Tecumseh Engine good for Minibike?

[DudeRadster]

Hey guys,

My parents had this old snowblower sitting in the attic that they said I could use to make a minibike over christmas break. It's some old rusted out thing that my parents bought when they first moved here to MN from FL. It's a Tecumseh HSK845 4.5 horse with an electric start. it's pretty small and lightweight as engines go. The official Tecumseh specs say that it's 139 CC. The main reason why my parents don't use it any more is because it is getting old and doesn't like to start in the cold, even with the electric start. I am thinking of buying a minibike frame and bolting it in. It supposedly tops out at 3700 RPM, so I think I will get a decent speed from it. What do you guys think? I don't want it so powerful that I will pop wheelies at 1/2 throttle, but I do want it to be able to maintain a better speed than me simply pushing it when going up hills.

Here is the official Tecumseh specs page:

http://www.smallenginesuppliers.com/html/engine-specs/tecumseh/features/hsk845.jpg

It's a bit dirtier than that picture and I think I will need to work on the engine some more, but do you guys think it will get the job done?

 

[HellSpawn]

Its actually a 2 stroke. You'd have to mix your fuel, But it'd make a kickass motor for a minibike. Plenty of power and torque, and don't quote me, but I'm pretty sure the stock rod in that thing could easily handle more than 6k RPM if the governor was removed.

 

[DudeRadster]

Cool. I knew it was a two stroke, I used it to blow out my neighbor's driveways for two years until we got our new snowblower. I think I'll do a little more research before I remove the governor, though. Any ideas on what I could use for a torque converter? Would I even need a torque converter?

 

[Russ2251]

Would I even need a torque converter?

Nope...as long as you don't go ape **** on the the tire size.
Governor is easily disabled and engine will last for forever as long as you keep a load on it. Don't free rev it.
Side note:
Hopefully, it is not a stepped shaft.
You will need an air cleaner.

 

[HellSpawn]

Just read that you live in Minnesota, whereabout? Im from the Wadena area, about an hour from St. Cloud. Nice to see some more Minnesotans on here.

 

[DudeRadster]

Not sure what the tire size will be, but how big do you think the limit would be on them?

I live in Rochester...I live in a neighborhood and we just have a little 2-car garage. And we have two cars. So I can't do much work in the winter...but I can't do that much work in the summer either. I go to a friend's farm to ride my go-kart that I built.

I have an idea for an air cleaner. Could I take a tin can and a metal funnel and then stick a piece of foam into the can, and then weld the can and funnel together. This would be after I get a welder, of course, but in theory it seems like it could work. I don't mean craft felt or styrofoam, I mean good padding foam. My parents bought a bunch of it in bulk when they reupholstered my sister's Honda Civic. It's green and about an inch and a half thick.

 

[DudeRadster]

Just as a comparison, I don't want to make a tiny little circus motorcycle. I was hoping for something around this size:

http://www.northerntool.com/shop/to...64?cm_sp=Upsells-_-Top Sellers-_-Product Page

EDIT: Ack, sorry, double post. Meant to edit my above post.

 

[Russ2251]

11 inches in diameter or less.
Larger than that and it's time to consider a jackshaft and/or CVT.
Small tires will only require a standard centrifugal clutch...about $30.
4.10x3.50x5 tires. (11" ± diameter)
12 tooth clutch.
72 tooth driven.
Perfect.

 

[Russ2251]

That's a BIG bike and 180lbs. Tires are 19" in diameter.
4.5hp is too small to realize any performance.
2 cycle engines notoriously lack torque on the low end.
A big 4 cycle would serve you better.

 

[DudeRadster]

Okay, I'll get a minibike kit from Northern Tools, then. I'll take it over to my friend's backyard. His place isn't quite big enough for my go-kart, but the demensions of their minibike kit would fit pretty well. I could race his little rallying gokart

 

[Russ2251]

I could race his little rallying gokart

You'll kick his ***.