Strange 1" engine shaft, how to put on a 3/4" clutch

[squiresuzuki]

Hello,
Glad to me a new member. I'm making my first gokart and I need a lot of help. I just bought a tecumseh 8HP engine off of craigslist. this is the engine. I was not aware of the bore size when purchasing. Anyways, I'm only 15 years old and am on an extremely tight budget (in fact, I'm making the frame out of wood). I found this 3/4" clutch for a great price (40) however the engine shaft is a wierd (i think). basically, it's about 1" for half the shaft then tapers down to 7/8" near the tip of the shaft. What is the best method to combine a 3/4" clutch and a weird shaft? Should I get it machined? I don't know anything about metal or hardly anything about engines/mechanics. Thank you!!!


Here's a pic of the shaft. Notice the slight tapering.


Another, side angle:

 

[devino246]

You would need to have it machined down. A wood frame sounds like a terrible idea, especially when paired with an 8hp engine. Dont start building a kart until you have an idea of what your doing. I wouldnt suggest trying to cheap out on a kart.

 

[squiresuzuki]

Okay thanks. How much would that cost?

 

[devino246]

No idea, probably not cheap

 

[modelengineer]

I think the problem is the pics aren't big enough

I would also advise against the wood frame. I'd go for a metal frame, and it would be much easier if you just sold the 8hp engine and bought one with a 3/4" shaft.

Alternatively you could use a belt tensioner clutch which would be cheaper and much better than a centrifugal clutch (manual, less maintenance, cheaper, cooler ), but it can be difficult to make. However if you're up to welding up a frame you should easily be able to make a belt tensioner clutch. Search on the forum for how it's done.

 

[squiresuzuki]

Can't really do metal...I don't have a welder and don't know anything about it really. I've heard about making a tensioner, but it would be much preferred to do chain (because I can't afford a live axle. I'm doing single wheel drive here with this thing and I don't see any pulley alternatives.

 

[fowler]

u realy cant do wood its weight to strength is poor
how about buying an old kart and do it up

 

[squiresuzuki]

Hmm. How much would a simple metal frame cost?

 

[fowler]

ebay or craigslist
in aus tradeing post
(these being buy /sell sites)

 

[BugMan1960]

I seen people go to the town dump yard and find go cart frames...heck I sold one years ago for 20 bucks...wood just wont hold up..my 8hp motor gives my steel frame hell.. save up for a cheap mig welder..i paid about 100 bucks and worth it..can even find them used on craigslist. My new one came with a how to weld book...hope this helps. Good luck!

 

[squiresuzuki]

Wow, thanks. That's a lot of help.

 

[squiresuzuki]

Wait, back on the topic of the engine, is there a way to just remove the shaft and replace it with a 3/4" one? Or is the shaft connected permanently to the crankshaft?

 

[fowler]

yes it is one peice
but i dont know about replaceing the whole crank shaft

 

[BugMan1960]

ok back to the motor...just a thought...basically you just need to build up the small part of the shaft...alot of the go cart or go katy hobby is rigging...what " I " would try is weld up the shaft to build it up and possibly grind it back down to the right size...would take a welder and a hand grinder...but doing it slow should get it done...just a idea. Hope this helps...it wont be perfect but on a tight budget it may just work.

 

[devino246]

ok back to the motor...just a thought...basically you just need to build up the small part of the shaft...alot of the go cart or go katy hobby is rigging...what " I " would try is weld up the shaft to build it up and possibly grind it back down to the right size...would take a welder and a hand grinder...but doing it slow should get it done...just a idea. Hope this helps...it wont be perfect but on a tight budget it may just work.

Would be very hard to get it perfectly round. Also, he doesnt have a welder.

 

[BugMan1960]

That would be about the only cheap way to do it..cant use wood hehe

 

[dave1701]

You should look on craig'slist and get a frame. Sell your engine and get a 3/4 shaft one. fix up the frame if bad. Stick motor on frame.

 

[devino246]

That would be about the only cheap way to do it..cant use wood hehe

Or he could just do like modelengineer said and sell this engine and buy one with the correct shaft.

 

[solomon]

Its so hard to find a crank that fits. Especially on those Tecumseh model engines. You could attempt to turn it down with a file, no welding up would be needed as the smallest taper is 7/8" already and he is aiming for 3/4". You just jeep filing until the clutch fits, and then use a dremel tool and cut a keyway. A machine shop can turn it down on a lathe for around $50, if you cut the keyway yourself.

 

[EagleTalons]

You could use a file. Just turn the engine on and file away till the clutch fits. It will ruin the file.