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) |
| Not too Fast Written by myhotrod, on 03-28-2008 13:53 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 13:25 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 13:59 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 13:45 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 20:02 ...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 11:10 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.... |
| 1999 Roadstar Written by huygens, on 05-12-2007 11:08 I just did the mod with a 99 roadstar. Used the 2.5 needle kit. Cleaned out the carb while it was down and also removed the AIS at the same time (installed plugs and vac plug. At higher the top end the engine now acts like it is starving for fuel, mostly at higher speeds, but at the top end of each gear as well. Bike will not go over 95, although I really dont need to go that fast, I would like it to accellerate properly in lower gears. Any ideas? huygens |
| 2003 road star Written by silverbackoo, on 05-11-2007 03:56 When I purchased the bike it had 312 miles and a former owner that died on the seat. He hit sign post with his neck, but I got a great price. Anyway the bike always sputtered around 95 MPH I thought it was the infamous rev limiter so I accepted it but the sputtering kept starting at slower and slower speeds. With 53,000 miles on the bike and when the starvattion got to be a probelm between 55 and 65 MPH and anytime I needed power very long I knew it had to be fuel related because it became more more sensitive to tank level. I decided I had to do something. Did a lot of dumb stuff. Cleaned the Carb (twice). Installed a 4 psi fuel pump. Removed the intank strainers. installed and over sized fuel filter. After seeing the above article and riding down the road with the fuel pump in my hand for twenty miles determined the fuel pump control wasn't working correctly my pump wasn't running consistently after startup. I could have done as one contributor suggested and wired the fuel pump into the headlight or ignition circuit I feel that would have also solved the problem. However I decided to try pumpless. Anyway having little patience I removed the fuel pump and carb redrilled the needle valve housing by hand with a 3/32" drill bit. (3/32" is 2.38MM) a little short of the 2.5MM in write up. I also chamfered the the needle valve body from the upstream side. Made a nice cone to increase the velocity of the fuel into the final body section. With flow dynamics I would guess the chamfering made more difference than the drilling. Anyway Ran the bike at 100MPH WOT with 400lbs of me in for 10 miles no stavation. A lighter rider should have gotten a better top speed. It didnt sputter it was just fully loaded. Ran it hard until the tank was just above empty it held 4.8 gallons of fuel when I got tired of riding back and forth in front of a series of gas stations. I am not sure why MPG increased a little, but the bike has never ran smoother. |
| Written by 2005Roadstar, on 05-10-2007 08:32 Did the fuel pump removal mod a week ago today and so far, so good. Thanks to Emery for a very well written and easy to understand article on how to do it. Couldn't have done it without you!!! Aaron |
| Written by LROD, on 04-05-2007 16:10 I did this on my 06 RS...still have electric fuel pump |
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