taking it to the 1/8th mile friday, any predictions??
Please post your times.
Does it help a bunch tochange theignition module to get the rev limit above stock5,200 rpm?
Mine kicks in right at 6,000 RPM (2005 1200C), and I believe that is where it's 'set' from the factory on all the 2004+ 1200's.
Far as how well your 1200 will run against the guys with modified street legal cars, it just depends on the specific car and it's performance potential.
Most of the verified time slips I've heard about from guys running their 1200's at the track (most in the Tulsa area) show quarter mile times in thelow 13 second range.
no secrets on the bike, just a 1200 conversion, higher compression and drag pipes. we'll see what happens friday night. fast or slow, it will be fun.
Increasing the displacement from 883cc to 1200cc will no doubt provide a very noticeable power increase, but unlessyou usebetter flowing heads and higher lift and duration cams you will will still be limited to the amount of a/f mixture entering the cylinders.
As most known, the difference between the factory 2004+ 883's and 1200's is more than the displacement. The 1200's also have a better flowing head/cam setup, which flow much better than the stock 883 heads and cams.
my buddy who's never taken a bike down the track will be driving.
Key statement here. I'm guessing 9.3 at 60 mph.
OFG, I've seen it published several places that the later model 1200's have a 5200 rpm rev limit due to the increased weight of the larger stock cast pistons, to protect the lower end from excess wear & tear. My 04 1200 limited out at 5200 with the stock ignition module.
Here is information directly from HD when they were talking to the press about the new 2004+ engines:
"To enhance engine cooling, new cylinders and heads have larger fins while new oil jets are directed at the bottom of both pistons. New pistons have an improved high-speed ring pack designed to help extend upper-end life. Lighter pistons and connecting rods boost the Evolution 1200 redline from 5500 rpm to 6000 rpm. Many engine covers and gaskets have been changed to improve sealing. A new timing system uses the flywheel to determine engine speed timing, reducing engine complexity and enhancing calibration and spark delivery. The traditional XL Evolution timing cover is retained for styling purposes."
Have fun, Good Luck!
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https://www.hdforums.com.au/Default....amp;view=topic
Maybe it's bad info?????
The Best of Harley-Davidson for Lifelong Riders
OFG, I can't vouch for the info in this article but it's one of several I've come across.
https://www.hdforums.com.au/Default....amp;view=topic
Maybe it's bad info?????
I do know for a fact that my 2005 1200C, with stock ignition, doesn't hit the rev-limiter until right before 6,000 RPM, so it seems to agree with the published info from the HD engineers.
I'll talk to my Harley mechanic friend and see what he has to say, as he also owns a late model 1200C and has run many dyno tests, etc., on his bike.
By the way, last I heard he had right at 92,000 miles on the stock engine.

It's all a question of Ave. Piston Speed and therefor the stroke determines the redline. HD uses 4,000 ft/minute ave. piston speed and that means that all sportsters can be reved to 6,300 rpms safely. 88" (and 95")big twins can rev to 6,000 rpms and 96" (and 103" and 110")big twins can rev to about 5500 rpms with HD factory parts.
If you take 24,000 and divide it by the stroke (in inches)you'll get HD's factory stock redline for any new HD engine (or at least you'll be close).


