DR750 & DR800 owners thread

Discussion in 'Thumpers' started by MCmad, Jul 14, 2008.

  1. Silent Hunter

    Silent Hunter Been here awhile

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    Hang in there buddy, my DR800 had the same problem a couple of years back too. No spark, no matter what.

    Ended up changing the CDI, Stator coil, and starter engine and for good measure, I change the wire harness as well.

    After that the bike was ok for several months until the fuel pump busted.

    The bike was in the shop for nearly 1/2 a year.... :cry
  2. wundis

    wundis Adventurer

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    Ill play with the carbs tonight. In the meanwhile, I had a light bulb moment.
    Does anyone have a spare (an old one would do the trick, too) float valve sitting somewhere? The thing i'd like to see is how much pressure in grams it needs to have for the small spring inside to compress fully. In exchange for the measurement ill buy you a beer next time you're in Lithuania! :freaky
    I'm going to measure the values myself using my girlfriends kitchen scales (when she's asleep obvioulsy) on the float valves ive got (2 new oem, 1 old strong, 1 old weak).
  3. spen

    spen on my arse

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    Is the bike turning over ??? or completely dead
  4. Ladder106

    Ladder106 It's a short cut, really

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    Wundis,

    Does it always run OK when you first start it?

    If it runs well for those first few seconds and then starts to miss and run very rich (black smoke)as the engine warms, then, I'd check the enrichening (choke) circuit on the carbs. It may be that your choke plunger (valve) is sticking open or the cable (on later SR43s) is hanging up and even though the knob on the bars is all the way down, the plunger in the carbs is still open.
  5. wundis

    wundis Adventurer

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    OK, now here are the results of the 2 old float valves I have:
    The weak one takes approx 20g to fully compress the small spring inside.
    The stronger one takes an incredible 55g to fully compress. I'm pretty sure a difference like that would cause some serious inequalities between the carbs.
    The new ones are going to be somewhere in between, probably around 30g judging by the fact that they were only a bit stronger than the old weak one.

    Anyhow, does anyone know what role those springs play in the function of the carb?
  6. wundis

    wundis Adventurer

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    Ladder, it's a bit hard to tell, because always means like 6 starts right now :)
    I would say it runs ok after it sits for a while (a day or so) and petrol evaporates from the carb, letting the float sit on the mid level (spring out).
    It's not few seconds after you start it, it's more like 20-30 seconds.
    It reacts when i push in choke, though it did not occur to me that perhaps the plunger can stick on one carb. I must inspect. Thanks for the idea.
  7. wundis

    wundis Adventurer

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    I'm just gonna continue posting, maybe someone will have any idea of whats going on...

    Removed the carbies once again (checked float level before that with the hoses - it was waaay off in the + zone, like +5 and +8 mm ).

    dissasembled - visually nothing wrong, correct float height by calipers, everything seems just fine. upon thorough inspection I did not like two things:

    1. the float valve seat (or the part that has an oring) is kind of loose. when you push it in, it doesnt stick tight, but rather pops out like half a mm or so. i tried rotating it to fit the oring better - didnt help. dont know if this can influence the fuel level, but it just doesnt feel tight enough.

    2. the long plastic tube of the float that has an oring on its end doesnt feel tight either. if i put pressure on it- it sticks slightly deeper inside, plus i can lean the float assembly back and forth if i put pressure on it. again - don't really know how it is supposed to be.

    and finally, i;ve checked the weight required to compress the spring on the oem float valves - its barely more than on my old weak float valve - 22 grams each.
    confused :/

    PS the choke plunger seems to be working just fine.

    PPS i think i'm getting better at removing carbs :ear
  8. mait

    mait Been here awhile

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    Wundis, what is the fuel level height compared to bowl gasket level when measuring with clear hose?

    Valve seat should go all the way in so that it sits against carb body. Coat the o-ring with some harmless oil, it will help it going in.

    The same about float assembly connection tube, all the way in. It is plastic, so there will be some flex.
  9. wundis

    wundis Adventurer

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    Mait, one of them is approx 5 mm over the gasket, the other one approx 8 mm. Ill try greasing it with oil and then sticking it in, good idea.

    Also, when I compared the old seats with new orings, and new seats with stock orings I was surprised by the difference in tension - the new one is all flappy, its very easy to remove, while the old seat with new oring needs some work before replacing the oring.

