Couple of my 545/550mk1 builds

[oper8r_error]

If they can't restart with one pull after getting warm, something needs fixed

 

[hacskaroly]

If they can't restart with one pull after getting warm, something needs fixed

Those are good looking saws, glad to hear they are running great for you. The metal tape you used between the cylinder and the plastic shield, what brand is it and where did you get it? I need to get some for a couple of 562s I am working on.

 

[Motorka]

I use tesa aluminium tape.

tesa® Aluminium Tape

tesa® Aluminium tape is a special self-adhesive plumbers tape perfectly suited to quickly repair any metal surface, such as heating appliences or gutters.

www.tesa.com

 

[hacskaroly]

I use tesa aluminium tape.

Awesome, thanks for the tip, I will look to get some of that!

 

[Sloughfoot]

Awesome, thanks for the tip, I will look to get some of that!

HVAC supply and lots of hardware stores keep it.

 

[chipper1]

Best handling 50cc saw ever made.

 

[oper8r_error]

Best handling 50cc saw ever made.

Without a doubt. They were really forward thinking towards the end-user experience in the 50cc category.

Those are good looking saws, glad to hear they are running great for you. The metal tape you used between the cylinder and the plastic shield, what brand is it and where did you get it? I need to get some for a couple of 562s I am working on.

The tape I have is from the brand IPG or itape.com

It is a thinner foil than the stuff that is purposed for HVAC. It's very easy to cut and mend.

I used some black permatex "adhesive sealant rtv" to fix tears on this particular intake boot. Should hold up.

 

[oper8r_error]

Today I swapped a coil+solenoid on an ebay 545 runner. To my surprise, the saw had an AT-12 on it... score. Anyway, replaced the seals (one seal I resued with a new spring), replaced the airleaking, torn boot. Saw started easily enough cold following standrad SOP.

Upon running it though, I encountered "revboost" trying to do its thing on a regular non-stuffed crank 545. This caused it to rev poorly from idle. It also just wouldn't low idle. To my layman eye's I figured swapping those parts for something 100% from a 545 (although not same saw) was my next step.

It worked. Kept the AT-12 with a AT7 solenoid.

 

[David Young]

I have some to build, any building tips? things to watch out for? Porting suggestions. the package was the right size but had gremlins, the gen 2 I understand runs stronger and better but is close to the size of a 60cc saw in my opinion.

 

[oper8r_error]

I have some to build, any building tips? things to watch out for? Porting suggestions. the package was the right size but had gremlins, the gen 2 I understand runs stronger and better but is close to the size of a 60cc saw in my opinion.

Don't overthink airleaks. Be thorough down to the crank seals, but don't worry about splitting the case if the crank shaft is tight and the bearings are intact.

The AT system needs a 'mostly' closed system to run but it can compensate for a little some airleaks (like say a small crank seal leak). That said, an out of tune AT saw will behave erratic much the same an airleaking saw will.

The big things you want to see:

1. For cold start: does it burp when choked and start high idle after air purge?
2. After a minimum of 60 seconds running high idle (a out of tune saw will still run high idle), put the tip of the bar in some wood and start 3/4 to WOT throttle for another 60 seconds. Listen for the AT hunting between rich and lean as it cuts.
3. After a proper long tuning cut and the saw is hot, does it "low idle" properly without stalling?
4. After turning it 'off' and still warm, can you restart with one pull at low idle?

This is kind of where I am at. If one of my saws doesn't immediately low idle before it's warmed up, I am not concerned. Once these saws warm up, the throttle response and ignition seem to find their groove. Cold, not so much. I blame the more under square, stroker design. That said, the way they rev makes my MS261 feel pedestrian.

 

[David Young]

I have one that would not idle, start and wot were normal. I tore it down, didn't find an obvious airleak. It is still safe and sound in the box...
in pieces.

 

[oper8r_error]

I have one that would not idle, start and wot were normal. I tore it down, didn't find an obvious airleak. It is still safe and sound in the box...
in pieces.

Once they lose compression the idle is the first to go. I would replace the piston ring.

 

[lehman live edge slab]

Without a doubt. They were really forward thinking towards the end-user experience in the 50cc category.


The tape I have is from the brand IPG or itape.com

It is a thinner foil than the stuff that is purposed for HVAC. It's very easy to cut and mend.

I used some black permatex "adhesive sealant rtv" to fix tears on this particular intake boot. Should hold up.

I used the same tape 2-3 years ago on a 562 mark 1, it helped but by no means cured it completely of the hard warm starts. Also opened up a couple small holes in cover and put frog skins on to help let heat out and had reprogrammed with newest updates. Definitely better but not perfect even after that all was done.

