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Motorcycle Repair/Carburetor repair service

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Question
Bill:

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?

Thanks,

Jeff Laskowski/Gig Harbor, Washington

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

http://www.hinshawsmotorcyclestore.com/

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...

http://www.ebay.com/itm/Honda-New-CB550K-Carburetor-Intake-Boot-Carb-Insulator-5

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

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Bill Silver

Expertise

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.

Experience

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.

Organizations
VJMC (Vintage Japanese Motorcycle Club) of North America

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

Education/Credentials
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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