    Ah, as robmoto says, it's a process of illumination...
  10. Ladder106

    Ladder106 It's a short cut, really

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    Dunno if this will provide another diagnostic point or not.....but....

    How about using a small remote gravity feed fuel source ( I use an old primus fuel bottle). That will eliminate the force of the fuel pump and only provide "head" pressure (about 1/2 pound per foot of elevation....dunno the metric equivalent) from gravity.

    So, if the bike runs OK with the remote bottle, you know the pump is pushing fuel past the float controls. Then it's just a matter of finding out why it's leaking.
  11. robmoto

    robmoto Long timer

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    Well I would assume it is to stop a blunt affect of the needle banging on the brass float tab and seet when the fuel is getting sloshed around .
  12. robmoto

    robmoto Long timer

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    Measure to see if there is a difference in the DIA of the seet to the old ones , if smaller thers your problem.
    Did you try what I said about leaving the fuel on and see if fuel drips out the over flows if so I would be looking at the seeling of those O rings arrond the seet.
    OR maybe your not a good float height setter upperer :D.
  13. wundis

    wundis Adventurer

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    Made a remote fuel tank yesterday, I fed it through the fuel pump (obviously, non working). I did not start the bike this way, as at the time I had petrol everywhere (shaky hands) and the float level was too high anyway.


    Ok, seems reasonable enough. But what about the differences in spring strength?

    I'll check the diameters today.
    I did try to leave the fuel on, it's not dripping out of the overflow pipes.

    Tonight I plan on doing two things:
    oil on orings whilst placing them - if that wont help ill try using old seats with new float valves - as the old seats have tighter orings.
    Obviously ill test them after each try.

    Will keep you posted.

    I thought about not being a good float height setter, but theres a lot of information on how to do it properly, i would think i have done it correclty, it's just testing upsets me - its ok by measuring with calipers, but a tragedy when using fuel hoses to test.
  14. robmoto

    robmoto Long timer

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    Well if the fuel I think ain,t coming out the overflow tubes your O rings would be seeling OK the seet and O ring part are held in place by the cage and it is held in place by the bowl.
    I will measure the preasure gram weight of some second hand ones when the little pin bottoms out , will do now if me scales still work.
  15. robmoto

    robmoto Long timer

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    Wudis , I removed the very fine wire bit that hooks over the brass tab on the floats and held the needle with long nose pliers and without shaking pushed down until the spring pin thingy was fully compressed, I tried this with 2 different needles and the scales said 28 to 30 grams.
    ON assembly are you hooking this fine wire part over the float tab, just thought I might ask.
  16. wundis

    wundis Adventurer

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    Ok... thanks for the measurement. I owe you a beer. Make sure you drop by next time you're in Lithuania :)
    Anyhow in this case my problem can still be my initial theory - the springs are weak and can't keep up with the rising fuel, which in turn raises the foats.
    But how it is possible on a new OEM part? Shame the damn float valves are so expensive :/

    And yes, i'm hooking it over the float tab.
  17. mait

    mait Been here awhile

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    What I would do if I were you
    Forget about the calipers and adjust the float level using clear hose method.
    If it makes your bike run OK you have time to decide if you want to buy new float valve assembly or not.

    Edit: I do not always act reasonably. Please consider twice before you follow any of my advice :)
  18. wundis

    wundis Adventurer

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    I wish I could do that mait, but as soon as I start thinking what could happen if I set a lower float level to match the hose method, and then once running the floats do get fixed on the mid point, the level is going to be too low, and we all know that this isnt good... remember bluesman's bike.

    By the way, I wonder if that can be applied to DR Big carbs. The thread is originally based for GS500, but afaik they use the same carbs... There should be a plenty of yamahas riding with the same float valve (perhaps not the same float seat though).
  19. mait

    mait Been here awhile

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    Has anyone measured current draw on DR800 starter motor while cranking cold engine?
    Or does anybody know the wattage of the starter motor?

    I bought one of those Lifepo4 batteries and want to use a quick disconnect plug for it. I would like to buy the smallest possible plug but big enough to handle the Amps.
  20. p3dro

    p3dro Adventurer

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    Thanks for the words of encouragement guys!

    It's totally dead, no turn now after new cdi and re-wound generator.

    Work at the garage has stopped as they are waiting for Suzuki to post them a wiring diagram they can follow.

    Does anyone have one they can email me please? - the bike is a SR43A-100535.
    The link on the first page is like my DR, dead :(

    Thanks again.
    Pete