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Join Date: Nov 2007
Location: Chandler, Arizona
It is normal for the rpms to go really high with the choke all the way on. Mine will quickly go over 3000 rpm after the choke has been on all the way for a few seconds. You need to back off the choke to keep the rpms down. As KM said, do not ride it with the choke on. I warm mine up until the needle on the temp gauge reaches the second mark from the left before taking off. If it only does this with the choke on, I'd say it is normal. If you get fluctuations in idle speed with the choke off, then something is wrong.
I had an issue where the idle would remain around 3,000 rpm with the choke off, for 10-15 seconds after blipping the throttle, before returning to normal. It turned out to be a bad diaphragm on the coasting enrichener on the front carb. But many things can cause a fluctuation in idle speed. A vacuum leak, plugged jets or a passage in the carb, problems with the enrichener system including the cable, problems with the throttle and cable, problems with the vacuum diaphragms on the top of the carb.
Does it do this only when the choke is on?
I am a motorcyclist, NOT a biker.
1997 Vulcan 750, purchased about a week ago
2006 Sportster 1200 Low
2013 Royal Enfield Bullet 500, converted to carb
2001 Yamaha XT225, heavily modified
2004 Honda Rebel 250
1979 Vespa P200E
2002 Vulcan 750 parts bike
1994 Yamaha XT225 parts bike