HS40 convert to lighted

copyman

Well-Known Member
#1
Hi, Hoping Markus sees this but appreciate anyone else who can help.
I bought this HS40 “internal points” engine. Seller is a guy I've bought from before. He said this engine came off a Rupp. Since it was black with slanted intake and mini bike throttle setup, exhaust I took his word. It has the new style throttle that is factory riveted on and had the silver foil rectangle decal which makes me think it’s a later model (1982)? Model #55515H, Serial #2070B (stamped on top of blower housing). Engine is apart now and want to convert to lighted. I can get the stator with the 2 lighting coils and aluminum flywheel with the recessed magnets for HS40 but after reading some posts on here about different flywheels not sure what I need? Attached some photos to help identify. 1st pic is before I took apart (sorry only before pic I have), the rest of the pics are same engine apart and painted white. The decal pic is what was on black engine when I got it.
Thanks for the help
 

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#3
If you’ll get on parts tree, unless you have a parts manual, they give you a break down….look under say engine 2?…..

a Tecumseh parts manual will give you different applications for different motors….numerous breakdowns…they even have a pink section that Lists mini bike specific engines and the specific parts used on those motors…..
 
#5
That looks like a big block flywheel….the hs40 will still be aluminum I believe with the magnets embedded in the flywheel…..but I’ve been wrong on so many occasions…..
 

copyman

Well-Known Member
#8
Thanks guys for the replies so far,

Just looked and Parts tree shows this engine as having external ignition on main parts diagram and also a points version on diagram #3. The lighted diagram show the external engine using a complete round coil. This must of been when they were converting to external ignition and made 2 versions of engine, one with points. Now really confused.

Also heard from a friend and he thinks I need a cast iron flywheel with the magnets glued all around inside of flywheel (like Triley posted but smaller for the HS40) to make engine I have lighted. Maybe same FW the HS50 lighted engine uses?

The guy who has the HS40 stater (see pic below) also has the aluminum FW with recessed magnets as in Skipp's pic. Was going to buy both but now not sure.

Thanks again
 

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Triley41395

Well-Known Member
#10
Thanks guys for the replies so far,

Just looked and Parts tree shows this engine as having external ignition on main parts diagram and also a points version on diagram #3. The lighted diagram show the external engine using a complete round coil. This must of been when they were converting to external ignition and made 2 versions of engine, one with points. Now really confused.

Also heard from a friend and he thinks I need a cast iron flywheel with the magnets glued all around inside of flywheel (like Triley posted but smaller for the HS40) to make engine I have lighted. Maybe same FW the HS50 lighted engine uses?

The guy who has the HS40 stater (see pic below) also has the aluminum FW with recessed magnets as in Skipp's pic. Was going to buy both but now not sure.

Thanks again
I definitely don't know much about lighted motors but I can tell you that my flywheel and coil/stater are from a 1982 H50 troy built tiller Screenshot_20211012-211623_Facebook.jpg Screenshot_20220801-081357_Gallery.jpg
 

copyman

Well-Known Member
#11
Thanks for taking the time to post those pics. Is that an H50? Or do you have model & serial #

The coils on the HS40 I believe are on one side like the attached pic? This is the type I can get.
 

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markus

Well-Known Member
#12
Thanks guys for the replies so far,

Just looked and Parts tree shows this engine as having external ignition on main parts diagram and also a points version on diagram #3. The lighted diagram show the external engine using a complete round coil. This must of been when they were converting to external ignition and made 2 versions of engine, one with points. Now really confused.

Also heard from a friend and he thinks I need a cast iron flywheel with the magnets glued all around inside of flywheel (like Triley posted but smaller for the HS40) to make engine I have lighted. Maybe same FW the HS50 lighted engine uses?

The guy who has the HS40 stater (see pic below) also has the aluminum FW with recessed magnets as in Skipp's pic. Was going to buy both but now not sure.

Thanks again
That setup will not work with the flywheels that were made for your engine (large taper). even if you found one, The airgap/size or stator plate is different. Finding lighted parts for a late model points engine is a very tall order, not much in that timeframe that called for it. so when it comes to small frame and that particular coil setup (12v 3amp AC 2 leg) the were pretty much non existent and something would most likely have to be made/converted. If your engine block has mount lugs for and external solid state coil you can use late model parts which I have spares of, in 12v 3amp plug n' play setups.
 

copyman

Well-Known Member
#13
That setup will not work with the flywheels that were made for your engine (large taper). even if you found one, The airgap/size or stator plate is different. Finding lighted parts for a late model points engine is a very tall order, not much in that timeframe that called for it. so when it comes to small frame and that particular coil setup (12v 3amp AC 2 leg) the were pretty much non existent and something would most likely have to be made/converted. If your engine block has mount lugs for and external solid state coil you can use late model parts which I have spares of, in 12v 3amp plug n' play setups.
Hey markus,

