chain tension for new sprocket

my question is, how many links do I take out of the chain to have proper tension? Does anyone know?
Not a single post answer for this. Every install is different according to many variables. Prompts questions back at ya.
1. Is your back wheel a coaster brake or multi speed cluster?
2. Does the frame have drop outs or slide adj. for rear wheel mounting?
what is the ideal tension for a chain on these bikes?
Follow this thread http://motorbicycling.com/showthread.php?t=56080&highlight=chain+slack
What are some good lubricants and where can you buy them to ensure optimum performance?
I use Amsoil Interceptor or Dominator 2 cycle oil mixed 4 oz. per Gal. That’s a 32:1 mix. I also use religiously ½ oz of K-100 per Gal fuel stabilizer (Ethanol in our gas is not good nor is water). I buy from Napa close to home. For the drive chain I have a wipe rag wet with Marvels mystery oil and wipe dirt and grime off the chain in my closed fist. For the Bevel gear clutch cover side I use a pea size blurp heavy auto grease just in where the gears mesh. No More though, If you use too much you will mess up the clutch surfaces.
Many people choose different products, All valid methods.
I do not use chain tensioners on my bikes.
You will need to buy beg or borrow a Chain Break if you don’t have one. Also consider replacing your kit supplied chain with a # 41 machine chain and a connecting link (some call it a half link)@ tractor supply. Cost about 20 bucks a box which is enough chain to fit 2 bikes 1 master link comes with it..
If you choose to forego the tensioner check out my Albums Happy Chains.
http://motorbicycling.com/album.php?albumid=1499
Doesn't end here though. Use the search function Read as much as you can. Good luck and above all Please be safe.

The chain should have 1/2" to 3/4 " up and down movment. I formerly used PJ1 chain lube but it was messy. Now I use surf wax and it dosn't make a mess of the tires, rim's and frame.

For sizing the chain set the rear wheel where you need it for the peddal chain. With the engine drive chain on the bike with the new sprocket.... Position the master link of the engine drive chain where it can easily be worked on. Remove the master link use a 3" piece of hanger with the ends bent in a u to hold the chain,this will let you use both your hands to pull one chain end over the other and mark the pin your going to remove. Insert your master link in one side of the chain so you get the right link. If you have a decent chain breaker you can break the chain in place on the bike. Eyeball the pin your going to remove carfully some of us have made mistakes when in a hurry and punched out the wrong pin.

Good Luck!

I went from a 44 to a 40, I use a sprocket adapter wrapped around the hub of a coaster brake wheel. I weigh around 155 and my bike is heavy with worksman front drum and rear coaster. I got hills and valleys where I live and have found the 40 T to work well for me and I can do about 35 tops on level ground wide open. My motors happy cruise speed is 27 mph. Plenty fast enough. Keep in mind a lawnmower has more power than your bike.
If this is your daily transportation reliability is your goal. You can spend a lot of money on speed, And a lot on reliability. These are hobby motors with that said-pick your pension. Pay close attention to head nuts, intake/exhaust nuts, and chain tensioner if you use one. Vibration will cause your engine mount studs to back out or nuts to loosen. I don't mean to discredit the machine but intend to stress safety on these bikes. They can hurt you. Your safety is up to you.

just to add to the good advice already given above. I use bacon grease on chains. Works great and is free after a Sunday morning breakfast.

A chain breaker is almost a must have but you can use a hammer and nail too. Just drill a hole in a scrap pc of lumber. LOL, it really is one of those things where ya need a bigger hammer.

Was great to read how much fun your having. These crazy things really are a blast.