Manco Scorpion - drive issue with chain/sprocket

[AGrayson84]

Hey everyone, I picked up a Manco Scorpion 606 from a buddy the other day and finding that it needs more work that mentioned. It needs a new belt, which I was already aware of, but I was able to get some motion out of the current belt the other day and the go-kart just jerked around as it has a hard time going forward (belt was also slipping).

I jacked up the rear suspension to get the rear tires off the ground and tried rotating the drive by hand. There seems to be a mis-alignment with the small and large sprockets. When I rotate the drive in a forward motion by hand, you can watch the chain have a hard time setting itself on the teeth of the front large sprocket. The chain also slightly rubs on the edge of the driven pulley (you can hear it in the video below), but that may be due to it not rotating fast enough by hand to keep tension on the chain.

I'm very mechanically inclined but I've never played with a CVT drive like this and without tearing down the driven shaft and the rear axle to look for the issue I'm not sure what might be causing this mis-alignment and what it might take to fix it.

Here is a video of the sounds it is making as I rotate the rear axle. I originally shot this in HD with my phone, but I had to rotate the video in YouTube so now it looks like crap, but hopefully this might be enough to give you the idea of what is happening:

http://www.youtube.com/watch?v=QlPV9ElH6EM


Thanks,

Andrew

[x-bird]

Ouch; that needs a spacer between the driven and the small sprocket. looks like the chain pins and plates are catching the driven pulley. that is also probably lifting the chain from the sprocket. From the looks of it, you want to dismantle both the drive clutch and driven, clean & lube them, wire wheel the chain and lube it before starting it up. If you type in "clean and Lube comet" you should find several threads about it that also have a link to a website that has details on where to lube them. You'll need snap ring pliers in addition to the wrenches.

[AGrayson84]

Thanks for the reply! So I'll look for a thin washer or two, to help the chain clear the driven assembly... I just hope it doesn't cause an alignment issue with the belt next haha. I did disassemble, clean, and regrease the drive clutch the other day... but the lithium grease slung out the excess... so I'm going to need to find a better lube that won't sling. Any suggestions on anything that's not expensive?

Also, should the driven clutch have a wider opening for the belt area (let the belt sit deeper into the pulley) when the go-kart isn't moving?? Or should the driven clutch have a narrower opening in the belt area (causing the belt to sit further out of the center of the pulley) when the kart isn't moving? I'm trying to determine if there's a problem with the driven clutch or not. Thanks!!

[x-bird]

For the clutch, driven & chain, you should find a dry lubricant (sprays on wet, solvent evaporates leaving a lube film behind.) Grease is not recommended for these. A little bottle of tri-flow from Ace, pep boys etc. should do it for about $6.00

Both the clutch and driver expand and contract based on the load. When you disassemble the driven, the spring backs off. When you put it back together, you need to rotate the outer sheave tighter -- there's three "ramps", you need to advance it over the first one you encounter under spring tension and and hold it together while putting the snap ring back--lots o fun lol. I've attached an overhead view of checking alignment of the pulleys to give you an idea, remember though, the inner sheaves are not perfectly flat so ifyou used a straight edge on the driven like i show, it'll have a 1/16th or so of a gap on either side. the picture shows a slight misalignment.

[AGrayson84]

Thanks for the suggestion on the dry lubricant... I'll definitely grab some!

Not sure if I honestly understand the driven part... it'll probably make more sense once I take it apart. What exactly is the "sheave"? Does sound like a 3-hand job putting it all back together

My driven belt section, with the kart sitting still, is wide open, allow the belt to drop all the way into it. Based on how the gearing should work in my mind, the driven shouldn't allow the belt to fall down further into the area where it rides until you reach a higher speed. The belt riding further out on the driven section would make for lower gearing at lower speeds, which makes it easier to accelerate from a slower speed of course. So I'm kind of confused as to why my driven assembly allows the belt to fall all the way to the shaft in the center? I'll take a picture tomorrow if I can remember haha.

Thanks again for the help!!!!

[metalstudman1]

Here's some reading material!!! This is the best printed info on your CVT I ever found:
http://www.*****************/asymapp.htm
Also PB Blaster Dry Spray lube is sold almost everywhere that will work for your clutch & driven.
Sheaves = pulley halves
Belt should set flush with the top rim of the driven when adjusted properly and the correct belt is used.

[AGrayson84]

Thanks so much for the link, that broke it down very well!

Oh I took a look at the driven assembly earlier today and the sheaves are close together when sitting still, not spread apart like I thought I had seen. Does this mean I'm in the clear on the driven assembly???.... No. Blah. Found out that the flat sheave, the one right against the small chain sprocket, has been bent. That's why the darn chain pins were catching on it.

I hadn't seen one anywhere, but have any of you seen just the flat sheave sold separately anywhere? Or am I looking at having to buy the whole driven clutch assembly?? Thanks again!

[metalstudman1]

On the driven the sheaves are closed/close together when idle and open up with power.The clutch is open when idle and close up when power is applied. I don't know of any place that sells just one sheave/pulley half.

[x-bird]

if it's been run while bent, i wouldn't trust the other half anyway. I have no idea how much use my 7-inch dia driven saw with it's previus owner, but it started chewing up belts. turns out the rivets were loosening up and it had cracks radiating out from all of them, both sides. Play it safe--you're better off just replacing the entire driven. If you've ever seen a torn grinding disc chunk fly off a grinder, imagine that occurring with a piece of jagged steel.

[AGrayson84]

Originally Posted by metalstudman1

On the driven the sheaves are closed/close together when idle and open up with power.The clutch is open when idle and close up when power is applied. I don't know of any place that sells just one sheave/pulley half.

Thanks for the clarification. I was pretty that was the case, but I guess I was still calling the driven assembly a "clutch" but I guess that's not necessarily accurate haha.

Originally Posted by x-bird

if it's been run while bent, i wouldn't trust the other half anyway. I have no idea how much use my 7-inch dia driven saw with it's previus owner, but it started chewing up belts. turns out the rivets were loosening up and it had cracks radiating out from all of them, both sides. Play it safe--you're better off just replacing the entire driven. If you've ever seen a torn grinding disc chunk fly off a grinder, imagine that occurring with a piece of jagged steel.

Yeah looks like lots of things were neglected for some time on this go-kart, so I'll do like you said and just get a new driven assembly. The darn brake pedal won't return when you press it down, and the spring is in place at the pedal. Stuck my hand near the caliper to feel for any problems and the darn thing feels loose as heck. Appears to have an oil leak somewhere between the engine and the steel plate that is used to separate the engine from the CVT system. Throttle pedal didn't return when pressed down, so I replaced a spring and it works better but something still seems wrong there too with the throttle operation at the engine side of things. I'll tackle that once I read more about the engine linkages.

[x-bird]

there's an npt pipe plug on both ends of the bottom of the block, hopefully, you just have a loose one. before trying to tighten it, clean it up with some brakekleen and check for cracks around it from overtightening. Sometimes there's also leakage from the governor arm pass through--not much to be done about that one but give it an occasional cleaning under there.

when you say caliper, do you mean the brake drum and band? there's a couple stop bolts that go into the drum's hub to lock it to the axle--might be loose. There's also an annoying to work around u-brake that acts as a safety/keeper for the brake band, if the liner material is worn off the band it may be riding off the drum and into the keeper, locking it up.

be careful with the throttle/governor linkage springs, if they're original, it's best to leave them be. take some pics and post if you can. once you start messing with those stupid little things, it can be the devil to get it set up properly again.