Al,
You are right, the MS 390 does have a lot of plastic, but so does every other saw just about anybody builds anymore. I think all would agree that modern saws have way more performance per pound than back in the day of the 056 and other big Macs and Homelites.
I hope the following will help everyone understand the marketing strategy for why some STIHL saws are made the way they are. I posted most of this in another forum and had several comments to the effect that now it kind of makes sense. STIHL makes saws considered for homeowner, or occasional use, farm and ranch or semi-pro, and professional use. They all have the same warranty, one year for homeowner and 90 days pro. I honestly believe they all are well designed and good value if you look at return on investment for run time, performance, and just plain fun and ease of operation. That is of course based on proper care and use.
So you have to decide on a price range and how hard you plan to use it.
The breakdown pretty much goes like this:
MS 170, 180, 210, 230, 250, 192, are light duty use. They have a clamshell or engine pan design, called modular, where the crankshaft is pinched between the cylinder and the engine pan, making the engine module, and everything else bolts to the module. The bar bolts into the plastic tank housing. This makes for ease of manufacturing and keeps cost down, so the price is lower at retail.
Here is the engine module for a MS 180 project saw I am building:
The MS 290, 310, 390 are designed the same, but have a heavier crankshaft and are considered more of a mid-range saw. The bar has one bolt into the engine pan and the other into the plastic tank / handle housing. Notice the extended area on the engine pan sticking out, for the rear bar stud:
All of the above mentioned models have an aluminum engine pan, chrome or Nikasil coated cylinder, four open transfer ports, and plenty of plastic holding it all together.
The MS 270, 280 are more of a semi-pro model, with a magnesium engine pan and housing holding the crank in, and the bar, but still a clamshell design. These saws are a newer design with more current engineering in them, and are a great performing saw with plenty of power and performance. I really enjoy running this model. The 290, 310, 390 is a much older design, but has plenty of power and a proven track record. Here is a view of the engine pan on a MS 270 I recently went through:
See how much more material there is, and both bar studs thread into the mag engine pan.
When you move up to the pro models there is a big difference in design, and they cost more money. The MS 260, the older 034 and 036, the newer MS 360, 361, 440, 460, 441, 660, 880 are all pro models, designed for logging or commercial use. Now you have a split magnesium crankcase, that holds the crank, and both bar studs, in a rigid configuration, with the cylinder held on with four screws, and a plastic tank housing and handle assembly. Here is a MS 441 crankcase with the crank and piston installed:
The pro saws have closed transfer ports. The older models have two ports, the 361 has four. Where this all comes together is that the 361 weighs less than a 390, and has more power with less engine size. It is engineered to a higher level of performance, and is a newer design. So if that is the size of saw you are after then is it worth the difference in price to you to pay for a pro saw?
The MS 441 is stratified scavenged, with 6 ports and piston recesses to control the scavenge air coming in from the 2 extra ports, but is still a pro design. You will see stratified scavenging on probably every new STIHL saw coming out in the future. Here is the carb, cylinder, and piston from a MS 441 I just finished up:
Down the road for repair will also make a difference. I can have the piston in my hand in 5 minutes on a 361. It will take a complete teardown, just about to the last bolt, to get the piston out of a modular design. Will that matter if you only cut a cord or two a year? Probably not. But the labor and parts cost to have the dealer install a new piston and cylinder in a modular saw will usually exceed the value of the saw, even on a 390. But a pro saw it usually will not. And a saw used by a pro may get over a 1000 hours on it in a year. So it is worth the repair.
I have friend that actually cut over 50 cords of wood with an 017, which became the MS 170. He did very little maintenance on it and was more than pleased with the use it gave him, and bought two more.
So I guess it all comes down to budget and use. Research the models and decide how big a bar your minimum is and then decide on a pro model or a lighter duty model. But I know for a fact any STIHL when used right will be fun and hold up well.
But probably the most important thing is to buy from a local dealer that will give you good service and support. And if it isn't a STIHL dealer that is OK too, as long it is a good model saw that meets your needs. I just like STIHL the best. Most of the other saw brands are similar in design as well.
Also be aware that the number system does not indicate if a saw is pro or not.
The MS 360 and MS 361 are both pro saws. he MS 390 will be replaced by a MS391.
The handle color doesn’t really mean much either. My 040 and 041 both have black handles, as did nearly all the old saws:
My MS 200 T and the MS 192 T both have black handles, but the 192 has a clamshell modular engine and the MS 200 does not.
Yes the MS 250, MS 390 has orange and others don’t, but who knows what color the next generation of saw will be?
Regarding limiter caps, they are there to keep the user from adjusting too rich. The only adjustment to be made is leaner for altitude.
Here is one being removed:
Always replace them so the screw does not vibrate around. I trim off the little bit of plastic on the side so I can adjust as needed, not within the ¾ turn range they normally give.
So I hope some of this helps somebody here reading this. I know this forum tends to have more pro user types instead of newbies or homeowners, but hopefully the info discussed is of value.
Eddie
