Anatomy of a DR350 carb. Help with nomenclatures.

Discussion in 'Thumpers' started by oo7alfa, Aug 19, 2009.

  1. oo7alfa

    oo7alfa Adventurer

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    I just got done tearing my carb apart on my DR350 to clean it and took pictures all the way along so I would remember how to put it back together. I got to thinking that maybe these might come in handy for someone else thinking about doing the same thing. I have taken apart a few small carbs before, a weedeater, my Honda lawnmower, but I am not very experienced so I was a bit worried taking it apart in the first place.

    The reason I took it apart in the first place was I am having a bit of a problem. I can run for about 5 minutes at not quite full throttle, then it decides it wants to die on me. I pull over and wait about 30 seconds and kick it again, it restarts perfectly and I go about another 4 or 5 minutes and it does the same thing again...rinse and repeat...

    If I am just running at lower rpms I don't stall out. So, it seems to me that maybe my Float bowl is emptying and not filling up quickly enough, then when it dies, it refills and starts up again. Good guess?

    Anyways, I was hoping, before I go into all the pictures, for some help naming a few of the jets and such.

    Can someone tell me what this screw is?:
    [​IMG]

    Which jet screw is this and how do I tell the size?:
    [​IMG]

    The float needle? Again, are there different sizes?:
    [​IMG]

    This is the Slide?
    [​IMG]

    And what is this called?
    [​IMG]
    #1
  2. oo7alfa

    oo7alfa Adventurer

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    More pictures:
    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
    #2
  3. mudmantra

    mudmantra Been here awhile

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    Check your fuel flow from you tank too. The stock tank fuel valves go bad a lot. Look up your carburetor on bikebandit under OME parts, and it well give you a brake down of each item. Replace all your O rings too. 1. drain screw 2. idle mixture screw, adjustable for mixture. 3. float valve, 1 size, has an o-ring under the seat. 4. slide. 5. drain/ main jet access cover. And it looks like you've already removed your main jet. I'd replace that carburetor float bowl gasket too. have fun!:D
    #3
  4. Olas

    Olas the darkness

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    Clean your carb out thoroughly with chemicals and compressed air thought ALL of the small orifices and you should be good to go. GET A SERVICE MANUAL.
    #4
  5. matey peeps

    matey peeps Bead Buddy

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    If you have to ask what everything is I'd advise you to STOP. Get a manual or turn it over to a qualified mechanic before you lose something and render it useless and expensive to replace.
    #5
  6. oo7alfa

    oo7alfa Adventurer

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    Thank you for the concern. I may have overstated my inexperience. As I said, I have taken apart a few carbs and was able to get them clean and back together and running, with no manual at all. Also, this is why I have taken good pictures and laid out everything the way it came out of the carb as well as a couple of drawings with the number of turns on the screws in before taking them out. I am not concerned with getting it back together correctly, I am more interested in what items are adjustable in size to see if a PO had messed with the jets at all. People are always talking about oversized jets and things and I am trying to figure out how to determine what size is in mine.
    #6
  7. oo7alfa

    oo7alfa Adventurer

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    Thank you. I actually have already replaced my Petcock with a brand new one from a Yamaha Raptor and it has been working perfectly, at least for a few hundred miles. I was thinking about possible rust in the OEM tank clogging up the petcock.
    #7
  8. mudmantra

    mudmantra Been here awhile

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    yeah rust and dirt in the tank could be slowing or stopping the flow. Most petcocks have screens that can get clogged. Try this, unhook your gas line from the carburetor, then turn on the gas and have it flow into a container. It should flow real good and long. Fill about a cup up to see if anything strange is going on in your tank. I just checked a tank that had a vent check valve installed backwards. The engine would start, run, then starve for gas after a while. Check your vent if you have one too. Be careful and put the gas back in the tank when your done. good luck!
    #8
  9. oo7alfa

    oo7alfa Adventurer

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    Well, I did what you suggest last night, and the flow is very good and nothing unusual in the fuel. I cleaned out the carb and put everything back together. It starts easily right away and runs at quarter throttle and higher just fine, but it is dying when it goes down to idle. The only thing that I did differently was the fuel mixture screw, it was at 3 full turns out originally, I figured I would go with the manual and set it at 2 1/2 turns out. Once I realized it was not idling at all I turned it out another 1/2 turn, but that didn't help at all. Once it drops below about 3000 rpms it dies immediately. Suggestions?

