another HS40 project

markus

Well-Known Member
#1
Digging trough boxes the other day I realized I have way more HS40's stashed away than I thought I did! Like 4 late model blocks that I have picked up becuase they were low useage or new. Going through the crankshaft boxes I found a late model small frame H/HS40 ball bearing shaft that specs out really well too. I have a few alternator systems for the solid state small frames.....soooooooo, I'm thinkin' a nice HS40 electronic ignition, 12v 3amp lighting system, Ball bearing shaft. Probably best suited as a slanted application (unless someone needs a standard mount HS40?) IMG_1932.JPG

think I have most everything I need onhand, at least to start. Nothing special, New stock rings in this honed bore come in @ .017 so I will use .010 over rings to bring the gaps down to the low side of the specified gaps, 3 angle valve seat cut, and just a deburring/smoothing of the ports, actual Tecumseh parts including a correct oem carb, etc.. Unless I get a special request I do plan to make it angled application and most likely Black in color, so it can be decaled a few different ways and be a good replacement for a lot of the spoke wheel mini cycles with lights. Gonna start cleaning a prepping journal and mating surfaces this evening, its too dam hot and humid out in the shop right now!
 

markus

Well-Known Member
#5
Just got a little more done, got sidetracked thursday and friday. Did some conservative port work and also 3 angle valve cut. Seats were good but since I now have the tooling and dont have to call in a favor from a buddy to get seats redone.....everyone gets a trim :D

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Squared out all the mating surfaces, prepped all the journals, Rod, cam, lifters. Cut the valves/set lash, cut the rings to mid spec. Then It all got washed in the parts cleaner, and then a nice final bath in hot water and soap scrub with a nice blow dry.

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together as a short block as of now, Going though shrouding/bolt ons and getting stuff into the stripper/degreaser solution and get everything clean and ready to media blast.

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markus

Well-Known Member
#6
the Lighted flywheel I had found for this project had some rust and moisture staining on it. For me that means I have to take a little more time and remove the magnets and reglue them. Its easy to forget that these glue on magnet flywheels flywheels are between 12-46 years old now, and lighting versions will always be "pulling" on the magnets when at rest so they are more susceptible to having something eventually come loose. Ever since I found a loose magnet on an engine probably 10 years ago, a part of my routine when I mess with any steel flywheel with internal magnets is to get a little rough with the magnets, to see if the glue is going to fail......I would rather have it pop loose on the bench than come free, stick to the stator or alternator and lock up the engine when you go to pull start it. That can mess up the stator, alternator, and or the magnets! It may set you back a day if your on a tight schedule, but one of these popping loose can really ruin your day of riding, but at least it wont happen when its running.

So I got one to pop free with a forceful tap with the handle end of a rubber handled big screwdriver. That showed some moisture tracking through the glue/epoxy that they used so that told me to get the others off there to be safe and just redo them all. I popped all them off, popped the starter gear off too as I wont need that, did a media blast and removed all the glue residue from the magnets and the inside face of the flywheel.

I have a pattern made for this style particular late model lighting wheel as I have built a few with the proper magnets so I just use that and mark the locations. If you are doing this and don't have that luxury, you do want to make sure that the magnet/s goes back in the exact location they came from. and in the correct polarity! Location is of course even more critical on the Points versions as it need to fire the coil at the right time so before you go popping them off all at once and cleaning the spot/s it came from removing any trace of where it was, you do want to mark that spot and orientation that magnet comes off.

