Project Stumpbroke MS361

[Stumpys Customs]

I've got an answer to a question that a friend of mine asked me. Will a modified 361 cut with a stock 460? One way to find out.:msp_biggrin: He sent me his 361 that already had the muffler modified by me. Then sent me is Bone stock 460 to get our answer.

I'll go through the build up of the 361 & make ya'll wait for the results.

This is what I started with. As I mentioned the muffler has already been modded. I wish I had a baseline vid of it with a stock muffler to show the overall gains between completely stock and modded, but it wasn't untill after I had the saw done that I remembered I had a stock muffler in the storage shed.:bang:

And the muffler modded baseline video running a 28" 3/8 full comp and 7 pin rim in some red oak.
[video=youtube_share;fJpCjtdHsvI]http://youtu.be/fJpCjtdHsvI[/video]

 

[Adirondackstihl]

:matrix:

 

[RiverRat2]

it's gonna be a long day!!!! Just sayin!!!

 

[Stumpys Customs]

Of course the squishband had been machined & the base cut to get the squish to .022".

 

[Stumpys Customs]

Here's the finished product on the port work.

All pretty standard stuff. :msp_biggrin:

 

[cutforfun]

looking good, the saw looked good pulling the 28 incher with just a muffler mod(wonder how a mm 261 would do:jester are you going to mess with the timing, i have been going back and forth weather to do it on a stock saw or not:msp_confused:

 

[hqv]

opcorn:opcorn: Watin' for moar. ;]

 

[Stumpys Customs]

I did upgrade to a bigger carb. I ended up using one off of a MS390. I started out using one off of a MS460 but it had idle issues the same as the 361 I have for myself. Once I installed the 390 carb all issues were gone on both saws.

There are few minor mods that need to be done to the 390 & 460 carbs to use them on a 361. The choke shafts, and both covers need to be swapped also an impulse passage needs to be drilled into the body.

I use both of the covers off of the 361 carb (Right)
note: pic was take after the choke shaft had been swapped.

This pic shows the difference in the venturi size.

These pis show the passage that needs to be drilled for the impulse line

Other than that it is a direct swap.

 

[Stumpys Customs]

looking good, the saw looked good pulling the 28 incher with just a muffler mod(wonder how a mm 261 would do:jester are you going to mess with the timing, i have been going back and forth weather to do it on a stock saw or not:msp_confused:

If you are talking about the ignition timing, I did advance it 5 degrees. The port timing was also altered a lil bit.

 

[Stumpys Customs]

I dug up some pics of how I gut these mufflers.

The outlet on the muffler in this pic is smaller than the one that's on this saw.

 

[Stumpys Customs]

Well that's about all the pics I got. I guess I throw in some vids. That's what ya'll are waiting for anyways.:msp_sneaky:

Stock vs modded vid
[video=youtube_share;4JKOVHC3cSk]http://youtu.be/4JKOVHC3cSk[/video]

 

[Lignator]

looking good!


does the 361 have a limited coil? if so, will it be getting an unlimited coil?

 

[Stumpys Customs]

Now for the ported 59cc VS stock 77cc vid

[video=youtube_share;tmBg1kCDeBg]http://youtu.be/tmBg1kCDeBg[/video]

 

[Stumpys Customs]

looking good!


does the 361 have a limited coil? if so, will it be getting an unlimited coil?

Thanks,
It's unlimited.

 

[blsnelling]

Looks to me like the 361 gain 3 seconds in a 30 second cut to equal the 460.

 

[Stumpys Customs]

Looks to me like the 361 gain 3 seconds in a 30 second cut to equal the 460.

Something like that. :msp_smile:

 

[nmurph]

Looks like a 5-6 second improvement ~20% gain over a MM saw.


Is that the stock oiler and does it put out enough oil for a 28" bar?

 

[blsnelling]

361 MM = 30
361 Ported = 27
460 = 27

 

[Stumpys Customs]

Looks like a 5-6 second improvement ~20% gain over a MM saw.


Is that the stock oiler and does it put out enough oil for a 28" bar?

Just the stock oiler. It oils just enough to make a few cuts, But I wouldn't want to work it all day with a 28" unless I hated the bar & chain. The owner usually runs a 18" or 20" I believe so it'll be fine.

 

[woodgrenade]

Hey Stumpy,

Where does that passage terminate for the impulse line? Just a few mm into the body of the carb? Also, how did you go about swaping choke shafts? Simple unbolt one and bolt up the other?

Thanks, great job and a good read.