HS50 Questions

[massacre]

Hello,

I am kind of a new with these HS50 engines, I still can't believe it's a 5hp from the size of the engine and the weight lol.
Motor has compression and spark, other than that I know nothing about it, I just bought it today.

My questions are:

Are there any performance parts like billet rods/flywheels readily available for these HS50s? I was thinking of taking the governor out and installing billet rod/piston/flywheel. Will the cast crank take much abuse? Are there aftermarket cranks available for these?

I noticed the intake manifold looks like a periscope, can I just build my own straight intake and then put like an 18mm Mikuni on it with a remote tank?
Is there a HP/TQ threshold with these blocks? They are awfully small and light for their size and I'm guessing it's because the castings are thin. Any confirmation on this? Is there a thread that explains this? I am searching now but mostly getting "H50 vs HS50" type threads, haven't found one yet that lists any performance parts or even factory parts upgrades if there are any.
I'll keep looking in the meantime, thanks in advance for any help! Any advice, just let it fly

 

[massacre]

I found a thread with a link to an ARC billet rod, still looking for flywheel/piston etc.

 

[David wulf]

Your not going to find a billet flywheel, not made by anyone. The OHV 5.5 Arc rod fits , and if your lucky you can find a dyno cam for it .
I've got one that has a little done to it . It's got the rod and a 255 dyno cam . Stock piston and flywheel, the intake port has been reshaped with epoxy and running a clone carb .

 

[massacre]

Wow thanks for the response, your engine looks great!
I noticed your crank is tapped, mine is not. I should probably do something about that lol. I don't want to soup mine up too crazy but I do like the security of billet parts VS stock stuff.
I plan on making my own intake and exhaust.
I will keep an eye out for a cam, who makes valve springs?

 

[ole4]

Isky can regrind your cam (expensive) and supply springs. Also on ebay you can get this cam.

Tecumseh Dyno Cams Camshaft 245 Go Kart Racing Parts U12 | eBay

 

[massacre]

Thanks for the responses guys! I appreciate it

 

[massacre]

Was wondering what year this engine is, is it a 1976?
Tag # is
HS50-67003
31030

Located on a small tag on the PTO side, not stamped into the shroud like my H60 or on a sticker like my H35. I think it will run off ether, might fire it up just to see then start tearing her down.
Thanks guys for any help!

Would post pics but my phone is broken

 

[markus]

Its a 1973. you may find an aluminum flywheel on it, if you do you may want to ditch it for the steel version wheel for that engine.

 

[massacre]

Its a 1973. you may find an aluminum flywheel on it, if you do you may want to ditch it for the steel version wheel for that engine.

Thanks Markus.
Wow, how come the aluminum flywheel is bad news? Is it a bad casting?
I'm kinda on the fence about dismantling the motor here at home. All my good tools are at work lmao. Motor has broken studs/bolts where exhaust goes. I'll have to address that at some point.

 

[markus]

Thanks Markus.
Wow, how come the aluminum flywheel is bad news? Is it a bad casting?
I'm kinda on the fence about dismantling the motor here at home. All my good tools are at work lmao. Motor has broken studs/bolts where exhaust goes. I'll have to address that at some point.

I don't know if there is physically anything "wrong" with them, but tecumseh did discontinue them rather quickly and went with the steel and removable plastic fins. It was probably a cost cutting measure overall but it made for a stronger and actually serviceable wheel.

If you compare them side by side they weigh the same so there is no advantage there, but if you were to say drop the bike and indent the shroud/recoil the aluminum fins would get damaged etc.. The steel version, the fin section is plastic and could be replaced. It should in theory handle higher rpms better. The disadvantage on the steel wheels I have found is magnets are glued on, I am finding magnets will come loose easy after 35 years so I find myself testing the strength and usually always re gluing them on before the wheel goes back on an engine anymore to avoid any further problems for me or others.

I only suggest maybe changing the wheel in your case if it is AL because your looking into building it up a little and running it harder than normal, I never seen a damaged aluminum one come off a standard engine or anything like that though.

Have fun with it, I found 2 early HS50's parts engines in the past 2 months that I am trying to save what I can from. The first version blocks are slightly different as they have a threaded exhaust port, and a few minor casting changes. I am hoping and can restore at least one that will be true/correct recreational version out of the 2, they were both true mini bike engines though, so the bores are worn, unlike snowblowers where they don't get the abuse and dirt run though them like the MB/kart engines did usually.

 

[massacre]

The first version blocks are slightly different as they have a threaded exhaust port, and a few minor casting changes.

Wow Markus, thanks so much for the information!
My HS50 does have a threaded exhaust port, and the port is on the right which is opposite of an H35 I have sitting here.

