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Old 12-28-2007, 02:09 PM   #80
grizzzly
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Joined: Apr 2007
Location: socorro NM 505-five five zero-2583
Oddometer: 3,268
Quote:
Originally Posted by motu
It acts like the secondary butterflies on a progressive car carb...DCD Weber for example.The diaphram operated secondary comes in at about 1/4 throttle.So the small primary carb works at slow speed,keeping air speed high for good fuel atomization.With a big carb,like 40mm or so on a big single,when the throttle is slammed open air speed practically stops,and the bike dies....so they need an accelerator pump to richen them up.Keeping the intake air speed up at low revs makes for a nice smooth running engine.The Yamaha set up works well,but the carbs are hard to extract to do any work on them.I reckon there is a lot of ham fisted attempts at carb repairs on these bikes by people who don't know how they work.....then they blame the set up.
Thank for the info, I havenít ever seen anything quite like it. I just picked up the bike (90 xt600 2100 miles looks like new) it had been setting for about 4 years so I am cleaning the sludge out of the carbs
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