Clinic
You CAN do it...
Change the Float Bowl Needle Valve (and lose your fuel pump) |
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| Written by Emery LeBlanc - Delphi(EM44) | ||||||||||||||
| Friday, 02 December 2005 | ||||||||||||||
![]() NEEDLE VALVE SET REPLACEMENTReason for changing the STOCK needle float valve setI own a 2000 Silverado, and love this bike. Shortly after I had the bike broken in, I decided to see what our rides could do flat out. Well at just under 100MPH, the bike stuttered a bit and began missing. I attributed that to the “REV LIMITER” kicking in. To make a long story short, this spring, still with the same bike, but now with Samson Shogun 2 ¼ inch full pipe system and Küryakyn twin velocity breather, perfectly jetted, I seemed to be hitting that so called REV LIMITER earlier. This caused me to investigate this problem further. After sacrificing ride time and some cash, using my own ride as test vehicle … You can read the post to follow the history; Here is the conclusion. Our Mikuni 40mm CV type carburetors have a 2.0 flow size needle valve set. This corresponds to 2.0 mm hole size, which also equals a 200 DynoJet size. Once you add up all the orifice sizes that fuel leaves the bowl from and compare it to the only entrance size of the needle set, you find that the MAX inlet capacity is just a bit under sized to the MAX consumption limit. Most will never run there ride in this situation, therefore will never “starve” the bowl. But, anybody who’s modified there bike requiring increasing the fuel capacity to the engine, i.e. larger jets, should strongly consider replacing the needle valve set of the carburetor bowl. We re-jet the carburetor to make sure our fuel mixture stays correct, in order to maximize the performance and to NOT lean out the engine and endanger it, but we forget another component in the fuel delivery system, maybe as important, if not more, the needle valve set! Ah yes, as a BONUS, if you swap the needle valve set with this larger one, the fuel pump becomes unnecessary! That’s right, you don’t need it anymore. I would like to also mention and give a special thanks to Joel (Odo) Parker for his help and assistance in double testing and confirming the test results. Parts required#2.3 13370-07F00(Suzuki p/n) (old p/n 13370-19E00) Yes these are Suzuki part numbers, but or carbs are manufactured by Mikuni, who also also makes carbs for Suzuki and this needle valve will interchange with ours. The 2.5 is recommended for running with NO fuel pump. |
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Comments (10) |
| rev blues Written by bootscoot, on 03-01-2009 17:57 thanks i knew sombody had to have figured this out ! do you have any idea what actual red line is ?gettin old prefer not useing trial an error.so far i figure you just saved me about $250.in shop charges!thanx bootscoot |
| pump Written by yamaha14, on 01-14-2009 09:09 Do I have to replace the needle valve when I remove my fuel pump on my 2003 RoadStar |
| Need to get this done Written by RoadieRider, on 12-07-2008 17:51 I'm tired of my buddies on their HD softails riding off and leaving me... is their anyone in Northern Missouri that can do this MOD? I can do the basics... but this is over my head!!!! |
| Outstanding!!!!! Written by Kai, on 07-10-2008 11:22 Did this and the bike actually runs better... |
| Not too Fast Written by myhotrod, on 03-28-2008 12:53 After reading the above posts on how fast stock Roadies go. I must comment. I bought a new '01 Midnight Star. After about 500 miles of break in I wanted to see what the top end was. With a buddy running next to me on a 800cc Suzuki we both topped out at 105mph. That was 4000rpm's in 5th gear it will not hit the 4250rpm rev limiter. Without building the motor up I installed a Max Air air cleaner, rejetted the carb, installed a Dyna 3000 ignition, and a set of Monster Pro 2 into 1 headers. I have achieved 120mph(buried the speedo) pulling 4800rpm's with the rev limit set at 5000. I know have it set up with 110" jugs, 10.25:1 pistons, Colt Cams, oversize valves, PSI Big Air carb, with custom made ported intake manifold. As soon as it gets warm looking to see if it will run on top end with my bothers Valkerie. |
| FUEL PUMP REMOVAL Written by zappa, on 09-22-2007 12:25 HEY GUYS & GALS THIS IS MY FIRST TIME ON.YOU HAVE AN AWESOME WEBSITE HERE, HAS SHOWN ME ALOT.GLAD THERE IS SOMEWHERE TO GO FOR STUFF ABOUT MY ROADIE.IT SEEMS TO ME A WHILE BACK WHEN READING ABOUT THE REMOVAL OF THE FUEL PUMP I READ THAT SOMEONE SUCCESSFULLY DID IT WITHOUT CHANGEING THE FLOAT BOWL NEEDLE VALVE IS THIS CORRECT OR I'M I JUST TRIING TO GET OUT OF WORK? ZAPPA |
| fuel pump or not ? Written by roadster, on 07-19-2007 12:59 I have a 2006 midnight 1700,, Im at cross roads with removing the fuel pump. Unsure if i will gain from it, As it stands its jetted, hyper charger pro one, and hard krome big 3 pipes, the bike honestly pulls hard easly too 100mph and is not straving for fuel. At the moment i have a high flow pingel fuel cock for it. will i gain any with dropping the pump and changing the needle vavle ? would like to hear some comments, thanks, |
| FUEL PUMP GONE Written by Rockpile, on 06-01-2007 12:45 I TRIED THIS. HAD TO PURCHASE THE S#2.5 13370-08F50(Suzuki p/n) FROM THE DEALER $95.00 SO I HOPE THIS IS WORTH IT. PRETTY SIMPLE, LEFT CARB ON BIKE. ONLY REAL PROBLEM WAS THE FLOAT PIN RETAINING SCREW-HAD A BITCH OF A TIME GETTING IT OUT. RAINING HERE NOW, MY ROAD TO GET DOWN TO THE PAVEMENT IS TO STEEP, TO SLICK. I AM GOING TO GO AFTER WORK. 2 1/2 HRS BY THE TIME ALL WAS SAID AND DONE-GREAT ARTICAL GUYS. THKS |
| At wits end... Written by huygens, on 05-12-2007 19:02 ...so to speak. Did the fuel pump removal. Did the AIS removal. Did the gas cap vent mod. Used 5/16 fuel line. Used 3/8 fuel inline filter (removed element for testing). Drained tank and cleaned petcock. Removed and cleaned carb twice. Verified I used 2.5 Needle and Seat (checked stamp on side of seat). Removed plastic filter in carb inlet. Reverified float setting. checked and adjusted TPS settings. Light to moderate acceleration is fine. Heavy to all out acceleration suckes the bowl dry. At this point, if I coast for a few seconds I can accerate lightly again. Top speed (If I accelerate moderately) is 95. Sunday driving style is fine, but if I was to get on it and go, it sucks (no pun intended). Thanks in advanced for the help.... Huygens |
| 1999 Roadstar PS Written by huygens, on 05-12-2007 10:10 I as well tried running the bike with no gas cap to see if it was a breather problem on the tank. No difference. Thanks.... |
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Comments (10)





