OHV tecumseh 6.0 upgrades

[Jhoppe]

I just picked up a yerf dog with the 6hp tecumseh powersport. I have had a kart with this engine before and i was not pleased with the performance. I want to do a mild build on it and was wondering if polishing the rod would be enough to remove the governor without grenading the internals. I know arc makes a billet rod, but I'm not looking to put much $$$ into it.

I will be retaining the stock cam, but I may improve the valve springs if I have a heavier set around. I am also going to jet the carb just a bit. Only a size or two up in my bit set. Will also do an improved intake and a header.

Is it worth the work for a few extra horses or should I just buy a predator? (Which will cut into funds for other improvements to the rest of the kart)

 

[J.S.@SMS]

Take a look at these two videos. 6.0 tecumseh with a shaved head, no governor, header, and carb jet. (And i think a honda carb. It's been a while since I've watched these particular videos.
https://m.youtube.com/watch?v=KPk92Nwr9Fk

https://m.youtube.com/watch?v=w40uG8Et45E

PS: All in they had $28.25 in the kart.

 

[Jhoppe]

I've watched those. It's a predator carb. I know it can be run without the governor, I just wonder how long it will last. It wouldn't be hard for me to just polish the rod if it will help. I want to do all those mods. My mechanically inclined older brother seems to think shaving the head on this project is a waste of time. He seems to think a longer spark plug will achieve the same effect much easier. I'm going to try it and if it doesn't work, then I will shave the head. I forgot about a port and polish. I will get to those if I'm not satisfied when I'm "done"

 

[bob58o]

IMO the best upgrade for that engine is to replace it with a 212.

 

[Budget GoKart]

im not saying tecumsehs suck but they kinda do every tecumseh mower or kart in my neigbor hood doesnt run its sad but the briggs are all still chuggin along happily!

 

[Jhoppe]

Tecumsehs are not the best. They can be made serviceable. I am wondering if I can make it serviceable without spending money

 

[Kartorbust]

Yes you can make it serviceable. However with the governor removed, you will run into the issue of the engine breaking apart. How long that takes is a gamble. The dipper for the splash oil on these engines isn't meant for high speed, so it could fall behind and seize the engine. The connecting rod could snap. Or magnets on the flywheel could fly off.

 

[Jhoppe]

I understand those are the risks. I am just trying to mitigate those risks as cheaply as I can. The cart needs a lot of love, so I dont want to blow my budget on an engine when the only problem is it's a tecumseh

 

[65ShelbyClone]

If replacing it with a Predator is an option, then just cheap mod the Tecumseh and run it till it blows. You'll learn more and will only be out a few bucks.

I would mill the head, port it, make a header, add some timing with a flywheel key, and get a carburetor for of a larger Tec engine so the governor can be retained. Then adjust the governor up to maybe ~4500 and run it.

Polishing the rod won't do any measurable good. Tecumseh rods are some of the thinnest you'll find in a utility engine. They are the weakest link IMO when running without a governor.

 

[bob58o]

If like mine, the cam is plastic. So not sure how it will hold up to heavier springs. It may be fine. What is the plan for the “improved” intake? For some reason, I seem to remember reading that the stock manifold is terrible for flow.

 

[Jhoppe]

I was just going to ditch the Airbox and make an adapter for a K&N style filter. I may fab a straighter intake pipe, but I'm not sure if it will have enough effect to justify the time that would take. I am not sure if the cam is plastic since I haven't cracked the case.

 

[65ShelbyClone]

It's been a long time since I got rid the OHH65, but I seem to recall the intake being pretty easy to port where the sharp turn is.

 

[Jhoppe]

This is what I was thinking, but I'm not sure its THAT much better than just porting the intake I have.

 

[KartFab]

ok so i have done some upgrades on mine. I installed the chinese $20 mikuni on it with the stock intake. which is crap. Glad to see you fixed yours up. I had to jet the main by drilling it out by a few thousandths. I should have probably stayed at .034" but i went straight to .035" on the main jet.. oh well.

So to kind of clear things up here, if you do stage 1 mods on a predator 212, you will get almost the same power (~8 hp total) as you would if you upgraded your tecumseh with a .245 cam, carb, springs, billet rod, and open header (~8.1hp). These numbers would be around 10.1-10.3 hp on an inertia dyno.

As you can see the non-hemi predator makes more torque down low, and the hemi predator makes more torque up high. The non-hemi run was a hot oil, cold engine run, as it actually was making about .1 hp lower than the hemi for the other runs that day. Just some food for thought. Also, chances are, if you open the crankcase cover and head in the tecumseh, you will find a plastic camshaft, aluminum bore, and no bearings on the crank, and no bushings in the block anywhere for the cam, nor for the crank.

The dyno graph on the tecumseh cuts out in the 4000 rpm range, but when i switch to the 20 lb animal springs, it will rev past 6000 rpm.

Either way, if you did the same type of mods on a predator (slide carb, mild cam) you would get about 13 hp on my dyno, 16+ on an inertia dyno.... so for about the same amount of money.... 8.1 hp, or 13 hp? thats a tecumseh vs a predator right there.

 

[Jhoppe]

I'm not planning on a cam, because I cant find one. So I'm down to just free upgrades. I haven't made the intake, those are actually off another thread. I am planning on the regular carb, but the cheap VM22 isn't off the table.

 

[KartFab]

there are ohv tecumseh cams for sale on ebay, seller theuglychicken or something like that. sells them out of puerto rico, so its still us shipping.

 

[Jhoppe]

A 365 is a pretty heavy cam for what I'm thinking. I may grab one anyway because I'd be nice if I change my mind, but if I was going that extreme I would probably just buy a predator. I was thinking more like a 255 or 265

 

[Budget GoKart]

I just got a 6.0 ticumseh is it bad it spat a blue flame out the carb?

 

[KartFab]

Looks like that guy sold out of the mild cams he had. A 245 or 255. Would have been great :-( I want to say that there may be some information out there about cam compatibility. IIRC the tecumseh Flathead cams might work?

 

[bob58o]

I’m not sure I’d want to upgrade the cam in a Techumseh without upgraded springs and a billet rod. And if spending money on upgraded parts, I’d rather put that money into a Predator. So like I said previously, IMO the best way to upgrade a Techumseh is to replace it with a Predator.