tecumseh 8HP torque converter problem

[colbyjack46]

Ive got a Tecumseh 8HP motor on a series 30 torque converter, it never seems like the driver is getting enough tension with the belt. the engine runs not quite 100% so I dont know if its just not a high enough RPM due to the engine or what, anything helps!
thanks

 

[bob58o]

I imagine the skateboard's deck is too heavy for the 3" diameter wheels and a 65 lb passenger when using a 1:1 gear ratio.

You didn't really give any info, so I just filled in some of the blanks.

 

[colbyjack46]

Lol makes sense I didn’t put much info up.
The Tecumseh 8hp drives the 30 series torque converter with a 7” diameter driver(not sure that’s what it’s called). That’s got a 12 tooth gear driving a 40 tooth gear. The wheels are 8” diameter with 12” turf treads. The kart is a Manco 706B I’ll post some pics

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https://drive.google.com/open?id=1r0yWhC-NvtzwxHFtuO7hbUh8oOydAH37

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https://drive.google.com/open?id=1d3JzmVXIxYvUCS4dCIImrXGHkwQMhv3-

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https://drive.google.com/open?id=1iu5PsaebcGf7UBuI692BxE2kznDWr-bO

 

[bob58o]

Are you sure those tires are 12" tall? from ground to top? They look more like 15 or 16" tires to me???

I was going to say that gearing is the issue, but maybe not. With the 7" DriveN Unit Pulley, highest gear is around 3.7 :1.

3600 RPM with 12" tires in "high gear" is only 35mph.
Tires aren't huge (if they are indeed 12" tall, but I don't think they are), kart doesn't seem to weigh a ton, it is an 8HP engine, plus it has a TC. I suppose it depends on if there is one or two passengers. You might be able to get away with that gearing with a single passenger, probably not with two.
I'd probably start off with a TC and engine tune up. Clean the carb and try to get some of those original 8 ponies back. Maybe you are due TC maintenance and a new belt?

I'm guessing it is a combination of the TC needing maintenance, a borderline gear ratio, and the engine coming down with a case of the Teckasheemas.

If it were my kart, I'd be using something like a 54T sprocket instead of the 40T you have. You can also achieve a more desirable gear ratio by using a smaller than 12T sprocket.
40:10 with 7" is 4.5 :1 in high gear.
40: 9 with 7" is 5.0 :1 in high gear.

If the tires are 15 or 16" like I guessed, then I'd have to change my answer. With taller than 12" tires, the gear ratio you have is no longer border line. It is just bad.
With 16" Tires and a 7" driven unit pulley, I'd want a 60-72T rear sprocket if keeping the 12T front sprocket.

 

[colbyjack46]

Thanks for the tips and advice I'll see what I can do about a tune up and improving my gearing. Most of TC is new except the driven and I got a new carb 2 months ago when I got the frame and engine, but like you said it could just be getting old and need to be tuned(or replaced).

 

[bob58o]

Thanks for the tips and advice I'll see what I can do about a tune up and improving my gearing. Most of TC is new except the driven and I got a new carb 2 months ago when I got the frame and engine, but like you said it could just be getting old and need to be tuned(or replaced).

And about those tires? Are they really 12" diameter? If the rim is 8" it looked like a 4" sidewall to me. Any markings on them? If they are bigger, gearing is probably the main issue instead of a dirty carb.

What is going on with the spacer behind the driver unit? It looks all mangled.

 

[colbyjack46]

Yeah they’re not 12 inch they’re 16 don’t know why I thought 12. and the spacers is a rusty old washer because if the driver is all the way on the shaft it’s not a straight line to the driven so the belt is creating extra friction. Could having the wrong belt size be the problem on the TC? It seems a little loose but I got the one that go powersports said would fit.

 

[bob58o]

Sure if the belt is too long, the driven unit won't shift properly.
But like I mentioned, the main issue is going to be the gear ratio.

16" Tires and 40 :12 with a 7" driven unit pulley is over 45mph at 3600 RPM.
Your kart may never reach 45mph. Meaning the TC might shift and then not accelerate anymore or your TC may never shift out (keeping you in low gear all the time).

If I remember correctly (I can't find the picture now), if you pinch the belt with your thumb and finger around the top and bottom of where it goes around the crankshaft and give it a tug -pulling away from the driven unit, there should be only about 1/4" gap between the inside of the belt and the shaft.

 

[KartFab]

Ive got a Tecumseh 8HP motor.... the engine runs not quite 100%

Another case of the tecrapsehs

 

[colbyjack46]

https://drive.google.com/open?id=1l27TPpYD5WYlp8QAfb7j8H615PIgorSa
Are Tecumsehs really that bad of an engine?

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Also @bob580 is that the proper spacing like you mentioned earlier?

 

[Tpdingo]

https://drive.google.com/open?id=1l27TPpYD5WYlp8QAfb7j8H615PIgorSa
Are Tecumsehs really that bad of an engine?

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Also @bob580 is that the proper spacing like you mentioned earlier?

The motor itself isn't bad, but the carburetor is total junk.

 

[bob58o]

Also @bob580 is that the proper spacing like you mentioned earlier?

So apparently I did not remember correctly. Should be less than a 1/4".
https://www.gokartsupply.com/tcbelts.htm

You can fiddle around with anything you want, but you NEED to change the gear ratio. Your gear ratio is the the most concerning problem to me. A proper belt (if yours is wrong) will help too.

 

[colbyjack46]

Awesome I’ll work on that thanks for the advice!��

 

[KartFab]

https://drive.google.com/open?id=1l27TPpYD5WYlp8QAfb7j8H615PIgorSa
Are Tecumsehs really that bad of an engine?

---------- Post added at 06:04 PM ---------- Previous post was at 06:02 PM ----------

Also @bob580 is that the proper spacing like you mentioned earlier?

YES! they are, but arent. The carburetors are the biggest complaint, but thats because they are a pain to clean. Once they are clean, they are actually really good.

Cleaning a typical carburetor involves unscrewing some jets and bolts and wire brush/spray down. Cleaning a tecumseh carburetor, well, thats something an experienced person should do. I could never get them cleaned out, but then talked to someone who did back in the day... Tecumseh carbs were so bad that tecumseh (before they went out of business) went around teaching dealers how to clean their carbs. Some helpful hints beyond the basic carb clean include, remove and replace welch plugs, and look for that microscopic hole in the bolt threads that holds on the bowl, that is actually supposed to be there and controls the idle.

The rest of the engine parts are pretty good. Most of the tecumsehs I have ran into, though, suffer from... aww they just dont run rigght, etc. All of it comes down to the fact that they are old and worn out. Worn out bore/rings, bad valve seals etc. I actually had a tecumseh engine that I thougth was in good shape, but when i tore it down, the ring end gap was literally about 1/8" or more. couldnt even measure it it was that bad. (end gap should be what, .006"-.045" ish?) If you want to get a tecumseh to run right you may need to fix the bore, do a valve job, and put on a different carb.

 

[J.S.@SMS]

My tecumseh 195cc had some issues when i got it. I did the pretty much necessary things: replaced the carb with a new choke style carb, replaced the air filter (pre filter was still good), changed the oil and cleaned the plug. The engine now runs like a champ and starts on the second or third pull. And mine also has problems with the tc not moving into the direct or od stage. However my problem is likely the tires since their about 21".