You are here:

Motorcycle Repair/honda c 50 with modified cilinder 72 cc


i have problem with buji end with supapes.scuzemy but i  now a little englis .but i hope to help my.

Cristi, I am absolutely guessing at your question. I really don't understand the words you have chosen about your bike problem.

When you increase the cc in the engine, you must add larger main jet to the carburetor or use a larger carburetor. This is especially important if you have modified the air filter and/or the muffler/exhaust pipe. You may have to raise the slide needle, if adjustable or add a thin shim, below the clip to raise it slightly.

If the compression has been raised a lot, you may have to use a colder spark plug  #6 to a #8 in NGK. If the ignition timing is adjustable (magneto), verify that it is set correctly to the F mark on the flywheel. If ignition is CDI, then no changes can be made.

Maintain the valve adjustment settings from the factory.

If this doesn't answer your question, perhaps you can find a friend who speaks/writes better English to help you send another question here.

Bill Silver

Motorcycle Repair

All Answers

Answers by Expert:

Ask Experts


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.

©2016 All rights reserved.