turbofiat124
Well-Known Member
- Joined
- Mar 23, 2011
- Threads
- 83
- Messages
- 288
Right now I have a go-kart with an 8 HP B&S engine and a mini bike with a Tecumseh 3.5 HP engine. As usual both engines won't idle/run correctly due carburetor issues. I'd like to get these things running this summer.
Last time I fooled with the 8 HP B&S engine, I came to the conclusion that the reason that engine won't idle is throttle shaft is worn out. I sprayed WD-40 on the carburetor one day while trying to adjust the idle mixture and stalled the engine. I replaced the throttle shaft, rebuilt the carburetor. It will run but won't idle. I guess it's getting too much air. A new updraft carburetor for this B&S engine costs around $125. I can go to Harbor Freight and buy a new Chinese engine for that! I bought a used carburetor at flea market for $10 but have not installed it yet to see if it's any good.
With the Tecumseh engine, I once had this bike running great. But after it sat over one winter, the E10 must have messed the carburetor up. It wouldn't idle in the spring. I tried cleaning the carburetor but to no avail. I've found cleaning/rebuilding carbs is hit or miss.
I found a new carburetor off Ebay for $25. Now the problem is the throttle will only open 1/4 way when the engine is running. With the engine not running, the throttle will open all the way. I know that makes no sense so what does the maximum throttle position have to do with the engine running or not. It has something to do with the governor. On both of these engines, the throttle cable connects to a spring mechanism which connects to the governor arm then a rod connects to the throttle plate on the carburetor.
I have fooled and fooled with this Tecumseh engine to the point I'm blue in the face and still can't get it right. ARRGGHH!!!
I'd like to know if it's possible to install a slide valve carburetor like what's on my Tomos TX-50 and my 110cc ATV. Like the one below.
If it's possible, then how to match the carburetor. An 8 HP engine is supposed to be around 300 ccs and a 3.5 hp engine would be around 150 ccs. So would I need to go by CCs or the venturi size on the original carburetor?
I realize I'd need to fabricate an adapter plate and throttle and choke cables but that shouldn't be a big deal. Is it possible to use a carburetor like this on an engine with a governor?
What would I have to do, wire the governor closed or wire it all the way open?
I can see the purpose of a governor on a lawnmower where you hit tall grass and the engine speeds up automatically so you don't have to constantly adjust the throttle but on a go-kart or mini-bike the engine speed is controlled by the throttle or accelerator. Why is the throttle cable connected to a spring mechanism then to the governor arm to a rod then back to the throttle plate on the carburetor in mini-bike and go-kart applications? Can someone please explain this Rube Goldberg setup?
Last time I fooled with the 8 HP B&S engine, I came to the conclusion that the reason that engine won't idle is throttle shaft is worn out. I sprayed WD-40 on the carburetor one day while trying to adjust the idle mixture and stalled the engine. I replaced the throttle shaft, rebuilt the carburetor. It will run but won't idle. I guess it's getting too much air. A new updraft carburetor for this B&S engine costs around $125. I can go to Harbor Freight and buy a new Chinese engine for that! I bought a used carburetor at flea market for $10 but have not installed it yet to see if it's any good.
With the Tecumseh engine, I once had this bike running great. But after it sat over one winter, the E10 must have messed the carburetor up. It wouldn't idle in the spring. I tried cleaning the carburetor but to no avail. I've found cleaning/rebuilding carbs is hit or miss.
I found a new carburetor off Ebay for $25. Now the problem is the throttle will only open 1/4 way when the engine is running. With the engine not running, the throttle will open all the way. I know that makes no sense so what does the maximum throttle position have to do with the engine running or not. It has something to do with the governor. On both of these engines, the throttle cable connects to a spring mechanism which connects to the governor arm then a rod connects to the throttle plate on the carburetor.
I have fooled and fooled with this Tecumseh engine to the point I'm blue in the face and still can't get it right. ARRGGHH!!!
I'd like to know if it's possible to install a slide valve carburetor like what's on my Tomos TX-50 and my 110cc ATV. Like the one below.
If it's possible, then how to match the carburetor. An 8 HP engine is supposed to be around 300 ccs and a 3.5 hp engine would be around 150 ccs. So would I need to go by CCs or the venturi size on the original carburetor?
I realize I'd need to fabricate an adapter plate and throttle and choke cables but that shouldn't be a big deal. Is it possible to use a carburetor like this on an engine with a governor?
What would I have to do, wire the governor closed or wire it all the way open?
I can see the purpose of a governor on a lawnmower where you hit tall grass and the engine speeds up automatically so you don't have to constantly adjust the throttle but on a go-kart or mini-bike the engine speed is controlled by the throttle or accelerator. Why is the throttle cable connected to a spring mechanism then to the governor arm to a rod then back to the throttle plate on the carburetor in mini-bike and go-kart applications? Can someone please explain this Rube Goldberg setup?