Hoping someone can help me on a problem I'm having. I thought I was on my way to putting a HS-40 back in the mini bike. I picked up a HS-40 motor on a snowblower. Engine ran good. I already had the lighting coil and flywheel from 4hp Tecumseh. Decided to put a new headgasket on it , but thought before I did I trial fit the flywheel. Guess what the crank hole is too big. So now I check bore and stroke. It is the same as the H-35. The sears motor h-35 seams to have a bigger head gasket. So my question is is there different hs-40 motors that had a bigger crank taper to take the lighting coil flywheel. I know this is a older model with points. I'll post some pictures tomorrow. Garry
Help on Tecumseh Engine
Thanks I'm not up on the Tecumseh's. Sure helps to get help from members on this forum. The snowblower motor has the dual shafts, but I thought it was just a matter of leaving the second shaft or cutting it. Should I be looking for a single shaft HS-40. Would that be the correct crank. Any other thoughts on this. Oh yes I forgot to ask you last time , do you have decals or make them for the DMP Trailchamps. Thanks Garry
The head gasket on an H35 and lower (h30 h25) is smaller overall than and hs40-50 The blocks look pretty similar in looks and size but the head is physically smaller. flywheels between the 35 and 40/50 are not interchangeable, and depending on year and style shroud flywheels for the same size engine are not interchangeable (you can't put a lighted flywheel from a 70's HS on an 80's HS as they changed the taper, you can put an early aluminum flywheel on a mid 70's steel flywheeled HS, but then you have to change all the tins/shrouding as well and vise versa)
I would not depend on any numbers if the shroud looks like its been off or possibly another color or different patina, the shrouds and backing plates were interchangeable on all the "small frame" engines so alot of times they do not match.
you should get some good photos up of all sides of the blocks and parts, and get some more accurate measurements.
I would not depend on any numbers if the shroud looks like its been off or possibly another color or different patina, the shrouds and backing plates were interchangeable on all the "small frame" engines so alot of times they do not match.
you should get some good photos up of all sides of the blocks and parts, and get some more accurate measurements.
Thanks Markus that helps explain the differance in crank. I was not aware of the hs-40 being differant. I went out thinking a old points engine is what I needed. Here is some pictures. The mini bike has the lighting coil in it but I'm positive it is bigger than a 4hp. The hs40 looks exactly like the h35. The sears is in a old chopper bike , bad picture. Garry
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I had already answered what the engine in the bike is in this thread http://www.oldminibikes.com/forum/tecumseh-engines/111147-dmp-engine.html It's a "medium frame" tecumseh engine, we usually call them "big block" in the mini bike scene :laugh: actually nothing on that engine will cross with the other "small frame" engines you have except for the magneto/charging assy under the flywheel.
1st pic is really blurry but it appears to be an HS40 engine, engine on the left on your table is an H25-30-35 2.5-3.5 hp and I would say its probably a 1971-74 due to the 2nd version of the throttle control. engine on the right is an HS40 and if the shroud that came off it is the one sitting next to it its a 1968 or earlier year 1969. you should be able to get the specs and year of the tags on both engines, the H possibly has stamped number on the top of the shroud instead of a plate.
lighted flywheels for the HS40's are not uncommon, there is usually an assy listed on ebay at just about any given time, the small H engines are not as common they were only really utilized pre 1970 when the HS40 was still relatively new and not used too much yet. They don't show up as often. One thing that IS critical when converting to a lighted flywheel on both engines is that the flywheels are wider, tecumseh used flat base studs on the shrouds for the recoils on those engines for clearance instead of the little welded on nuts. You can use those shrouds but you need to test fit, usually grind down the nuts a bit and also use screw/bolts that don't protrude to do it, or some of the shrouds used rivet on recoils, so either really short rivets or reverse them and install from the inside, the recoils for the rivet units have smaller holes than the bolt on kind.
1st pic is really blurry but it appears to be an HS40 engine, engine on the left on your table is an H25-30-35 2.5-3.5 hp and I would say its probably a 1971-74 due to the 2nd version of the throttle control. engine on the right is an HS40 and if the shroud that came off it is the one sitting next to it its a 1968 or earlier year 1969. you should be able to get the specs and year of the tags on both engines, the H possibly has stamped number on the top of the shroud instead of a plate.
lighted flywheels for the HS40's are not uncommon, there is usually an assy listed on ebay at just about any given time, the small H engines are not as common they were only really utilized pre 1970 when the HS40 was still relatively new and not used too much yet. They don't show up as often. One thing that IS critical when converting to a lighted flywheel on both engines is that the flywheels are wider, tecumseh used flat base studs on the shrouds for the recoils on those engines for clearance instead of the little welded on nuts. You can use those shrouds but you need to test fit, usually grind down the nuts a bit and also use screw/bolts that don't protrude to do it, or some of the shrouds used rivet on recoils, so either really short rivets or reverse them and install from the inside, the recoils for the rivet units have smaller holes than the bolt on kind.
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Thanks for the reply Markus. I was not sure about the hp size for the motor on the bike. It was on it when I bought it. When I removed the shroud I noticed the flywheel had been damaged from before. It was just like you said about the longer bolts hitting the flywheel. I cleaned them up with a small dremel grinder. I noticed the shroud was modified also. The motor does run nice no smoke but he welded the muffler to the block. Would be nice to find a older hs-40 that would of came on that bike. I'll just keep looking, but in the meantime I can have a little fun getting out with my son. Oh yes I have one more picture I'll post tomorrow. It's the older DMP trailchamp I picked up. It has a 6.5 tecumseh powersport with comet clutches with a extented aluinimum trailing arm. The chopper bike has the proper trailing arm to put it back to the way it was if it does not work. Haven't tried to start it but I see no reason it won't run. I guess having one of these bikes years ago with lights makes me want one now. Garry
