Centrifugal clutch questions, gearing, & maybe a TC?

[jason4207]

Hey guys!

First post and first kart.

I bought an old little single-seater.




Paid $200 for it. It came with an old 5hp B&S engine w/ no governor and no air filter. The engine ran fine, but I had to spray a little gas in the carb to get it going (per the instructions from the seller).

A couple weeks later the engine seized up while my son was riding. He thought it was out of gas, but the crank would not turn over at all.

So, instead of dropping a lot of time and money into it, I just grabbed a HF 212cc Predator engine for $99.

I got the throttle setup pretty good and used a spring to help with idle return.




First problem I had was that the crankshaft didn't stick out as far, so it was impossible to line the chain up properly. I ended up marking and then drilling some new holes in the engine-mount plate. That worked fine for a while, but the weekend before last the sprocket gear on the clutch was destroyed after several continuous hours of use. I think the chain was slightly out of alignment, the chain is kinked, or a little loose (or some combination). I also should have oiled the clutch after that much use, but only read about that afterward.



BTW, can you use brake cleaner or something else to clean the clutch? I know you have to oil the sleeve bearing, but wasn't sure about cleaning.

This past weekend I installed new rear bearings, a new brake drum and band (desperately needed!). I was able to adjust the axle sprocket, so I can now use the stock engine-mount slots. I have a new chain ready to go on. All I need now is a new clutch gear.

I'm pretty sure my clutch is the Northern Tool variety, and I've seen these replacement gears online:

http://www.mfgsupply.com/gomini/gominiclutch/gominiclutchcent/gominiclutchcenthilliard.html

Mine had a 12t gear on it, but it seemed to limit the kart. Plenty of take-off torque, but it hit top-speed very quickly. Stock rpm is 3600 and an online calculator shows 21.42mph with my 66t axle sprocket and 11" tires. I have added a spring to the governor which lets it rev up a little higher (4200rpm???) and based on that assumed rpm I should be at ~25mph. I know it'll go over 30 easily, so I was thinking of getting a 15t replacement gear. I was also thinking of getting 2000rpm springs to replace the stock 2300rpm ones since my engine idles at 1850rpm. Thoughts? Advice?

Before the incident I was wanting to get 13" tires that are a little wider. I figure that would give me the speed I need and a better ride when going off-road (will mainly be for on-road use, though). Thoughts? Advice?

And now I've gone and done a bunch of research and am considering a TC as well. I found this knock-off on eBay:

http://www.ebay.com/itm/go-kart-Comet-30-series-torque-converter-kit-replacement-TAV2-12T-35-218252-/330685230599?pt=Go_Karts&hash=item4cfe602e07

Is it as good as the Comet or GTC? I like the cost savings, but don't want something that'll fall apart. Does the knock-off have the same range (2.7:1 - 0.90:1) as the Comet?

Will I need any additional parts to make the conversion from centrifugal to TC? Does anyone have experience putting a TC on the 212cc Predator?

It looks like high gear on the TC will only go up slightly and give me ~26mph. But with gobs more torque!

And I can then either get a larger sprocket for the TC (is that possible?), get a smaller axle sprocket (Northern Tools has a 60t), or ideally, find those 13" tires that I want at a decent price.

So, right now I'm stuck trying to decide if I should fix the centrifugal clutch or go for the TC. I'm leaning toward TC at the moment...especially if I can get that knock-off for $100 less than a Comet/GTC. And I'm in the market for some 13" tires if anyone knows a good place to find them cheap.

 

[klicky96]

Well, if you have a hilly-type area you are riding on or you need more torque, then you should go with the TC. If you upgrade to, lets say, 16"-20" tires, I'd definitely through a TC on it. But for now, you should be good.

 

[landuse]

I can't see to well from the pics, but have you got a live axle. If not, a TC is not going to work for you.

 

[jason4207]

Well, if you have a hilly-type area you are riding on or you need more torque, then you should go with the TC. If you upgrade to, lets say, 16"-20" tires, I'd definitely through a TC on it. But for now, you should be good.

I don't really need more torque; it jerks my head back as it is. I actually want more speed. Now I have to do something since the gear is stripped, so I was thinking of going to a 15t gear instead of the stock 12t gear. However, I was also thinking of just putting that money into a TC instead. It won't give me the additional speed I'm after right away, but if I can find some 13" tires I think I'll be golden; the speed I want and plenty of torque as well. I also would like the kart to behave better at low speeds as I don't like the jerky action of the centrifugal clutch. If I go to a 15t gear it will take even longer before the clutch is fully engaged. And I'd really like to see if I can do burn-outs w/ the extra torque of a TC!

I can't see to well from the pics, but have you got a live axle. If not, a TC is not going to work for you.

Yes, it's a live axle; 2WD.

==============================================

Re-posting a couple questions in case they got lost in all that text above:

1) Can you use brake cleaner or something else to clean the clutch? I know you have to oil the sleeve bearing, but wasn't sure about cleaning.

