Carb tuning, Dr350 Tm33 pumper
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Thread: Carb tuning, Dr350 Tm33 pumper

  1. #1
    Senior Member rivershot's Avatar
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    Smile "Update"Carb tuning, Dr350 Tm33 pumper

    So after fighting with the 33 that came on mine only to find out it was worn out, I ordered a brand new one.

    I compared the jets before putting it on all the same, float level checked with the clear tube method, good.

    Put it on, 2 turns out on the pilot, hit the magic button, fired right up, idled good, took off for a ride and all is great until fuel throttle, anything above 7/8 throttle and it's like hitting a rev limiter, redlines no problem at 3/4. Sitting on the side stand, same thing but, if I twist quick all the way it shuts off like you hit the kill switch.

    Am I correct in thinking the main from the other carb could have been opened up and I need to swap them or order a size or 2 bigger? It has zero issues until you pass 3/4 of a twist on the throttle, good idle, no lag, new fuel lines and filters, good cap venting. Only the thing I can think of is not enough fuel in the carb and I need to raise the float level but, it checks out right at the bowl, body seam.

    On another note, can I combine the 2 vent lines and run them up with a filter on the end?

    I know it's not a TW but, it should be basic carb tuning.

    3-26-17

    Well, I decided to do some things before tearing into the new carb. This bike was built well 2 owners back, high dollar aluminum air box, over sized header and FMF pipe along with many other thing, big brakes, skid plate, 5.5 gal tank, suspension work, and many other small mods.

    It also came with many parts, some of these being, stock exhaust, and a new over sized stainless header. One thing I wanted to do was make it a little quieter, so I put the new header (had to cut 3/4'' off) and the stock pipe on, that cut the noise in half from that end, now the intake was the loudest part, closed that off by about 75% and what do you know, no more full throttle popping. Still has some running to go, cause it now has a little mid range flat spot, but not bad and is plenty good for riding until I get caught up on some other projects.

    Those projects mostly consist of my 69 MGB-GT, shop re organizing, and 101 honey do things but, at least for now I have 3 running bikes
    Last edited by rivershot; 03-26-2017 at 05:29 AM.
    littletommy and Ken like this.
    2001 TW200
    1999 DR350SE
    2002 Sportster 1200
    Suzuki Ozark 250 (Broke)
    Rokon RT140 (in a basket)
    Belarus AS250 tractor

  2. #2
    Senior Member Tweaker's Avatar
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    So I like these two threads for tuning carbs:

    https://tw200forum.com/forum/technica...rb-tuning.html

    https://tw200forum.com/forum/technica...y-93-carb.html

    It does sound like like a lean main jet, doing a plug chop would help identify. Buying a few jets is not a bad idea to have for rejetting and is easy to try. Once you get the main jet right you could try changing the needle height. Did you check the needle setting on the old carb?

    Doing the carb vent mod should work good for the DR too I would think.

    Make sure you don't have any air leaks in the mounting boots.
    Last edited by Tweaker; 03-13-2017 at 10:31 AM.
    littletommy and Ken like this.
    ”Everything You Know is Wrong”

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    Twin 2014 TW200's made side by side on the assembly line, Moose rear racks, Protaper ATV high bars, DG oval pipes, kick starters, rejetted carbs, 130 main jets, 2 -3 -.020 shims on the needles and @ 2 1/2 turns on the pilot screw, #34 pilot jets, Acerbis hand guards, Shinko 241 front tires, modified Krator foot pegs, 14-55t sprockets, Ricochet skid plates and 90 degree fuel filters.

  3. #3
    Senior Member Mattwings's Avatar
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    DR350, if equipped with the petcock vacum port, can have fuel flow problems as well, common to replace the vacum petcock with a 660 Raptor part. Lot's of stuff online about the DR350 and carb, I installed a custom Six Sigma jet kit it and it runs 100% better. Thats what I have now (petcock and carb kit), works great.

