Husqvarna 50/51/55 - Meteor P&C Performance Build

[PogoInTheWoods]

Sometimes I wonder if compression is as valuable as we make it seem Poge.

The jury is still out on that in my opinion....

The significance of whatever level of compression is obviously related to other factors in determining performance, hence my comment wondering about the point of diminishing returns when increasing compression relative to port numbers, timing, etc.

All I know is there's definitely a reason folks delete base gaskets and replace worn rings.

To hear more cowbell, of course!!!

 

[gaspipe]

More cowbell!!!

 

[Duke Thieroff]

The significance of whatever level of compression is obviously related to other factors in determining performance, hence my comment wondering about the point of diminishing returns when increasing compression relative to port numbers, timing, etc.

All I know is there's definitely a reason folks delete base gaskets and replace worn rings.

More cowbell, of course!!!

Absolutely, Poge.

I don't know any better so I have to ask is there a rule of diminishing returns on compression itself?

So the difference between 110 and 150 is huge, but is the difference between 150 and 190 as huge, since all the minimal requirements have been met?

 

[boxygen]

Where's da vid eee ohs of this monstah?

 

[shorthunter]

Now let's look at the Meteor kit. Bore is 46mm, stroke obviously remains 32mm.

A couple things jumped out at me right away. The plating is nice and the finish is good. The chamber looks smaller than the OEM jug. The ports have a generous chamfer.

The intake port is shaped much nicer.

The transfers are a different design. They are also not as 'clean' and evenly shaped as the OEM jug. Meteor could benefit from a little more attention to detail here, as I feel it would add more visual presentation of quality. To be realistic, other than the relatively small number of gearheads here, the end user will never see the inside of the saw. They wouldn't likely even know what they were looking at, or recognize a power or performance difference. They would be happy with an affordable, and in this case, available alternative to OEM.

The exhaust port...easy on the ring.

I assembled and measured port timing of the Meteor kit.

Ex = 100
Xfr = 121.5
Int = 69.5
Squish.062" with .009" OEM gasket.

Those upper transfers look ridiculous. Good luck maintaining transfer velocity.

 

[Four Paws]

It has been a few days since my last update. I put a little over a tank through the saw. I did this in 4 sessions - about a 1/4 tank at a time. After innitial assembly, the saw started right up as one would expect. I warmed it up and made some cuts. By the 4th session, the saw was performing noticably better, and compression had come up about 10 psi. I went to video the saw a couple evenings ago to obtain a baseline of the Meteor kit out-of-the-box performance. My coil took a dump - figures. I have one headed my way and should be able to resume work in a couple days.

In the meanwhile, I wanted to add my thoughts on the compression, and the transfers, and some other nuggets about the Meteor kit.

I live at 5000' ASL, so 135 psi on a stock saw is 'good' compression here. That correlates to about 155 psi at sea level. The fact is Compressing a gas takes work and creates heat. I believe combustion chamber design, flow and ignition timing have as much or more to do with performance than compression. There is no doubt that bumping compression is an easy way to gain torque in the cut. I do believe there is a point of diminishing returns on compression.

As far as the transfers: In this Meteor kit, and in any 2-stroke cylinder, you will get most of your gains in the transfers. I do not know how this cylinder was cast, however it does appear that a bridge was installed in an open port with a support beneath. This support is nothing more than a square block, and will definitely break the flow and cause turbulence. Closed port cylinders are more 'desired' here on AS, but open port saws can be made to run very strong. What it comes down to in my experience is shape...the shape of the transfers. This essentially dictates the path that the mixture takes through the transfers and out across the piston. The longer the path, the better in my mind. The more hook and curvature, the better.

Look at the hook of the OEM closed port transfers. Look at the long vertical case-fed transfers on the Meteor jug.

My final bit of information on the Meteor kit is this: It has a combustion chamber approximately 1cc smaller than the OEM jug, and 1mm larger bore.

 

[Four Paws]

Those upper transfers look ridiculous. Good luck maintaining transfer velocity.

