Jacobson 2 stroke.
- Thread starter Sprocket86
- Start date
- Tags jacobson stroke
Jacobsen (NOT Tecumseh) J-321 rated 2.5hp and is one of the smoothest running and best performing (for its size) 2 cycle mills I've owned.
Lose the muffler as they are exceedingly heavy and can get in the way. Slap a small megaphone on it if noise is not an issue.
It appears that you have a diaphragm carb on there. Mine came with a Walbro bowl carb which I swapped out for a Tillotson pumper.
Pto may be an odd-ball size. One of mine measured 0.5625" (9/16").
I was fortunate to find a brand new short block on EBAY which came with a 3/4" shaft.
Worked very well on my MXK yard kart and Fox Doodle Bug.
Pic was taken in summer of 2007.
Jacobsen powered yard kart
Lose the muffler as they are exceedingly heavy and can get in the way. Slap a small megaphone on it if noise is not an issue.
It appears that you have a diaphragm carb on there. Mine came with a Walbro bowl carb which I swapped out for a Tillotson pumper.
Pto may be an odd-ball size. One of mine measured 0.5625" (9/16").
I was fortunate to find a brand new short block on EBAY which came with a 3/4" shaft.
Worked very well on my MXK yard kart and Fox Doodle Bug.
Pic was taken in summer of 2007.
Jacobsen powered yard kart
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Hey thanks for the info Russ. I sent you an email the other day regarding tillotson carbs.
I knew this was a gem when I laid eyes on it and with out a doubt, this is the smoothest 2 stroke I've ever heard run. I was wondering if I could use the carb off this engine on my LB duraforce?
The PTO does look somewhat short and no tapped bolt hole on the end, will have to investigate further. Cool pic btw:thumbsup:
I knew this was a gem when I laid eyes on it and with out a doubt, this is the smoothest 2 stroke I've ever heard run. I was wondering if I could use the carb off this engine on my LB duraforce?
The PTO does look somewhat short and no tapped bolt hole on the end, will have to investigate further. Cool pic btw:thumbsup:
Should work although it may be on the small side of optimal.
Incidentally...
I re-posted my Duraforce powered Fox Doodle Bug on YOUTUBE. Don't know if you have seen it or not.
Incidentally...
I re-posted my Duraforce powered Fox Doodle Bug on YOUTUBE. Don't know if you have seen it or not.
Thanks for the reply's guys and I'm debating if I'm go to cannibalize that edger to make another mini bike power plant. I'm pretty sure the PTO will be the deciding factor.
Do these engines have a cast iron or chrome cylinder and what about the bottom end, needle bearings I presume?
Anybody have any more pics?
Thanks.
Do these engines have a cast iron or chrome cylinder and what about the bottom end, needle bearings I presume?
Anybody have any more pics?
Thanks.
The lack of a tapped PTO will be a problem. I would get it drilled. Mine is tapped and the setup I was going to show you off mine uses that to extend the shaft to fit a clutch.
I'm a big fan of these motors and wondered why these never joined the likes of West Bend, Homelight and McCulloch for choices of kart power plants back in the day. I had some good message board conversations over at Vintagekarts.com about this and long story short while the engine is considered very dependable and very smooth, it just didn't have the power those others had. And the 6.2 cu size would have made it illegal if tricked out to make faster anyway. I think the cutoff was 6.1 believe it or not. At least for the one class it came close to being good for. So we do what we can with these lil diamonds in the rough. It's fun to me to use a motor that is kind of off the beaten path. I have a couple of these kinds of motors that I am fond off. A two cycle Fuji/Robin that I got off a Jacobsen Greens Mower and a 4 cycle Robin Subaru EX21 is another. That Robin Subaru is a beast and I can't believe its not more popular for fun karts and minibikes. I'm gonna show the world what that one can do soon! Mwaaa ha ha ha
I'm a big fan of these motors and wondered why these never joined the likes of West Bend, Homelight and McCulloch for choices of kart power plants back in the day. I had some good message board conversations over at Vintagekarts.com about this and long story short while the engine is considered very dependable and very smooth, it just didn't have the power those others had. And the 6.2 cu size would have made it illegal if tricked out to make faster anyway. I think the cutoff was 6.1 believe it or not. At least for the one class it came close to being good for. So we do what we can with these lil diamonds in the rough. It's fun to me to use a motor that is kind of off the beaten path. I have a couple of these kinds of motors that I am fond off. A two cycle Fuji/Robin that I got off a Jacobsen Greens Mower and a 4 cycle Robin Subaru EX21 is another. That Robin Subaru is a beast and I can't believe its not more popular for fun karts and minibikes. I'm gonna show the world what that one can do soon! Mwaaa ha ha ha
Really, that's pretty cool 
I'm really debating if I should use pursue this further or not. The crank is an oddball 11/16" and is stubby. I was thinking a primary chain to a jackshaft turning a clutch, then to the rear wheel. This way I can increase the stall speed of the clutch witch should help out this 2.5hp 2 cycle power plant during takeoff.
I'm really debating if I should use pursue this further or not. The crank is an oddball 11/16" and is stubby. I was thinking a primary chain to a jackshaft turning a clutch, then to the rear wheel. This way I can increase the stall speed of the clutch witch should help out this 2.5hp 2 cycle power plant during takeoff.
I have one apart and the block in the ultrasonic tank right now.
Ball bearing PTO side, caged needle flywheel side, loose needle mains in a steel race inside an aluminum rod.
It would never be competitive with a 610 even if it wasn't a few CC over 100. Crossflow with the heavy humped pistons just won't rev that high and make power. Add a little compression, square off the ports and bevel the port area edge of the piston to gain a little pop, but I don't see the potential for a killer.
But, the 4 threaded holes on the "bottom" make it easier to mount than a drunken sorority girl.
Checking quench before teardown yesterday.
Ball bearing PTO side, caged needle flywheel side, loose needle mains in a steel race inside an aluminum rod.
It would never be competitive with a 610 even if it wasn't a few CC over 100. Crossflow with the heavy humped pistons just won't rev that high and make power. Add a little compression, square off the ports and bevel the port area edge of the piston to gain a little pop, but I don't see the potential for a killer.
But, the 4 threaded holes on the "bottom" make it easier to mount than a drunken sorority girl.
Checking quench before teardown yesterday.
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