Tecumseh LH195 versus the HS50/HSSK50

delray

Well-Known Member
#21
just wanted to ad one more style compression release unit that tecumseh made for there italy made engines. this one is pretty neat. something like they use on the smaller engines with the release unit on the back side.
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#22
Another great Tecumseh thread!
Thanks to everyone for weighing in.
The LH195 cam looks like it might be a good option!
Obviously it looks like it might need some modifications to the lifters, but nothing too serious.
At this point, performance parts are so hard to find, that sometimes you gotta figure something else out.
I’d like to get one of those cams and see what it’s all about
 
#23
I have a *ton* of Tecumseh powered mini bikes. Way too many. But they all share one thing, the Tecumseh HS50 family (though a few have HS40 engines.) By family I mean HSSK50 and HS50 (which are pretty equivalent), rated at 5 horse power. The only real change happened in the 1990s when Tecumseh decreased the bore size .020" and switched to thin piston rings and a smaller exhaust valve. But to be frank, that's a pretty small change, and one you would be hard pressed to tell when installed on any given mini bike.

But in the late 1990s, Tecumseh came out with a new motor, the LH195. It is basically an HSSK50 engine. It has the exact same bore and stroke as a mid 1990s HS50/HSSK50 engine (the thin ring piston and small exhaust valve). So what is different? I mean why a new motor? And WHY is the LH195 rated at 5.5 horse power (instead of 5hp like the HSSK50) at 3750 rpm????

I have not come across many LH195 engines. In fact, I only have one. Bought a snowblower and harvested the LH195 motor, and converted it to mini bike format. Put it on a Fox Thunderbolt 170, and rode it a bit. The engine worked fine, no issues. Did it seem like it was more powerful? (Seeing how it's advertised as 5.5 hp.) I would have to say no. It was running a 16mm slide carb and an open exhaust (through a torque converter). It seems pretty much like all the other HS50/HSSK50 engines...

But here's where things get off the rails... Lately I've been going back through the Tecumseh motors, and cleaning up some prior work. For example, on the LH195 it's running a 16mm slide carb. But i never removed the governor. It was just sort of hanging there. It looked unprofessional like that, so i thought it would be a good idea to split the case and remove the governor properly.



Upon splitting the case, the first thing I found was the mechanical compression release on the cam had come apart! I had *no* idea this happened... the parts were in the bottom of the case! It didn't do any damage... everything was cool... the bore was really nice on this engine too. But it made me think that *any* sort of compression release (be it mechanical or bump style) is a bad thing, and I shouldn't be running it. I mean come on, i know to pull the starter cord until i get to the compression stroke *before* i do a full pull! duh!!

Since I had the case apart and the cam out, I thought it would be a good idea to check the cam. I had a hunch that the reason Tecumseh gave the LH195 a 5.5hp rating was that the cam is different. In fact, the cam is different, it is a different part number than the HS50/HSS50/HS40 cam. There's probably a reason for that, and sure enough, it's a damn good reason!

Bottom line... the LH195 comes with a Dynocam 245 with a mechanical compression release! I kid you not on this... I have a Dynocam 245 sitting right here, and did the measurements... The dynocam 245 and the LH195 cam are nearly identical. Heck it's like a christmas gift inside a late model Tecumseh engine! But that said, there are some caveats... That is, at some point, Tecumseh neutered the LH195 and switched to a plastic cam (and light duty cam springs)! Obviously you don't want that variety of LH195. But any who, below are some pictures that compare a Tecumseh HS50 cam, Dynocam245, and LH195 cam and the lobe sizes.

Note I will check the lifters and see if they are different than an HS50. I will also measure the actual valve lift (and how it compares to a Dynocam245.) Perhaps they did something different there. But my hunch is, that's not the case...

Comments appreciated...





Still a great read, gonna have to find those two steel 37040 cams in the shed. Thanks again!
 
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