 

[David Young]

I used the same tape 2-3 years ago on a 562 mark 1, it helped but by no means cured it completely of the hard warm starts. Also opened up a couple small holes in cover and put frog skins on to help let heat out and had reprogrammed with newest updates. Definitely better but not perfect even after that all was done.

Is the saw muffler modded as well? I think looking at the differences between v1 and v2 gives us some great insight to what they found as issue and how to fix them. If I remember the carb bulkhead on the new version is much thicker material.

 

[lehman live edge slab]

Is the saw muffler modded as well? I think looking at the differences between v1 and v2 gives us some great insight to what they found as issue and how to fix them. If I remember the carb bulkhead on the new version is much thicker material.

Yes muffler mod, well apparently husky figured the only way to “fix” was to completely redesign the whole saw and then modify the redesign with a dished piston to help the bearings out.

 

[oper8r_error]

Yes muffler mod, well apparently husky figured the only way to “fix” was to completely redesign the whole saw and then modify the redesign with a dished piston to help the bearings out.

I used the same tape 2-3 years ago on a 562 mark 1, it helped but by no means cured it completely of the hard warm starts. Also opened up a couple small holes in cover and put frog skins on to help let heat out and had reprogrammed with newest updates. Definitely better but not perfect even after that all was done.

I only have experience with the 50cc platform.

I am also putting AM muffler's on them because the baffling sits on the roof of the muffler instead of OEM where its on the floor. I can get them as cheap as $8per on ebay.

I want to get ceramic spacers and maybe an asbestos sheet to sit between the crank case/oil tank and exhaust.

As for the Mk2 redesign, my guess it was overkill directed by corporate looking at warranty work. Had they released the design with a traditional carb to iron out regular new saw teething issues without AT on top of it, I bet the mk2 would of today would be even lighter...

 

[lehman live edge slab]

I only have experience with the 50cc platform.

I am also putting AM muffler's on them because the baffling sits on the roof of the muffler instead of OEM where its on the floor. I can get them as cheap as $8per on ebay.

I want to get ceramic spacers and maybe an asbestos sheet to sit between the crank case/oil tank and exhaust.

As for the Mk2 redesign, my guess it was overkill directed by corporate looking at warranty work. Had they released the design with a traditional carb to iron out regular new saw teething issues without AT on top of it, I bet the mk2 would of today would be even lighter...

Pretty sure regular carb wouldn’t fix vapor lock/hard start because of excessive heat in air box. My thought is if they could have fixed it without redesigning the entire saw they would’ve. No way a company spends more to completely reengineer a saw if it’s able to be fixed and ran in current state reliably. It wasn’t fixable and they were loosing customers so it needed to be made better. The 441 Stihl had issues blowing up at first because the intake boot was too hard and would crack/tear and then leak. They pulled it and made a run of 044’s made the change to the boot and the 441 was fine but damage to the saw’s reputation was already done. Other than a pain to work on the 441 was a good saw with first generation mtronic.

 

[oper8r_error]

Pretty sure regular carb wouldn’t fix vapor lock/hard start because of excessive heat in air box. My thought is if they could have fixed it without redesigning the entire saw they would’ve. No way a company spends more to completely reengineer a saw if it’s able to be fixed and ran in current state reliably. It wasn’t fixable and they were loosing customers so it needed to be made better. The 441 Stihl had issues blowing up at first because the intake boot was too hard and would crack/tear and then leak. They pulled it and made a run of 044’s made the change to the boot and the 441 was fine but damage to the saw’s reputation was already done. Other than a pain to work on the 441 was a good saw with first generation mtronic.

Without AT keeping saws running that otherwise, shouldn't have been, the heat wouldn't have been so excessive. It did its job too well...

I can say, the second my chain starts dulling the saw starts to lean out and the heat picks up rapidly.

That said, they did move and shorten the gas line before the model was discontinued.

 

[oper8r_error]

I'm going to cut cedar tomorrow. I am bringing a couple saws but I will have different roles for the 545 and 550.

I will have the 550XP w/ a 8t sprocket and a 16" full chisel LPX chain. This will be hopefully be my main saw to start and it should get through the lighter stuff without sweating.

The 545 will have 7t sprocket and 20" w/ husqy micro chisel. It is more set up for felling and bucking.

I am predicting my 550 will dull fast and once it does that saw will be out of commission. Hopefully, I get through a tank.

Don't mind the shovel, needs to he swapped for a rake.