Motorcycle Repair/Dead cylinder


I have just been given a Honda CB400T that has been sitting for about 3 years or more.

I put in a new battery, drained the old gas and refilled with fresh gas.  It started up fairly quickly, but it is only running on the right cylinder.  Right side header pipe very hot, Left side is cold.  Pulled the plug and installed a good one from another running bike, the one I pulled had gasoline all over it, but no fouling of oil or carbon....just gas.
No difference from replacement plug.....................condition same.

I'm thinking maybe a bad plug wire or coil????



Hello Terry,

First, check left cylinder for spark.
To do that, attach a spare spark-plug to the left spark-plug cap, place it on the cylinder-head so the metal shell makes contact and crank the engine to see if there is spark.
If not, get back to me.
DO NOT remove the left plug while carrying out this test.
Any fuel left in the cylinder could splash out and ignite by spare plug sparking.

Since the bike has been sitting for so long, for sure the carburettors have to be cleaned.
Especially the fuel jets get clogged by gasoline residue.

Clean them thoroughly and get back to me if anything goes wrong.

Best Regards,

Motorcycle Repair

All Answers

Answers by Expert:

Ask Experts


Lazaros Ampatzidis


I can help you on EVERY issue involving POST-1980 Japanese Motorcycles plus KTM and Husaberg. My field of expertise includes Engine, Transmission, Fuel system (carburation & EFI),Electrics and Electronics. Maintenance, repair and tuning. Road and off-road suspension tuning. Please don't ask me about non-Japanese Motorcycle, especially American built on which I have low to zero experience.


I'm a rider and hobbyist since childhood. 25 years motorcycle workshop mechanic.15 years motorcycle racing mechanic. In order of experience high to low:Kawasaki,Suzuki,Honda,Yamaha,KTM,Husaberg.

Hellenic (Greek) Technical School.Internal Combustion Engines Engineer. Automotive Electronics.

©2017 All rights reserved.