Help Me Build a Better MS660

[Freudianfloyd]

Well my saw is together, but I am paranoid about starting it up. I really dont want a catastrophic failure. So I am stalling, but at the same time wondering what a proven break in for these saws would be? What fuel/oil ratio, what rpms, go up and down the rpm range?

I dont have a bar yet, so I cant really break it in cutting, atleast not right now, unless I can use the bar and chain from my ms271.

 

[Leerod83]

Same mount as the 271. 40:1 minimum I'd say or maybe even 32:1. Run it!!!!

 

[Freudianfloyd]

Well.....after about 3 pulls the rope broke. Got it rewound and tied, and it works some, but the rope must be stretching.

Anyway, I put it on choke, pulled it about 3 times and it hit. Pressed the decomp button in, move the selector up to high idle, and after a few pulls, it hits but damn near rips the rope out of my hand and pops the decomp. Push it in, pull a few more times and it does it again, over and over. I feel like I'm going to break something. Cant get it to fire on ether (I know) either.

Any suggestions?

 

[Freudianfloyd]

I know it has a ton of compression, but cant say for sure how much without a gauge though, but it takes quite a bit of force to move.

I have great spark. And plenty of fuel. I'm sure its flooding, but I have no idea why. The low and high were both set to 1 turn out.

And I put the piston at tdc and the magnets on the flywheel are lined up on the coil, so I dont think the flywheel is bad.

No idea what it could be.

 

[Freudianfloyd]

I did mix the fuel about 32:1, could it be oversaturated with oil?

 

[buttercup]

3% oil is on the safe side, 4% is ok for the first fills but it might gather burned sot build up in the long run.

 

[Leerod83]

It sounds like it's flooded badly but wouldn't be a bad idea to double check the flywheel key to make sure it's not sheared. Also the metering lever in the carb could need adjustment. Next time you try to start it only pull it twice on choke even if it doesn't pop before going to high idle.

 

[jltrent]

Those AM carbs are pot luck. Like I said in an earlier post I would get an OEM carb. I had an AM carb on a 660 for a while and it was bad to flood on startup.. Put a new carb kit in the original OEM one and it ran/started like it should.

 

[Freudianfloyd]

It sounds like it's flooded badly but wouldn't be a bad idea to double check the flywheel key to make sure it's not sheared. Also the metering lever in the carb could need adjustment. Next time you try to start it only pull it twice on choke even if it doesn't pop before going to high idle.

I checked the key earlier and it is fine.

It sounds like it's flooded badly but wouldn't be a bad idea to double check the flywheel key to make sure it's not sheared. Also the metering lever in the carb could need adjustment. Next time you try to start it only pull it twice on choke even if it doesn't pop before going to high idle.

Its Alive!!!

I think you got it. I adjusted the metering lever and it fired right up. When I had the carb apart earlier it looked like the lever wasnt moving the float much, after adjusting it, it moved quite a bit more.

Thank you for your help.

 

[Leerod83]

Glad to hear it!!!

 

[Freudianfloyd]

Glad to hear it!!!

you dont realize the power this saw has until you start a 50cc saw right after and it feels like a toy. Let's hope it lasts.

Now to order a bar and chain.

 

[Wood Doctor]

you dont realize the power this saw has until you start a 50cc saw right after and it feels like a toy. Let's hope it lasts. Now to order a bar and chain.

Yes, they do have power (6.5 Hp) and they can be used to cut big trees:

That's a 36" bar. The sawyer is just under 6' tall. Good luck, Floyd!

 

[Freudianfloyd]

Well I went out to make sure the saw started again. My method was 2 pulls on choke, even though it didnt pop, and then pull on fast idle, or what is supposed to be fast idle, and then when it didnt start I resorted to holding the trigger and pulling it. It fired pretty quick with that method. I need to get the carb tuned.

 

[Wood Doctor]

Well I went out to make sure the saw started again. My method was 2 pulls on choke, even though it didnt pop, and then pull on fast idle, or what is supposed to be fast idle, and then when it didnt start I resorted to holding the trigger and pulling it. It fired pretty quick with that method. I need to get the carb tuned.

When the engine is cold or has sat overnight, you may have to pull 3 or 4 times on choke before you hear the pop. Then shift to fast idle and pull one or two more times. That's my method with Stihl and Husqvarna saw engines.

 

[Freudianfloyd]

When the engine is cold or has sat overnight, you may have to pull 3 or 4 times on choke before you hear the pop. Then shift to fast idle and pull one or two more times. That's my method with Stihl and Husqvarna saw engines.

It usually is for me also, ut so many people were saying you may not hear the pop and they only do 2 pulls whether they hear it or not, and me trying to avoid the flooding issues I had before, figured I wouldn't take my chances.

 

[Wood Doctor]

It usually is for me also, ut so many people were saying you may not hear the pop and they only do 2 pulls whether they hear it or not, and me trying to avoid the flooding issues I had before, figured I wouldn't take my chances.

You can also look at the decomp valve rather than try to hear the pop. Usually it stays down until a pop occurs and then it pops up -- not always, however. I have had saws that pop the decomp out on practically every pull, even when the don't fire. One thing for sure, cold Stihl engines like to start with some throttle assistance and usually ignore you on low idle. That's why the fast idle setting is important.

Check to see that your engine throttle control is actually holding a fast idle when you click up a notch from choke.

 

[Freudianfloyd]

You can also look at the decomp valve rather than try to hear the pop. Usually it stays down until a pop occurs and then it pops up -- not always, however. I have had saws that pop the decomp out on practically every pull, even when the don't fire. One thing for sure, cold Stihl engines like to start with some throttle assistance and usually ignore you on low idle. That's why the fast idle setting is important.

Check to see that your engine throttle control is actually holding a fast idle when you click up a notch from choke.

Thats what my decomp does, it pops even without firing. It's not, I was using the toe of my shoe to hold it partially open. I've heard several people say that fast idle doesnt work on their saws.

 

[Wood Doctor]

Consider placing a short 1" length of ordinary fuel line at the point shown by the arrow:

That shim will then assist the switch rod's push against the trigger to hold the fast idle. You can check the action by examining the trigger itself that will then be partially closed.

 

[Freudianfloyd]

Consider placing a short 1" length of ordinary fuel line at the point shown by the arrow:
View attachment 757310
That shim will then assist the switch rod's push against the trigger to hold the fast idle. You can check the action by examining the trigger itself that will then be partially closed.

I will have to give that a try

 

[Freudianfloyd]

Wood Doctor, I found a thread online when researching a fix for this issue and ran across a 3d print file for a spacer to go in this place that somebody gave credit to you for. I have since printed it, and will give it a try when I get home from work.