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DR350 Thread

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

  1. slartidbartfast

    slartidbartfast Life is for good friends and great adventures Supporter

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    It can, but it makes the camchain tighter and also opens up the squish area, which can have the effect of reducing the CR at which pinging can occur, thereby negating the reason for doing the CR reduction.
  2. Alaska1WD

    Alaska1WD Long timer

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    It also changes the timing a little bit, not sure how much the timing would change and if it even matters when talking about 0.2mm, but it's worth a mention. I'm not feeling like maths today.....To increase CR, you can use gasket maker instead of a base gasket, they're roughly .15-.25mm thick and aren't under any real pressure, unlike a head gasket. No base gasket might be a good way to boost compression by 0.2-0.3 or so? You would have to polish the piston edge to keep the squish clearance the same, but that should be easy...

    Squish area increasing is the main bad side effect of extra base/head gasket. Polishing a piston head center area by a fraction of a mm is a better idea as it doesn't change the timing, but it lowers the compression while keeping the squish the same. It will take lots of oil measurements and math to get the polishing/sanding correct, but you can get your 10.5 CR 385cc down to a better 10, 10.2, ect if you're getting some ping/knock and want it to go away. I'm tempted to run a 385cc in the low 10's myself, but I have 2 complete larger bore kits (435+441) on hand to swap in this spring, so I think I'll just use them and target an ultimate 91mm 463cc in the far-off future....
  3. MrPulldown

    MrPulldown Long timer

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    Take a grinder to the top of the piston.
    :hide
    Greg Bender likes this.
  4. Alaska1WD

    Alaska1WD Long timer

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    Would anyone be interested in comparisons between the different types of top end combustion chamber volume? I have DR's, Eigers, Arctic Cats, and a King Quad 400 top end that are able to be used on a DR350/S/SE. I can CC the heads with oil and Plexiglas. Might be cool if there are differences, as differences = choices for each person's uses for their DR!
  5. Alaska1WD

    Alaska1WD Long timer

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    Only need to reduce the piston's head thickness by 1/8 to reduce compression by 0.4, accounting for squish area and everything.... The reduced compression decreases pressure by 1/16 or so, so the piston barely gets any weaker. Seems solid to me...

    GREAT idea for the 385cc guys who keep having ping/knock/ect issues. Some guys don't want to move the pickup coil and run premium fuel all of the time, so dropping the CR a bit would be a great solution.

    Could someone with a bad DR350 piston chop it in half and measure how thick the center is in mm's please? It would be a useful number for future maths.

    My original plan was to sell my DR350 oil cooler, but nobody was interested. I think I will save it for my 463cc in a few years, gotta keep the beast cool somehow!
  6. 2old2Bbold

    2old2Bbold was 2bold2getold

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    We use to take dome top VW pistons and put them in a lathe and turn the dome off flat or even a little dished. Need to check the thickness of the top of the piston afterwards.
  7. slartidbartfast

    slartidbartfast Life is for good friends and great adventures Supporter

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    ~ 1/2 degree for a 0.2mm gasket
  8. dean-o

    dean-o Dabs often

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    anyone have a 62683-27c00 dust seal among their parts goodies?
    its the cup that goes over the aluminum spacer on the lower end of the suspension linkage. ill try to post a pic.

    Attached Files:

  9. gladhandbart

    gladhandbart Adventurer

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    Hey, everyone, I have a 99 SE and have a couple questions. Has anyone ridden one with customized dirt / cartdige 350 forks (racetech gold valve, custom shim stacks, etc) AND one with an RMZ fork swap or equivalent? I'm just trying to decide which would be the best route to go. I don't expect to ever have a mx bike, but I don't want to be lacking in the dirt. I'm making into as good of an adventure bike as I can and want it to be strongest off pavement.

    Also, I have a couple gasket leaks on the case. I figure I might as well inspect as many of the internals as I can while I'm at it. I come from the heavy duty diesel world, so I'm wondering if anyone sells gasket or rebuild kits for these.

    If anyone can speak to these, I'll appreciate it!
  10. Greg Bender

    Greg Bender Long timer

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    I have ridden a stock 1993 dirt model...then upgraded that with the racetech cartridge. It was a huge improvement. Then I bought my 1999 SE and the stock front suspension on it was even better than the racetech cartridge in the 1993 forks. I have never ridden an RMZ fork swap or equivalent. Personally, I remain very happy with the stock suspension on my 1999 SE (though suspension technology has definitely improved in the last 20 years). In all of the above forks, I replaced the springs such that they would work with my weight.

    Regards,

    Gregory Bender
  11. Kestrel

    Kestrel Gear Driven Cams!!

