new member here with a tuning question on a ms660 build

[1goug76]

I have just completed a farmertec 660 build, I watched every video on youtube i think, and read about every post on this sight and a few others so i can learn from others experiences/mistakes. I wanted to build a reliable saw for personal use when the few times call for a saw with a little more grunt than my 362. My wife bought me the kit for christmas and I upgraded the crank to a hyway unit, used all oem gaskets and seals, along with oem rubber parts. got the hyway dual port muffler, clutch, chain break, and also new chain adjuster from hl supply, and went with a meteor piston and cylinder with an oem decomp. last but not least i ordered a walboro wj-76-1 carb so there isnt alot left that is farmertec, but i just replaced every part that people may have had problems with in posts or videos.
I mixed up some gas 40:1 last night and fired it up for the first time. I set my carb screws at 1 turn out on both and it fired on the 4th pull. The saw idled good, no chain movement. I then began to turn L screw to reach my max rpm but it didnt really increase rpm much just a slight change in pitch not much more than that. Then the idle was still pretty good so I throttled it up a few times, got it good and warm, shut it down, let it cool. did two more heat cycles and tuned the H screw. I didnt have a tach but tuned it just where its a little fat at WOT.
My question is, now that the saw seems to run fine, I can turn my idle screw all the way up and it does nothing, if I turn it down the saw will stall, as expected, but I bottom the screw out before i get anymore rpm out of it. Im just wondering if there could be something wrong somewhere. my L screw doesnt make much of a difference while being adjusted either. It will stall the saw when richened up, but it wont go real lean like my 362 will. My settings right now are a little less than 1 turn out on low side and almost the same on the high side. the saw is running great, but the lack of idle adjust has me stumped. the tang is contacting the idle screw, did I buy too big of a carb?

 

[Westboastfaller]

Not responsive. Did you get lots of heat into the saw and it didn't fluxuate the revs on its own?

 

[1goug76]

Not responsive. Did you get lots of heat into the saw and it didn't fluxuate the revs on its own?

yes I let the saw warm up pretty good, there was no fluctuation in the revs by itself. I vac and pressure tested the saw and it was airtight, held .5 bar for 5 min, needle never moved.
tank tested out good also, i just cant figure out why my idle screw does not increase rpm's. its bottomed out and id say saw is turning around 2600-2800rpm. other than that saw runs fine, but its not right so i dont want to go cut any wood with it and blow it up.

 

[Westboastfaller]

Did you just warm it up way of reving it or you worked it in the wood for a while?

new carb you say.

Weather temps and fluctuations? normal???

 

[1goug76]

Did you just warm it up way of raving it or you worked it in the wood for a while?

new carb you say.

Weather temps and fluctuations? normal???

just got it warmed up by revving, it was 8:00pm so i wasnt going to cut in the dark, yes its a new walboro wj76, temp was around 35 degrees.

 

[Westboastfaller]

ok I see that^^^ I was writing
Ive had many carbs like that in time. Never a new one though but it happens.
Well that's a shame. usually when they get hot the revs will drop and you can't keep it running. So not damaging to the saw but can throw you off your game. More of a safety issue.

See if they will replace the carb for you?
That's what I think anyway
See what others say

 

[1goug76]

ok I see that^^^ I was writing
Ive had many carbs like that in time. Never a new one though but it happens.
Well that's a shame. usually when they get hot the revs will drop and you can't keep it running. So not damaging to the saw but can throw you off your game. More of a safety issue.

See if they will replace the carb for you?
That's what I think anyway
See what others say

thanks, there is a winter storm on our heels right now here in Pa. tomorrow and monday are out but tuesday im going to try it in some wood, if I cant get it right Im going to try the farmertec carb on it and see what happens.

 

[Ozhoo]

Did you sacrifice a chicken under a full moon? Sometimes that helps with this Chinese stuff.

 

[Westboastfaller]

There ya go. Make sure that choke is all the way back. I could have an issue if you are coming out of a warm shop when its cold out. Best way when you do that is to
start it up as soon as you go outside then try your adjustments. never good to bring it from a warm shop start it up then shut it off and let ir ride in the back of a truck


edit ...continued

 

[1goug76]

There ya go. Make sure that choke is all the way back.I could have an issue if you are coming out of a warm shop when its cold out. Best way when you do that is to
start it up as soon as you go outside then try your adjustments. never good to bring it from a warm shop start it up then shut it off and let ir ride in the back of a truck


edit ...continued

I brought it outside on my porch and started it right away. Like I said it starts and runs fine, instant throttle response, but the idle screw doesn't increase revs, I thought maybe there is something I'm missing

 

[Westboastfaller]

I brought it outside on my porch and started it right away. Like I said it starts and runs fine, instant throttle response, but the idle screw doesn't increase revs, I thought maybe there is something I'm missing

No I don't think so.
OK good info. If you started it as soon as you went out and it
wasn't responding with throttle and low setting the first time then it would not be a temp fluctuation then. I can't see you missing anything. Yeah I would swap it out

 

[drf255]

Did you add an oem piston pin bearing?

Did you play with the case to get the chain adjuster to work? My understanding is that the casting is out of whack and that’s why the adjusters don’t work.

Set the Idle screw at 1 out and see how she responds. If it has poor acceleration try richening the L. Also if it has a hard time finding idle after you come out of a cut, richer the L.

As long as your High tune is holding and you have a stable idle, I wouldn’t worry much.

