Tecumseh hsk50 snowblower conversion Arctic Cat

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dwadholm

Member
#1
#1
Good morning everyone,

I came across a deal on an older MTD snowblower with a 5 hp Tech and a lighting coil that I just couldn't pass up. I bought it for the electric starter and tires to put on my snowblower and I was hoping I could use the engine on our old 1971 Arctic Cat Climber Minibike.

You can see from the pictures below we stripped most of the snowblower parts off and now I am trying to figure out how to make this thing work. I really want the lights to work on the old minibike and this lighting coil tested out great and the engine runs strong.

Bad thing - 1" crank with only a partial keyway.

What do you guys think is the best approach to make this crank work (1" clutch) or convert (turn it down to 3/4" and shorten it up). My son has access to a metal shop at school but I'm not sure he knows what he is doing... :confused:

Some pics:















Any ideas on what would be the best approach?
 
D

dwadholm

Member
#10
#10
bikebudy said:
If you want to pay the extra, this one is tapped on the end for a bolt

Tecumseh HS50 HSSK50 LH195SA Snow Blower Engine Crankshaft 37245 | eBay
Click to expand...
I bought this one. It came today.

I've rebuilt 2-stroke Snowmobile engines but never a small 4 stroke.

Looking at it I should be able to pull the flywheel, open the side cover, unbolt the rod cap & slide the crank out.

Then just reverse with the crank / cam dots lined up. Does that sound right or am I missing something?
 
bikebudy

bikebudy

Banned - Must pay $500
#11
#11
Pretty much it, just have the timing dots line up and not fight with the valve lifters.

Should be no pressure on the cam, lifters and have the dots match.
 
D

dwadholm

Member
#15
#15
Got a box full of parts from OldMiniBikes Warehouse yesterday.

Picked up a mini bike throttle control - it seems like the tab requires bending to make it work. At full closed throttle it doesn't even touch the idle screw.

Also, I picked up an air cleaner assembly and this exhaust - https://www.OldMiniBikes.com/Flathead-Tecumseh-Exhaust.html. I was a little dissappointed the listing for the exhaust until today said "with bracket". Mine didn't come with a bracket so I called and they said the part changed and there was no bracket. It also appears to be painted or coated in the picture and it is just raw steel.

Looking forward to getting this thing mounting on the old Arctic Cat.
 
D

dwadholm

Member
#16
#16
So I got this thing together, tuned it up some & it ran great on the stand for testing.

Drove the mini bike around & it falls flat at wide open throttle. Back off & it will Rev out again until 3/4 then fall flat (you can see the butterfly valve forcing shut)

Tried to tune it on the bench & now it's sputters anywhere but idle.

Air filter seems to have gas in it. Runs better when I remove the air filter but not perfect.

Carb is clean & rebuilt. Not sure where to go from here...
 
markus

markus

Well-Known Member
#17
#17
are you still using that same carb? did you plug up the primer or leave it on or leave the tube vented to the atmosphere? Did you drop the bowl again to double check for debris and thorough cleaning of the mixture jet and all the tiny holes in it. also a good check that the float is not sticking. Seeing fuel in air cleaner is an indication its flooding out, If the primer hole is blocked the only venting it has is a very tiny breather hole that is unreliable, it needs to be opened up if you cap the primer tube

Heres what I do with the primer carbs when I convert:

markus said:
Heres the bowl type (top left I drilled out the small vent hole to the larger size so I could cap the primer inlet off, bottom left is undrilled, right is normal non primer with the larger vent)
Click to expand...
If its not overflowing from the bowl and more like puking fuel out/spitting back when trying to run, then you need to look at timing or ignition issue but I would drop the bowl first and see whats in there and go from there.

On your throttle kickback You may have to adjust out the governor a bit, its setup for fixed throttle and probably a pretty heavy kickback. I have noticed that with some snowblower engines I have converted.
 
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D

dwadholm

Member
#18
#18
markus said:
are you still using that same carb? did you plug up the primer or leave it on or leave the tube vented to the atmosphere? Did you drop the bowl again to double check for debris and thorough cleaning of the mixture jet and all the tiny holes in it. also a good check that the float is not sticking. Seeing fuel in air cleaner is an indication its flooding out, If the primer hole is blocked the only venting it has is a very tiny breather hole that is unreliable, it needs to be opened up if you cap the primer tube

Heres what I do with the primer carbs when I convert:



If its not overflowing from the bowl and more like puking fuel out/spitting back when trying to run, then you need to look at timing or ignition issue but I would drop the bowl first and see whats in there and go from there.

On your throttle kickback You may have to adjust out the governor a bit, its setup for fixed throttle and probably a pretty heavy kickback. I have noticed that with some snowblower engines I have converted.
Click to expand...
I just removed the primer tube and left it uncapped on the carb. Thanks for the pictures. Should I cap that and drill out that vent hole?

The mixture jet is new from the rebuild kit. So is the needle (I used the same seat but I have the new one still...) I took the carb off again last night and there are no obstructions.

It is not overflowing from the bowl. The air filter was just wet on the bottom with fuel. We were going to try running it again this morning without an air filter to see if that helps it run better. I can plug up that primer as well...?

I don't know what you mean by throttle kickback. The throttle butterfly stays about 1/2 open until it starts then it goes down to the idle screw.
 
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markus

markus

Well-Known Member
#20
#20
dwadholm said:
We capped the vent & drilled out the hole. The small vent that was there was partially blocked.

Here's a video of it running after the fix.

https://youtu.be/Xs9JWF5oviw
Click to expand...

sweet! I am glad futzing with the carb helped :thumbsup: Its sounds pretty solid in the video. BTW 40 degrees!!!! That actually sounds nice right now, It was around 90 here yesterday about the time you took that video :censure: we didnt have much of a "winter" down here, It got hot faster than normal....its gonna be a crappier than normal summer here I fear!

Have fun....in your jackets :laugh:
 
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