MS361 Big Bore Kit Review

[epicklein22]

Damn, Lake is killing it in this thread. I can't stop laughing. lol

Hey stihl041s, I see you down there. Clear your mail box......I still want that 029....

 

[Lakeside53]

What is so different about the cylinder, comparing to an 036? Looks the same. Diff stroke? Sure would be nice to bolt that kit on a 034 Super.

Bore and stroke for 034S and 036 is 48mm X 34mm. What does the 361 have? How about cyl mount holes and case bore? The wheels are spinning in my peanut brain. LOL

lolol... way way different....

 

[Lakeside53]

Damn, Lake is killing it in this thread. I can't stop laughing. lol

Hey stihl041s, I see you down there. Clear your mail box......I still want that 029....

It's the beer speaking.

burp...

 

[superfire]

couple ????

will this strain the bearings? will the oil pump hold up to more torque? also will this kit fit a older stihl ms 360?
thanks for the review Brad

 

[GASoline71]

036/360 are not the same animal as the 361.

Gary

 

[Lakeside53]

will this strain the bearings? will the oil pump hold up to more torque? also will this kit fit a older stihl ms 360?
thanks for the review Brad

The oil pump is non-issue, and in any case it's the same (except stroke) as the 460...

yes, it will put more load on the bearingss, but more importantly with anything that increases the HP, the cooling...

Gary answered the 360 question..

 

[FATGUY]

Hey Brad, thanks for sharing this with us?

 

[Four Paws]

opcorn: HAHAHA.

 

[windthrown]

The 361 vs the 360

The MS 361 was a completely new design from the Stihl engineers, not an updated 360. The 361 engine has four long closed transfer ports compared to the two short closed ports on the 360. The 360 has 61.5cc displacement, and the 361 has 59cc. The 361 also has a different ignition with an advance curve. Emissions on the 361 are lower than the 360, and it gets better fuel economy. The 361 has a tad less power than the 360 (1/10th of a HP). The 361 has a spring mount handle that really cuts down on the vibration, compared to the rubber mounts of the 360. I have run them side by side and the 361 has way less vibration. The 361 is a tad lighter than the 360 as well, but you would not notice it (about .2 pounds more on the 360).

 

[blsnelling]

The 361BB is running. Squish on my OEM ported cylinder without a base gasket is .017". The BB kit was the same, even on all four sides. I don't have a base gasket so I put it together with ThreeBond 1194. Three pulls to pop and three to running. The idle needle was a little lean and idle speed was a little low. It idles well. I let it idle until the cylinder was good and warm and shut it off. I immediately pulled a compression check and it was a solid 150 PSI. I typically see 10 PSI more compression when cold. Plus this engine has seen no revs. Just a few blips of the throttle. My OEM P&C has 175 PSI cold, so maybe 15 PSI less on the BB kit. However, if compression is 160 cold with no run time, that's excellent. Throttle response is instant just like a stock saw. I also might add that my muffler is ported. Running no base gasket and a ported muffler are typical mods the average Joe can do himself, so this should be a fair test.

There was a kink in the assembly process though. The edges of the skirt hit the case and could not make a full rotation. There are indentations in the case where the piston skirt goes at BDC. These pockets are too narrow for this piston skirt as shipped. I decided I wasn't willing to grind on my case and risk metal in the bearings for the sake of testing this kit. Instead I narrowed the skirt. I'm sure that's what will end up being shipped anyway. Baileys is after a bolt on kit with no mods required. You will see in the pictures that the skirt is a lot wider than stock. Even after I narrowed it, it's still a little wider than stock. Diameter wise was VERY close, but it clears. If this were to hit, you would either have to grind the case or shorten the piston skirt considerably. But it clears.

The only other thing is the placement of the decomp valve. It's way off center. So much so that you can't use it. If you push it in, the plastic will hold it down. It would be a simple matter of relieving the engine cover a little if you need the decomp. For most, the solution is to plug it. You don't need it on a 60cc saw.

One little nit picky thing. I think the kit should come with the stud that the engine shroud fastens to. I had to remove mine from my OEM jug.

I might also recommend that the mounting flange be cut about 0.017" thinner. That way a cylinder gasket can be used and end up with a squish of 0.020". I see no reason to have a 0.037" squish. Compression and power would both suffer.

I'll put it through a couple more heat cycles and then put it to work.

1. Stock piston that's been ported = 2.2 oz
2. Stock wrist pin = 0.4 oz
3. Stock jug that's ported 18.4 oz

This is how the stock piston sits down into the case.

Here's the BB piston as shipped hitting the case.

This is how much wider the skirt is.

The solution was to make it narrower.

It now clears.

Overall diameter is close. It's just resting against the case in the back.

 

[blsnelling]

A thin layer of ThreeBond 1194. This replaced 1104.

Baileys ring compressor. Yes, that is a dirty saw you see. Contrary to popular belief, my saws do come off the wall and get used ocassionaly, LOL.

This heat shield is port matched to my OEM jug

The spark plug is nicely centered.

The decomp pressed in.

The decomp pulled out.

 

[gonecountry]

Good job man I was waiting all night for this, figgered it would be sooner or later, Cant wait for more.
And a vid!

 

[Metals406]

Wow! A lot of grinding could be done to match your heat shield!

Wonder what this kit would do all Snellerized!!??

 

[volks-man]

reading with interest.

can grinding the skirt cause any balance issues, i.e. piston heavier in front causing a rocking action at the top and bottom of the bore during travel?

waiting for a test in the wood!

 

[Lakeside53]

Just an observation... it amazes me that a company would spend the money to copy a piston/cylinder and still screw it up. Why would you make a prototype that doesn't have the decomp located corrrectly and a skirt a width that fits the crankcase (ignoring the oval issue)? It's not like this is the first time this has happened... (046BB, 066BB) sure, maybe not all Stihl cases are the same, but that's part of the copy process -get enough target samples to make something that works. The autoparts industry has "plug and play" down... Looks like AS users are beta testers again and again... Even Brad is only a sample of 1.

 

[Jumbo Jimbo]

So this must mean that Brad's 361 can cure cancer even faster than stock 361s, right?

 

[Lakeside53]

So this must mean that Brad's 361 can cure cancer even faster than stock 361s, right?

na.... Chinese manufacture... opps.. Taiwan (maybe), sorry (maybe) negates the cancer cure.

So.. all you guys that hated China in past threads are going to fit these? :greenchainsaw:

 

[Gologit]

na.... Chinese manufacure... opps.. Taiwan (maybe), sorry (maybe) negates the cancer cure.

So.. all you guys that hated China in past threads are going to fit these? :greenchainsaw:

Don't know. Probably not. I have 2 361s and they'll probably still be chugging along after I'm gone. The older one has quite a few hours on it and the compression is still very good.

What kind of gains in performance are we talking here? Or is just a matter of price between the BB and OEM?

 

[epicklein22]

na.... Chinese manufacure... opps.. Taiwan (maybe), sorry (maybe) negates the cancer cure.

So.. all you guys that hated China in past threads are going to fit these? :greenchainsaw:

Man, I was just waiting for you to post once I saw those mods brad had to do to the piston just to get it to work.

Well, at least Baileys picked a good guinea pig. lol Brad should be able to set them straight.

 

[Jumbo Jimbo]

Oh ok I didn't know they were made in Asia (it doesn't matter which country because they all make junk.) But thanks for the information Lake.