    This is the wholy grail or reliability and power, lots of feedback that this is really as good as it gets. Further mods=more finicky, less reliable, harder to tune. Pumper is probably easier to dial in than CV however. I just did the snorkel mod, as I ride in dusty and or wet enough to want some protection against both.
    AirBoxMod

    Six Sigma- Good kit, good instructions, has options for a range of tuning and they will support you if you buy the kit. You tell them your set up, they build a kit.

    6 Sigma Jet Kit - 6 Sigma Jet Kit
    littletommy and Tweaker like this.
    2002 TW200 "The Punisher"
    1998 DR350r
    1996 KDX 200
    Riding in and around the great state of Michigan (usually)

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  5. #4
    Senior Member rivershot's Avatar
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    Thanks Tweaker for the links and info. I haven't gotten into the needle adjustment. The old carb had so much play, you had to adjust the idle after every twist, slide had more play than a shot glass in a pint of beer.

    I hope to get back on it this week and do some more comparison between the 2 but, I'll have to take a lot of that with a grain of salt. The pumper plunger was missing, the splash guard was missing and as said about the slide, it was grooved and sloppy.

    No air leaks with a propane torch just running the gas.
    littletommy, Tweaker and Ken like this.
    2001 TW200
    1999 DR350SE
    2002 Sportster 1200
    Suzuki Ozark 250 (Broke)
    Rokon RT140 (in a basket)
    Belarus AS250 tractor

  6. #5
    Senior Member rivershot's Avatar
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    Quote Originally Posted by Mattwings View Post
    DR350, if equipped with the petcock vacum port, can have fuel flow problems as well, common to replace the vacum petcock with a 660 Raptor part. Lot's of stuff online about the DR350 and carb, I installed a custom Six Sigma jet kit it and it runs 100% better. Thats what I have now (petcock and carb kit), works great.

    This is the wholy grail or reliability and power, lots of feedback that this is really as good as it gets. Further mods=more finicky, less reliable, harder to tune. Pumper is probably easier to dial in than CV however. I just did the snorkel mod, as I ride in dusty and or wet enough to want some protection against both.
    AirBoxMod

    Six Sigma- Good kit, good instructions, has options for a range of tuning and they will support you if you buy the kit. You tell them your set up, they build a kit.

    6 Sigma Jet Kit - 6 Sigma Jet Kit
    No Vacum port,, twin petcocks from an Acibis tank, aluminum air box that I would like to snorkel.

    Thanks for the ideas, keep'em comming
    littletommy and Ken like this.
    2001 TW200
    1999 DR350SE
    2002 Sportster 1200
    Suzuki Ozark 250 (Broke)
    Rokon RT140 (in a basket)
    Belarus AS250 tractor

  7. #6
    Senior Member Mattwings's Avatar
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    They (I think most bikes)? are really picky about air volume, I would keep closing off the airbox until it runs worse, then open it up from there. There may not be enough air pressure to keep air flowing at WOT. Twin petcocks doesn't sound right, sounds like the stock set up, maybe take a pic?
    Ken likes this.
    2002 TW200 "The Punisher"
    1998 DR350r
    1996 KDX 200
    Riding in and around the great state of Michigan (usually)

  8. #7
    Senior Member rivershot's Avatar
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    Will try to get some pics up later today.
    2001 TW200
    1999 DR350SE
    2002 Sportster 1200
    Suzuki Ozark 250 (Broke)
    Rokon RT140 (in a basket)
    Belarus AS250 tractor

  9. #8
    Senior Member rivershot's Avatar
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    You can see the plastic over the air box in the 2nd pic. It still needs lots of little things but, it'll work for now.
    Attached Images Attached Images
    Mattwings likes this.
    2001 TW200
    1999 DR350SE
    2002 Sportster 1200
    Suzuki Ozark 250 (Broke)
    Rokon RT140 (in a basket)
    Belarus AS250 tractor

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