Carb woes

[A.W. Dyck]

I've had a recurring carb problem for quite a long time now -- like several years. What happens from time to time is when I travelling with the engine at a low rpm, I will suddenly lose power and the bike will sound like it is blowing raspberries. I had a dealer clean the carbs two years ago, and it cured it for a short time. By the end of the season, the problem was back. This year I decided to clean the carbs myself. In the process I had to drill out a pilot air and a couple of pilot fuel jets. ( On a couple the tops of the jets were already stripped which made me wonder how the dealer cleaned them.) I replaced the jets, reassembled the carbs, installed and synched them. The bike idles beautifully but runs rough at higher rpms now. Any ideas?

Arthur

[TopCatGr58]

Hey A.W.,

Lot's of things to consider. You've got a 79SF. You didn't say that it used to run okay at higher rpms when it was missing at lower rpms? Surprisingly, what can seem like a carb problem can also be an electrical one. The pick up coils and their wires are notorious for breaking down, breaking, and causing intermittent firing depending on what rpm, how much the timing plate is flexing due to action of the vacuum advance and cent. advance mechanisms! Read the tech tips on pickup coil wire fix. Also the bowl vent tubes can get clogged, either in the tubes, where they attach to the airbox if you still have the OEM.

Write back with more details if needed.

[A.W. Dyck]

Thanks for the advice. No, I never had any problems at high rpms. I wasn't thinking in terms of electrical although I had considered the spark advance. I'll take a look at thepickups tomorrow.