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Motorcycle Repair/1977 Honda CT125


Hello Bill,  I have a 1977 Honda CT125.  The drive train was noisy so I went by a local shop who determined that the chain needed replacing.  I had this done at the shop since I did not have the chain break tool.  We inspected the rear sprocket and it was OK.  Road it and it was noisier than before so had another look at the shop and the front sprocket has worn teeth, also some bend backwards, and replacement was suggested.  I am considering the possibility of doing this job myself.  Is it difficult?  Do I need to break the chain or could I just slip it off if I loosen the back wheel enough?  I am reasonably handy with tools and have a good selection of general tools but no specific motorcycle tools.  Also, any suggestions for ordering this part?
Thanks in advance for your assistance, this is a great resource.
Best regards for the new year,
Don Kulak
Vancouver Island, Canada

Don, as long as you are using the same number of teeth on your new sprocket, you shouldn't have to break the chain, although I would assume your new chain has a master link in it.

Beyond that, just loosen the rear axle and chain adjusters, then slide the rear wheel forward. You might want to loosen the sprocket bolts first with the bike in gear, in case they have never been out and are stubborn to loosen and remove. With the outer chain cover removed, you should have clear access to the countershaft sprocket bolts and sprocket. Loosen the bolts and remove the retainer and slide the sprocket off the output shaft. Insert the new one in the chain links and slide it back onto the shaft, reinstall the retainer and two bolts and replace the cover. Check and adjust your chain so you have about 3/4" to 1" of slack in the middle of the chain and you should be good to go.

You will need metric sockets to remove the front sprocket bolts and wrenches for the rear axle and chain adjusters, otherwise it is an easy task. for reference illustrations.

Bill Silver

Happy New Year...

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Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

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