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DR350 Thread

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

  1. abraham_lincoln

    abraham_lincoln Been here awhile

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    Nov 10, 2019
    Oddometer:
    132
    Location:
    USA
    Ill try to keep this as brief as possible.

    Went for a trail ride a few days ago, took the freeway home ~15miles. On my way through town i was getting a surge/hesitation at WOT

    Went home and took the float bowl off and cleaned things up a little, took the main jet out and made sure everything was good.

    Went for a ride, bike seemed fine at WOT, parked it and went home.

    Today i went to go for a ride and warmed it up. Started up and idled fine, but then it died minutes later and i noticed gas was coming from the carb. Took the bowl off again and checked the float valve. Everything seemed fine, reassembled but it would begin leaking again..

    So then i took the carb completely off and went through everything, made sure the float valve was sealing which it was.

    Put the carb back on, bike fired right up, idled fine for a good 5 minutes or so, revved fine with the throttle, no leaking fuel. So i hopped on to go for a ride around the block and while backing out of the patio it died and i could smell fuel, looked down and it was leaking again. ..??

    Gave up and parked it for the day. Little confused as to why this is happening. My bike has the vacuum line delete, two ports are blocked off on the carb but theres a 3rd port that fuel came out of when i removed the carb and flipped it upside down, is this an overflow port or should this be plugged as well? Not sure where else to go with this

    Edit- also wanted to add that the diaphragm was soft and pliable and free of any holes or tears as far as I could tell
  2. DookieMcDaniel

    DookieMcDaniel n00b

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    Jun 27, 2019
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    Oak Harbor, WA
    I installed the 385cc big bore kit on my 99, have done an airbox mod, but am running the stock CV carb and exhaust. I had seen somewhere on here that Jesse from Kientech had suggested a 37 pilot/140 main. The only way I can get it to idle is with a 42.5 pilot, but as soon as I give it gas for higher rpm, it sputters and cuts off. I've tried 140, 145 and 150 on the main. Should I go higher? Lower? Any suggestions would be appreciated.
  3. Boblosi111

    Boblosi111 Adventurer Supporter

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    Jul 6, 2019
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    Have you moved the needle up any?
  4. slartidbartfast

    slartidbartfast Life is for good friends and great adventures Supporter

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    There's an O-ring under the needle valve seat that rots away after a few years. I'd start by checking that - if you've not replaced it before, do so anyway.
    Greg Bender and Trixie like this.
  5. Anonawesome

    Anonawesome Scenic Rider

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    What @slartidbartfast said. If you can remove the brass valve seat easily, it's bad. Should take some effort to take out, and some lube to get back in.

    Also the carb only has one vacuum port. I will post a pic of what should be plugged below.

    The other ports are a breather which keeps the inside of the bowl at ambient air pressure, and a fuel drain that also acts as an overflow.

    Plugging the breather could cause pressure to build and flood the engine, or the carb. Even water from a creek crossing could cause this to happen. This is what the popular "T vent" mod fixes. I personally just leave mine open because I typically stay away from water, and I've never had problems, even in heavy rain.

    The drain is the same hole that drains when you open the drain valve, so many people think that the valve is leaking if it's letting out fuel. Not the case. If the carb is filling up too much, the overflow bypasses the valve to let the fuel out.
    If you plug this hole, fuel could overflow into the intake, cylinder, then into the crankcase and ruin your oil.
    When you take off the bowl, the overflow tube is a long brass tube attached to the bowl. Its height is respective to how high the fuel level is before it starts draining.


    Only plug the vacuum port, and I recommend vinyl caps rather than the rubber one pictured. The rubber ones crack and let air in, and it can be hard to spot the problem. The vinyl ones often come in colored kits.
    https://www.autozone.com/fittings-a...assorted-vinyl-vacuum-cap-20-piece/143716_0_0


    [​IMG]
    plugeye likes this.
  6. DookieMcDaniel

    DookieMcDaniel n00b

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    I've got 2 shims on the needle
  7. Alaska1WD

    Alaska1WD Long timer

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    Im pretty sure I know what's wrong. It's not actually a main jet issue, your stock carb simply needs a needle that lets more fuel by in the mid-range. Your 99 has an EPA-strangled needle in it, it needs replacing. The best is a 6-notched dynojet steel needle, kit no 4223 I think. I have one and it's easy to tune. Dynojet also makes one numbered 3197, not sure what's the difference there. Costs about 45$, but it's really worth it.

