Go-Kart Differential with Built-In Centrifugal Clutch

[ekrekeler]

Honda GCV190 Go Kart Project

Hello, I am relatively new to these forums (considering that this is my first post, I am VERY new), however I am interested in building my own go-kart. I have with me a Honda GCV190 187cc 6.5HP engine from an HRB217 Type TDA lawnmower that I would like to use. It is still in good condition, and I don't have any reason to go out and buy a new one other than the fact that that it is a vertical shaft, which makes things for a beginner a little difficult. I've done a little research, both on this forum and a little Googling, and I have come up with a possible idea.
I would like to make use of the pulley that is already machined into the engine shaft, and use a belt to convert the power to horizontal rotation. Obviously I would like to have a centrifugal clutch, and I would prefer to have a differential on the rear axis. Being a newbie, I would prefer to make it as simple as possible, so I was wondering if there is any way to get my hands on a differential with a built-in clutch that I can attach to the belt coming from the engine. The easier the better, because I can remember from my Lego days that I am not a very good engineer when it comes to power conversions. I do have one thing that I might want to take into consideration though: considering the the 6.5 HP, might I consider installing a transmission as a later project? Will I be able to get anything more out of a gearbox? Any and all suggestions are welcome!

The Krekeler

 

[landuse]

Welcome to the forum.

How good are your fabrication skills? Welding experience? Why I ask is because you are making things VERY difficult for yourself as a noob kart builder. Trying to use a vertical shaft engine successfully is not the easiest thing to do first time round.

Post some pics of your engine for us. AFAIK, there aren't any differentials with build in clutches

 

[OzFab]

Basically, you have three choices:

1. A right angle gearbox (RAGB). the most common & useful form can be found on small MTD lawn tractors (see pic below)

2. A peerless gearbox (again, found on lawn tractors) or

3. A transaxle assembly

None of these options has a built in clutch

 

[ekrekeler]

How good are your fabrication skills? Welding experience? Why I ask is because you are making things VERY difficult for yourself as a noob kart builder. Trying to use a vertical shaft engine successfully is not the easiest thing to do first time round.

I am completely new to welding and fabrication. The most I have ever done to anything that has an engine is change the oil, flush the radiator, replace the thermostat and the air filter on a car, and gap spark plugs. All I have experience with is maintenance, not engineering and building it. So yes, this will be an advanced and probably multi-year challenge for me.

Post some pics of your engine for us. AFAIK, there aren't any differentials with build in clutches

I finally got around to taking those pictures. And honestly, as long as I'm not riding it too rough, do I even need a clutch for an engine this small? Just hook up the engine straight to a peerless gearbox like Fabroman suggested? Also, how adequate of a go-kart can I get out of this engine?

 

[OzFab]

Dude, do us all (including yourself) a favour, read this thread & follow the directions...

Those pics are HUGE & take forever to load; no one is gonna wait that long just to see the pics, much less comment...

 

[ekrekeler]

Thank you for the tips. I have fixed the images.

 

[OzFab]

Wonderful, lots better, thank you; the page doesn't take a year & a half to load now

 

[OzFab]

Wonderful, lots better, thank you; the page doesn't take a year & a half to load now

Now,

I am completely new to welding and fabrication. The most I have ever done to anything that has an engine is change the oil, flush the radiator, replace the thermostat and the air filter on a car, and gap spark plugs. All I have experience with is maintenance, not engineering and building it. So yes, this will be an advanced and probably multi-year challenge for me.

...& lots of fun for us

Don't worry, we can talk you through just about anything... you may want to watch a few youtube vids on welding though...

And honestly, as long as I'm not riding it too rough, do I even need a clutch for an engine this small? Just hook up the engine straight to a peerless gearbox like Fabroman suggested?

Umm, yes, you do; it's not about how rough you ride it, it's whether you want to stop! With a direct drive setup (as you described) as soon as the wheels stop moving, the drive setup also stops moving... including the engine...

Also, how adequate of a go-kart can I get out of this engine?

