stroked 046

[klickitatsacket]

What if you could have a stroked out 046. Lets say.... a 2mm longer stroke. That is exactly what you had when you have with the new MS650. Sort of. I looked at these on paper when they first came out and just could not figure out why anyone would want one. Same weight at the 066 and less displacement.
I recently had a customer send me one of these MS650 saws to work over. Apparently his Midwest dealer told him this was the saw to have. After getting it and then running it next to his brother-in-laws' 066 he was quite disappointed and sent it my way for a stage III T conversion.

Here's the deal. I pulled it down to start finessing the works and before I started I ran measurements and checked the timing. The silly thing is an 064 with a poly flywheel or a stroked 046. However you choose to look at it. the really cool thing though is that the port work in them is very similar to the old 064 engines with the big intakes. The transfer timing is way retarded but this has to do with the small vent in the muffler, as it is really tiny and of coarsethe baffles. I just got done porting the cylinder and in the morning I will have it put back together and let you guys know how she took to mods and post a few numbers on here. I really do not expect much more than what I have seen in the 064's I 've done in the past though.

over all this is what I have noticed

Good

Large intake
larger transfers
$200 less than 660
compression release
660 lower end

Bad
retarded transfers
small muffler port
side cut skirts
5.1 cubic inches
660 lower end

Hmmm.....

poly flywheel
660 lower end


Opening up the muffler alone will make a big difference in this saw. Adjusting the transfer timing along with opening up the muffler will be huge. The cost savings along with after market piston cylinder sets from Bailey's and you can be into a 660 a little cheaper. If you wait though and get the big bore kit that is to be out in January then I think you have a bonified buy. The 660 low end does add extra weight and does not impress me near as much as if it was a stroked 460 with the smaller overall size. I am real interested in seeing if one of the old metal flywheels will fit on this saw and if so I want to see how it would benefit the torque band.

I am thinking I might have got caught up in all the hype and book. After looking objectively at this engine; I think I might have found a real gem under the cover. I will let you guys know more in the morning after she hits the wood.

 

[Lakeside53]

The metal and poly flywheels have a different size internal taper fit. The poly was not put on just to improve throttle response as is thought (was there much wrong with the old response before?) but to stop the 066 from breaking the end of the cranks. Stihl handed out a lot of free cranks before beefing up the crank and changing the flywheel to poly.

 

[B_Turner]

The metal and poly flywheels have a different size internal taper fit. The poly was not put on just to improve throttle response as is thought (was there much wrong with the old response before?) but to stop the 066 from breaking the end of the cranks. Stihl handed out a lot of free cranks before beefing up the crank and changing the flywheel to poly.

What year did Stihl change the flywheel to poly?

 

[Kneejerk Bombas]

The metal and poly flywheels have a different size internal taper fit. The poly was not put on just to improve throttle response as is thought (was there much wrong with the old response before?) but to stop the 066 from breaking the end of the cranks. Stihl handed out a lot of free cranks before beefing up the crank and changing the flywheel to poly.

You may be right as to the reason they changed, but the poly flywheel improved the throttle response and the gyroscpoic resistance to turning the saw while spinning high RPMs.
It was about 7 years ago they made the change.

 

[Lakeside53]

late 1995. The big end bearing on the crank was also enlarged. Prior to that it was bascially a big bore 064, and that was too much for the cranks.

 

[BostonBull]

So back to the original post....will this top end fit on an 046 with a modified cover and be a "stroked" 046? I think this would be very nice.

 

[B_Turner]

late 1995. The big end beraing on the crank was also enlarged. Prior to that it was bascially a big bore 064, and that was too much for the cranks.

My 066 was built in 2001, I believe. Any changes since then in the 660?

 

[Lakeside53]

Just cosmetic changes in the plastic (MS styling) and a slightly longer clutch bearing. They has it pretty much all figured out by 2000:hmm3grin2orange:

 

[Lakeside53]

So back to the original post....will this top end fit on an 046 with a modified cover and be a "stroked" 046? I think this would be very nice.

You can't stroke a saw unless you modify the throw of the crank.

 

[chainsaw1]

I am looking forward to seeing of what the power gain is going to be on my saw. Sounds like it might not be too bad. Thanks for moding it for me Dean

 

[tek9tim]

I'm sure you'll be happy.

 

[Four Paws]

You can't stroke a saw unless you modify the throw of the crank.

Yup - and I doubt that the 660 lower end would swap into the 046. That means machine work, and a crank that isn't designed to stand up to the power being produced. Either way you look at it, if one did make it work and complete the 'stroker 046' I think its lifespan would be seriously reduced.

Interesting thread though! Keep us posted Dean.

Josh

 

[klickitatsacket]

the 064 was basically a stroked out version of the 046. Actually it was the other way around because the 064 was first and the 046 was based on the 044. The 046 and the 064 both have the same bore of 52mm with the 046 have a 38mm stroke and the 064 having a 40mm stroke.

