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The Lounge / Re: The motorcycle thread
« on: January 29, 2018, 02:25:57 PM »
Most carb problems happen when the bike sits. If things are running really poorly you need to clean out your carbs. There should be a fuel/air mixture screw. That's pretty much the only adjustment you'll need for tuning. Your best bet is to find a guide for your bike. The end game is to have your spark plug tan coloured. If not enough gas is getting through you will have white spark plugs, If too much gets through you'll have black plugs. Oil can cause blackness too. There is also an adjustment for idle. You can adjust an idle stopper so that the throttle returns to 1000rpm or 2000rpm when you let go. (I think most should be set just over 1000rpm)
For the more technical parts of how a carb works; There is a slow jet that allows gas through when the bike idles. At full throttle the main jet will be supplying most of the gas. In between it will slowly transition. The fuel screw adjusts the opening in the fuel line. (sort of)
The reason one carb is handy for maintenance is; To tune most 1970's Honda fours for example you need to set the timing, then valve clearances(otherwise you could tune to accommodate improper settings), then you set your fuel mixture on each carb, Then you have to hook up 4 vacuum gauges to each of the 4 carbs and adjust the setting on each carb slide so you have identical vacuum readings at idle, half throttle, then full. One carb doesn't need this last step.
I learned the most from reading clymers and hanes manuals. Definitely worth picking up. Just read through once or twice before you dig into anything. Some instructions are unclear or they tell you how to take something apart and then say "do the reverse to assemble"
For the more technical parts of how a carb works; There is a slow jet that allows gas through when the bike idles. At full throttle the main jet will be supplying most of the gas. In between it will slowly transition. The fuel screw adjusts the opening in the fuel line. (sort of)
The reason one carb is handy for maintenance is; To tune most 1970's Honda fours for example you need to set the timing, then valve clearances(otherwise you could tune to accommodate improper settings), then you set your fuel mixture on each carb, Then you have to hook up 4 vacuum gauges to each of the 4 carbs and adjust the setting on each carb slide so you have identical vacuum readings at idle, half throttle, then full. One carb doesn't need this last step.
I learned the most from reading clymers and hanes manuals. Definitely worth picking up. Just read through once or twice before you dig into anything. Some instructions are unclear or they tell you how to take something apart and then say "do the reverse to assemble"
