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I will keep a carbon copy here of all my blog posts on my personal Cycle Blog @ http://mast3r7.blogspot.com/

XLForun.net only allows 4 pictures per blog post, so to see all of the images and details of posts, follow the links to http://mast3r7.blogspot.com/

I will write not only about what is going on with my current Sporty Project, but also about Lifestyle and HD ownership as well, enjoy.

-Big Al
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Air Cleaner Install, Baffles & CV Carburetor tunning

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Posted 19th June 2010 at 15:58 by Big Al-1200c
Updated 28th June 2010 at 09:09 by Big Al-1200c

About a week ago, I took apart the Carburetor to do some re-jeting and install a new air cleaner (AC). When I took the AC and CARB apart, I found that the Stock AC assembly had been replaced with a K& N AC Heavy Breather Kit. Also, once I removed the float bowl, I found that the stock Emulsion Tube (Needle Jet Holder) had been replaced by some after-market tube that not only looked different but it didn't fit stock Keihin Jets, instead it uses its own jets. Installed it had a #170 Main Jet, a #40 Slow Jet and an Adjustable Jet Needle.


Before I continue, lets look at the status of the bike the way I got it.

Stock 1200c Engine
Vance & Hines Straightshots Exhaust System (missing the baffles)
K & N Heavy Breather AC Kit
Dyna Jet, CV Kit: with Emulsion Tube, #40 Slow Jet, #170 Main Jet & Adjustable Jet Needle.


On the configuration listed above, the bike ran like shit. the power off-idle and mid range were non-existent, and the bike had a bad case of the carb-farts, even after it was well warmed up. it also stumbled any time I tried to settle the throttle at any cruising speed. The only time it ran better than mediocre was at high RPM.

Oh and the bike was loud! Like COP Magnet Loud. A few time driving out of the neighborhood, I passed a LEO and watched as he made a u-turn and followed me for a few miles, waiting for me to do something stupid, to give him an excuse to pull me over. But I kept it at low RPM (farts and all) and they left me alone.

I installed the V&H Straightshots Original Baffles, in the exhaust. That took all of 15 minutes, an Allen wrench, socket set and adjustable wrench, did it at work during my lunch break. Immediate results, bike ran smoother and quieter, had more power on the low end and screams with power at mid to wide open throttle.



Fast-forward a few days later; a good Friend (rocketmangb from www.xlforum.net) send me a stock emulsion tube he had laying around and some Allen bolts to replace the Phillips ones on the Carburettor while I was at it. So, I take the AC off, remove the top of the Carburetor, remove the adjustable Jet Needle, replace it with the Keihin NOHK Jet Needle.





Once the piston and top end were cleaned, reassembled with new Allen bolts and now moved to the bottom of the carburetor (float bowl). There I replaced the Dyna Jet Emulsion tube with the stock one, installed a Keihin #175 Main Jet, Keihin #45 Slow Jet, cleaned the float bowl, and reassembled using the Allen Bolts. Also replaced the the Phillips screws with Allen ones on the pump housing.







Cleaned the Carburetor throat, re-assembled the carburetor, installed the new Screaming Eagle PRO Hi-Flow Air Cleaner Kit, rode the bike for a few miles to warm it up, and then it was time for setting proper idle speed and idle mixture, the only tedious and complicated part of all this work and the one that 99% of the time people get wrong. Being that I am not an experienced motorcycle mechanic (far from it), I already know that it is going to take time and lots of trial and error.

There is all kinds of writing on proper tunning of the Keihin CV Carburetor. Every one of them with a different approach. After trying different ones, I desided that for my untrained ear (you need a great ear for engine speed and smoothness to do it right) , the best chances for me to get it right was to go with the Tune-By-Spark plug method.

With this method, you start with a handful of new plug sets, already gaped and ready to go, set proper idle speed, then you check the plugs once the bike is warmed up. You remove them as soon as you kill the bike, and read them, and adjust idle mixture screw accordingly.

Then you swap the plugs with a new clean set, start the bike and immediately take off for a short ride, never opening the throttle more than half way. Once at cruising speed, transmission to neutral, pull in the clutch and hit the kill-switch, coast to a stop and check the plugs. Use that reading to adjust the slow jet and needle position.

Now you need a stretch of high way with a high speed limit and low traffic. Then, install another fresh set of plugs, this time you'll start the bike and take off at 75% to Wide open Throttle, once you reach top legal speed, 65-70 MPH, pull in the clutch, transmission to neutral, hit the kill switch, and safely coast to a stop, check the plugs and adjust your main jet size accordingly.

This method is more tedious than tunning by ear, but it is easier for an less experienced DIY mechanic to get right. Once I am finish with this I will update the results, but before I do this, I have to take care of the breaks, as I was working on this, I noticed the breaks needed attention, and my next post cover that endeavor.

Remember, to always use gloves when checking the plugs 'cause they will be extremely hot.

Ride Safe, Ride Often...
-Big Al
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