Been playing with a MS400C

[Stihl User]

Problems with my 400c - will only run on full choke, as soon as i hit throttle she shuts off

took carb off and cleaned it, there was no noticeable dirt/dust

took muffler off to inspect for scaring - nothing i can see that would suggest scarring

replaced spark plug

i do not have a compression kit to test but it feels no different

fuel in non-ethanol 40:1 synthetic mix

any suggestions???

Thank You

 

[StihlPotlicker]

I was skeptical about this saw, because it's so close to a 462. After using a 661, my 462, and then down to the 400, the lighter weight was easy to feel. Throttle response is insanely quick, and power doesn't feel to be too far behind the 462 (at least for what we were doing).

Already have a Bark Box and Air Cleaner System from West Coast Saw on the way.

Price was $891 with the 20" Sugihara bar.

View attachment 907195

even nicer ported

 

[farmer steve]

Problems with my 400c - will only run on full choke, as soon as i hit throttle she shuts off

took carb off and cleaned it, there was no noticeable dirt/dust

took muffler off to inspect for scaring - nothing i can see that would suggest scarring

replaced spark plug

i do not have a compression kit to test but it feels no different

fuel in non-ethanol 40:1 synthetic mix

any suggestions???

Thank You

Have you done a reset? Only thing I can say to try if you haven't.

 

[Stihl User]

Have you done a reset? Only thing I can say to try if you haven't.

Ok
let me back up a little

saw 1st began problem when my son used it and then brought home for me to fix

initial problem was saw would start run then go high rpm and shut off

So i reset the saw as per Stihl guidelines = i did this 5x to no avail

 

[lone wolf]

@dmb2613

 

[Stihl User]

my CS-590 with muff mod beat out my stock 400c = barely, but finished first thru dry Ash

 

[Stihl User]

Unless someone has any insight i will pull the head for a complete inspection......

 

[Lightning Performance]

Unless someone has any insight i will pull the head for a complete inspection......

It's likely not internal. Junk in the fuel would be my first look. Siphon the tank dry and look for water first. Then go into the injection for cleaning. It sounds like the hung H circut is delivering too much fuel or not enough down low to rev at idol like that. Lean low and rich on high is sure sign something is a muck. Is there a chance the PTO seal is now cooked?
Purple colored clutch or drum seems to lead to seal issues shortly after being cooked from slipping the clutch.

 

[Lightning Performance]

What did you see for pricing currently?

 

[Stihl User]

It's likely not internal. Junk in the fuel would be my first look. Siphon the tank dry and look for water first. Then go into the injection for cleaning. It sounds like the hung H circut is delivering too much fuel or not enough down low to rev at idol like that. Lean low and rich on high is sure sign something is a muck. Is there a chance the PTO seal is now cooked?
Purple colored clutch or drum seems to lead to seal issues shortly after being cooked from slipping the clutch.

Thank you for this and i will check.

i am going to pull the head when the culprit (my son) gets home

Gas was dumped before reset and other

 

[Lightning Performance]

Thank you for this and i will check.

i am going to pull the head when the culprit (my son) gets home

Gas was dumped before reset and other

Check the clutch springs to see if they are still tight. If they are loose dig deeper there. Check the case and jug bolts if you do dig into it more.

 

[sean donato]

You need ro remember it's still a basic carb with the addition of the fuel solenoid. Same troubleshooting as a carb saw.
Actually surprised your 590 out runs it. Neighbor has a 620p and my 400 beats it by a fairly large margin.

 

[lone wolf]

Unless someone has any insight i will pull the head for a complete inspection......

Saturday I had some trigger time on a 400. It had nothing for the 56-68cc saws at the GTG but the 400 was pretty fresh and the others were ported. If a 362 had ran like that when it came out it probably would not have gotten the hate it has. I wonder if @dmb2613 has ran one yet?

Dave is the one who told me about how good they ran and I bought one based on his comments.

 

[lone wolf]

OP have you tried a new Solenoid yet?

 

[Stihl User]

You need ro remember it's still a basic carb with the addition of the fuel solenoid. Same troubleshooting as a carb saw.
Actually surprised your 590 out runs it. Neighbor has a 620p and my 400 beats it by a fairly large margin.

Sold my 590 and now have a 620p with muff mod.

Have not yet tested against the 400c because..........27 year old kid used the 400c

 

[lone wolf]

You need ro remember it's still a basic carb with the addition of the fuel solenoid. Same troubleshooting as a carb saw.
Actually surprised your 590 out runs it. Neighbor has a 620p and my 400 beats it by a fairly large margin.

I cant believe it can out run the 400 sum ting wong.

 

[lone wolf]

Thank you for this and i will check.

i am going to pull the head when the culprit (my son) gets home

Gas was dumped before reset and other

Well if you are going to do all that pressure test it while there

 

[Stihl User]

I cant believe it can out run the 400 sum ting wong.

It was just a second faster but i was not impressed = also it was not broken in yet

It definitely ran better after 20 tanks

Maybe a problem saw off the shelf??? = wouldn't be the first time

 

[lone wolf]

It was just a second faster but i was not impressed = also it was not broken in yet

It definitely ran better after a 20 tanks

Maybe a problem saw off the shelf??? = wouldn't be the first time

What diameter log and were both saw wearing equal chain?

 

[lone wolf]

What diameter log and were both saw wearing equal chain?

Re do on a video with chains being equal.