River Rat's MS460

[Mastermind]

I had no idea about there being a D cylinder, turns out mine is one of them. I can tell what it means in the pics, does it make that much of a difference? Is the only change in the combustion chamber, or are the ports different as well?

I'm surprised you only went through 70' in a month! I was in a test log the other day after putting together a 361 and must have made 8' of cookies. I guess I have too much fun lol.

Two of the "D" jugs here now are not any different than the regular ones in terms of port timing, but there is one that is "special". There is a difference in squish clearance between the "D" and regular jugs though. The "D" style jugs have a smaller combustion chamber, so they have about .014" more squish clearance.

When I get done with them, you won't be able to tell one from the other though.

 

[MustangMike]

Were the Ds early production or in the middle some place? Also, was the one with "better" port timing mfged by a different co? I know numerous Co s made 044/440 jugs, but I don't know that much about 046/460.

 

[Mastermind]

All are Mahle jugs......

The transfers are MUCH higher in the "special" one.

That one is the oldest I think......it was on a 046 rather than a MS460.

The higher the transfers, the more the engine will pollute......EPA is the reason they got lowered.....

 

[Four Paws]

Just curious on the stock numbers...what was the blowdown on the good jug vs. The later EPA version?

 

[Mastermind]

I didn't check the stock numbers.......and blowdown ain't really much of a concern of mine.....but the transfers opened at 116 degrees or so on the "better" jug. Exhaust height was about 101.......so prolly 15 degrees of blowdown VS 20 or so on the newer jugs. (I'm just going by what I've checked on these in the past) I use a measurement from the squish band down to determine my desired port height, that's how I knew the transfers were higher in a certain jug.

I look at opening and closing points.......check this tidbit out.

An overlooked number that is far more important than blowdown is case compression.

If the intake opening/closing point is 80 degrees, and the transfer opening point is 120, then you have 40 degrees of case compression......also known as primary compression. That part of two stroke performance is probably the most critical, and most overlooked point in two stroke theory. Not enough case compression, and you have a lazy spooling turd of an engine.

 

[blsnelling]

Yup. Short blowdown is critical for a hot 046/460.

 

[RiverRat2]

I didn't check the stock numbers.......and blowdown ain't really much of a concern of mine.....but the transfers opened at 116 degrees or so on the "better" jug. Exhaust height was about 101.......so prolly 15 degrees of blowdown VS 20 or so on the newer jugs. (I'm just going by what I've checked on these in the past) I use a measurement from the squish band down to determine my desired port height, that's how I knew the transfers were higher in a certain jug.

I look at opening and closing points.......check this tidbit out.

An overlooked number that is far more important than blowdown is case compression.

If the intake opening/closing point is 80 degrees, and the transfer opening point is 120, then you have 40 degrees of case compression......also known as primary compression. That part of two stroke performance is probably the most critical, and most overlooked point in two stroke theory. Not enough case compression, and you have a lazy spooling turd of an engine.

Does that mean you can fix my newer model lazy less polluting Jug?????

 

[Trx250r180]

Were the Ds early production or in the middle some place? Also, was the one with "better" port timing mfged by a different co? I know numerous Co s made 044/440 jugs, but I don't know that much about 046/460.

The 046 came out much later then the 044 ,if you notice they all have decomp valves on top ,i do not think ks ever made jugs for that saw if that's what you are thinking ,mahle and maybe gilodarni or blank stihl branded ones in the later ones or however you spell it ,lol ,the early 046 had a good running out of the box "D " cylinder like the one Randy is talking about ,but like he said ,he mods them all the same so in the end they all run pretty close

How about crank case volumes ? the 440 is around 1/2 inch narrower than a 460 so there is less air down there moving around ,any thoughts on this ?

 

[Mastermind]

I think the hybrids will never be able to build as much pure torque as a 046. They are more of a high revving hot rod type of saw though.

 

[Trx250r180]

I think the hybrids will never be able to build as much pure torque as a 046. They are more of a high revving hot rod type of saw though.

Exactly my take also ,they feel more like a hot rod ,my 460 i had did not sound as fast but it could be leaned on a little more ,the lighter nimbler handling chassis is why i like them for firewood saws .

 

[Deleted member 83629]

randy how do you measure power in saws by bar hp or ?

 

[Mastermind]

I have no idea.

 

[MustangMike]

Great info guys, thanks, so there is some benefit to the heavier 046/460 for bucking.

 

[GrassGuerilla]

I think the hybrids will never be able to build as much pure torque as a 046. They are more of a high revving hot rod type of saw though.

Would it be a fair assertion to say that a hybrid 044/046 "acts" like an 046 with crank stuffers? Or is there more to it?

Edited for clarity.

 

[Mastermind]

It's a case of there not being quite enough case volume to get all you can out of the 77cc top end in the grunt dept. But for high rpm HP, the smaller case is a good thing. It makes for a high flow velocity engine. I'm having trouble typing what I'm thinking here........I hope I'm making sense.

 

[redfin]

Clear to me.

 

[Trx250r180]

What he is trying to say is if you put the 46 jug on da 44 it will zoom zoom mo bettah

 

[Mastermind]

It will raise the point where it makes the most power. Yeah......that's it.

 

[stankers]

Any chance one of those 460's in the line up is heading to Charleston?opcorn:

 

[Mastermind]

Yes sir.