Quicker Rear Sprocket changes

Does anyone know if there is a device on the market that allows for a quicker rear sprocket change for the Lo206.

Does anyone use anything that allows for this or is there a popular method?

Im just trying to cut down on time in the pits when I need to change out a rear sprocket?

Thanks

What part is slowing you down? Getting the sprocket on or tensioning the chain? Are you using split sprockrts ir solid?

https://wwwsmart-revolutions.com/pin-it-sprocket-hub/

That link is to the MFGr’s site. You might pay more or less at a kart shop site.
https://www.usakartparts.com/product-page/pin-it-sprocket-hub

A video in in this thread

Polish your axle, make sure your brake bell doesn’t bind on the key, file the setscrew marks off it as you take it off, and use a one-piece sprocket! Two bolts for the hubs, two bolts for the brake bell, two bolts for the sprocket hub, six setscrews, and out it slides. For a 206 three bolts are enough on the sprocket, then slide it all back together and align.

What’s your current method?

You can cut the sprocket in a single spot and maneuver it over the axle (depending on the axle size). I’ve never tried that with a 50mm axle.

Use split gears that are cut in two places.

Use a system like the pin-it.

I’ve moved to basically only single cutting sprockets, assuming they are #219. Even with a 50mm axle with the right sprockets the flex back fine, and then you are a lot less likely to deal with the “tight-loose” phenomenon.

The other special sprocket hubs may work, I haven’t tried them. What works for me is to use a sprocket hub that is threaded so they become “studs”. Keeps you from having to use two hands to tighten the nuts. We use a two bolt sliding mount like this Sliding Mount.
A sprocket change consists of;

  1. Loosen the two nuts on the engine mount about a full turn each.
  2. Slide the engine back, the chain will become slack.
  3. Lift the chain off the old sprocket and let it hang down.
  4. Remove the nuts holding the old sprocket using an electric impact gun (we use a Dewalt) Don’t let the impact gun fling the nuts to the stratosphere. Clean the nuts with some brake clean.
  5. Remove the old sprocket, clean it and put it in your sprocket holder. Check the hub for dirt, grit, damage, etc…
  6. Place the new sprocket on the hub making sure the alignment marks are correct.
  7. Start all the nuts back onto the studs on the hub. Do not tighten them down, finger tight is fine.
  8. Lay the chain over the new sprocket and rotate the axle until the split line of the sprocket is straight up and down.
  9. Wearing a glove or using a rag, grasp the top and bottom runs of the slack chain and pull them together. This will make the chain lay across both split line gaps and align the spacing of the sprocket.
  10. While holding the chain like this tighten the sprocket bolts. We use the impact for this - don’t go crazy.
  11. Slide the engine forward to the correct chain tension and tighten the two engine hold down nuts on the sliding mount.
  12. Check the chain for free running and correct tension.
    Done.
    We can change a sprocket this way in about five minutes not counting putting up on the stand or letting it cool off.
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Our engine mount has four bolts, the trick to that style is to figure tighten it and then use a cross pattern to slowly tighten each corner just like you do when putting on a head. This prevents the engine from becoming uneven and messing up your chain tension.

It takes me just a few minutes to change a gear most of that is spent reaching for the gear rack. It takes practice to do it quickly.

This has brought me to another thought. Just like the driver the mechanic needs to practice and work on their race craft. A weekends race can be won or lost in the garage on Monday a week before the race when making plans.

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Use the Pin-It sprocket hub. Super fast and allows the sprocket to float eliminating the runout issue with two piece gears. Kartingdepot.com is the best price I found on them.

The conventional engine mounts that adjust and tighten from the bottom can be a big part of the problem. Some mounts tighten down evenly and square with the axle, others not as well. There are a lot of things welded to the frame right where the mount goes, kicker stubs, frame cross members, bearing hangers, etc… The tube can distort and cause a chronic chain misalignment when the mount is tightened. This is especially critical on low powered classes like LO206 - you can’t afford to waste any! That’s why we went to the sliding mount. You can set up the lower part of the mount to correct any issues with filing, shimming or special torquing procedures. Just make sure the mount is square to the axle. We use a chunk of aluminum, a 123 block and some clamps but just about anything will work. Once the base is good the rest will follow. The sliding mount also makes pulling the engine off for clutch service very easy and quick. Engine Alignment

Been can you share a pic of your setup?

We are getting ready to build our dual four stroke engine kart in the next few days. I’ll try to get some pictures then.

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Ohh would like to hear/see more about that too.