Chain coming loose

remove the coaster brake lever bolt. This is small bolt that holds the coaster brake lever to the left side chain stay. There will probably be a strap wrapped around the chain stay with bolt going through the strap and the lever. This usually requires a 10mm wrench (sometimes it is 8mm) for the nut and a Phillips or flat head screw driver (some times it's another 10mm bolt head).
The axle nuts are usually 15mm nuts. Loosen these (they usually don't need to be removed all the way) and push the wheel forward to put some slack in the chain. Lift the chain off the rear cog and you will be able to pull the wheel out of the drop outs.
To install, slide the wheel into the dropouts, put the chain back on the cog, pull back on the wheel and tighten the nuts finger tight. Reinstall the bolt through the coaster brake lever and then tighten the axle nuts, pull back on the wheel while tightening the nuts so the chain is tight. Then tighten up the coaster brake lever bolt. (if you tighten the axle nuts first, you won't be able to move the coaster brake lever into place to get the bolt in)

if you have atleast 1/8" of teeth still on chain .take a link or 2 off good to go saved you beer money.

loosen seat post clamp with correct size allen. once its loose push down and twist the seat untill its where you want it then tighten the seat post clamp

Two places to tighten the chain and it requires you to loosen the nuts on BOTH sides of the bike, almost at the same time. Start at the fan wheel (top) of the bike. First thing you need to do is to loosen the little nut at the hub of the fan wheel on both sides. Unscrew it almost to the point of taking it off, but leave it screwed on the end of the bolt so it will stay on the bike. Then use an adjustable wrench to loosen the nut a bit on one side and then do the same on the other side OR use both hands and loosen both at the same time by unscrewing with adjustable wrench in opposite directions on both sides. Once the wheel is loose, you want to sit in front of the bike and pull both of the large nuts at the same time toward you and the chain will tighten. The goal is to have the fan wheel centered and for you to be able to see about 1/4" inch of clear gap behind the nut on both sides. Then use your fingers to tighten the nuts to the frame just enough until you can use the adjustable wrench again. I have sometimes used a flat head screwdriver to insert into the gaps to prevent the chain from loosening up. The tighten the nut on both sides of the bike. Be sure you tighten the little nuts as well (they are called chain tensioners). That SHOULD do the trick. However, if your bike chain is still too loose, you need to do the same for the chain at the pedal area, That requires the same thing all over again, but in most cases, the chain loosens at the top part of the bike (fan wheel place). However, if you do work on the pedal area, you want the chain to be pushed toward the fan and not toward the **** side of the bike. It may sound crazy but that's the only way to tighten the chain. give me a thumbs up with my solution.

Generally there is a screw or screws on the back or somewhere to tighten the chain within a certain inch wise range.

you need to put chain back on and move the back wheel back so the chain is tight tighten the nuts up and should be okay

Take the chain off?

Loosen the axle nut and the lock nuts for the chain adjusters on each side of the swingarm. Turn the adjuster to move the rear wheel to the rear to tighten the chain.

You want to adjust the chain so that you have 1 inch up and down play in the chain. By this I mean 1/2" above center and 1/2" below center of the chain as it sits on the bike, 1" up and down inclusive. Adjustment should be made at the point where the chain is the tightest. Roll the rear wheel while checking the chain tension. Find the tightest point to make your adjustment.

Move both chain adjusters the same amount to keep wheel straight within the swingarm. Once adjusted, roll the wheel a couple of turns and check the adjustment of the chain again. Once finished, tighten adjuster lock nuts and retorque the axle nut to 50 foot pounds of torque.

Good Luck, Steve

To tighten a loose chain you need to pull the cotter key pin from the rear axle then loosen but do not remove the nut. It just has to be loose enough to slide in the swingarm. At this point there are tension adjusters on the ends of the swing arm you tighten them to take the slack out of the chain. NOT TO TIGHT! You should have 1 inch of play in the chain this is up down play not front to back. I push the chain up the highest it can go and measure how far it falls. NOTE: TURN THE TENSION ADJUSTERS THE SAME AMOUNT THE SAME DIRECTION IF THE AXLE IS TWISTED YOU WILL THROW THE CHAIN. This can make for a bad six months!

Make sure you follow the directions carefully. You might try leaving the flat washers out or substituting thinner ones. Worse case you will have to go to a bicycle shop and purchase a longer axle. Make sure you keep careful track of how you disassembled it and take pictures or make drawings. The hardest part with replacing an axle is getting the proper resistance on both sides so the bearings don't bind. Check www.sheldonbrown.com for some helpful articles.