I removed the intake manifold earlier today, there was a bunch of black rubbery stuff like RTV but still sticky. It was inside the intake port, I thought it was to make an intake-to-block gasket, maybe some melted into the port. I can see that the port has a serious D shape, I might weld that up and try to straighten it a little. I want the governor gone, it's just needlessly complicated for what I plan to do. I have no beef with a cast iron flywheel, that motor seems pretty small so a decent sized flywheel is prob better anyhow.

 

[markus]

Yea I want to fill the intake too like Ole had done in the past as I want to use a Dellorto ua19 for the one I am doing for my Trail Blazer. But I have to lock down a remote tank setup in order to do that first (to get the fuel flow). It would just be easier in the long run to have that port pretty much match an HS40. People make gaskets out of interesting things, I swear someone used an innertube for a gasket on one engine I redid :laugh:

 

[massacre]

So I started disassembly of this engine tonight, got to the flywheel and had to pause there as I don't have an impact here at the house at the moment. I don't want to jinx anything but none of the bolts broke coming out yet lol. There was definitely a mouse living in the shroud lol.
There is a ton of endplay in the crank(at least it seems that way to me) but other than that - it had compression and spark and spun over pretty good.

 

[ole4]

is this a magneto engine or external coil?

 

[massacre]

This engine has points and condenser and the magneto (i'm assuming) is behind the aluminum flywheel. I was able to get the flywheel off by prying slightly with a screwdriver and lightly tapping the crank with a hammer. Just kept turning the flywheel a little and tap tap tap, turn, tap tap tap and eventually it came off. In fact everything came off real good, couple of the side cover bolts were a little tight but that's it. The bore had a ridge that I was able to remove with a scotchbrite pad to get the piston/rod out. The crank journal looks awesome, going to get a rod for it.

Here's a couple pics during disassembly, I didn't even drain the oil just kept the motor at an angle and drained it after removing the side cover. Didn't spill a drop, just got lucky I guess lol

Oil looked a little sludge-ey and kinda sparkly too and grey, I'm guessing prob from the bore or piston skirt, or the cam/main journals, you can see this at the bottom of the cover.

And down to the bare block.

I am thinking of porting this intake port a little bit it is real funky it is round on 3 sides but then has a teardrop in one corner. I was thinking about welding up the teardrop and making the port completely round. Would this increase velocity or flow, or hurt it?
How are people cleaning these blocks?

Also this engine has that light green color. What was the name of the company that made the lawn equipment that the green engines came on? Also, I would like to put this back to kinda stock appearing but am not crazy about the light green color. What other colors were offered by Tec for these engines?

Thanks for any help you can provide, it is much appreciated.

 

[massacre]

Well so much for that engine.
It had broken exhaust studs, they were protruding some, enough to get a couple nuts on them. MIG welder would not work. TIG welder worked but then they just snapped off flush. Added more filler metal to bring the stud out enough to get some vise grips on, then heated block with a torch.
Torch was too hot, ruined surface of block in a couple places so I just threw it in the trash. I'm not machining all these surfaces on a $25 engine.

So now I have a complete 1973 HS50 except for the block lol. I was thinking of putting a pipe in the exhaust port and then weld a flange onto that.
If the surfaces can be saved I might do that.

 

[FirePowerMinis]

Well so much for that engine.
It had broken exhaust studs, they were protruding some, enough to get a couple nuts on them. MIG welder would not work. TIG welder worked but then they just snapped off flush. Added more filler metal to bring the stud out enough to get some vise grips on, then heated block with a torch.
Torch was too hot, ruined surface of block in a couple places so I just threw it in the trash. I'm not machining all these surfaces on a $25 engine.

So now I have a complete 1973 HS50 except for the block lol. I was thinking of putting a pipe in the exhaust port and then weld a flange onto that.
If the surfaces can be saved I might do that.

Exhaust port is too big any way. You can thread a pipe in, leave some sticking out, slip your pipe on the stub. A neck-down piece will get you back to decent size.

 

[massacre]

Thanks!

 

[massacre]

Is a 67028 block going to work with all of the parts from a 67003? Seems like they are close in number and visually they look the same or close enough. Can anyone confirm?
Thanks!

 

[markus]

Is a 67028 block going to work with all of the parts from a 67003? Seems like they are close in number and visually they look the same or close enough. Can anyone confirm?
Thanks!

Yes, if the other engine is later than 73 it will be the updated version most likely, so it will not have a threaded port in the exhaust (just the flange mount) and there will be a bung for a bracket mount that will hold the fuel line away from the flywheel on it

early version on the left, later on the right

Its kind of like the aluminum flywheels found on the early ones, you dont see the part number change for them in the listings, they just seemed to update the parts and make the others obsolete. They ended up makeing a flange with a threaded insert on it for a screw on muff instead of threading the blocks.

From what I have seen you can use even a late electronic ignition block and I would not doubt that possibly a new replacement block might even have the electronic ignition provisions on it (you just cant use those parts with the early shrouds, flywheel, cranks, etc... The late ones will have the mount points for the magneto, but sometimes the will have to drilled and tapped.