I like 24 hour set JB weld, but a good strong 2 part epoxy of your choice will give you years of good service. So armed with my JB weld and my Compass (to verify I had the polarities right as I glued them on), and some clamps to set and hold them, I went at it:

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old shed finds

Well-Known Member
#8
Digging trough boxes the other day I realized I have way more HS40's stashed away than I thought I did! Like 4 late model blocks that I have picked up becuase they were low useage or new. Going through the crankshaft boxes I found a late model small frame H/HS40 ball bearing shaft that specs out really well too. I have a few alternator systems for the solid state small frames.....soooooooo, I'm thinkin' a nice HS40 electronic ignition, 12v 3amp lighting system, Ball bearing shaft. Probably best suited as a slanted application (unless someone needs a standard mount HS40?) View attachment 260757

think I have most everything I need onhand, at least to start. Nothing special, New stock rings in this honed bore come in @ .017 so I will use .010 over rings to bring the gaps down to the low side of the specified gaps, 3 angle valve seat cut, and just a deburring/smoothing of the ports, actual Tecumseh parts including a correct oem carb, etc.. Unless I get a special request I do plan to make it angled application and most likely Black in color, so it can be decaled a few different ways and be a good replacement for a lot of the spoke wheel mini cycles with lights. Gonna start cleaning a prepping journal and mating surfaces this evening, its too dam hot and humid out in the shop right now!
Sweet.... You got it going on !!
 

markus

Well-Known Member
#9
This next part of the build you may find "riveting", at least I did :)

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Why Rivet's......Why NOT! As you can see on an original to the left Tecumseh used them for this application, from the end of 1970 actually. Good enough for them, good enough for me. Plus its lighter and more aerodynamic (think of how much faster this thang is gonna run with that shaved weight off it! :cool:)

Backing plate on, Governor arm hooked up, stop tab has been shaved off so the throttle control gets the increased travel it needs for the mini bike/karts etc.. Installed the alternator, Don't forget the little plastic spacer that goes on the crankshaft on these electronic ignition units, Its what keeps the key from sliding back!

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Every time I straddle one arm around the engine attempting to hold it and the strap wrench and work the T wrench with the other I say "this is the last time I do this, I'm building a workstand to hold the engine soon as I am done with this one" Could this be the last straw???? I doubt it :)

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.015 off the head to get it trued up and and a little tighter. cleaned up some era correct bolts for this engine and the slanted application Dipstick.

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Started on the Shroud today, I though I was gonna get away with maybe only some light prep but of course there is some pock marks and couple of tiny dings top rear corner that showed up after a soaking and then media blast....dammit! That will hold me up for awhile, I despise doing bodywork anymore. If I have to mix up and spray the good stuff to get it all fixed I will probably bust out a couple other pieces for some other engines, that need filled/block sanded.

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markus

Well-Known Member
#10
Well, A.D.D. and a some kidney stones rattling around inside me kinda set me back on this. I got the bright idea I needed to build an HS50 at the same time, so I started one one of those as well. If I go same color on the two I can mix up enough color for both and maybe save me some time and only clean the gun out once!

Shroud came out good, so I rebuilt the recoil assembly and installed it (HS50 I started is the one on the right)

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Today I decided to start on carbs, I have a few NOS HS40 service carbs still in stock but when I was going through my used carb bodies I spotted this HS40 bore size Snowblower/primer type body that has good idle circuit still that I bored the center out to larger HS50 size. I did another one previously and it worked really well on a lightly modded H35 I did so I am going to throw this one together to at least try on this one to see how it does before paint. It really worked well with the smaller Idle circuit holes and the larger internal main bore, so hopefully It will work out well on this "blueprinted" type build too.

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In addition to up-sizing the centerbore I had to also:
Drill the atmospheric vent larger due to removing the primer port
pull the primer nipple and fill inlet with with JB weld,
remove the ate up throttle shaft, modify a good one for full travel
Modify the carb body to better hold the return spring when a foam seal is installed on the throttle shaft (the older bodies do not have a notch cast in and the spring can slip)
pull the later model plastic 90 degree fuel inlet and install an old style 45 curve (for slanted application)
Remove old choke lever, relocate choke detent spring and fit the proper 1971-up HS style choke lever for header application
Few other little mods I do to them as well. When the JB is dry tomorrow I will start the "rebuild/assembly" of it.

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Hopefully the "juice was worth the squeeze", If its problematic, no biggie as I have ones to fall back on still and can just take the good parts off it and transfer to another body.
 

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