DR350 Thread

Discussion in 'Thumpers' started by leonphelps, May 16, 2007.

  1. plugeye

    plugeye MC rescue

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    thread an m5 screw into the emulsion tube. using a vise, begin to press the tube out, the slide guide should move enough to extract it.
  2. MrPulldown

    MrPulldown Long timer

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    I have never been able to push out an emulsion tube and slide guide. I recall things starting to deform and nothing moving so I stopped.
  3. motolab

    motolab Long timer

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    I can't recommend doing that as standard M5 screw has a 0.80 pitch whereas a Mikuni large round main jet has a 0.75 pitch.

    Regards,

    Derek
  4. Hatch

    Hatch Perpetually lost

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    ahhh I had to look up how to remove that - I'm not going to go that far on this carb. If the guide is shot, I'd rather just get a pumper carb. Thanks for the info, I'll keep plugging away at the normal stuff.
  5. motolab

    motolab Long timer

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    Determining whether the slide guide and therefore the emulsion tube are worn out is normal stuff.

    Regards,

    Derek
    brianpeck and plugeye like this.
  6. irk miller

    irk miller Been here awhile Supporter

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    I have an airbox from a dirt 350 parts bike you can have for the ride, if it's worth the trip from the US. Let me know in a PM if you want pics to see if it's worth the cash.
  7. Steinarsv

    Steinarsv Who cares about the destination?

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    Aww, thanks, but i allready bought one from flea bay. But i have not heard from the seller yet.

    I'll call out if i don't get anything from him? ❤️
  8. MrPulldown

    MrPulldown Long timer

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    A pumper is not always considered an upgrade.
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  9. Hatch

    Hatch Perpetually lost

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    For sure. I dropped the needle another clip and it is much better, need to ride more now to evaluate.
  10. brianpeck

    brianpeck Been here awhile

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    The biggest arguments AGAINST a pumper would be worse performance thru elevation changes, and increased fuel consumption - correct?

    After riding the bike I picked up for a buddy that came with a pumper, I have to say I really liked the (seemingly) better throttle reaction. But still not sure if it's worth $400+ to upgrade...
  11. Hatch

    Hatch Perpetually lost

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    Not for me. I dropped the needle 2 clips, air screw 2 turns out, seems to run fine now.
  12. MrPulldown

    MrPulldown Long timer

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    Basically. The pumper delivers more performance but at a cost. Additional cons included faster wear of the slide/body and needle. However new they are cheaper than a BST.

    I plan on slapping a pumper back on one of my drs someday.
  13. motolab

    motolab Long timer

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    Add to that lack of mixture-strength uniformity across the rpm range for a given opening, and that while the TM33's slide guide (and therefore emulsion tube) wears out just as it does on the BST33, it's not removable/replaceable.

    Regards,

    Derek
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  14. Sword777

    Sword777 Been here awhile

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    So I have a weird leak in my carb I cant track down. It is not the usual suspect of the float needle. It leaks very slowly and noticed it by the smell in my garage. I watched a drop or two come down from where the throttle lever shaft or where the carb connects to the engine. I tightened up things i could get to without taking the carb off,but now it still leaks. Any idea where it is coming from? It runs down from here, including the drain plug and the throttle stop screw. Not sure if the rubber where it connects to the engine is loose (but that would require the float to leak right?) or what about where it appears its coming out of the throttle lever?
  15. motolab

    motolab Long timer

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    The fact that lowering the needle by two clip positions caused the symptoms to subside points to the issue having been a too rich mixture, however the mixture is likely to currently still be too rich. Let's put some numbers to this to provide some perspective: The correct mixture produces 3-3.5% CO at small openings and ~4-4.5% CO at larger, lean symptoms occur below ~2-2.5%, and rich symptoms above ~10-13%. In that huge span between correct and 10-13% CO, horsepower progressively drops, but there are otherwise no symptoms. This means that before, the mixture was likely to have produced north of 10% CO at the combination of throttle position and rpm the symptom manifested during, and it is now at or just below 10-13% (since one clip position is usually worth ~1% CO).

    FWIW, the BST33's idle mixture screw is a fuel screw rather than an air screw. This is important because a fuel screw richens the mixture by opening and an air screw richens the mixture by closing.

    That said, by what method was your setting arrived at?

    Regards,

    Derek
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  16. Hatch

    Hatch Perpetually lost

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    Man, you went way over my head (again) :lol3
    Good to know about the fuel screw.
    Seat of the pants method?? I just tried different settings and rode around the block, until I got a result that was smooth through the rpm range.
  17. motolab

    motolab Long timer

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    The fuel screw should not be used to tune other than the idle mixture. I recommend the following method:

    Start the engine, let it warm up and ride the bike around until it's hot. Using the idle speed screw, adjust the idle speed to 1400 rpm. Adjust the fuel screw so the CO is ~3-3.5%. If gas analysis is not available, coming from the lean side, adjust the fuel screw so that the strongest idle is achieved. You will notice there is a threshold where it becomes rich enough (enough turns out) to run strongest, beyond which no change is noticed. Adjust the idle mixture screw ~1/8-1/4 turn out from this threshold. Adjust the idle speed back to 1400 rpm (as it is likely to have changed). Leave the mixture to the leaner side of these settings if the bike will be seeing altitudes much higher than the one it was set at. Set to the richer side if you would like the engine to idle well earlier during warm up. For diagnostic purposes, report back withe the resultant number of turns.

    Regards,

    Derek
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  18. DaveJ_U.P.Rider

    DaveJ_U.P.Rider Adventurer

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    A few pics from my DR350 rides over the past couple of months. This bike takes a licken and keeps up with much newer bikes out in the woods... Still puts a smile on face every time I get out on it !! FB_IMG_1603160698449.jpg FB_IMG_1603160430826.jpg FB_IMG_1603160446478.jpg FB_IMG_1603160468696.jpg FB_IMG_1603160755666_kindlephoto-7337501.jpg
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  19. irk miller

    irk miller Been here awhile Supporter

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    Finally back in the DR350 game. I traded a 91 dirt only DR350 three years ago for a BMW F650, but missed that bike ever since. Not being able to tag it was the major reason the bike was expendable. I held out for a good deal until this last month when I was able to trade a 2002 XR200r for a 1992 DR350s. The bike had very low compression and definitely has seen some abuse, but overall it's been pretty easy to get back in order. I've already fixed leaking intake valves, swapped for a fresh jug and a JE high compression piston and fresh rings. The PO made a gasket for the top cover, which gave crazy extra gap to adjust out of the rockers, but all that's been fixed. The cam and journals are perfect and the rocker pads haven't cupped at all. For the most part, it has been replacement of the seat cover and padding, new Renthal bars, grips and some wiring harness repair. I also swapped out the BST for a TM33, which has been completely rebuilt with a new slide, needle, gaskets, o rings, etc. Plastics have some unfixable rash, but they cleaned up well enough to take time to replace. I also have a dirt only parts bike to scavenge some parts from.

    [​IMG]
  20. Wahoo_

    Wahoo_ In over my head

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    I also want to echo the praise for this bike. It is by far the most fun bike I have ever owned.
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