You are here:

Motorcycle Repair/Carburetor repair service



I bought some mufflers a number of years back from you for my 1967 CA-77. The bike is a real head turner! Anyway ...... I picked up a 1978 Honda CB550K4 a few years ago (it has less than 8,000 miles on it). Three of the mufflers were rusted out so I installed a 4 to 1 muffler system. The acceleration was sub par and after a number of shops looked at it one mechanic determined that because of the different exhaust system. It was rejetted but only runs slightly better. A friend of mine looked at it and found that the outside carburetor on the shifter side is hardly pulling any vacuum. Can you recommend anyone to overhaul/rebuid all 4 of them?


Jeff Laskowski/Gig Harbor, Washington

The owner of Hinshaw's has a large vintage Honda collection in the store... I would start with them...

If the carburetor vacuum readings are low, that is generally a sign of engine compression issues, unless the fuel circuits are really blocked off in a major way. Have a compression check done after valve are adjusted to see if it is having any effect on the engine performance.

Changing the exhaust, plus the use of alcohol-based fuels causes engines to run lean. I would re-jet a stock bike these days, just because of the fuel issues. You might have to bump the main jets up 1-2 sizes. The needles might need to be shimmed up a bit, as well. These carbs were all about emission control, not performance.

You might well need new carburetor intake manifolds after all these years...

Basically, you need to do a full tune-up and check the fuel flow to the carburetors... there is a filter screen inside the tank that might be blocked, too.

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.

©2017 All rights reserved.