    Explains why you're trying 140-150 jets, you're trying to make up for the super low needle flow by adding extra gas!

    Buy 132.5 to 140 genuine mikuni jets ( I like jetsrus.com) and try each 2.5. Jesse's 140 is too rich for most, average for a 3x3 airbox is a 135. 137.5 for people who race around and are trying to keep the temperature lower, or 132.5 for highway bikes who want the last bit of power/range from running hot/lean, but have the wind flowing by to keep the engine cool.

    In short, more needle fuel and less main jet fuel!

    I keep my dynojet clip about halfway up, probably a good starting point. Kit comes with a little washer that is basically half of a clip spot, so you can really fine tune it. Good luck!
    Boblosi111 likes this.
  8. mentolio

    mentolio Been here awhile

    Joined:
    Jul 14, 2016
    Oddometer:
    680
    Here's a question for the masses: does anyone have a sealed bearing in their case for the countershaft sprocket? I was cleaning my DR350 bottom end cases to prepare for reassembly, and when I popped the countershaft seal out, noticed there was a seal on the outside of the countershaft bearing (facing out behind the actual countershaft seal). Anyone else have that? I don't recall if my 250 has a seal on the bearing, but I don't think so. Seems a little pointless to me, as there is an oil passage that looks like it's supposed to feed the bearing oil? Can't do that with that seal in the way...anyone know a reason NOT to remove this seal?

    IMG_5423.jpg IMG_5424.jpg IMG_5425.jpg

    I looked at my manual, but it doesn't really go into any detail regarding bearings. Parts fische doesn't show a seal on the bearing, but that could be a Suzuki oversight (generic line drawing).
  9. abraham_lincoln

    abraham_lincoln Been here awhile

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    I went ahead and ordered a carb rebuild kit. Hopefully the new rubbers will fix the issue as i recall the orings had definitely seen better days. The float valve and float seats werent very snug when fit into place neither.
  10. abraham_lincoln

    abraham_lincoln Been here awhile

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    Location:
    USA

    I wish i had taken pics when i had the carb off. My breather port has nothing in it like pictured above. Also my carb is slightly different as far as the float bowl goes (no large bolt on bottom and drain port is different)

    Im pretty sure there are two other ports, both of which are capped on the carb by the PO, though i could be wrong. Ordered a carb kit that should be here in a few days, ill update when i get around to it
  11. MrPulldown

    MrPulldown Long timer

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    That breather is the "T" vent mod. OE just has a nub.

    THe large hex on the bowl is for main jet swaps. Found only on the 90-93 S. The SE carb looks different.

    [​IMG]
  12. Thedktor

    Thedktor Adventurer

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    That is correct - do not remove the seal!

    Its all to do with how the oil is pumped up the shaft. DRZ is the same.
  13. mwitt08

    mwitt08 Adventurer

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    Oct 12, 2018
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    96
    Location:
    Dayton, Ohio
    Well here goes nothing. XR650L tank in hand. First time trying to mod together something like this, but I know plenty have written up the methods.

    IMG_1157.jpg
  14. Bigmatt5952

    Bigmatt5952 Adventurer

    Joined:
    Mar 13, 2016
    Oddometer:
    35
    Location:
    Michigan
    I’m in the middle of combining 2 bikes (96 street and 97 dirt with bbk). Goal is to have:
    Street legal frame
    E start (street)
    Higher output Alternator (street)
    Kick start (dirt)
    BBK, thumper racing 435cc 9.5:1 comp (dirt)
    Manual decomp (dirt)
    DR dirt rear shock, racetech tuned
    Drz 400 front suspension (dirt)
    New plastics and seat concepts seat (dirt)

    I want to ensure the killer dowel pin is addressed. Mine is drilled thru so I’m going to split the case and weld it. Is it easier to split the case from the clutch side or alternator side?