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    For what it is, the late model SE/dirt forks are quite good. The valve itself is well constructed, and isn't really the limitation... The shim stack could use some tweaking to fix some issues with rebound, but it's far from terrible and doesn't really justify racetech's valve.

    The rear on the other hand... people tend to think the issue with the rear has to do with swingarm flex, but that's not really the case. The rear shock valve has some undersized passages that can't flow fluid fast enough during high compression. Same with the shock shaft, and the hose that flows out to the external reservoir. As a result, hard edges and spikes can't adequately be damped, and thus the rear end feels hard and 'kicks'. You CAN change the valve in the shock, but you can't really do anything about the undersized passage in the shock shaft and the reservoir hose. Running the shock with minimal compression is about all you can do. Some have looked into a swap for the rear shock, but there aren't really a lot of good options out there... Anything with a piggyback reservoir tends to not fit, and there aren't a whole lot of dirt remote reservoir shocks out there to choose from. Things like Kouba links tried to change the ratio a little bit, but it's still a handicap on what is a poorly spec'd shock.
    Greg Bender likes this.
  12. DanBManthe

    DanBManthe Adventurer

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    Hey guys, looking to get a little bit of help again.
    Abridged version of pertinent background: girlfriend crashed my 95 DR350SE a couple years ago, bike sat 2ish years, getting it back on the road now.

    Rebuilt the carb with good parts from motolab, diaphragm is in good shape, carb is clean, getting fuel, charged battery, I reset the idle mixture screw close to where it was previous to being replaced. Valves are in spec.

    I don't know for sure where the needle needs to be since it's new. I set it the same as the old one. When I went to start it it would crank just fine but I never got a single pop. I didn't smell fuel though the exhaust.

    How do I know if I'm too rich? Too lean?
  13. abraham_lincoln

    abraham_lincoln Been here awhile

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    Usually if youre too rich youll be able to smell gas pretty quick. I would try adjusting the air/fuel mix and increasing the idle adjuster. Make sure youre using the choke and if you have a kickstarter too try giving that a go.

    Sometimes my estart will turn and turn and not start, but then i set it to TDC and give it a nice full kick and it fires right up. Giving it a little gas can help, and if you suspect flooding then give a few turns with the throttle wide open

    But before all that I'd make sure I'm getting a spark first
  14. DanBManthe

    DanBManthe Adventurer

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    Thanks, I'll start there.

    I should note the bike has new fuel lines and filters too. No kick start. I also cleaned and oiled the air filter.

    Not that it's relevant but obviously it ran when it was crashed. We were on about a 100 mile ride. That's right up there with "ran when parked. "
  15. slartidbartfast

    slartidbartfast Life is for good friends and great adventures Supporter

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    Are you sure the filter is passing fuel?
    plugeye likes this.
  16. DanBManthe

    DanBManthe Adventurer

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    Yup.

    I am using brand new clear yellow fuel lines, clear filters and I cracked the bowl drain to be sure that the bowl has fuel
  17. DanBManthe

    DanBManthe Adventurer

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    Checked the spark tonight, and I'm definitely getting good spark with my tester. Basically a bolt ground to a point and the other end a bolt ground to a point that is clipped to ground. You know the kind.

    I also tested the plug itself and got good spark. Not the brightest blue but more than enough to fire the mixture.

    The plug was definitely dark so I'll lean it out a bit. She always ran well, no black or blue smoke and I was able to get close to 80 mpg on road rides. Never checked the mileage off road.

    I attached a picture. Don't ask me why there's an E3 plug in the bike, I don't know. It ran great until the crash and subsequent "storage" 20200223_205655.jpg
  18. gladhandbart

    gladhandbart Adventurer

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    Thanks for the reply, Gregory. I sent an email to cogent dynamics to see what they have to say about it.

    I've never come across anyone trying to replace the rear shock, but I believe you. I assume even something like an E model DRZ shock wouldn't fit right? I want to get the suspension set up and not regret trying to do swaps later on down the line. Dual sporting / adventure biking is all about compromising, but it would be nice to decrease that which is compromised!
  19. Kestrel

    Kestrel Gear Driven Cams!!

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    Clearance in the back is tight. A piggyback reservoir would hit the exhaust header, or airbox or carburetor boot.. There's really no room up top for any sort of reservoir.... and so Suzuki ran a remote reservoir.

    Sadly, there really aren't any remote reservoir dirt shocks out there anymore that could be converted for use in the DR350.
  20. MrPulldown

    MrPulldown Long timer

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    Not even sure what this picture is of. Spark plugs for our bikes do not look like that. I'd start there.