Help With Pulley Alignment on predator 212 / YD3203

[bigboi86]

Have a YD 3203 just bought. It has a predator 212 on it. Got it home and as we are driving from stop, it has issues lurching or jolting, it appears the pullies are not aligned and it’s causing the driver pulley to grab the belt, causing the jerkiness

holding a straight edge against the flat side of the driven wheel pulley, there’s somewhere around the 3/8 inch gap between the straight edge and the flat side of the driver pulley

So it looks to me like the driver pulley needs to either move away from the engine about 3/8 of an inch or the driven pulley needs to move closer by that distance, or they both need to be moved to close the gap and align the flat sides of the driver and driven pullies

But, there is only maybe 3/8” left of the spindle(?) for the clutch contraption to sit on, so if I added 3/8 inch worth of spacers, or probably really any more between the driver pulley and the engine, there won’t be enough spindle (?) for the clutch to sit on.

sorry, I don’t have a lot of experience with small engines like this or go karts, but I’ve always wanted one and my boys are ready for me to get it running right!

 

[Sparkwizard]

Can you loosen the bolts holding the engine down to the frame and move the jackshaft plate? It looks like a seperate plate between the engine and the frame. Adjust your alignment, adjust your chain and your belt and tighten the bolts. Look at that and if that doesn't work, wait for someone smart to chime in.

 

[Hellion]

wait for someone smart to chime in.

Someone just did: you. The rest of us are idiots.

Your driven pulley, for one, should be immaculate and polished smooth but I see crusty rust in there. That’s not good for the belt’s health so it looks like it’s time for a service interval …which should be do-able with these torque converters. And I agree with the jackshaft assessment mentioned above, if it can move and correct the problem, that is.

Good photos, by the way

 

[Hellion]

Original engine was a Tecumseh OHV 5 or 6hp which probably had slightly different geometry, meaning that when the original engine was bolted in, the engine shaft was better located to where the pulleys and sprockets all lined up perfectly. No telling how long the kart has been operating in this current state. Probably chews up belts on the regular…

Yerf Dog 3203 Owners Manual:

https://www.bmikarts.com/PDF/3203A_T.pdf

 

[panchothedog]

It looks like you have some kind of spacer between the sprocket and the driven clutch. The sprocket and clutch are both keyed to the shaft. Get rid of the spacer ( or whatever it is ) and replace it with a washer about .050" thick. You will have to cut a slot on the inside of the washer for the key. One washer may not be the exact distance needed, but I think you get the idea. You have plenty of wasted room taken up by that spacer to fly your alignment problem.

 

[panchothedog]

If that is not a spacer, and is part of the sprocket, there are sprockets available with different shoulders. Or you could have it milled down. There's nothing you can do on the engine end. The shaft of the predator is too short. I've been down this road on 2 or 3 karts. Move the driven over. You don't need that much space between the chain and the clutch. Spell check B S. To fix your problem, not fly your problem.

 

[Hellion]

The shaft of the predator is too short.

I have taken notice of this statement many times before but have yet to measure between engine families to compare, or in other words to prove it to myself; aka seeing is believing. Thanks for the reminder

 

[JimD]

You are correct , you definitely have an alignment problem. Take the spacer off the crankshaft because you don't have enough shaft for the 4-spline to fit on the end of the crank. That 3/4" spacer next to the crankcase behind the flat sheave has to come off. Get the driver fixed first then let's tackle the driven unit. You can gain inward movement of the driven by doing a couple of things. The sprocket on the jackshaft doesn't need set screws so you can shave that off in a lathe or with a flapper disk. All the sprocket needs is a key the length of the sprocket once you trim it down. The key has no where to go so that is why you don't need the set screws. Some genius put that sprocket in as a replacement and that is where the problems started.

And they are very good pictures.

 

[panchothedog]

If you move the driver closer to the engine as recommended in post #8 ( good idea ) your alignment problem will be worse. Probably an inch to an inch and a half. In this case go to the OMB Warehouse, or Go Power Sports website and find their aluminum motor plate. It's a half inch thick and bolts to your existing motor mount ( where your engine presently sits.) It has 4 bolts protruding upward onto which you bolt the engine. Everything is slotted and it allows engine movement for and aft, as well as side to side, by about 2 inches. They cost around $40 and will fix the problem. If I wasn't so technically challenged, I would post a link. But I don't know how to do that.