dr650try001

YOUR LINK HERE:

http://youtube.com/watch?v=-ePYi2T1Kgo

Note : • ------ • see UPDATE below. New info about my popping and backfiring! • The newer video with the fixes is at : • • dr650_try_002 • This is my first cut at adapting a 39mm keihin fcr-mx mx_rob style carb to my Suzuki dr650. • Basically I followed a thread I found at thumpertalk.com : • http://www.thumpertalk.com/forum/show... • I'm getting some popping and backfire right now with no load and twisting the throttle. Under a load it rides pretty good. • If I turn the DaZine screw all the way in it dies unless I hold the throttle open. It hits max idle rpm at 3-3/4 turns out. • I had it set to 2-1/2 turns out for the video. It pops less if I back it out another turn. • Next weekend I'll run through the valve adjustment, do some intake and exhaust leak tests, then possibly revisit the jetting. I am in the high desert of california (2300 ft. elevation, approx. 100 deg. F of dry heat). • I have a 2006 fcr-mx 39mm carb from a YFZ-450 quad. The jetting is currently 150 main, EMP needle clipped in the 5th slot down, #100 yamaha pilot air jet, #35 leak jet, #40 pilot jet. Also installed is a DaZine mixture screw and Merge Racing APS spring. • The float height is 9mm and the AP squirt clears the rising slide by about 2mm. • The IDS-2 exhaust has 10 discs installed and I am using a twin-air filter. • The top of the airbox is hogged out/opened up. • Here is the sudco/yamaha parts list I used : • 2005 YFZ450 FCR-MX OEM carb • --------------------------- • qty. 1 #100 pilot air jet Yamaha P/N 5TA-14943-27-00 • 2006 YFZ450 FCR-MX OEM carb • --------------------------- • qty. 1 #150 main jet keihin 99101-357-150 (sudco pg. 73 p/n 019-129) • qty. 1 EMP jet needle keihin N427-OC-EMP (sudco pg. 41 p/n 017-264) • qty. 1 #35 Leak jet keihin N424-52-035 (sudco pg. 72 p/n 019-750 ) • qty. 1 #40 pilot jet (Slow Jet) keihin N424-21-040 (sudco pg. 71 p/n 019-007 • (I used sudco international catalog #34) • UPDATE 07132008 : • ----------------- • I know from searching the thumpertalk forum the popping and backfiring is probably wrong, with the likely cause being a very lean condition. • The causes I've seen listed by Eddie Cisneros and MX Rob are : Vacuum leak, exhaust leak, valve adjustment. • When I pulled the IMS tank, I noticed the suzuki handlebar choke cable end was cocked at an odd angle. The suzuki choke cabling is interfering with the tank. Also I have concerns that the pins in the two chokes, the Keihin and the Mikuni, are not identical. The mikuni pin is a little thicker. So I reinstalled the keihin manual plunger choke. The suzuki cable is coiled and tied to the frame now. However, this did not help my backfiring/lean problem. • The next thing I checked was the valve adjustment. They were correct. • The next check was smoke-testing the exhaust. I'm not a smoker but the store up the street sells swisher cigars. I tried the grape flavor. I blew a few puffs around the midpipe seam and the header flange with the engine idling. No disturbance to the smoke, so that's good. • Next I tried using my propane soldering torch to blow some gas around various areas of the carburetor. I opened the valve a little, then played the stream of propane gas (UNLIT!) around the front of the carburetor as the engine was idling. Found it! Two places I hit with propane gas caused the RPM to jump and smooth out. • One place was the cylinder head boot. When I installed the carb, I guess it's heavier or I did not tighten the clamp enough, and I also think the rear boot was putting a little downward torque on the carb. This caused the top lip to open a little bit. So I got some M4X25 cap screws to replace the phillips head screws on the clamps, and also rotated the rear boot to a more natural position. Now I can tighten the clamps properly. • Still, there was one more thing. This is a little bone-headed on my part, but I guess it's okay as it was a used carb from ebay. Above the the choke, there is supposed to be a cap covering a gasket, spring and plunger. All those parts are missing so there is a huge vacuum leak! When I cover that hole with my thumb, I can feel the suction and my idle really cleans up, and I get a big increase in rpm. • The 2006 YFZ-450 carb diagram shows these as parts 32, 33, 34 and 54. See : • http://images.powersportsnetwork.com/... • The parts are : • 32 PLUNGER, STARTER 5TA-14371-00-00 • 33 SPRING, PLUNGER 5TA-14335-00-00 • 34 SEAL 5TA-14997-00-00 • 54 CAP 5TG-14225-00-00 • The parts are on order. I will install them soon and make a new video.

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