MS460 Magnum- Hard Starting After Storage

[Steck]

I have an early 2000’s MS 460 Magnum with factory .68 main jet. Has opened up exhaust and running max flo filter. Rebuilt the carb with a factory Walbro kit. After the saw sits for a month or two, I have to pull it a good 8-10 times before it pops over on full choke. I believe I have it tuned well and it runs well and has great power in the cut. Am I crazy or is this normal? It should be noted that after it turns over on choke but isn’t running, I can hear a bubbly, squeaky noise like air is being pulled in somewhere. Any suggestions?

 

[Michpatriot]

Carb boot or pulse line would be first on my to check list..but could be seals or crank case gasket sucking... Vacuum\pressure check will tell what you are replacing.

 

[Steck]

Thank you. That’s what I was thinking and makes perfect sense. It feels like the saw loses prime after sitting and has a hard time sucking fuel. After running a while and seemingly running fine, I get a rare blip in acceleration much like the sensation felt when it’s actually running dry. I will start with the impulse and fuel lines. Thank you again.

 

[Steck]

While we’re at it, I’m fairly new to saw repair and every repair is a learning experience for me. How does one perform such vacuum check?

 

[Duce]

Block intake and exhaust and pull vacuum from impulse line or spark plug hole. If saw has decompression, block that also.

 

[Duce]

While we’re at it, I’m fairly new to saw repair and every repair is a learning experience for me. How does one perform such vacuum check?

Mini-vac or similar vacuum pump will be needed, want to hold around 7 lbs.

 

[Loony661]

I run a 460 as my main felling saw and it gets used almost daily. However, sometimes it does sit for a month or 2 depending on weather. With that being said, usually from a “dry start” it takes 5-6 pulls max on full choke to “pop”. Any more than that tells me your saw does have a problem - especially if you are hearing a squeal.. Like those above have said, start with the basics: Fuel and Impulse lines, and new carb diaphragms/gaskets... That’s what gets your fuel up to the carb. Best of luck!

 

[Steck]

Thank you all! Hopefully I get a few hours soon to take a look at it. Not much down time this winter… heating with an OWB and it’s been the coldest winter since I put it in. Lotsa wood

 

[qurotro]

8-10 is normal for saws that sit.. I would even call it good. If the saw is run daily, every cold start is 8-10 that's no good.