XR650L carburetor options?

Discussion in 'Thumpers' started by MuscleGarunt, Jan 20, 2012.

  1. MuscleGarunt

    MuscleGarunt Been here awhile

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    I'm looking for a drop in replacement or kit that uses the stock airbox and intake manifold. I am aware of the XRs Only Mikuni kit which is a pumper for 450 or so and the Sudco Keihin FCR41 kit which is 550. Are there any cheaper options? I don't need an accelerator pump. Does anyone make a kit for the XR650L with a round or flatslide non pumper slide carb in the 200 to 300 range? Google has turned up nothing.
    #1
  2. PistonPants

    PistonPants Crankcase Scavenger

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    Why not modify or jet kit the stock CV? Good bang for the buck. De-snorkel the air box, massage the stock carb, good to go.

    Peace
    Piston
    #2
  3. MuscleGarunt

    MuscleGarunt Been here awhile

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    I did that, drilled the slide, dynojet kit, 58 pilot jet, desnorkel, baffle removed from exhaust. it made a huge difference. The only thing is low RPM performance is really crappy with a CV carb and only one lung.
    #3
  4. mcma111

    mcma111 Long timer

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    Use a XR650r carb
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  5. MuscleGarunt

    MuscleGarunt Been here awhile

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    Does it fit right in with no modification or adapters? If so that sounds like the ticket!
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  6. mcma111

    mcma111 Long timer

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    Yes it does. Here is what you need to do to the jetting:

    Jetting for the XR carb is 65s slow/pilot and 165 main and a HRC needle on the second slot from the top
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  7. rufus

    rufus We're burning daylight...

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    I did that.

    Lots better throttle response at low rpm. Smoother, easier starting. But from 1/3 throttle on up it seemed slower and flatter than with the stock CV. I changed jets about 50 times (realistically...20) and never got it to run as good as the CV does at road speeds.

    I switched carbs back to back and finally went back to the stock CV.
    But IT sucks.
    I have an FCR on order from sudco. If that satisfies me then i will get the do 2nd and 5th gear mod.
    #7
  8. rufus

    rufus We're burning daylight...

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    I looked for ,but never found, an XR 600 carb. It should fit right in. My 650L has never run as good as the 600 I had.
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  9. Wattner

    Wattner Long timer

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    I used a Mikuni flat slide non-pumper for years.... I bet Sudco still has the parts to get it for you!

    IMO, they work better than the stock CV, but nowhere near a pumper... KeiHin is the best!
    #9
  10. katbeanz

    katbeanz earthbound misfit, I

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    +1, I wore one completely out, then got another. xrsonly does them for an xr600 replacement carb, but they'll do you one to fit an L
    It won't be enough carb for the 728 though, nor my TM40. :cry :evil
    #10
  11. MuscleGarunt

    MuscleGarunt Been here awhile

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    Thanks for all the replies! Great information from everyone.

    Is the HRC needle something I will need to order?
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  12. MuscleGarunt

    MuscleGarunt Been here awhile

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  13. darenative

    darenative Been here awhile

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    With the R carb, your stock throttle cables need to be modified or you can purchase an R carb with throttle assembly.

    I'm in the middle of the swap so I'm not a wealth of information, but the few times I've ridden the bike with the R carb, I could tell low end throttle response is hands down better the the cv carb....
    #13
  14. MuscleGarunt

    MuscleGarunt Been here awhile

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    So assuming I get the Mikuni TM 40 can I go with my current jet sizes from my CV carb? Everything I am reading is talking about smaller jets in this carb for same motor? Anybody done this before?
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  15. MuscleGarunt

    MuscleGarunt Been here awhile

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    Anyone done a TM 40? I'm about to take the plunge and be the first here pretty soon or one of the few anyway.
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  16. jesusgatos

    jesusgatos fishing with dynamite

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    Instead of buying that overpriced kit from Sudco that comes with the old-style slant-slide FCR, why not just grab an FCR-MX carb off any of the newer 450's? That's what I'm planning on doing.
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  17. MuscleGarunt

    MuscleGarunt Been here awhile

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    I found a good deal on a TM40 Mikuni pumper for the XR650R they say. Things I have heard say the R carb bolts right up to the L then just the jetting and maybe cables. I measured and it looks like it's a go ahead. I had a Mikuni pumper on a XT500 and that bike had mega power.

    Man talk about price scalping, Sudco is spendy.
    #17
  18. MuscleGarunt

    MuscleGarunt Been here awhile

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    TM40 fell through so I sourced a XR650R carb. It is a little but longer than the stock carb. It takes some pushing and wiggling to get it in the intake manifold. The bell for the air box is bigger and longer than stock but with some careful screwdriver prying gets it on all the way. Stock cables will work if you shorten the housing on both cables, not easy by the way. I went with the jetting recommended by the nice man earlier in this thread and it works great, thank you very much.

    The skinny is, this does fit, but it's not the easiest. But with a little determination and swearing and busted knuckles it will work. Throttle response is way better and power is increased. Just give it some gas and it does a wheelie!
    #18
  19. jesusgatos

    jesusgatos fishing with dynamite

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    Any interest in carb adapters for the newer-style FCR MX carbs? I used one of Noss' universal FCR adapters on my 650R with a 39mm FCR off a late-model CRF450 and it ripped, but the adapter dimensions weren't quite right. So we're going to have them make some custom adapters for the XR650R and the XR650L. I don't have a 650R anymore, but my buddy James wants one and I need to have some 650L adapters made for these bikes. Figured we might as well make them available. His regular universal adapters cost $65, so am guessing these will probably be a little bit more expensive, but can't imagine they'll end up costing any more than $80. It's pretty easy to find good deals on used FCR MX carbs ($300?) because there are so many of them out there (being used on virtually all of the modern 450cc motorcross bikes). So this can be a relatively low-cost upgrade, and the performance is flat-out awesome. Fitment is pretty straightforward. There are no clearance issues, so this is literally a bolt-in deal and you can even use the stock FCR throttle cables and twist-grip (stock CRF cables are perfect length with aftermarket tripleclamps and taller bars). Shoot me a PM if you want one!


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    #19
  20. thebigman

    thebigman bout a dollar 3.98

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    yep :clap
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