MS460 starter rope grabs very abruptly

[9ninjas]

When starting my MS460 Mag, the starter rope will grab very abruptly pulling the rope out of my hand. This doesn't happen everytime I pull the rope though. This is noticed if the decomp valve button has popped "up" after she spits, trying to start. I can almost hear like a piston slap when this occurs. If I push the decomp valve back down and pull again, the starter rope might or might not grab again and it might or might not start running. While running, it appears to run fine with good power and idles fine, and sounds good. Only issue seems to be with the starter rope hanging up.

 

[dall]

how are the starter paws on the recoil they may need replaced

 

[Woody912]

I rebuilt an 036 without a base gasket and did not put the decomp button back in, about broke my arm a few times. button back in and all is good

 

[dall]

but he is saying the starter rope may grab or may not grab when he pulls on the rope

 

[9ninjas]

I rebuilt an 036 without a base gasket and did not put the decomp button back in, about broke my arm a few times. button back in and all is good

If I pull it with the decomp button out, then it is definitely harder to pull but does not grab suddenly and try to rip my fingers off as it does when I pull it and it tries to start and grabs and I notice the decomp button "up".
I haven't looked at the start assembly as it doesn't do it on every pull so I figured there wasn't an issue there but if the starter paws are only "grabbing" somehow intermittently then that could maybe cause it.

 

[Woody912]

but he is saying the starter rope may grab or may not grab when he pulls on the rope

mine would basically jerk the rope out of my hand like it suddenly locked up. Loose ignition module could do that but mine NEVER does it when the button is down. only when I forget to depress it

 

[Chainsaw Jim]

It's likely you're just ripping on the cord a little awkward to let this happen. If you pull the rope slowly until the compression locks it before you rip it then you won't even need to use the decomp button. It's a real firm, short quick pull you want to do...not a long "lawn mower like" pull.

 

[JonCraig]

Sounds like something's up with the recoil/starter pawls to me.

 

[9ninjas]

It's likely you're just ripping on the cord a little awkward to let this happen. If you pull the rope slowly until the compression locks it before you rip it then you won't even need to use the decomp button. It's a real firm, short quick pull you want to do...not a long "lawn mower like" pull.

I do that, using a slow pull until the comp locks it, and then a quick short pull, but if it attempts to fire (decomp button pops up) then it just locks up and pulls the rope out of my hand as Woody912 says above. maybe i'm just gun shy on it now as it really does just lock it up and jerks the rope out of my hand. So maybe i'm not pulling hard enough to overcome the compression once it does pop up the decomp button. But it seems like it just started doing this after the saw sat for about 3 months before being started. And no I didn't run the gas out of it before because I kept thinking I would be using it before I stored it for the winter. So used it a few times in the last week and was going to run her dry for winter storage but wanted some help on sorting this out.

 

[9ninjas]

Sounds like something's up with the recoil/starter pawls to me.

If the decomp button doesn't pop up when attempting to start, then it pulls just fine with no lock up (but with some resistance). But while pulling and it does lock up and jerks the starter rope basically out of my hand (or at least make my fingers hurt) I notice that the decomp button has popped up. I have tried to pull through this lock up but it is too hard.

 

[Woody912]

It's likely you're just ripping on the cord a little awkward to let this happen. If you pull the rope slowly until the compression locks it before you rip it then you won't even need to use the decomp button. It's a real firm, short quick pull you want to do...not a long "lawn mower like" pull.

yea, I always pull it up over until it is firm before I yank. Had a 17.5 Briggs once that would lock up, finally discovered the cylinder was filling with gasoline and hydralocking. Would have to pull the plug and drain gas to start it. I realize saw is a 2/c but is this a possibility? Seems like my saw floods easily when starting

 

[Chainsaw Jim]

You probably need the carb tuned better or rebuilt so it starts like it should. You can also keep your thumb on the button while you pull if you ground start it.

 

[Wood Sniffer]

I think it might be a slight tuning issue or perhaps bit of mantines. I've known other saws and a couple motor bikesto do basicly what you are describing. but they wernt stoping per say but going backwards. All had low run time on them so had high comp.. It can bout rip your arm outa socket or kill your leg while trying to through ya over the handle bars.

 

[Woody912]

I think it might be a slight tuning issue or perhaps bit of mantines. I've known other saws and a couple motor bikesto do basicly what you are describing. but they wernt stoping per say but going backwards. All had low run time on them so had high comp.. It can bout rip your arm outa socket or kill your leg while trying to through ya over the handle bars.

brother told me he saw a guy pop a head off a bike although I think that one was leaking water into a cylinder.

 

[HuskStihl]

Try a new decomp

 

[struggle]

when you start a MS460 with strong compression this is normal. IF you start one that has been ported it can be way worse.

The 460 is a saw you have to be committed to when you pull the rope. They are a strong saw and can pop and pull the rope right out of your hand.

IF you are low on arm strength then not much you can do here with this other than try replacing the decomp. If saw fires it will close decomp every time and pull you hand along with it.

 

[JonCraig]

I've never experienced this with my 460, but my Homelite Super XL 925 that just got a new piston & ring comes close to what you describe (and it has no decomp). So maybe you're onto something by suspecting the OP's decomp.

 

[Full Chisel]

when you start a MS460 with strong compression this is normal. IF you start one that has been ported it can be way worse.

The 460 is a saw you have to be committed to when you pull the rope. They are a strong saw and can pop and pull the rope right out of your hand.

IF you are low on arm strength then not much you can do here with this other than try replacing the decomp. If saw fires it will close decomp every time and pull you hand along with it.

Agree 100%, the 461 I ran had very high compression and needed a swift and confident pull to fire it or the handle would rip through. If you continue to have issues, I would recommend starting it on the ground vs. drop starting if that is your current procedure. Especially for cold starts. Personally I don't bother with decomps but on bigger saws they definitely help.

 

[Chainsaw Jim]

Those 460's do seem to have that habit if you don't explode through the pull. After building my first one I was nervous when I first tried to fire it up and didn't pull hard enough. Man that damn thing sure tore my arm off. I thought I phucked the whole thing all up and destroyed it, but I decided to rip the **** out of it and it fired up without kicking. I swear I still feel it in my shoulder to this day.

The decomp button should be replaced if it pops up without the engine firing or popping.

 

[struggle]

If you think a 460 can be tough to start you should try a ported MS880. You need to eat your Wheaties that day.