Do you know what size or brand it is? If it's under 5hp, you will have problems... such as, it won't go very fast...

 

[ekrekeler]

Umm, yes, you do; it's not about how rough you ride it, it's whether you want to stop! With a direct drive setup (as you described) as soon as the wheels stop moving, the drive setup also stops moving... including the engine...

Sorry, I had a stupid moment. Now I know. However, does anyone know how exactly I should attach the clutch to the engine? Can I find one that I can slide right onto the shaft and secure? (No dirty thoughts here, please. I couldn't think of a better way to put it.) That would probably be the easiest option. If anyone could provide a few web links to such a part, that would be awesome.

Do you know what size or brand it is? If it's under 5hp, you will have problems... such as, it won't go very fast...

As I mentioned in the first post, the engine is a 6.5HP Honda GCV190. It weighs 28 lbs, give or take a few pounds. My scale is a bit off because it's old. Note that I also measured the weight when I did not have a gas tank on it because the gas tank is built into the actual lawnmower, not the carburetor.


I am wondering whether I should build or buy a frame. I am new to welding and machining, so that's a drawback if I decided to build my own. However, if I were to buy a frame, it would be hard to find one that would work with my engine. Again, web links would be useful here.

Lastly, I am looking for speed over acceleration here. What would be my best option for power conversion from the engine to the rear axis for this? Fabroman has suggested using a RAGB, a peerless gearbox, or a transaxle assembly.

 

[OzFab]

does anyone know how exactly I should attach the clutch to the engine?

Something like this?

As I mentioned in the first post, the engine is a 6.5 HP Honda HRB217 type TDA.

Oh,

I am wondering whether I should build or buy a frame. I am new to welding and machining

That is a drawback, do you know any welders who can oversee your work?

Lastly, I am looking for speed over acceleration here.

Which means a small lightweight frame is necessary; adding excess weight will only slow you down...

Also, keep in mind that a high drive ratio is not necessarily a good idea; there's no point building a kart to reach a massive top speed if it won't move to begin with...

What would be my best option for power conversion from the engine to the rear axis for this? Fabroman has suggested using a RAGB, a peerless gearbox, or a transaxle assembly.

All things considered, IMO, the best option is a RAGB, followed by a simple (FNR) transaxle but, there are pros & cons to each:

RAGB:
Pros: More ability to play with gearing

Cons: More moving parts, may or may not be easy to source...

Transaxle:
Pros: Umm...

Cons: Not designed for high speeds, can be difficult to achieve proper gearing, difficult to mount adequate brakes...

 

[ekrekeler]

So I decided to open up the engine today. I was surprised to find that converting it to a horizontal shaft might not be that hard. The only thing that might be a challenge is getting the carburetor to work properly with the throttle levers after rotating it ninety degrees...

Upon opening the case, I noticed that the crankshaft already had a built-in oil flicker.

It dips low enough to get a good amount of oil stirring (as soon as I turn it on its side, that is). I might have to weld something onto it though, because I'm not sure that it would "flick" enough oil around the engine. It's shaped like a triangle, so it might just cut through it.

I would like to know what other people think about that. Also I think that the speed governor would become utterly useless in this position, being that gravity would constantly be pulling it downwards. Do I really need a governor anyway?

Also, the engine has a ventilation system for the crankshaft. It draws air from the filter and comes out through a "jet" in the crankshaft.

Here it is in the grand scheme of things. And yes, that's a bicycle pump hooked up to the ventilation intake. I was having a little fun with it.

Will I have to do anything for the ventilation system when I turn it sideways, or will it function normally? It won's be below the oil but it will be pointed towards it.

Lastly, the crankshaft has multiple openings to drain oil. Should I plug some of these up, so as to keep some oil in the shaft? I've heard of some people doing this.

I have some more photos attached. Thanks in advance!

The Krekeler

 

[zbuck]

I bet that you are not giong to like this post. For all the time and trouble of trying to convert that engine from a Vert to a Hort'z. I would put that engine back together and put it back on the lawn mover it came off of and go to HF and buy a 99$ Hort'z engine a be ahead of the game. As for a frame, I would look around and find a good used one.as evidently you have no fab/welding skills and again you would be ahead of the game.

