goatchin
ArboristSite Operative
damn...screamer for sure.
MS440 -> 460 Conversion and Build
- Thread starter blsnelling
- Start date
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Once I get some real work time with it, I expect it will.
Wild Knight
ArboristSite Guru
Did you weight the saw before and after the BB kit? I am curious how much of the weight difference between the 440 and 460 you lost when you upgraded parts, if any. Do you still save weight by upgrading and porting a 440 vs simply buying and porting a 460?
I did not. There couldn't be more than a couple ounces difference in the two P&Cs. Yes, the 440 is lighter than the 460, 1.6 lbs. 13.0 vs 14.6. That's a measurable difference. So now I've got the same power in a lighter more nimble package.
I want one.
If it wasn't a Stihl, I'd say you'd been possessed by the Saw Troll!
Sawdustmaker
Addicted to ArboristSite
I just weighed a 044 and a 046 cylinder. 20 oz for the 044, 21 oz for the 046
they have different crankcases, the 046's is bigger which is where the weigh diff is
Thanks for checking that out. I'm not surprised at such a small difference.
Now for the not so good news. I nearly burnt it up today. I'm still sorting through it, but I think I've got it narrowed down. I had the saw tuned nicely and then it just went crazy lean on me. I couldn't tune it down. Air leak? So off came the tank. I did a vacuum test and had a very slow leak. Hmm. Off came the the flywheel and clutch and I pressure tested it. I sprayed Windex around the seals. No leak. No leak around the base. I found that I had a small leak in the decomp but the culprit was the sleeve on the crank. The seal on that side doesn't seal on the crankshaft, but on a sleeve that fits over it. I doubt this is an issue once the clutch is back on and the sleeve is tight against the bearing. So I don't think it's an air leak.
I pulled the jug to check things out. It had gotten hot but not seized or transfered at all. It had to have only been a few degrees shy though. The piston and cylinder both had both polished in placed. I hit the piston with 0000 steel wool and the cylinder with 400 grit paper lubed. No harm done. Once back together compression was still 180 cold.
So what is it? Is the carb not able to put out enough fuel? Do I need a smaller jet? I don't think so. The saw is crazy rich going into the cut and then it just goes crazy lean. Same thing with tuning WOT. I'll have it 4-stroking and then it just starts screaming.
Then I remember something important. That new fuel line I put on felt really soft. I pulled it off and the thing is way larger in diameter than normal and so soft it's not funny, just like an old line that's gone mushy. I've not yet had a chance to run it again, but I'm fairly convinced the fuel line was collapsing. At least I'm sure hoping that's what it is. I replaced the fuel filter with another somewhere along the line too.
What do you guys think of my analysis?
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Sawdustmaker
Addicted to ArboristSite
sounds plausible for sure.
It's sure had me nervous all day. I made my initial cuts first thing this morning. That's when I noticed it going lean. I tore the saw back down before the video was made. I thought it was fine. Later I decided to put some more fuel through it and it was doing it again. That's when I went to playing with the carbs and fuel hose.
I put the original fuel hose back in it and I'm going to put it back together with a 68 fixed jet in place of the 66.
I put the original fuel hose back in it and I'm going to put it back together with a 68 fixed jet in place of the 66.
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wigglesworth
Booned
That sux. Good thing you caught it.
Definitely sounds plausible. Did you check the tank vent?
Sawdustmaker
Addicted to ArboristSite
That's why I posted my issue here. Many minds are better than one. Especially when you're a little stressed. At least it wasn't out of fuel, lol
Now that you mention it.......................... Oh the simple things
Don't you just love working on a saw that may or may not have an air leak.
yo2001
ArboristSite Operative
funny, I just went through the same sort of thing with my 064. The saw ran fine but the saw kept running out of fuel at WOT going lean and the h jet would not adjust the condition. Even going rich on the jet, the saw will start rich and surge lean. Took the saw back and found the fuel line ( replaced recently) pinched at the middle where the hose suppose to seat. Reinstalled back to normal.
Erick
Addicted to ArboristSite
Brad, Check the tank vent first.. easy enough just loosen the cap and see if it still goes lean.
ZAMA or Walbro??? (sounds like ZAMA)
I went with a 70 main jet on mine, seems to be about right.
Fuel line could be collapsing but probably not unless your fuel filter is restrictive/clogged.
Also check the inlet screen to make sure it's clean
Check the inlet needle hight, if it's to low the carb will just flat run out of fuel at high demand.
My guess is tank vent or ZAMA.
ZAMA or Walbro??? (sounds like ZAMA)
I went with a 70 main jet on mine, seems to be about right.
Fuel line could be collapsing but probably not unless your fuel filter is restrictive/clogged.
Also check the inlet screen to make sure it's clean
Check the inlet needle hight, if it's to low the carb will just flat run out of fuel at high demand.
My guess is tank vent or ZAMA.
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I was hoping you'd show up, especially since you've done this mod. I wish I'd thought of the tank vent right when it was acting up. That's exactly what it sounds like. It's hard to tell if these little things work. I did not hear it make and break seal internally as I blew and sucked on it like another one I have does. I swapped them out.
It's Walbro HD17A carb. I swapped the original 66 jet with a 68 out of a HD16 I have. The carb is clean with good diaphragms. What should the needle height be?
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Erick
Addicted to ArboristSite
Brad, the metering lever on an HD should be level with the carb body just run a straight edge across the carb body the lever should just touch the bottom of the straight edge.
The tank vent is easy enough to check without waking the neighbors,
just empty the fuel tank and purge the fuel line. Pull the line from the carb, put the cap back on the tank and pull a vacuum on the fuel line if the vent is working it will bleed off, if you can hold a vacuum the tank vent is bad. You can also check your fuel line for collapse, just pinch off the line at the filter and pull vacuum it should hold it's integrity up to about 10lbs or so. 
As far as carbs and jets go I would imagine that the porting is pretty similar to your 460 so if your 460 is running good on the 68 jet I'd say you'd be just fine with it on the 44. Check the carb venturi on the HD17 vs. the HD16 some of the HD's had a smaller venturi (by like 1mm) not sure if the 17 is one of them (and I'm thinking it's not) but you might want to check it to be sure.