The linkage being stuck can lead to odd issues as well. Someone on the forbidden site makes the missing spacer that is an issue with the control rods on those China 660’s.

 

[1goug76]

Did you add an oem piston pin bearing?

Did you play with the case to get the chain adjuster to work? My understanding is that the casting is out of whack and that’s why the adjusters don’t work.

Set the Idle screw at 1 out and see how she responds. If it has poor acceleration try richening the L. Also if it has a hard time finding idle after you come out of a cut, richer the L.

As long as your High tune is holding and you have a stable idle, I wouldn’t worry much.

The linkage being stuck can lead to odd issues as well. Someone on the forbidden site makes the missing spacer that is an issue with the control rods on those China 660’s.[/QUOTE

Yes I used an oem piston pin, bearing, and circlips. I used parts from the FarmerTec and Hyway chain adjuster to Frankenstein one together. It works but nothing to write home about, I will go with an oem one as soon as I get a chance.
The idle screw I’m talking about that does nothing is the main idle screw (LA). The L screw and the H screw seem to be fine, I have great throttle response, and she’s just a tad fat on the top end. I pulled the plug and the electrode looks perfect, the color of a paper bag, I just don’t understand why my LA screw is bottomed all the way out and it’s idling about 2800rpm, which is perfect but it just doesn’t make sense to me that it would be bottomed out and that’s as high as it will go.
Maybe I’m just over thinking things because it’s a Chinese saw and I’m expecting something to be wrong, but it’s a wolboro carb and has Stihl right on the top of it. I’ve seen posts where guys say the wj-76 is the carb to use on these 660’s. I do have an oem throttle rod I’m going to throw at it this evening and see what happens.

 

[drf255]

Take a good look at how the LA needle moves the butterfly. Make sure its working.

Check linkage as well.

 

[kenton.a.frank]

Take a good look at how the LA needle moves the butterfly. Make sure its working.

Check linkage as well.

I was going to say the same thing. Remove the carb and visually look to see that the LA screw is actually moving the throttle butterfly. I’ve also heard of the throttle linkage being wonky on these kits. Perhaps it isn’t quite right? I do t want you throwing parts at it but that’s what I’d look at.


Sent from my iPhone using Tapatalk

 

[Westboastfaller]

Per as what you said in your OP then your low jet is not working properly at all either. You say when you richen it then its stalls but it won't get lean?. it should pass the sweet spot and then starve out with a cough.
Sounds realy out of wack here

 

[1goug76]

Per as what you said in your OP then your low jet is not working properly at all either. You say when you richen it then its stalls but it won't get lean?. it should pass the sweet spot and then starve out with a cough.
Sounds realy out of wack here

It will stall when turned almost full lean on the L screw, it just doesn't rev as high in the sweet spot like my 362 does, it's just a noticeable change in pitch, or cleans up I should say, then it goes lean and dies when I go a quarter turn further. I'm sorry I should have clarified that a little better in my op. I was just comparing it to how my other saw behaves.

 

[Rick Stephens]

I built an MS660 recently and it had issues restarting. Found plenty of particles of black unknown crap in the brand new carb when I went through it. I don't care if its FT or Walbro, take it apart and clean everything, and check needle lever height, seen too many of those screwed up from the factory. I stuck OEM controls on my Farmertech build ($13 for lever and trigger), along with a few other OEM parts like you did. The controls seem to help with more predictable choke and high idle settings. Soon as I could, I tuned the high in the cut with a tach hooked up. Tuning fat is fine and safe, but it can really make a difference tuning with the tach hooked up while pulling.

Hard to know how a carb is gonna run right out of the box on a new build kit. Seems to take a tank or two of fiddling.


Rick

 

[1goug76]

I built an MS660 recently and it had issues restarting. Found plenty of particles of black unknown crap in the brand new carb when I went through it. I don't care if its FT or Walbro, take it apart and clean everything, and check needle lever height, seen too many of those screwed up from the factory. I stuck OEM controls on my Farmertech build ($13 for lever and trigger), along with a few other OEM parts like you did. The controls seem to help with more predictable choke and high idle settings. Soon as I could, I tuned the high in the cut with a tach hooked up. Tuning fat is fine and safe, but it can really make a difference tuning with the tach hooked up while pulling.

Hard to know how a carb is gonna run right out of the box on a new build kit. Seems to take a tank or two of fiddling.


Rick

Thanks for the info, I will tear the carb down and check the needle height, I checked out my throttle rod and it was bent a little so I put the oem one on and it's a little better. I did notice that the tab that the idle screw rides on just barely touches the screw and looks like it's tweaked a little. I'm going to bend it over a tad so it contacts the screw a little better, I'd say with the oem throttle rod, metering lever height confirmed and the tab tweaked I should be on to something.

 

[Westboastfaller]

It will stall when turned almost full lean on the L screw, it just doesn't rev as high in the sweet spot like my 362 does, it's just a noticeable change in pitch, or cleans up I should say, then it goes lean and dies when I go a quarter turn further. I'm sorry I should have clarified that a little better in my op. I was just comparing it to how my other saw behaves.

That's the thing about trying to
troublesoot on line. Its how we precieve it as to the route to take.
So then yeah that certainly brings the throttle adjuster in to play as it was said by a few people.

Sounds like it is in fact your issue per as your last post? Hopefully you have it and all eles is good with the build once you lay the heat to it. Once you get some throttle you would need to take your low back some as it sounds.