just picked up this cool engine

[evanfrucht]

hey everyone. i just picked up this engine up along with a 1968 3hp briggs. its complete although the seller did crack the original little 90 degree air filter adapter for the carb by dropping it he said. bummer but looking for a new one or i could fix mine probably. anyways heres the pics.

engine # : 112573 (on little tag behind carburator)
other number on the block is 203470

i took pics of the air filter to carb 90 degree elbow/adapter that is cracked. im looking for one! i'm going to try to jb weld it the crack up but really want to find one

 

[evanfrucht]

does anyone know where i can find more info on these engines?
i want to build a custom gokart or minibike around it

 

[deezildennis]

does anyone know where i can find more info on these engines?
i want to build a custom gokart or minibike around it

May try joining Smokstak and see if one of the 2 stroke guys can help you out.

 

[lawn-boy biker]

Jacobsen model j-321 @ 2.5HP. Sometimes they are mistakenly identified as a Tecumseh or PowerProducts.
One of mine is powering a Fox Doodle Bug.
Your PTO may be unusable for anything other than its original intent.
Take off that pulley to see what you actually have.

 

[evanfrucht]

Jacobsen model j-321 @ 2.5HP. Sometimes they are mistakenly identified as a Tecumseh or PowerProducts.
One of mine is powering a Fox Doodle Bug.
Your PTO may be unusable for anything other than its original intent.
Take off that pulley to see what you actually have.

ok, if the shaft is an odd size i'll probably attempt to just make my own sleeve or something. it looks like it may be 3/4 inch and thats what im hoping. i've seen some pics of a few engines identified as 321's but mine doesn't look exactly like any other ones i've seen on this site. it has a bigger gas tank and is just a little different. it also doesn't say 321 anywhere on it. what makes you think mine is a "j-321"?

 

[lawn-boy biker]

what makes you think mine is a "j-321"?

I don't think it, I know it.
Mine came off of an edger and the label clearly stated it was a j-321.
My 2nd one came off an old reel mower which was not usable as it had a splined shaft to turn a gear reduction unit.

The j-321 is very common on snow throwers and are painted black. The orange ones (such as yours) are somewhat earlier.

I do not use the original carburetor as it is far too restrictive. I opted for a Tillotson chainsaw carb.
Original carb is good for utility purposes and not for gokarts or mini bikes.
If you are planning to use a centrifugal clutch, the muffler has to go away as the clutch will not fit otherwise.

 

[evanfrucht]

ok. thank you very much for the info. i was just going off the engine number which i'm finding doesn't help much for identification purposes. i sent an email to the jacobsen company looking for more info on the engine but i'm not sure they will even get back to me. based on a few pictures i think my engine may have come off an estate mower... also it's just my wild guess but since the engine number is 112573 my engine may be from 1973?

....anyways, i was able to get the thing running. i cleaned out the gas tank and carb, tinkered with it a bit and it now runs ok. the other good news is that i took off the pulley and was very happy to find a 3/4 inch shaft... pretty convenient considering i already have a 3/4 clutch in my shed i've never used.

i like your idea of using another aftermarket carburetor to let the engine run at its full potential... although my engine seems to be running pretty powerfully since the carb was adjusted. do you remember exactly what kind of carb you bought, i searched "tillotson chainsaw carb" on google and didn't find a carb like the one in your picture.... i found this on amazon and was thinking of trying it, what do you think? https://www.amazon.com/CARBURETOR-T...sr=1-1&keywords=two+stroke+carburetor+3hp#Ask

i'm going to post a video of the engine running as soon as i can figure out how.

also did you customize your muffler using part of the original one?

 

[lawn-boy biker]

...do you remember exactly what kind of carb you bought, i searched "tillotson chainsaw carb"...?

I used an hl239b (used on Solo chainsaws) which I originally purchased on Ebay about 10 years ago and is NLA.
Any carb with a .750 venturi (or less) should work.

did you customize your muffler using part of the original one?