2) I was also thinking of getting 2000rpm springs for the centrifugal clutch to replace the stock 2300rpm ones since my engine idles at 1850rpm. Thoughts? Advice?

3) I've gone and done a bunch of research and am considering a TC as well. I found this knock-off on eBay:

http://www.ebay.com/itm/go-kart-Comet-30-series-torque-converter-kit-replacement-TAV2-12T-35-218252-/330685230599?pt=Go_Karts&hash=item4cfe602e07

Is it as good as the Comet or GTC? I like the cost savings, but don't want something that'll fall apart. Does the knock-off have the same range (2.7:1 - 0.90:1) as the Comet?

Will I need any additional parts to make the conversion from centrifugal to TC? Does anyone have experience putting a TC on the 212cc Predator?

 

[landuse]

1. Take some sandpaper and take the glaze off the clutch pads. Do the same with the inside of the clutch housing. I am not too sure about brake cleaner. You just don't want to get any lubricant anywhere other than the bronze bushing

2. Should work, but not going to make any real difference to the working of the kart. You will be able to ride at lower speeds without the slippage of the 2300rpm engagement springs. This means less wear.

3. It is a knock-off, so it wont be as good. It will however work fine.

Just my 2c worth......

 

[jason4207]

OK, I ordered the TC last night, but now I'm regretting it. After looking at a lot of pics of it from various angles, I don't know how I'm going to get it to work. The 12t gear on it looks too close to the engine. With a centrifugal clutch the gear is almost at the very end of the engine shaft, but on the TC it is very close to the engine housing (from what I can tell from the pics).

The only way I can think to make it work is to weld on a new engine mount plate closer to the center of the kart and then somehow attach the sprocket to the axle between the bearings. Unfortunately, I don't have any kind of easy access to welding equipment and my experience welding is very limited (metal shop in High School 18yrs ago).

Can the TC somehow be mounted differently or reversed so that the 12t gear is further away from the engine? Or am I just not looking at the pics correctly?

 

[qtband]

I'm not sure, but you're going to have to move the sprocket location on the axle. The TC doesn't have a gear on the engine, only on the driven clutch part of the TC. You'll get a better idea when you mount everything to the engine.

 

[jason4207]

Here are some pics of the area. Click on them for higher resolution.









From what I can tell the 12t sprocket on a TC is behind the driven pulley, but that isn't my concern. In relation to the same gear on a centrifugal clutch it appears that this gear is closer to the crankcase which means I'll have to move my axle sprocket closer as well to maintain chain alignment. But, I can't move the axle sprocket any closer without it dragging on the brake-band-holder-bars.

I'm guessing this means I'll have to move the axle sprocket way over closer to the center of the axle. I assume I'll need some kind of metal disc to take the place of the current location of the axle sprocket to keep the brake band from slipping off the drum. And also make a new engine mount or move the one I have. The axle is not slotted between the bearings, so I guess I'll have to drill a hole in it or something to have some way to secure a new hub and sprocket in that location. And then if I get welding done I'll have to completely strip it and re-paint it for it to look right.

That is a lot of extra work. Am I missing some easy bolt-on solution here? I really don't want to have a pay a shop for all that welding and drilling. I assume it'll get pretty expensive pretty fast.

I'm thinking my money might be better spent returning the TC, getting a 12-14t replacement sprocket for my clutch, and getting the 13" tires I want.

Any suggestions?

 

[klicky96]

I know this is gonna sound kinda stupid to some guys on here. But you could actually add a jackshaft behind the TC, have the chain from the TC go to the jackshaft and then from the jackshaft to the axle sprocket. If i am correct, I believe you could use 2 12T sprockets on the jackshaft so that you do not decrease much in speed and still have the same amount in torque. Im not entirely sure on that because I have honestly never used a TC. But it looks like you have room to do that. Other members, please tell me if this will work or not so that I know if Im right or not.

 

[qtband]

I believe that the TC he ordered has an engine mounted jackshaft.
You can mount your engine in the center and it will give you plenty of room. Pick up a hub and sprocket and you should be golden. As far as no slot (keyway) in your axel, you can carefully cut one in with an air grinder, Dremel or a Roto Zip. You could also just leave the old sprocket there.

 

[klicky96]

I believe that the TC he ordered has an engine mounted jackshaft.
You can mount your engine in the center and it will give you plenty of room. Pick up a hub and sprocket and you should be golden. As far as no slot (keyway) in your axel, you can carefully cut one in with an air grinder, Dremel or a Roto Zip. You could also just leave the old sprocket there.

I understand that, but im talking about adding an extra jackshaft behind the engine.

 

[jason4207]

It looks like I might be able to mount the engine 20mm towards the left rear tire with just a couple of holes drilled in the plate. But to do that 2 of the engine mounts will be on the edge of the mount hanging on by washers. Hope that makes sense and I'm not sure how safe it is. Plus, I don't know if that will be enough lateral movement until Monday when the TC arrives.