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Tuning the 39mmFCR for DR650

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new thread since the old one is so deep.

mxrob covered most everything, but some of us have issues.

mine i believe is with the AP. motor bogs on a quick snap off idle & the low end to mid response feels sluggish if i try to accelerate hard.

i looked at the yamaha carb breakdown & calls out a #40 leak jet.

has anyone checked leak jet sizes? i'll be checking mine this weekend.

the actuator rod length is also critical. i'm playing with the AP timing, but so far no improvements.

outer plug was fouled a bit, inner plug looked perfect.

still using a 162main with GSXR muffler i just installed saturday

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50 pilot jet is too big.

48 max more likely a 45.

you also need to do the o-ring mod.

you connect the ap linkage arms together with a thick 4mm o-ring.

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i'am running a 45 pilot with a 40mm at 2500ft with 10 1/2 piston. could go one smaller. with 39mm without piston had a 42.5 ran great all the way to 7600ft.

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I'm at sea level. I swapped to a 45 pilot this evening and adjusted to 1.25 turns out on the fuel screw, and it's still rich but idles slightly better now. Performance is unchanged - no better or worse than when I had the 50. Plugs are still black but the big cloud of black smoke on decel is not as bad. I have to wait on a smaller 42 jet from Sudco. I'll run the 45 this weekend and check mileage for comparison.

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some times when i find the pilot jet range is getting pretty small i will remove the pilot air jet all together and then get back to a larger pilot jet.

its all about response to the fuel screw.if the bike idles with the fuel screw fully in,the pilot circuit is to rich.

what needle are you guys running?

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This is from his web site

10/04/07 Jetting update: After hours of testing and playing with a multitude of jetting combos it looks like the proper jetting is going to be: 100 slow air, 200 main air, 50 pilot, EMN needle-5th clip and a 168 main. This is for sea level.

10/6/07 Jetting update: If you just have to run the stock Buick sized muffler then you'll need a 162 main with the EMN needle in the 4th (middle) clip position. Again, this is for sea level. No other changes are required.

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on the DRZ with a wide open muffler at sea level EMN,clip 3.

on the DR 650 i would also go to clip 3 on the EMN.

for mileage misers,a EMR clip 3 would be a better choice but will give up a little oomph off idle.

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Still setting mine up but I'm going to try the JD kit. They recommend using the YFZ450 kit with the 45 pilot jet, their red kit needle at the middle clip position, 165 - 170 main jet, and the o'ring mod. I run with the airbox lid off, a K&N filter and an unrestricted Staintune exhaust at sea level. Hope to get it installed and running this weekend if the weather cooperates.

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I can't wait to hunt down a 42.5 pilot and change needle settings. Is the third clip position from the top or bottom? There may be saviour for this carb yet! I was actually considering going back to the BST since the mileage and overly rich running condition. I'll probably opt for a new set of plugs as well. My idle has been all over the place and I actually think my power is down with the bike running so rich.

Rob, get that snow thawed! I can't wait to see that wide band in action!

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I can't wait to hunt down a 42.5 pilot and change needle settings. Is the third clip position from the top or bottom? There may be saviour for this carb yet! I was actually considering going back to the BST since the mileage and overly rich running condition. I'll probably opt for a new set of plugs as well. My idle has been all over the place and I actually think my power is down with the bike running so rich.

Rob, get that snow thawed! I can't wait to see that wide band in action!

Yeah, no kidding! I dislike this white stuff. I did try the EMR like Eddie mentioned... but as he mentioned I did not like the hit the power took. Maybe some of you wouldn't mind the power loss and response to swap for fuel mileage. Logic says we wait till I get the wide band set up before going off in ten directions. :banghead:

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with the o-ring mod with the EMR may be a better choice.

either way,clip 5 and clip 4 are to rich with the EMN.you will be able to run clip 3 wit the changes in ap that the o-ring makes.

one of the best things about the fcr is that its a super easy to work on.

i think the main issue is the the bikes that a re overly rich on the pilot circuit.it has a major impact on normal riding.

you guys should not be getting sub 40mpg unless you are being super aggressive.

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on the DRZ with a wide open muffler at sea level EMN,clip 3.

on the DR 650 i would also go to clip 3 on the EMN.

for mileage misers,a EMR clip 3 would be a better choice but will give up a little oomph off idle.

I went from the 5th position to the 4th and got better gas mileage but performance dropped a little. I also went to the 3rd position too, and you're right, it did give up some "oomph". I didn't like it so I went back to the 5th position, and that's where it pulls the best. I'll try the O-ring mod this weekend and see what effect that has.

I may just change out to a 165 main once I get the pilot circuit right.

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Logic says we wait till I get the wide band set up before going off in ten directions. :banghead:

I agree. I'm not going to change needles or mains until I get some feedback on your research.

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