I have been searching for a cure for the double dip in my dyno chart. After getting no positive feedback from Dynojet and Vance and Hines I gave Factory Performance a call. The technician I spoke with was very helpful and assured me that one of their carburetor kits would help smooth out my dyno curve. I decided to order the TiPro kit with titanium slide needles and I added their adjustable ignition advancer to my order.
|The Jet Kit came in a neat, organized box and included 2 sets of mains, a set of slide springs, titanium needles, good installation instructions, and much more. I also ordered 2 extra sets of titanium needles (1 set richer, 1 set leaner) just to make sure I would have the right ones.|
|The ignition advancer is variable from -7 degrees to +7 degrees. It is a clean 2 piece construction and is the only advancer available that has no exposed screws to fall out.|
I decided to check my valve clearances while I was installing the new Factory Performance parts. Here are some pictures of the work being done.
|I had to strip the rear bodywork to remove the fuel tank.|
|The left side fairing lower had to be removed to gain access to the ignition rotor. The rotor is used to set the engine to TDC cylinder 1 and TDC cylinder 4.|
|I removed the carbs and put paper towels inside the intake manifolds to stop anything from falling inside the intake ports. I then removed the coils, heat shield, and cylinder head cover.|
|I then checked the valve clearances. Two valves were tight so I changed the shims to bring them within specs. I used the engine starter to bump the engine over so I disconnected the fuel pump relay to prevent fuel spray.|
|After all valve clearances were determined to be within specs I reinstalled the cylinder head cover, heat shield, and coils.|
|The 40mm ZX11 carbs are ready to be given a dose of Factory Performance.|
|The carbs are rejetted and ready to go! I used the Keihin 148 main jets (Keihin main jet numbers are not the same as Dynojet main jet numbers). I selected the Factory 942i-56v titanium needles and set the clip on position 2. I also used the Factory Slide Spring number 525-39-28-19.|
I then reinstalled the airbox and fuel tank and took it for a test ride. My initial impressions were very good. When performing a 1st gear full throttle roll-on from idle (no clutching), the front wheel comes off the ground at around 6500 RPM instead of 8000 RPM. The first time I did one I almost flipped the bike over!
|I then removed my Factory Performance ignition advancer (+4 degrees) and installed their adjustable advancer. I set the adjustable advancer to +5 degrees of advance.|
After installing the new advancer I took the bike for another test ride. My bike definitely likes the additional degree of advance because I experienced a noticable gain in low to midrange torque. High RPM performance seems to be unaffected by the additional advance. The gain is most apparent in the 3000-4500 RPM range under both full and part throttle conditions. First gear 3000 RPM power wheelies (no clutch) are ridiculously easy. Just snap the throttle about 1/2 way and hold on tight.
After making many dyno runs trying various jetting combinations I have not been able to eliminate the double dips. I have tried changing the needles, needle height, springs, and main jets. I have also tried to use different needles on the outside and inside carbs. All of these changes produced no significant smoothing of the double dips.
On the dyno the bike did not seem to like +5 degrees of ignition advance. My top end power suffered from the additional advance. I am now running +3 degrees. I also discovered that the 148 main jets were too lean. My bike produced more power using 155's. My results follow:
Click here to check out a MPEG movie of my ZX11 on the dyno.
(Dyno.mpg - 673 KB)