Yes, but never used it.
Again, a centrifugal clutch may not fit with original pipe in place.

 

[evanfrucht]

first try

[video=youtube;B6aW0DQxBLc]https://www.youtube.com/watch?v=B6aW0DQxBLc&feature=youtu.be[/video]

second try with carburetor tuned a little better.
there is some sort of mechanism in the throttle linkage that constantly moves the throttle (i've never seen this before and am not familiar with two-stroke engines.... my guess is that this is just how the carburetor works)

if anyone could explain what i've described better that would be great. i took a close up of it on the video below.

[video=youtube;FaJMX6kST0U]https://www.youtube.com/watch?v=FaJMX6kST0U&feature=youtu.be[/video]

 

[Outlaw Ace]

That lever moving the throttle is the governor linkage, it keeps the RPMs under a set limit.

 

[jdblood202]

I don't think it, I know it.
Mine came off of an edger and the label clearly stated it was a j-321.
My 2nd one came off an old reel mower which was not usable as it had a splined shaft to turn a gear reduction unit.

The j-321 is very common on snow throwers and are painted black. The orange ones (such as yours) are somewhat earlier.

I do not use the original carburetor as it is far too restrictive. I opted for a Tillotson chainsaw carb.
Original carb is good for utility purposes and not for gokarts or mini bikes.
If you are planning to use a centrifugal clutch, the muffler has to go away as the clutch will not fit otherwise. View attachment 98913

I have a question, I'm also trying to rig up a Jacobsen motor for a mini bike. Did yours have the governor arm? If it did, what did you do with it? I didn't see it in the picture.

 

[lawn-boy biker]

Did yours have the governor arm? If it did, what did you do with it? I didn't see it in the picture.

Governor and associated linkage will not operate with anything other than the original Walbro carburetor and were therefore removed and summarily disposed of.

 

[jdblood202]

Ok, I gotcha. I'll have to remove mine. I have this carb I'm going to try. It's from a 2 stroke clinton.

 

[evanfrucht]

yes, my engine does have the governor linking in place, the engine is completely original. you can see it moving the throttle half way through the second video. i didn't even know what it was at first. i noticed it does work in conjunction with the original carburetor in a unique way.

 

[jdogg]

ok, if the shaft is an odd size i'll probably attempt to just make my own sleeve or something. it looks like it may be 3/4 inch and thats what im hoping.

If the shaft ends up being too short for a clutch you can still use a gear to jack shaft assembly.

 

[evanfrucht]

If the shaft ends up being too short for a clutch you can still use a gear to jack shaft assembly.

thanks for the response. luckily my shaft is 3/4 but it is kind of short, the depth of my clutch matches up with the shaft as i remember. also, there's some unusual markings and grooves on the PTO that could possibly make it difficult to secure a clutch there... good thought about using a sprocket and jack shaft if it doesn't fit, i thought that could be a good option. i also noticed another thread discussing a clutch on the jackshaft and it works well apparently.

 

[jdogg]

thanks for the response. luckily my shaft is 3/4 but it is kind of short, the depth of my clutch matches up with the shaft as i remember. also, there's some unusual markings and grooves on the PTO that could possibly make it difficult to secure a clutch there... good thought about using a sprocket and jack shaft if it doesn't fit, i thought that could be a good option. i also noticed another thread discussing a clutch on the jackshaft and it works well apparently.

:doah: Yes I forgot to mention clutch mounted jack shaft....I will need to do this on one of mine.

 

[JohnnyTillotson]

I did one up and put it on a tiny ex-electric pocket bike. It is now The Minioncycle. Son likes Minions, what can ya do? I was very attached to that engine. I like the quirky ones. I have a detailed shop manual in electronic form if anyone needs me to email it.

[video=youtube_share;fu8EW7Db8eU]https://youtu.be/fu8EW7Db8eU[/video]


They aren't very strong motors as far as pulling full grown adults around though. And that tiny PTO needs to be extended for a clutch. Mine uses an outter sleave.