690R carburetor conversion mod.

Discussion in 'Thumpers' started by Visigothic, Feb 27, 2011.

  1. Fabnut

    Fabnut Been here awhile

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    So no go with fresh fuel ? I was gonna suggest drain the bowl and check if it had water in it, but youve already had the carb off and most probably checked that.

    The TPS provides some ignition advance thru the rev range. Not sure it has such a dramatic influence as what you are experiencing, but its worth checking just the same as a process of elimination.

    [​IMG]

    [​IMG]
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  2. jesusgatos

    jesusgatos fishing with dynamite Supporter

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    Yeah, drained all the fuel and that didn't make any difference. Thanks for thinking of the TPS.
  3. Michał 123

    Michał 123 Adventurer

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    what is the carburetor flange connected to the head? I was able to start my engine, but I have a leak between the head and the carburetor, a makeshift connector, does this connector fit? 75036045000
  4. Fabnut

    Fabnut Been here awhile

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    Yes it will.
  5. NomadLarry

    NomadLarry n00b Supporter

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    Just finished my carb conversion. Took forever to get some parts but she’s finally done and runs great.

    Thx to all , specially fabnut.

    I couldn’t get a oem fuel pump so i went for a mukini df52-136 and blocked one outlet. The rest is all rfr parts.

    Still experimenting with jetting but so far MJ 168, pilot 42 was working great.

    Here’s a few pics

    Attached Files:

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  6. outbacktm

    outbacktm Bullrun Bison Supporter

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    Great looking machine, are the fairing panels that connect to the gas tanks a custom fab?
  7. NomadLarry

    NomadLarry n00b Supporter

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    They come with the nomad-RR travel tower kit..
    They do fit well but you need to be … patient i would say. Took quite a while to get them
  8. outbacktm

    outbacktm Bullrun Bison Supporter

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    Thanks
  9. Fabnut

    Fabnut Been here awhile

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    Great looking bike Larry and glad to know she’s up and running.
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  10. Michał 123

    Michał 123 Adventurer

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    I was able to start my quad bike, I have a ride, I have a problem with firing, I have to hold the starter for 5 seconds and repeat it 10 times so that it fires all the time hest the same as it starts it is fine, what can be the reason?
  11. Michał 123

    Michał 123 Adventurer

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    all jets are open, it seems to me that it is not a matter of left air carburetor, I also do not catch rfs installations do you think that I get a spark at the wrong point? when it starts, it works perfectly
  12. Michał 123

    Michał 123 Adventurer

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    each firing is a torment, sometimes it fires right away, e.g. it fires up, goes well, drives, after turning off the engine, it does not want to start after a few minutes of firing, it fires up and goes until the engine is turned off
  13. Michał 123

    Michał 123 Adventurer

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    the spark is really strong the fuel is also i think it's a bug with the electrics I know that in 525 rfs from which I have installations at ignition the module accelerates the ignition maybe 2 this is the problem
  14. NomadLarry

    NomadLarry n00b Supporter

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    Hi all,
    I have a problem that I can’t figure out so far.

    The bike is running great in trails and small roads but when i get on highways , let’s say constant speed higher than 90km/h , i run out of fuel. Here’s the thing, my fuel pump ( mikuni df52-136 dual outlet (1 blocked) is mounted very low on the bike. When the bike is full of gas i have no issues for about 100km , seems like gravity works for a while then when the tank is half full the pump just can’t give me enough fuel.

    So i mounted the pump higher, about same height than carb fuel inlet and now even with a full tank the bike won’t run at highway speed.

    I ran the bike at idle with a auxiliary tank plugged directly to the carb to see if the pump works , it does. Tried a spare one i had, same flow which btw doesn’t seem that great. Didn’t let the bike run long enough to have a idea if i would actually get 31lt/hr.

    When i ordered all my parts the oem pump wasn’t available. I just tried ordering one again, will see if i can get one now.

    One thing i was wondering, the hole on the inlet barb is very small( i check with lockwire , it’s somewhere between 0.020" and 0.032"), normal?

    I also made sure the vents weren’t clogged.

    I also have front tanks on the bike and it’s running the same no matter which tank i use.

    I also suspected the vaccum line so i have put a 1/4" tube inside the hose to be sure it wasn’t collapsing…

    Last thing, float needle valve is a 3.8 .

    Any ideas on what to check next would be greatly appreciated.

    Thx
  15. Fabnut

    Fabnut Been here awhile

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    Do you have the all 3 tanks on at the same time ? I have heard of hydraulic lock issues when all 3 three are tapped on.
  16. NomadLarry

    NomadLarry n00b Supporter

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    No , i have installed a valve. I choose either the rear tank or the fronts. Both fronts are linked together tho. Could always try to remove the valve and just run one tank to test..
  17. Fabnut

    Fabnut Been here awhile

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    Is your vacuum hose from the pump to the intake air tight at both ends ?

    Is it a robust enough hose that it’s not collapsing when under vacuum or have kink in it ?

    From memory I think I used 1/4 inch (6mm) reinforced fuel hose
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  18. NomadLarry

    NomadLarry n00b Supporter

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    Yea i did double checked the clamps.
    I tried finding braided vaccum hoses today but they didn’t had any where i went.
    I still have normal 1/4" I/D rubber hose with a stainless tube inside ( 1/4" O/D) installed.
    So my inside diameter is a bit smaller than 1/4".. Might not help the vaccum.
    Didn’t got any email today saying that the pump was still back order so hopefully i get one soon.
  19. Fabnut

    Fabnut Been here awhile

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    Just re read your initial post, and the hole in the barb fitting that you mention being 0.032 (0.8mm) is incredibly small, so i went and measured one i have below....
    If it is that small as you say, id say that might be your problem.

    [​IMG]

    [​IMG]
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  20. NomadLarry

    NomadLarry n00b Supporter

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    You just made my day
    Will remove my fitting and drill it.
    Thx a lot
    Fabnut likes this.