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Steve
Steve, Motorcycle Mechanic
Category: Motorcycle
Satisfied Customers: 7038
Experience:  30+ yrs. experience, MMI, HD technician, HD early, engine rebuild/performance, bike builder, kit bike program manager, CCI 2001-2004
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Installed a 2000 buell cyclone engine on a sportster and installed

Customer Question

Installed a 2000 buell cyclone engine on a sportster and installed a cv sportster carb with a 45 pilot jet and 200 main jet. The bike backfires out exhaust at all rpm ranges including idle. No adjustment to the carb helps. I installed the ignition module from the buell and also checked intake manifold for leak. Still backfires out exhaust bad. Engine ran fine when in the buell
Submitted: 2 years ago.
Category: Motorcycle
Expert:  Steve replied 2 years ago.
try a 48 slow jet. as for the backfire........any exhaust backfire indicates an ignition problem.check to make sure there are no wiring issues associated with the ignition and ignition power. the ignition gets it's power from the run/stop switch, through the coil.IF the wiring is all good, the most likely cause of your ignition problem is incorrect system voltage.to find out, measure the battery voltage under the following conditions:- ignition OFF- ignition ON- with the start button depressed- with the engine at 2000 rpm (fast idle) let me know what you find, if you need more help.Steve
Customer: replied 2 years ago.
Ok I'll try that. It acted like it was running rich so I tried a 42 slow jet with no change. I should note the bike ran fine with the stock motor until I installed the buell motor. And the buell motor ran fine on the buell. I have the coil from the buell would a coil from a 883 be any different than the 1203 buell coil?
Customer: replied 2 years ago.
I'll check those voltage today and let you know
Expert:  Steve replied 2 years ago.
I would use the Buell coil, since you have it.I would also use the Buell carb, if you have it. I say to bump the slow jet up to a 48 because 42 is lean for any sporty and 45 is the stock XL slow jet. these typically get changed to 48 to get rid if the lean mis-fire that is common on stock engines. let me know if you need help with the voltages.the differences between where this engine was and where it is.........is grounds, battery and wiring.
Expert:  Steve replied 2 years ago.
let me know if you need more help.
if not, please leave a POSITIVE RATING.
thank you,
Steve