Chain size


New Member
I have a 1974 honda trail 70 and have no chain...Now I want to go get a length of chain and master link to make my own does anyone know what size of chain to get??


I went to the local Honda dealer and told my story, they had 2 options- a roller bearing type (This was a couple months ago so I might have the term wrong) that was about $60 and a standard type chain for $13. I opted to save a few bucks and bought the cheapie. It was about 18 inches too long so I cut it to exact size with a Dremel grinding wheel and a hole punch and put it on and went on down the road. I've seen some comments in the threads that you should put new sprockets in when you put a new chain on, but I only put a new front sprocket on and it seems to work fine. I guess the rear sprocket wasn't too overly worn, we'll see how it wears.


Well-Known Member
A detailed explanation could get lengthy, so I'll try to cover just the high points. $60 is way over the top for any #420 chain, the best made (Iris, D.I.D.) retails in the the low $40s. They are made to tighter tolerances and using tougher (read:"more expensive") alloys. These are true roller-type chains, i.e. the individual rollers spin freely. They'll handle more than the 8hp rating of standard #420 and last many times longer if you have enough power to cruise at 45-50mph+. In your place, I'd have gone for the cheap stuff, too. It normally takes 2000-3000 miles to realize a payback on high-end #420 chain.

As for when to replace chains & sprockets, it's true that a worn chain will cause rapid sprocket wear and vice versa. If your sprockets are in good condition, then no need to replace them. If the sprocket teeth are worn to sharp points or, worse yet, have taken on a lean, they're toast. Normally, chains wear much faster than sprockets. Just replace the chain when it's worn to the point that the links just begin to not seat properly and you'll get thousands of miles from the sprockets. Learning how to judge chain wear takes a little experience.

For a stock bike, basic inexpensive chain should be fine. Cleanliness is the biggest wear factor. Start out by removing the sticky factory lube and replacing it with a dry-type. Any bike dealer should sell aerosols such as graphite-bearing lube or "chain wax". Occasional application will flush away sand/grit. If you're really motivated, completely degrease the chain and re-lube with molten paraffin submersion. It's a hassle, but seals the chain quite nicely and won't turn your chain into "shake & bake" the first time you go offroading.


Well-Known Member
Obviously rust, but another way to tell is hold it out on either end, link plates facing up/down and see how much curve it has. If it looks like an upside down ''U'' it's worn out/stretched. Do the same test with a ''new chain'' to know what a good one looks like. For a chain on the bike a quick test is go to the 3 o clock position of the rear sprocket and pull on one link of the chain, if you can pull it out over ''halfway'' or more ''off the tooth'' it's beat.
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Active Member
measure or look up the pitch length, do the math for "x" amount of pitches, ie 20, then measure the length over like "x" pitches ie 20, usually 10% is stretched, or lay on a clean floor in a straight line and push/pull back and forth, if it moves like train its junk