ms660 surging

[zeroskater58]

so ive been going through this ms660, and have replaced the crank seals, impulse line, and piston and cylinder on it. i also swapped out the carb, had a cheap chinese carb on it that the high needle would do nothing on so it pretty much would always want to run lean, or flood. i swapped the carb with a tillotson, cant remember the model number off the top of my head. after replacing the carb, it started surging, a little tiny bit at idle, not bad, but at WOT its surging pretty good, to the point it makes it almost impossible to tune. the idle speed screw does almost nothing for it as well, barely barely will get the chain moving screwed all the way in. what do you all think the issue is? my gut tells me fuel lines and/or pickup body, but wanted to see what you guys thought before i take it into the shop. thanks!

 

[L34]

Have you done press/vac test after rebuild?

 

[merc_man]

As mentioned above presure and vac test it for leaks.

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[zeroskater58]

As mentioned above presure and vac test it for leaks.

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i will see if i can get that done here soon. the thing that strikes me as odd, is that it wasnt surging like this with the china carb, but with the oem tillotson it is, which is why i was leaning away from air leak or more intermittent fuel delivery from a closing line or something, the tillotson is beefier tha the china carb, maybe more fuel pull. will check pressure and vac though. thanks

 

[president]

could it be you have that goofy intake boot
with the flap in it that would cause this?

 

[lone wolf]

i will see if i can get that done here soon. the thing that strikes me as odd, is that it wasnt surging like this with the china carb, but with the oem tillotson it is, which is why i was leaning away from air leak or more intermittent fuel delivery from a closing line or something, the tillotson is beefier tha the china carb, maybe more fuel pull. will check pressure and vac though. thanks

It acted up after you put on another carb. Was the replacement used or new?

 

[zeroskater58]

It acted up after you put on another carb. Was the replacement used or new?

brand new carb, which is why its a little confusing to me. saw ran like crap with the china carb, to get it to run at all was making it run lean. the new carb i replaced it with is a tillotson hs320a brand new

 

[zeroskater58]

could it be you have that goofy intake boot
with the flap in it that would cause this?

i dont believe so, but i will check the boot anyways

 

[lone wolf]

brand new carb, which is why its a little confusing to me

Is the fuel line old,real soft and collapsing maybe? Vac and pressure test the saw to eliminate that also. Then you have a good base to work off of.

 

[zeroskater58]

Is the fuel line old,real soft and collapsing maybe? Vac and pressure test the saw to eliminate that also. Then you have a good base to work off of.

cool, sounds like a plan. fuel lines are pretty squishy, so that was my thinking too with the collapsing. we shall see

 

[lone wolf]

cool, sounds like a plan. fuel lines are pretty squishy, so that was my thinking too with the collapsing. we shall see

Try that then take it from there.

 

[zeroskater58]

so, i got a fuel line from the dealer, and he said that these saws wont accept aftermarket carbs, only walbro or zama, says if its not the fuel lines its probably the carb since its not an oem. is there any validity to this, or is he just trying to sell me a carb?

 

[president]

so, i got a fuel line from the dealer, and he said that these saws wont accept aftermarket carbs, only walbro or zama, says if its not the fuel lines its probably the carb since its not an oem. is there any validity to this, or is he just trying to sell me a carb?

Get the wj 69 carb, and order a 70 mm jet from a 046 or 044 they screw in!

 

[zeroskater58]

Get the wj 69 carb, and order a 70 mm jet from a 046 or 044 they screw in!

unfortunately i dont have unlimited money to buy 70 dollar carbs, so if it is the carb, it will gave to wait

 

[president]

unfortunately i dont have unlimited money to buy 70 dollar carbs, so if it is the carb, it will gave to wait

post ad in wanted section for used one in the trading post.I get the cant afford thing
too.

 

[zeroskater58]

post ad in wanted section for used one in the trading post.I get the cant afford thing
too.

yeah, it sucks sometimes, but oh well. ill give it a try posting there if i cant get this one working right

 

[merc_man]

so, i got a fuel line from the dealer, and he said that these saws wont accept aftermarket carbs, only walbro or zama, says if its not the fuel lines its probably the carb since its not an oem. is there any validity to this, or is he just trying to sell me a carb?

I got the older 066 but i put a aftermarket carb on it and it works fine. I think he just wants to sell you a carb.

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[zeroskater58]

I got the older 066 but i put a aftermarket carb on it and it works fine. I think he just wants to sell you a carb.

Sent from my SM-G950W using Tapatalk

that was my feeling as well

 

[zeroskater58]

replaced the fuel lines, and it improved the surging a bunch, not smooth, but the surges are less, ill vac/pressure test it next, just wanted to update

 

[zeroskater58]

didnt vac test it, but i found that the little gas line that goes into the carb, its got barbed fittings on both ends, is very finicky about its placement. the way it was positioned it was kinking. after repositioning, its not kinking anymore, and the saw surging is gone, sounds good now both in and out of the cut. thanks for all the help guys!