diston chainsaw

homelite360 · Feb 27, 2002

i came across a diston DO-101 one man saw. the thing is a monster. i got it freed up this morning and started to tear into it. the more i tore into it the more my head started to hurt in the line of what were the engineers thinking. for starters it has 5 rings all stacked on each other. there is just one ring groove and it is about 3/8" wide and all of the rings are in there. then i pulled to cover to the gear case off and saw more gears than i could fathom. there 5 gears all together. 2 for the drive, 1 for the fuel pump, 1 idler, and a gear driving the carb. yeah the carb is driven by a gear. i had to stop for a few minutes on that one. it turns out that there is a mini turbo built into the carb. there was also a hand clutch on the thing. it is the oddest saw i have ever tore apart. here is a pic of the mini turbo

Methoss084 · Feb 27, 2002

Gotta love those Mercury engines, Wanna sell it?

homelite360 · Feb 27, 2002

nope i am going to hang on to it. it has given me so many headaches already it is not funny. now i understand you have one of your own. what color is it suspose to be. mine has a orange cover for the bar and sprocket and the rest is that grey. if you have any other expierences with them let me know cause i am venturing into unfamiliar ground. this is the first one of this type i have ever seen. i bought it for 45. i think i got a good deal what do you think? here is a full pic of mine

McC · Mar 2, 2002

I actually got mine to run, but the seal on the shaft of the "turbo" leaked so bad, it would fill the gear box with fuel in about a minute or two of running. The spring in the rewind broke this past summer and I haven't touched it since. I have thoughts of adapting an HL carb to it somehow, but I'm not a machinist, and thats who it will take to do that. The primary fuel pump is such an overkill, it pumps more fuel in a minute than that saw could use in an hour.

homelite360 · Mar 3, 2002

tell me about it the fuel pump being over kill. that saw suppries me cause all of the seals are like brand new in it. i couldn't get over it. every bearing and seal is in such good shape it is not funny. it makes me wonder if soemone went through it and rebuilt it some time in the past 10 years and then set it up for storage and it had just enough rust in the exhaust port to make it so it would not pull over with the recoil. i grabbed hte fly wheel and it freed right up wiht no problem. i have been thinking about building adapters for soem of my old macs so that i can use the hl's.

Methoss084 · Mar 3, 2002

I fired mine up about five years ago, fogged the engine for storage added a nice thick coat of turtle wax and hung it up on the wall with the rest of them. No time to play with it yet, got to many saw restos ahead of it. But, I can tell you that the Orange paint is original (cool color) for the DO-100, I'm not sure about the DO-101. Mine has a weird bar and chain combo where as the chain actually runs on the outside of the bar, the bar is about 6"wide and 20" long and the teeth on the chain resemble 3/4" harvestor chain. Most of the exterior hardware is wire tied together ie. aircraft style. It also has a stainless steel pull cord. I have not torn into it yet but will get to it in the next year or so. If you guys come across any disassembly gremlins let me know.

Thanks Josh.

McC · Mar 3, 2002

I had a pretty good thread going in June or July about this saw. Once I found a coil for the bendix scintila ign. I got great spark. Then I ran into the fuel problem. A couple years ago, an old timer saw me with the saw at a steam and gas show, he said "there's gremlins in those saws" so it's funny Josh asked about gremlins. I think he was refering to the fuel system. He saw me this summer as I was struggling to keep this saw running, have to hold it wide open all the time or it would flood and he said, "I told you there's gremlins in those saws". It just takes a lot of analizing to figure out what every thing does. The primary fuel pump is simple enough, it's just a small version of an automotive fuel pump. It pumps the fuel to the Stromberg carb and "bendix aviation" fuel pump. There is a return line to the tank from the bendix pump, that is where I believe my problem is. Instead of returning to the tank, my fuel blows by the o-ring seal on the shaft of the turbo and dumps into the gearbox. As for color, I think the early ones are all orange, and the later ones are silver with some orange such as the side plate. I have a couple 101's that are all orange, and a silver one, it has a later serial #. The chain that runs outside the bar is from the early version too. When running, this engine sounds a lot like an outboard, no surprise.