 

[ekrekeler]

For all the time and trouble of trying to convert that engine from a Vert to a Hort'z. I would put that engine back together and put it back on the lawn mover it came off of and go to HF and buy a 99$ Hort'z engine a be ahead of the game... as evidently you have no fab/welding skills and again you would be ahead of the game.

I admit this is true, however the actual frame of the mower it came from is cracked, the starter is worn down, and the handle height adjustment is missing the knobs that hold the handle in place. Overall, it's in bad shape and I would need a welder just to fix it. If I wasn't going to do something with the engine I would just trash it or give it away. That being said, I prefer spending more time over money. If this is going to take a while to get working, that's alright. Also, as far as I understand, converting it shouldn't take that much effort. J-B Weld can sub for any welding that I need to do. As far as fabrication goes, the carburetor is the only challenge, as I mentioned earlier. I figured that I could use a 90 degree flange such as this one to rotate the carb. A piece of scrap metal, some screw holes, and a little J-B Weld for the carburetor intake will make sure that it's seated properly and it won't move. As I said before, the thing I'm not sure of yet is getting the throttle system to work with the repositioned carb. Even if I can't get that working, the only part that was connected was the choke lever (not counting the governor). The actual throttle is built into the engine case. It's not that hard to choke it yourself when you're starting it up.

Please correct me on anything if I am wrong.

 

[firemanjim]

You can make your own throttle set up to work with the carb...

 

[Bosch]

I'm far from the most experienced guy here, but my two cents is that my kart has a Predator 6.5 hp motor that starts on the first pull EVERY TIME. When this motor gives me trouble, I'll throw it away and spend $110 on a new one. They're disposable engines. Go get one and forego all that work.

 

[KartFab]

That being said, I prefer spending more time over money.

Please correct me on anything if I am wrong.

Time is money. Let's assume you can make $10/hr. If you spend 10 hours and zero dollars on it and don't have the engine running in horizontal position mounted, then you just wasted $100 dollars., which you could have used to buy a new predator engine.

How much is your time worth? (No answer required)

 

[mckutzy]

We have seen many people come and go with this whole intention of converting these motors to horz. None who have boasted with the same MO, still have not delivered.

In the end, it is possible but not worth it.
Buy a pred/clone, save Time and what little money you have.

 

[firemanjim]

We can't force him into buying an engine. I think that this is more of a challenge to him, than just to save a buck. Maybe he just wants to see if HE can do it.... Let's not be counter-productive.....
We have all had one of those projects that you could a done an easier way, but you just HAD to prove that you could do it your way..... (pull start on the H3...) So if you can be of help to this guy, lend him a hand. After all, isn't that why we are here? To help one another........ ?

 

[OzFab]

Time is money. Let's assume you can make $10/hr. If you spend 10 hours and zero dollars on it and don't have the engine running in horizontal position mounted, then you just wasted $100 dollars., which you could have used to buy a new predator engine.

How much is your time worth? (No answer required)

That's being very generous; my (car) mechanic charges $90 an hour (& that's cheap), the local lawn mower repairer charges around the same; for one of those (who are professionally trained to do so) to do the conversion would end up costing stupid money...

Horizontal shaft engines are not as easy to come by over here & there's an abundance of vert shaft engines (every push mower & most riding mowers have one); I have close to a dozen verts in my back yard but, I'll still hunt for a horz as opposed to converting a vert...

 

[rmm727]

HRB217 is the code for the lawnmower model, not the engine. That code cross references to a Honda GCV190 engine. In other words a vertical shaft GC190 which is about 6.2hp. I have a GC190 on my DB30 and love it. I raised the governed rpm to 4000 rpm no load and it pulls great. I didn't want to run it no governor cause I've heard the timing belts fail. Mine and your's it appears came with the nice Honda aluminum flywheels so there's not much worry of them coming apart.