DR350 Thread

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

  1. Woodland_Johnny

    Woodland_Johnny Adventurer

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    Really appreciate the info. I will start running high octane fuel. Definitely will check the float and needle positions. And as far as the screw you're saying to turn out, thats the mix screw? The PO who did the dyna kit drilled the hole out so theres an adjustable screw there now.

    Always had the acerbis tank. When I got it, PO had a little hose with the little metal cap on it. These days I don't have anything over the gas cap nipple. But like I said, I don't seem to have the issue nearly as bad.

    I'll check float, needle. maybe mess with the mix screw for higher end fuel delivery... and run high octane gas. We'll see if that clear it up. Hopefully it will get me better mpg too... seems like other can still get low 50's even with BBK
  2. plugeye

    plugeye MC rescue

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    137.5 is huge for a BST33. stock is 127.5, start closer to that
  3. MrPulldown

    MrPulldown Long timer

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    Our guy is currently running a 145 MJ
  4. rockt

    rockt Long timer

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    I'll check float, needle. maybe mess with the mix screw for higher end fuel delivery... and run high octane gas.

    Not sure if you're reading that right. They're not talking about the float and the needle, they're talking about the float needle. It's a little arrow head like thing under the float tang that determines float height. It wears out and with the flooding symptoms you have, I'd just order a new one and replace it. When you've installed the new one, check your float height (I don't know the correct height off-hand but it's available). That will stop your overflow issue. Next set air/fuel mixture. Read up on it. If you already have the adjustable screw it's easy to do. Then go up the line... needle, (responsible for mid-range and a completely separate animal from the float needle), then main jet.

    Also find out what the compression is for your big bore kit, but yeah, to be safe, start using high octane fuel, preferably without ethanol.
  5. motolab

    motolab Long timer

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    Things that increase detonation risk (in no particular order): Lack of octane, too much compression, too much squish clearance, elevated temperatures/lack of cooling, lack of exhaust flow, improved cylinder filling, lean mixtures, overadvanced ignition timing, and oil consumption.

    Regards,

    Derek
    rockt likes this.
  6. Woodland_Johnny

    Woodland_Johnny Adventurer

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    Thank you. Turns out I did need the clarification! I went in yesterday and the little o-ring around the entrance to the bowl was not in good shape. I have new o rings on the way but had some from a new chain that fit pretty good. Pretty redneck, I know. I had an extra float needle too. They looked slightly different than each other but that in the end they were the same length. I replaced the one that was in there in case it was wonky. After it's back together it's still running very rich at idle. I didn't get a chance to mess with the air mix screw so I'll do that next.

    Thanks Derek for the detonation tips. I think my previous issues that caused my engine failure before were most likely running the bike long and hard with a lean mix, made worse by a potential oil starvation.
  7. Trixie

    Trixie Adventurer in my own mind

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    The air mix screw is actually a fuel mix screw on this carb. Turning it in leans the idle circuit.
  8. rockt

    rockt Long timer

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    Right, it adjusts the air/fuel ratio at idle. So turning it out allows more fuel and richens that ratio. I set mine years ago and haven't had to change it but for Woodland_Johnny's benefit (and to refresh my memory) to adjust you: 1. start at a baseline of 1.75- 2 turns out from (lightly) seated 2. fully warmed motor, adjust idle on the low side 3. turn out fuel screw 'til you get highest idle 4. turn it in 'til idle drops a bit 5. now readjust idle screw to 1400-1500 rpm. Does that sound about right? Please correct if I've given any misleading info. here.
  9. motolab

    motolab Long timer

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    What you're recommending here will yield an idle mixture that is too lean.

    Regards,

    Derek
  10. rockt

    rockt Long timer

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    Thanks Derek, I put it out there to get feedback because, a. I want to help Wooland_Johnny get it right and b. as I said it's been probably close to 10 years since I did it, (I try to keep my carb clean by using ethanol free fuel and draining it completely every Fall), so I want to make sure I have it right. Can you explain the right way to do it?
  11. motolab

    motolab Long timer

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    https://advrider.com/f/threads/dr350-thread.230695/page-3154#post-41072758.

    Regards,

    Derek
    rockt likes this.
  12. FlatlanderSJ

    FlatlanderSJ Adventurer

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    Along with a fuel cap check valve causing fuel starvation after a long ride another thing to check is that the petcock filters are clean and if you have an inline filter make sure it is clean and large enough. If they are not flowing enough it can run the bowl low on extended rides.
  13. rockt

    rockt Long timer

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    Thanks Derek, just a little confused though. In the link to the post you provided, you stated: "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)."

    So after you've achieved the strongest idle with the fuel screw, do you then adjust fuel screw another 1/8-1/4 turn out or are you saying adjust the (separate) idle adjuster 1/8-1/4 or, in your description, are you calling the fuel screw, the idle mixture screw? Not trying to be picky or split hairs and really value your input, I just want to get this right for me (gonna do mine again to make sure it's right), W_J and anyone else who could use this info.
  14. motolab

    motolab Long timer

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    The idle mixture screw on a BST33 carburetor is a fuel screw.

    Regards,

    Derek
  15. MrPulldown

    MrPulldown Long timer

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    Using a floor jack to install the rear wheel worked liked a charm. Non cush wheel, so easier.
    20210722_172749.jpg

    I had this cush wheel on. Tire still has some life on it (JK) but I want to put a new tire on for this weekends ride for my 94SE.
    20210707_135841.jpg
    [​IMG]

    Got the new tire spooned on last night. What a bitch. Super stiff. I'll install the wheel today to see how the 120/90-18 Tusk DSport tire fits. This is a DOT tire so narrower than a non-DOT. Tall knobs but narrow. Also using a cush drive hub so the wheel will be offset to the right. The MT21 (DOT) that I took off was a 120 but fit fine. A trackmaster 120 (DOT) will rub with a cush hub but not with a non-cush. That Maxxis is a 110 (non-DOT) and it barely fits the swing arm centered, but will rub the battery box at full suspension compression. Maybe I should dish my cush wheels so they are centered in the swingarm.
    20210722_224026.jpg
  16. Anonawesome

    Anonawesome Scenic Rider

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    Fuel screw and idle mixture screw are the same.

    The idle screw, is the one that's different. The point is to have it running ever-so-slightly rich at idle, so that you can ensure under all conditions, that it returns to idle, and doesn't "hang" above idle rpm when the motor is a little extra toasty.
    rockt likes this.
  17. rockt

    rockt Long timer

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    Fuel screw and idle mixture screw are the same.

    Thanks Anonawesome, that's what I wanted clarification on.
  18. MrPulldown

    MrPulldown Long timer

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    This is the screw that is covered by a brass plug and can not be adjusted until it is removed. Also the screw that you can not really adjust while on the bike while it is running as it is recessed in its hole. That is unless you have an "aftermarket" adjustable screw.

    The idle speed screw is just a throttle stop to give it "more gas".

    [​IMG]
    Hugh B and rockt like this.
  19. Royce Cochran

    Royce Cochran was 2bold2getold

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    [​IMG]

    Where you gonna mount that on you bike ? :lol3

    Kidding.... I sit on the ground behind the wheel and lift it with my feet/toes while sliding the axle in. No problem.
  20. Jeff@TheQuadShop

    Jeff@TheQuadShop TAT survivor

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    That's the way I do it as well, easy peasy.