Now the MS650 is nothing more than a slightly updated 064. Mostly it went back wards with limiter caps and a restrictive muffler. It didn't even get the new flip caps. I found a vented front cover for an old 064 and the thing bolted right up.

I just got done running this saw after modifying it and here are the #'s:
32" bar and skip chisel chain 3/8" .050
out of the wood: RPM 14,800
in the cut 24" doug fir: RPM 11,300
In the cut I could easily put 50+ pounds of down pressure on the saw with out pushing her out of the cut.
No timed cuts as I was by myself and it was not feasible.

So in the end here are my thoughts. I like her. If you are cost conscious and want a good saw with some grunt then give this saw a look over. Just remember you will have to take the time to open up the muffler and remove the limiter caps to get the most out of her stock. If you are willing to grind a little you can really get some good gains by raising the transfer timing and widening the intake and exhaust. Then there is the after market 066 piston and cylinder sets from Bailey's not to mention the 066 Big Bore kits that will be here in January. The extra weight might seem like a problem to many but with the extra weight you also get a tougher saw and a bigger fuel tank. A little trade off I guess, but for saving an average of $200, I think there are those that could live with it. For the guys who missed the old girl; the 064 is back with a new coat of make up. For those that are looking for an occasional saw with a little grunt and the cost of a MS660 makes you twinge; well you may want to take a look at the MS650

 

[Cut4fun]

Sound like I made the right choice for myself, Buy a used 066 and have it modded and still had money left over. The 650 would not sound like my choice to sink money into. Especially if I had a 066 sitting close by stock.

 

[Lakeside53]

Maybe I'm splitting hairs, but I'm not sure I'd characterize it as an updated 064.. The 650 came out after the 660, and is just a "small bore" 660. It was built to fill some mythical hole in the lineup. It's just like the 341 is to the 361, the 034 to the 036.. etc..

 

[Four Paws]

Dean,

You said raise the transfers - did you cut the cylinder base any? What was stock squish on the saw? What were the stock transfer numbers? Not looking to put you on the spot and try to steal your numbers, but I am just curious where the saw degreed stock. PM me if you want, or post it here...if you don't mind, how much did you increase transfer duration?

Thanks, Josh

 

[klickitatsacket]

I am at home right now but I will post numbers for you on monday. I did not shave the base but instead set the squish to .018. Fourpaws the transfers were raised conciderably.

Andy, The 650 is an 064 that has EPA muffler and carb on it. The only differance is that the transfers are lowered and widened out and the addition of a compression release. Other than that they are almost identical to an 064; Bore, Stroke, Intake and the Exhaust ports are identical. Even the 064 muffler bolts up to it. If I were to put an 064 top end on a MS660 you could not hardly tell the 2 apart other than the compression release.

 

[Lakeside53]

I am at home right now but I will post numbers for you on monday. I did not shave the base but instead set the squish to .018. Fourpaws the transfers were raised conciderably.

Andy, The 650 is an 064 that has EPA muffler and carb on it. The only differance is that the transfers are lowered and widened out and the addition of a compression release. Other than that they are almost identical to an 064; Bore, Stroke, Intake and the Exhaust ports are identical. Even the 064 muffler bolts up to it. If I were to put an 064 top end on a MS660 you could not hardly tell the 2 apart other than the compression release.

A 064 top end won't fit on the 660 as the cylinder base is different.

As I said, splitting hairs, but if you look at the IPL, they just took the latest model 660, put a small bore on it and made few cosmetic changes. The stroke on the 650 and 660 is the same (as you would expect with the same crankcase), just the bore changes. It was only made two years ago and is not based on the MS640. The 064 and 066 used different crank cases... The result may be similar, but its definitely based on an MS660. It even has the same cylinder base as the 066 - the 064 /640 doesn't. Not sure what relevance the muffler has - apart from the very early year(s), 064 all took the 066/66- mufflers and fronts.

 

[klickitatsacket]

let's slpit some more hairs. Wasn't the 066 originally based on the 064 and then redone to fix problems? Any how; I do agree that the 064 and the 650 are not the same critter but in the end you basically have the same saw when it is all said and done. :deadhorse:

 

[Lakeside53]

Yes, the 066 was originally a big bore 064 (with different cylinder mounting), and the early versions had several problems that got mostly fixed when they changed the crank and big end bearings. The 064 and 066 stayed as separate production from the beginning and over 12 years slowly diverged even more in component selection (flywheels, coils, brake handle systems - why??? etc etc) - the 064 eventually becoming the MS640 (not released in the USA). That production ended last year, and he replacement was the "small bore 660". Stihl finally figured out the trying to make "different" products with different parts just wasn't economically viable..