    Thanks again for all the help, it's appreciated!
    #9
  10. XDragRacer

    XDragRacer Long timer

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    Tried adjusting the IDLE SPEED SCREW (if any), in contrast to the PILOT SCREW (called by some, the "idle mixture screw")?
    #10
  11. mudmantra

    mudmantra Been here awhile

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    Did you remove and clean the pilot jet? It's a brass jet. kind of near the main jet. If it's plugged, no idle.
    #11
  12. oo7alfa

    oo7alfa Adventurer

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    Is it the one pictured just below and to the right of the Main Jet, still in place? If so, yes, I did remove and clean it.
    [​IMG]
    #12
  13. oo7alfa

    oo7alfa Adventurer

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    OK, so I figured out that someone put i a 140 main jet, stock is 132.5, but the airbox has not been opened and it has a stock exhaust. Do I need to replace it with a 132.5 to get it to run consistantly, or is it possible to work with this one?
    #13
  14. mudmantra

    mudmantra Been here awhile

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    OK na href="http://s797.photobucket.com/albums/yy255/shopdog/?action=view&current=14e3.jpg" target="_blank">[​IMG] I'd check your pilot jet again. Make sure it's completely.. 100 percent clear and check the numbers on it. Also when you installed the raptor petcock, did you cap off the vacuum lines? I believe the 2 lines above need to be capped off, or it well have a vacuum leak and a fast or no idle speed. I had a DJ138 in my carburetor.. but also a supertrapp exhaust and airbox mod. I'd run a smaller main jet with a stock exhaust. let me know if this pic worked.:D
    #14
  15. rivercreep

    rivercreep Banned

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    .........in regards to the pilot jet AND not just capping off any unused vaccuum ports but also checking the condition of any vaccuum hoses (look for cracking and dry rot)
    In regards to the pilot jet. That sucker (and it's circuits within the carb) are soooo small, you could have very easily gotten dirt into it while cleaning the rest of the carb. I'd clean it again and force gumout and then air through the circuit passages.
    What's the plug color?
    If it's black, the bike could be getting too much fuel at sustained speeds and simply fouling out and dieing when you return to low idle speeds.

    Also, before trouble shooting any carb issues; it's always best to make sure everything else is good like =
    air-filter, valves in adjustment, muffler not restricted with crap etc.
    #15
  16. oo7alfa

    oo7alfa Adventurer

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    OK, I pulled it apart again last night and recleaned it again and ensure the pilot jet was clear, it is stock at 37.5. I had capped off the vacuum line on the top starboard side when I switched out the Raptor petcock, however mine does not have the second vacuum inlet that your picture shows, the one facing down next to the float.

    The bike is now idling and running at all speeds, however, I am not really happy with the smoothness at idle. It will idle at 1800 rpms for a minute, then raise up to about 3000 for a second, then drop back down, it's all kind of erratic not rhythmic. I could run it this way and no one would even notice, but I will, and I would like it to be smoother.

    On a side note, taking the carb apart the second time was so much easier and less stressful. Knowing I can do it now makes it a simple task. Total time to remove, disassemble, reclean and reinstall was about 20 minutes!

    BTW, thanks again, and your picture helped alot. I hope you didn't take it apart just for me!
    #16
  17. oo7alfa

    oo7alfa Adventurer

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    I did just adjust the valves about 300 miles ago and check the air filter. I will say, the exhaust is creating a bit of Black residue on my rear fender. The spark plug looked good when I replaced it at the smae time as the valves.
    #17
  18. Truckin_Thumper

    Truckin_Thumper low profile

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    inspect your slide...make sure *IF* any holes were drilled they are GTG

    diaphram... make sure it has no tears or holes

    slide guide..... make sure the slide and guide move freely and no "snags"

    sounds like the slide is sticking

    Also the DR650 has the same carb (for the most part) and jets can be had from that.
    A 140/142 and an open air box is the ticket at sea level up to about 3,000 feet

    turn the air mix srew OUT (all the way in [snug not tight]) and then out between 2.25- 2.5 turns.

    set the float level according to KienTech

    you may also want to look at doing the "T" mad to the carb. Again KienTech

    http://www.kientech.com/
    #18
  19. oo7alfa

    oo7alfa Adventurer

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    Here is some video of it at idle. Give me your thoughts.
    View My Video
    #19
  20. mudmantra

    mudmantra Been here awhile

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    If you haven't already, replace these o-rings. also check your float setting.<a href="http://s797.photobucket.com/albums/yy255/shopdog/?action=view&current=ORINGS.jpg" target="_blank"><img src="http://i797.photobucket.com/albums/yy255/shopdog/ORINGS.jpg" border="0" alt="o-rings"></a> # 1 is an o-ring under the float needle seat.
    #20