Overtrained
Not crazy, Stoopid!
Whether it be for a chainsaw or any other small 2 stroke engine. Is this possible and how do I do it?
How do you run a 2 stroke engine in reverse??
- Thread starter Overtrained
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jus2fat
Two Harley Fatboys
My understanding it that it IS possible...though I've never seen it done...why would you want to..??
Also my understanding is that it was more by accident rather than intentional..!!
J2F
First you have to get the ignition to fire about 25 degrees Before Top Dead Center turning the opposite direction. Then, find a way to crank start it 'backwards'.
The recoil starter on my Wards/Hoffco can be used to crank either direction. Mater of fact, it was put together "wrong" when I got him. Had me going for a bit.
The recoil starter on my Wards/Hoffco can be used to crank either direction. Mater of fact, it was put together "wrong" when I got him. Had me going for a bit.
RandyMac
Stiff Member
I saw a guy on a Bultaco trails bike stall on a hill and roll backwards, the motor fired up, the rider had an awkward few moments.
TonyRumore
ArboristSite Guru
It's real easy on a 1976 Yamaha YZ125. A buddy of mine had one and ripped up a big hill but didn't make it over the top....stalled it. It started rolling backwards down the hill, turning the engine over in reverse. He figured if he just gassed it, it would fire up and go back up the hill. Wrong. It fired up all right, but in reverse. That bike shot out from under his ass so fast you wouldn't believe it. I was rolling on the ground laughing.
Tony
Tony
grantwolland
ArboristSite Operative
i found out it is possible by troubleshooting on my geardrive roper built sears H58. i couldn't get it to start after going through it. i could rotate the flywheel by hand and get a nice fat spark but as soon as i put on the recoil and pulled on the handle, no spark! i thought it could be grounding out through the recoil mechanism or something but i found out i rewound the recoil like i do every other recoil after replaceing the recoil spring. however the recoil pulley had provisions for winding the rope either clockwise or counter-clockwise unlike my other saws. after winding it the other way to rotate the engine "backwards" i got my spark back and it fired right up. it uses the tecumseh/power products AH58 engine and a single gear reduction. since there is no idler gear the engine has to rotate in an opposite direction for proper chain turning direction so to acheive this they run the engine in an opposite direction. So i suppose the ignition is the key. My two-stroke 1982 e-z-go golf cart uses a 0 degree timing engine and the direction switch on the cart tells which direction the engine runs to acheive forward or reverse travel rather than an actual transmission.
Overtrained
Not crazy, Stoopid!
First you have to get the ignition to fire about 25 degrees Before Top Dead Center turning the opposite direction. Then, find a way to crank start it 'backwards'.
The recoil starter on my Wards/Hoffco can be used to crank either direction. Mater of fact, it was put together "wrong" when I got him. Had me going for a bit.
So simply cranking the engine in the opposite direction won't do it? How do you change engine timing on something with a fixed keyway?
Overtrained
Not crazy, Stoopid!
My understanding it that it IS possible...though I've never seen it done...why would you want to..??
Also my understanding is that it was more by accident rather than intentional..!!
J2F
Let's just say I want to eliminate the bar/chain on a saw and replace it with a circular saw blade.:msp_wink:
MechanicMatt
Cut Split Stack Burn
SO is that what your building??????
Overtrained
Not crazy, Stoopid!
Trying to get all my facts straight before I make an ass out off myself haha. I have a good idea on what parts to use but it occured to me the engine platform I want to go with will be spinning in the wrong direction.
TonyRumore
ArboristSite Guru
Like this?
Overtrained
Not crazy, Stoopid!
Like this?
I can't afford a XL100 but yes just like that.
Overtrained
Not crazy, Stoopid!
That's got to be geared to move the blade in the right direction. The recoil on the XL100 is in the same position as the chainsaws, spinning the engine in the direction a chain should go.
john taliaferro
Addicted to ArboristSite
The saab 850 cc will run backards with the distributor centrifugal advance reversed , 4 speeds reverse 1 foward and different starter .
well you have to cut a new keyway, do you homework on the location and any decent machine shop can do a keyway.
Alternative way is to remove key, lap flywheel to shaft,install in proper location and make sure you get the nut tightened very well.
Alternative way is to remove key, lap flywheel to shaft,install in proper location and make sure you get the nut tightened very well.
Nitroman
Addicted to ArboristSite
Most two-stroke snowmachines have had engine reversing now for years: Polaris, Arctic Cat, Ski-Don't ect.
zogger
Tree Freak
So, you're building a circular saw with a blower on it! woohoo! "I'm a gonna rip this here 8 feet of 3/4 ply in .5 seconds"!!
beingeasy769
ArboristSite Lurker
Keep in mind, however, that the motor will not last long if you run it in reverse for long periods of time. When you rotate tires, you do not change direction because the material has assimilated itself to that motion. The internals of your motor operate the same. If run in reverse, under load, for more than a brief time, you will have a broken rod our blown bearings.
mitch95100
Saw Nut
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