640 Fuel Pump

Discussion in 'Thumpers' started by gunnerbuck, Jul 25, 2006.

  1. gunnerbuck

    gunnerbuck Island Hopper

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    Anybody know if you can get a new diaphram for the Mikuni fuel pump on the Adventure? The dealer quoted me over $100 for the pump itself but didn't have any kind of rebuild kit listed for it.
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  2. bmwktmbill

    bmwktmbill Traveler

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    Gunner,
    Is there a Mikuni number on the fuel pump? I saw several fuel pumps listed on the Mikuni America web site with parts available. Did you try Sommer for parts?
    KTM has to make these parts available to us.
    Bill in Tomahawk, WI.
    #2
  3. creeper

    creeper Still alive...

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    I believe the Mikuni pump is the base model DF52. There are variations of this pump with one, two and three outlets. If you look closely at the pump, you'll see there are two unused (undrilled) outlets on the back of the pump and 180 degrees opposite, there is the functioning outlet.
    I believe the pump KTM uses is a single outlet variation of the DF52-136. The funny thing is, when you go to the Sudco site and look it up, it's the only pump they ask you to call on rather than provide a part number for a rebuild kit.
    So... I suggest you call Sudco, or a Mikuni distributor in BC.

    That's all I got,
    C
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  4. DSM8

    DSM8 Where fun goes to die....

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    Hey Creeper,

    How does this pump work, since I dont see a return line to the tank I assume it is at a very low PSI.

    Are there any provisions that would allow the use of an aftermarket pump on the bike in liu of the factory one ?
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  5. creeper

    creeper Still alive...

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    31 liters per hour is the rating for the DF52. They are not like a positive pressure electric pump where a regulator might be required.
    Even a small Facet electric pump will flow 32 gallons per hour.

    I found a aircraft parts house that has both Mikuni vacuum and Facet electric pumps for 1/3 to 1/4 the price KTM and other motorcycle related outlets want.
    The Mikuni pumps listed (single and dual) do not appear to be direct replacements for the KTM/Mikuni pump, and might require a bit of fiddling, but for $20-$30... maybe you can afford to fiddle.

    In the event my pump takes a dump... I may experiment with a small Facet and an adjustable regulator. The float needle and seat on a BST40 for an Adventure is not a standard gravity flow item, but rather made for a low pressure line, (maybe why its $40) so if you could adjust pressure down to 1-2 psi, it should work. All an edjumacated guess on my part... but I tend to like Facet electric pumps and have used them extensively in the past, on bizzarro applications better not discussed here, with good success.

    That really is all I have this time... really.
    C
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  6. DSM8

    DSM8 Where fun goes to die....

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    Thanks as ususal for the Creep(y) advice. :lol3
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  7. meat popsicle

    meat popsicle Ignostic

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    Look a Chicken!!! :D
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  8. gunnerbuck

    gunnerbuck Island Hopper

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    Thanks Creeper, I was looking at the Mikuni pumps and one of the double outlet pumps looks identical, could be as easy as swapping the guts or putting a 2-1 T line hookup. Now if the pump is rated at 31L/PH an output test of the pump should be about 1/4 -1/2 a litre per minute or do they use another formula? If the pumps output is below standard will the effect show all the time or only when the tank reaches a point below a gravity feed?
    #8
  9. Odysseus

    Odysseus Stoic Philosopher

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    Has anyone else ever noticed that when creeper uses the phrase "I believe", he actually means, "I absolutely know for a fact"
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  10. meat popsicle

    meat popsicle Ignostic

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    Some of us never get tired of the taste of sneakers... either he has or he doesn't clean up after the dog much. :arg
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  11. creeper

    creeper Still alive...

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    I'm only slightly smarter than a rock... :tb
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  12. Odysseus

    Odysseus Stoic Philosopher

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    If that is true, I hate to speculate what catagory I am in. Dumber than a cucumber?
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  13. Carlos M

    Carlos M www.motoxplorers.com

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    Nice "creepinformation" (as ususal)!

    I didn't want to be without a replacement and the original diaphragm looked worn. I ended up shelling out for a complete new pump as I couldn't find a rebuilding kit.

    Somehow related... I have a recurrent problem with the fuel pump that looks unrelated to the state of the diaphragm: most of the times, when the bike goes into reserve (2001 640) the pump refuses to prime after I switch the fuel manifold into reserve. I found out that I can make it prime by blowing into the tank's breathing pipe.
    #13
  14. bmwktmbill

    bmwktmbill Traveler

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    Every day I learn a new trick.
    Thanks Carlos.
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  15. meat popsicle

    meat popsicle Ignostic

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    That's alot easier than putting a priming bulb in the fuel line; thanks for the tip Carlos. :thumb
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  16. creeper

    creeper Still alive...

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    That trick is so old... I'm pretty sure I'd forgotten about it for at least 20 years. Thanks for the reminder of a good, quick and "clean" alternative to the messier, clumsier methods of priming Carlos. :thumb
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  17. gunnerbuck

    gunnerbuck Island Hopper

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    Was able to find the 2 outlet version of the Adventures fuel pump thru Heeters Performance Centre at 1/3 the cost of the OEM unit. Also the rebuild kit for $10. I had a feeling that the KTM price was a little out there, kinda like there spin on filter VS the Hi- Flo, both made in a factory in Thailand and Hi-Flos can be had at 1/3 the cost.
    #17
  18. bmwktmbill

    bmwktmbill Traveler

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    Gunner,
    Was the correct part # 11-7903 for their rebuild kit for the square pump.
    Just trying to pin down what to order as a spare kit for traveling.
    Bill in Tomahawk, WI
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  19. gunnerbuck

    gunnerbuck Island Hopper

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    Bill, I believe Heeters part# for the rebuild kit was ET-79-1103, close to your #.
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  20. gunnerbuck

    gunnerbuck Island Hopper

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    Took the new pump apart for comparison to the oem unit, I noticed a couple of differences. The KTM pump has a helper plunger spring on the main diaphram and a spring and ball bearing stopper on the inlet, also the main diaphram is a rubber material as where the two outlet pump has a clearview plastic diaphram. I installed the rebuild kit to see how it would work in the oem pump:I reused the rubber grommits for the check valve diaphrams because the ones supplied in the kit are longer. Put the clearview main diaphram in place of the stocker and put the pump back together. I hooked up my remote tank and fired up the bike, it ran fine with gravity so I set the tank on the floor below the skidplate, no noticeable change. When I reved the engine I could see the fuel speed up in the clear line but the pump could easily keep up. So it looks like the kit works fine but I don't know if the clear plastic diaphram will be as durable as the stock rubber unit when the spring loaded plunger is pushing on it.
    #20