My Design

[Simon Thomas]

Then I put back the engine on its base to ensure I welded the 2 pieces of metal correctly as planned.

 

[Simon Thomas]

Next, I took my old the motorbike and tested the length and align with the wheel sprocket. In the same time, I had the chance to mark on its base where should I sit the engine.

 

[Simon Thomas]

After that, I welded four units of screw on its base to hold the engine. Initially I planned to drill the holes for the screws, however because not fit, I have to weld the screws on its base.

 

[Simon Thomas]

It is time to include the chain.

 

[Simon Thomas]

To control the rpm, I need to modify the system by attaching the bicycle cabel to the speed controller. The cabel end is then tightened with the wire connector to prevent the cable slipped from its position.

 

[Simon Thomas]

From the engine speed controller, the cabel is then connected to the bicycle hand brake.

 

[Simon Thomas]

This is the result of my work this morning.

 

[Simon Thomas]

Without installing the chair to sit, I ride it for a while by standing on the frame. It run well, except the brake system did not respond well. Perhaps I did not use it for some time. So I did not press the throttle to the limit.

And the centrifugal clutch produced the burning smell and heat as well. Without investigate further the problem, I decided to stop and continue next time because it started to rain.

 

[TeamCheap]

Nice update.

I'm glad to see you making good progress.

I wish I could get as motivated on mine.
I am about to go out in the snow storm and tack weld my 6X6 frame halves together, atleast I have good heat in the garage so its not to bad in there.(tee shirt temps)

 

[Simon Thomas]

Thanks TeamCheap. I feel that my 6.5hp engine is not strong enough. Same with the centrifugal clutch may not compatible with the load it has to bear. Thefore it caused the heat recently. I checked my work yesterday and realized some weaknesses.

I saw your current project "1 man 6X6". Very impressive and I admire you have initiative like this. I want to see the completion of your project as well.

 

[landuse]

Nice work Simon! You have come along quickly.

How many teeth do you have on your clutch, and how many do you have on your axle sprocket? If you divide the axle sprocket teeth by your clutch teeth, that will give you your gearing. You want to have at least 6:1 for your clutch to work well. Even better you would want it 7:1.

As an example: If you had 10 teeth on your clutch, and 60 teeth on your sprocket, this will give you a gear ratio of 6:1 (60/10). If your clutch has 12 teeth, then you will have (60/12) = 5:1. This figure is a higher gear ratio that the 6:1. (The lower the number means you have a higher ratio. The higher the number means you have a low gear ratio).

For a centrifugal clutch, you want at least 6:1 or less. I would suggest at least a 7:1 ratio for you, because your buggy is probably a bit heavier than a normal kart. The lower your gear ratio, the slower you will go, but the more power you will have.

 

[Simon Thomas]

Thanks Landuse. Sorry for taking a longer time with current project. I am still not 100% fit and recover from recent illness. Actually doctor found helicobacter pylori (a bad bacteria) in my stomach which they screen through my blood. After taking a week medication therapy, I still feel giddy that the ceiling and wall sometime spinning or at least moving. May be the side effect, still not sure. The second opinion from a doctor said may be I have problem with fluid in the ears. That's why I feel not balance. However, I don't want to think about all these therefore I have decided to continue on with whatever I could do, including doing the necessary works. In another word, enjoy this life with positive thinking. This has motivated me to continue with the current project.

Back to the gear ratio, I need to check back the teeth. I don't exactly remember. But your comments make sense that the engine was hardly pushing my kart. Some more I have a heavy cart frame.

Will get back to you once I have the answer.

 

[Simon Thomas]

Landuse,

I checked the sprocket teeth yesterday evening.

Axle sprocket teeth : Clutch teeth = 47 : 14 = 3 : 1. It is pretty low gear ratio. That's why it is easy to move on flat road and hardly moved on terrain road.

My first buggy design is still the best because it has the gear that I can choose whether on flat road of terrain.

 

[landuse]

Landuse,

I checked the sprocket teeth yesterday evening.

Axle sprocket teeth : Clutch teeth = 47 : 14 = 3 : 1. It is pretty low gear ratio. That's why it is easy to move on flat road and hardly moved on terrain road.

My first buggy design is still the best because it has the gear that I can choose whether on flat road of terrain.

I am sorry to hear that you have been so ill. I hope you get better soon. There is nothing worse than feeling bad.

A 3:1 gear ratio is WAAAY to high for what you have. You definately need to get a larger rear sprocket. I would suggest at least a 70T sprocket. This will however still only give you a 5:1 gear ratio, which is still a little bit high. I still think that you need at least 7:1 for a ratio.

You will find that you will burn your clutch out really fast with a high ratio, because the clutch can never engage properly.

I would suggest either getting a larger sprocket, changing your clutch to one with less teeth (like 10 or 12) or getting a jackshaft.

 

[Simon Thomas]

Landuse,

Thanks for your good comments.

Nothing much I could do with the present set-up of my 2nd design. FYI, actually I have modified the centrifugal clutch. The original one came with less teeth and meant for smaller chain type. Because I did not have the compatible chain size, thus I need to modify it. I sent it to a machinist and he welded it with a honda motorbike engine sprocket.

I also couldn't find a larger axle sprocket here until 70T. 47T is the biggest I could find in our town meant for the motorcross.

I will keep my 2nd design until I have new idea on how to improve it.

 

[landuse]

Just be careful that you do not burn out your clutch. I don't know how much they cost there by you, but here they are really expensive, and I wouldn't want to be buying one all the time.

 

[Simon Thomas]

Centrifugal clutch is quite expensive in Malaysia or rarely available. My story with my clutch unit now, I was lucky when I saw it sold at e-bay but need to order from Australia. I emailed the seller and they said they have their shop in Kuala Lumpur. On my working trip to Kuala Lumpur last year, I purchased 2 units because I don't want to have the difficulty to order it all the way from Australia. If I remember correctly, I spent about RM200 per unit. So for 2 units, I spent RM400. I currently spent another RM80 for the machinist to weld the motorbike chain sprocket on the first unit. Second unit is still un-touched.

However, my clutch unit is not meant for heavy duty. It is for light duty use. That's why it produced the burn smell recently after given a high load from the heavy kart frame and giant wheel.

Well, I take your advice Landuse. I will be careful.

 

[Simon Thomas]

I managed to do some works last Saturday as to fix the problem with my 1st design. The works were merely on cutting the motorbike wheel sprocket to be used as the sprocket hubs. In another word, cutting the used old sprocket as a hub to attach another sprocket.

I will attach the photos later.

 

[Simon Thomas]

I cut my used old motorbike wheel sprockets. 2 units actually. One for attaching another new chain sprocket and another one for the brake disc.

 

[Simon Thomas]

Attaching the cut sprocket to another new set.