Topic: my first carb rebuild/cleaning

[slowjo]

My bike is a 1972 CB750. The frame date is 6/71. I purchased it two years ago not knowing very much about motorcycles. I have always been a car guy but loved motorcycles. Since I have owned it I have done a lot of work to it turning it into a cafe racer. The next big thing I have planed to do is to clean/rebuild the carbs but not until this winter. The carbs are marked keihn 7AJF. I have a MAC 4 into one exhaust with the stock airbox. When I start it up it spits a little gas out the pipe when I rev it up and it likes to eat plugs. I go through at least two sets of plugs a year. When I take them out they are pitch black. I know its running rich but I will deal with this problem this winter. I would appreciate any information on what size jets or settings I should use for this setup. What rebuild kit I should buy? And any parts or tools that I might need to do this job right. Like I said I am going to Waite until riding season is over here in Northeast Ohio to try this. I will post some pics when I start the tear down.

[cookindaddy]

There is a lot of info here on carbs and carb rebuilding.

It occurs to me that while you are enjoying your ride this summer, you might try some of the basic adjustments, ones that you will need to do later on when you have the carbs rebuilt.

Perhaps you might surprise yourself and find out that your rich running condition might be solved through, say, checking the mixture screw adjustment: listening to the bike RPM while turning each one slightly and trying to get the "peak" in RPM.

Or perhaps dropping a carb bowl or two just to check what is in there and getting an idea of how clean the carbs are? It is not real easy to check the float height with the carbs on the bike but it can be done and too high a fuel level in the bowls could lead to rich conditions.

You can even check the fuel level in the bowls without removing them with a short length of vinyl tubing attached temporarily to the drain on the bottom of each bowl, undoing the drain screw and holding the tube upright against the side of the carb.