As usual thank you for the expert advice. Unfortunately this block doesn't have the 2 posts for external ignition. As I posted the parts diagram shows this engine block with the 2 posts on main diagram as well as internal points on diagram #3. Was this because it was when they were making transition to all external and had 2 versions of engine? Shoot I like the sound of "plug & play". Just to be clear what would I need to use your lighted setup? Will it be hard to find a whole engine with external ignition or just the block with 2 posts & external ignition flywheel? Since the parts diagram show this model with 2 posts can the crank etc be used from this engine if I found just the 2 post block & external FW?
I started out with making this Fox NON-Lighted but the frame came out so nice with powder coating and since I have the headlight & tail light figured I could just convert engine. No such luck!

Thanks again
Frank
 

markus

Well-Known Member
#14
Hey markus,

As usual thank you for the expert advice. Unfortunately this block doesn't have the 2 posts for external ignition. As I posted the parts diagram shows this engine block with the 2 posts on main diagram as well as internal points on diagram #3. Was this because it was when they were making transition to all external and had 2 versions of engine? Shoot I like the sound of "plug & play". Just to be clear what would I need to use your lighted setup? Will it be hard to find a whole engine with external ignition or just the block with 2 posts & external ignition flywheel? Since the parts diagram show this model with 2 posts can the crank etc be used from this engine if I found just the 2 post block & external FW?
I started out with making this Fox NON-Lighted but the frame came out so nice with powder coating and since I have the headlight & tail light figured I could just convert engine. No such luck!

Thanks again
Frank
on the electronic ignition era engines there is nothing under the flywheel. so they used that area for whatever "alternator" the equipment called for, you would need that style block at minimum to do anything with the later alternators.

Parts diagrams are generalized, and don't depict what your exact engine looks like or how it outfitted It has to cover say 100 different versions of that size engine. They are actually scans taken from the books and microfiche from back before Al Gore created the internet :). Most Tec parts search engines that are provided to vendors will only show you part numbers that pertain to your specific engine # only. so if you hover over a number and it does not show that part or go down the list and that number is not there, it was not on your engine.
 
#15
You need a damn book…if you’re going to be buying and selling these motors you should invest in a parts and service manual…the paper kind not virtual online shit…a real honest to goodness book…with pages….it actually list mini bike specific motors and their parts…you’d be amazed…and a better mechanic…
 
#16
Either way, you do not want to use an engine with a cast iron flywheel on a mini bike. Acceleration will be slower, and the weight of the flywheel will have more rotational inertia, so slower deceleration. That is why they are used on snowblowers, tillers, larger engines on tractors, etc.
 

cfh

Well-Known Member
#17
Though cast iron flywheels are not ideal, they are fine on mini bikes. i've built some pretty high performance HS50 motors with cast iron flywheels. And frankly, with an HS50, they only made an alloy flywheels for 3 years. And the weight of the alloy vs cast is nearly identical (within 10 grams) on the HS50. In this situation, cast iron is more than fine.

On the HS40 the ideal flywheel is the 32517 alloy flywheel (does not support lights.) it does give better performance than a cast flywheel as it is lighter in weight. but it's a hard flywheel to find as it was only used on HS40 motor before 1974. You can use this flywheel on A,B,C variety HS50 engines. But again, finding that flywheel is tough. There is an alloy version of this flywheel that supports lights, but it's even more rare (for example the flywheel used on HS40 equipped Rupp roadsters 1970-1973.)

bottom line... if you want lights, get what you can get, as long as it fits your flywheel/block.
 

cfh

Well-Known Member
#19
on Tecumseh motors cast-iron fly wheels are fine. Now if somebody sold a billet fly wheel for the tecumseh, great I’m all In! But that’s not an option unfortunately. So that limits you to just a couple alloy flywheel options that’ll work only on early versions of hs40/hs50 motors, pre-1981ish. And the alloy fly wheels are really hard to find to boot
 

toomanytoys

Well-Known Member
#20
Either way, you do not want to use an engine with a cast iron flywheel on a mini bike. Acceleration will be slower, and the weight of the flywheel will have more rotational inertia, so slower deceleration. That is why they are used on snowblowers, tillers, larger engines on tractors, etc.
I get what you are saying but honestly are you gonna notice that much difference? I’ve used tecumseh motors off 25 different pieces of lawn equipment for minibikes and honestly every one felt the same regardless of configuration.
 
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