Visualize those transfers with a piston in the jug, effectively providing the bottom of the uper transfer port. Cross sectional area is significantly reduced.

 

[boxygen]

Good stuff Four Paws. Thanks.

 

[Definitive Dave]

So is more turbulence better in the transfers and if I got that part right why is a curve better than a right angle for creating turbulence ?
I feel like I almost understand so much that I read, like true enlightenment is hiding just in the next room.
Dave

 

[PogoInTheWoods]

My final bit of information on the Meteor kit is this: It has a combustion chamber approximately 1cc smaller than the OEM jug, and 1mm larger bore.

All yours. Joey.

 

[stihlbro]

This is what a 55 does with too much compression. This was a factory open port with no decompression.

 

[wcorey]

So is more turbulence better in the transfers and if I got that part right why is a curve better than a right angle for creating turbulence ?
I feel like I almost understand so much that I read, like true enlightenment is hiding just in the next room.
Dave

I don't think turbulence in the transfers is a good thing, it's better to promote linear flow with smooth transitions to maintain velocity and direction.
Turbulence in a very controlled, focused manner is good once the charge hits the combustion chamber, first for scavenging purposes and then to promote propagation of the flame front.
Turbulence in an intake tract can be beneficial in the right places, like creating a boundary layer and preventing puddling. In a 4 stroke it promotes fuel atomization but when you think about the path the charge takes in a 2 stroke, what it goes through in the crank case is probably plenty enough...

 

[David Young]

I remember you two doing the 460 build off, man how time flies!

Boy that was a few years ago.

Times sure have changed tons of info now. It was hard to get people to share. That sure was a fun build. Josh did one hell of a job and I am still grateful to Wayne Slayton.

 

[David Young]

This is what a 55 does with too much compression. This was a factory open port with no decompression.

Was that a 46mm. What did you have for compression?

 

[stihlbro]

It was, had carbon build up. Very clean saw and run a 3/8 20 inch bar impressively. Had it sold and was showing the buyer how to start it. It would kick something fierce. Well I broke the recoil showing it, had the saw sold for 150. Bought a used. Recoil for 35, and added a decompression valve.

How did I do?

 

[David Young]

Looking good!

 

[Duke Thieroff]

Hey guys, just so you know...


I have a shipment of these cylinders coming in early next week and will be offering them for $115 shipped anywhere in the Lower 48!

That means you get:

• Meteor Husqvarna 55 Cylinder
• Meteor Piston
• Meteor Clips
• Meteor Wristpin
• Caber Rings

You can either drop me a PM, check out my site or drop me an email.

www.SawSalvage.com
[email protected]


I've also got some big things planned in the next month or so to offer a much larger array of new quality aftermarket parts including:

• Clutch Covers
• Chain Brakes
• Gasket Sets
• Bearings
• Wider Array Of Cylinder Kits
• Oil Seals
• Clutches
• Tanks/Rear Handles
  
• Fuel / Impulse Lines
• Oil Pumps
• Drive Sprockets
• Crankshafts
• Recoil Starters
• Carb Kits
• Carbs
• Ignition Coils

 

[s sidewall]

Installed that 55 kit on my son-inlaws 51 with a compresson release when I rebuilt his, good kit and so far no trouble. Runs and cuts like a beast now.

Sent from my Prism II from T-Mobile, Steve

 

[Duke Thieroff]

Definitely nice kits!

 

[Onan18]

Hey Duke,

How soon are you going to be offering clutch cover/chain brake assemblies? I need one for a 268XP, also could use a set of anti-vibe mounts for the same saw if you are going to be offering those as well.

Sorry don't mean to hijack the thread. The Meteor cylinder kits do seem like excellent quality from my limited experience with them (only used one so far). The 026/MS260 kit I put on my buddys' saw has tons of power, actually will out cut my 026 with OEM top end (although in fairness I think my saw is getting tired, but I bought it for $125.00 from a tree guy and it has been my goto saw for four years now).

Joe