    Which cam is better to use, the kick start or E start? Both have auto decompression but the decomp bump is in a different location.

    Is there any way to use a 1996 dr350 front wheel with a DRZ400 front suspension? The street has 50/50 tires and the dirt had 90/10 tires. I’d like to use both sets depending on the riding situation.

    thanks,

    Bigmatt


    image.jpg image.jpg image.jpg
  15. MrPulldown

    MrPulldown Long timer

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    I have a kick starter on my SE and the SE cam. I can kick it over pretty well now. I am not sure how the E start will like the dirt cam.
    You can adapt a 96 front wheel to fit a 98-99 fork. But I think the DRZ/RM fork uses a WAY too big of an axle for the 96 front hub. I explored this option when I went to an RM fork and bought an RM wheel.
    Case splits down the middle :-) I don't know which side is easier. But have you read distech and pablo's dr350 rebuild threads. They have a discussion on this I think. Both threads are valuable sources of info.
  16. Thedktor

    Thedktor Adventurer

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    Follow the manual - lay engine on left side, pull off right case. Crank will be semi-interference fit on the flywheel side main bearing - you will likely need some heat and the bearing might come out with it.

    20190530_202048.jpg
  17. Anonawesome

    Anonawesome Scenic Rider

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    There were two different versions of the BST33. None of the important ports were changed so don't worry about it. As MrPulldown mentioned, the bowl plug was probably for main jet swaps, but it's not actually very useful which is presumably why they got rid of it.

    The ONLY thing that should be capped is the vacuum port. For the breather, you can find a tee like my picture, then add some hoses to route up and down the frame, OR, if you don't experience a lot of water, you can just leave nothing on it like I do.


    The port on the top plastic cover doesn't do anything and doesn't need capped either. It's not actually a hole. On bikes with multiple carbs, it's an actual open hole, and is used to measure vacuum, so you can synchronize each carb.
  18. gladhandbart

    gladhandbart Adventurer

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    Wyoming
    Not to belabor this, but did you happen to see my above post, @MrPulldown? I’ll quote it here, but I’d like to hear from anyone who’s done an RM fork swap that can compare them to the DR cartridge forks and dirt shock. Thanks!

  19. plugeye

    plugeye MC rescue

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    use the e-start cam, use manual CR to kickstart.
    96 front wheel is a 15mm axle, the DRZ is a 20mm axle
    [​IMG]
  20. MrPulldown

    MrPulldown Long timer

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    I saw that post. But did not have the specific combination to compare. Since you asked I'll give you my 2 cents.

    I have only ridden a 90-97SE dampener rod fork before swapping to a RM. The RM fork lands jump very plush. But does not take slow speed hits well. Hitting a rock at higher speeds, like in the middle of a dirt road, is pretty harsh. A little better than the stock fork since it is stiffer. The RM dual chamber cartridge fork is probably set up more for MX type riding and not trail. I think the DRZ cartridge fork would probably be better suited for my riding.

    I have a write up in this thread of the various methods of doing the RM/DRZ (essentially the same fork externally) swap. 2 main ways.

    3 rear shock were made for the DR350. The dirt. The 90-93 S. And the 94-97SE. The dirt and the early year S are basically the same. The dirt got the straight rate spring and the adjustable rebound. The S the progressive spring and no rebound adjuster. The compression valving are probably close to being the same. The rebound however is different. Someone posted that the rebound oil passage on the dirt is larger thus you need to adjust the dirt shock to almost all the way slow to be useable. The S had decent rebound preset. If you are custom tuning either the S or the dirt would be a fine starting place.

    The difference between the S/dirt and the 94-97SE is travel. The SE use a welded lower clevis, and the piston stroke is shorter resulting in 10 inches of rear wheel travel vs the 11 found in the other 2. I found the SE to be very soft compared to the dirt shock I swapped in. But there are alot of variables including the spring, and the fresh oil.
    gladhandbart likes this.