappy rings. You might be losing compression via a larger ring end gap. Also, check the fit between the piston and cylinder. It should be pretty tight.

A 288 piston won't help your compression issue since the 288 slug is a flat-top. I think what would be most helpful is if you can find a new old stock OEM piston. It's been so long since I've looked for 045/056 parts I don't know what's out there these days.

 

[Entisol]

I'd be careful with taking material off the base of the cylinder - The flange on some of those cylinders is quite thin.

Check your ring end gap - some of the aftermarket pistons come with pretty crappy rings. You might be losing compression via a larger ring end gap. Also, check the fit between the piston and cylinder. It should be pretty tight.

A 288 piston won't help your compression issue since the 288 slug is a flat-top. I think what would be most helpful is if you can find a new old stock OEM piston. It's been so long since I've looked for 045/056 parts I don't know what's out there these days.

Good points. Thanks!

What's too thin on the base flange? I think this flange was around .220" (at the thinner ends) from the factory, so it’s ~.200 now. The top of the flange is not square, so measurements are approximate.

I'll check ring gap. I bought Cabers, but I did not check the ring gap in the cylinder.

The aftermarket piston was 2.123" wide. I think that’s within the range for a 54mm piston, but toward the narrow end. I'll look for a NOS piston. It's worth a shot!

 

[Entisol]

Seems to do just fine as is. A 28 will get you through 50” wood with less time and stress on the saw, however.

Fair points, but it's hard for me to settle when my 10mm 044 pulls as hard, cuts at higher RPM, and is 15 cc smaller!

 

[drf256]

I don’t know much about the model, but the 044 vs 045 is apples to oranges.

The modern 044 design has a tighter case and tighter ports. Tech has changed for the better.

In general, the older Gen saws had bigger case capacity and bigger transfer tunnels. So there is less case pressure to push charge, and adding the windowed piston just worsened it even more.

It’s a bigger displacement saw, and you’re looking to cut softwood with it. Your base is thin. On a saw that size, I’d like .250 of meat on that base. You’re at .180 now, so dropping the jug anymore would be detrimental.

You could find a stock piston and cut a slight popup and match the band to it. That would increase compression without any further base thinning.

You have big case capacity, so you have to fill the column of swept volume fully to make the most power and thus cylinder pressure.

I’d personally try the popup, you can do at an angle and match the band. Then raise exhaust to 100 and uppers to 118. Leave the intake alone but widen it a bit. That would be my guesstimate on what that model may like.

 

[Entisol]

Thanks for weighing in! I was hoping I’d hear from the Doctor. Your points make sense.

You have big case capacity, so you have to fill the column of swept volume fully to make the most power and thus cylinder pressure.

What are the implications here? Does increased transfer duration ease this limitation?

I’d personally try the popup, you can do at an angle and match the band. Then raise exhaust to 100 and uppers to 118. Leave the intake alone but widen it a bit. That would be my guesstimate on what that model may like.

Awesome feedback, just the kind of thoughts I was looking for. You may not be an 045/056 expert, but you’ve been into a lot more saws than me. Have a good one!

 

[Woodwackr]

trying to compare a 45 to a 44 is silly, imo.

 

[Entisol]

trying to compare a 45 to a 44 is silly, imo.

My post with the 044 video was not clear. I don’t expect the two saws to perform the same. The power curves are/will be very different, but I’m hoping the 87cc 045 will produce more horsepower than the 044. I’d anticipate the 045 peak at lower RPM. These saws do/will behave very differently.

Right now, I think the 044 is ahead of the 045 across the rpm range. I don’t have a dyno, so take it with a grain of salt. If I get the 045 to where it’s cutting at 9500 rpm, but it feels torquey and can pull a longer or hungrier chain than the 044, I’ll be happy. Right now, it can’t pull more chain, and it turns slower. The 045 wins in weight!

Is it unreasonable to assume the 045 is capable of producing more power than the 044? Are my expectations out of line? It’s a cool saw either way. @drf256 made a few points about case and transfer volume that I had not considered. I’m learning, whether or not I get what I want!

 

[Entisol]

A 288 piston won't help your compression issue since the 288 slug is a flat-top. I think what would be most helpful is if you can find a new old stock OEM piston.

You could find a stock piston and cut a slight popup and match the band to it. That would increase compression without any further base thinning.

If I can't find a factory 045/056 piston, do either of you have experience with the 54mm Husky 385 piston? I read on another forum that it's .795" from top of wrist pin to top of piston. The OEM slug from my 045 is about .735" to top of dome. I'd have to modify the 385 piston, but there might be enough meat on it for me to turn it down and still wind up with a taller piston. Looks like the skirts are plenty long too

 

[drf256]

I have no experience with the model at all. If you go in Meteor’s website, they will list all of their products with specs including compression height. You may be able to find a domed piston application that will work for you from some off model, plus meteor makes good stuff.

If you have the piston height, do an angled popup to approximate the arc of the squish band.

Pop-ups are something some like and some hate. Haters say the popup interferes with flame propagation and scavenging. Lovers feel that is aids in deflecting charge up towards the chamber.

Then there is an angle on the crown. That’s a tricky one that is likely beneficial and part of why the factory domed some slugs. The angle on the crown makes the upper open at a better angle and faster. Part of why a 90* upper roof makes more torque, it opens to a 90* piston crown.

 

[NateSaw]

Good points. Thanks!

What's too thin on the base flange? I think this flange was around .220" (at the thinner ends) from the factory, so it’s ~.200 now. The top of the flange is not square, so measurements are approximate.

I'll check ring gap. I bought Cabers, but I did not check the ring gap in the cylinder.

The aftermarket piston was 2.123" wide. I think that’s within the range for a 54mm piston, but toward the narrow end. I'll look for a NOS piston. It's worth a shot!

That piston is on the loose end at around 53.92mm. 53.94 would be ideal for a well used cylinder, imo. I like what you're doing here! I agree with previous. CHECK RING END GAP! Should be no more than 0.010" I believe. Also, I'm curious what your squish picture looks like. Sometimes I'll roll up some modeling clay into what looks like a Lil breadstick. Put it on top the piston in a few places with a thin film of silicone spray on the piston and squish /combustion chamber. Then bolt the jug on and crush it with the piston. Pull jug off and you'll have a cross section of what your squish /combustion chamber look like. I'd guess you aren't really getting full compression. However, a gauge would tell you something on that. Also, in my novice opinion, I'd shorten that blowdown a bit. Keep in mind, I've never looked at an 045/056.Happy tuning brother!

 

[Entisol]

Thanks @NateSaw and @drf256. I'll look for a piston available from Meteor that I can work with. When I tear this saw back apart I'll post better pictures of the squish band, combustion chamber, what I try, and how it works.

The picture below shows the cylinder when I initially pulled it off. The aluminum transfer cleaned up easily. The squish band is angled to approximately match the domed piston. Have a good one!