the DR200 thread

Discussion in 'Thumpers' started by klxrdr, May 13, 2007.

  1. Trailrider200

    Trailrider200 Long timer

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    maybe not. cats with a closed loop system must run 14.7:1 fuel ratio for it to work. this is much too rich going down the hwy. the excess fuel is burning inside of the cat so it will work.
  2. Trailrider200

    Trailrider200 Long timer

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    they were separate tests.
  3. jrogers110

    jrogers110 Adventurer

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    Thanks for the info. I looked up the gear ratios, and this is what I found:

    Gear = DR//TU
    --------------------------
    Primary=3.157//3.238
    1=3.0//2.636
    2=1.933//1.687
    3=1.437//1.2
    4=1.095//0.952
    5=0.915//0.818
    Final=3.0//2.867

    The percent change from 4th to 5th is -16.4% for the DR and -14.1% for the TU. So it seems that while the jump is bigger for the DR, it's not substantially different than the same jump in the TU.

    Since I really like the 4-5 jump in the TU, I think I would probably be fine with the jump in the DR.

    Your mods look awesome, and I have the ability to do them. I have a shop and no fear of diving in-- I have a Chinese dirt bike that has a problem with 3rd gear and I'll be doing a full transmission teardown to fix it. But these days I'm not all that keen to do a bunch of performance mods.

    There was a time in my life I would have been considering doing something like what you've done. But as I've gotten older, I've kind of lost my appetite for that. Sometimes highly forum-recommended mods I did worked out ok, but most of the time they were kind of a let down. Mods that were supposed to totally "wake the bike up" often only had minor (and sometimes no) real effects. More common were negative side effects in reliability and noise.

    Now days, I've come to just accept and enjoy a bike for what it is and what it was designed to be rather than trying to transform it into something it wasn't designed to be. As part of that change in my mind, I've also come to really like low-cc, low-power bikes. The whole "more fun to ride a slow bike fast" really works for me. I find that 250cc is about right-- they will go on the highway and are fun on the streets. In both cases, you can't just twist the throttle, you gotta think, plan, shift and use proper rev ranges to get the desired speed. I find that I really like that.

    I'd like a dual sport that replicates the TU experience, and I'm thinking that the DR200 is likely to be just that. If there's a quick/easy mod that is well-known to have real effects on the DR (like re-jetting if they have excessive factory lean-ness), I would do it. But the consensus is pretty clear that there is no such mod for the TU, and many have tried. The result of much experimentation with TU modifications is basically "forget about modding it for performance gain, it's already optimal-- just ride it." That's exactly what I'm doing with my TU, am very happy with it, and would have to be convinced to do otherwise with a DR.

    I definitely appreciate that, and I'll have to say that anyone with experience like you have confirm for the TU what you say for the DR-- that these bikes are very tough and are spec'ed with cams and rev limiters that are far milder than the engine is designed to handle. This means that a stock engine can be rev'ed and accelerated as much and as hard as you want (and for as long as you want) and you won't come even close to "abusing" it or causing any damage.

    You could be right, but I think I'm very "vibration tolerant," so I have a feeling that I would be ok with it.

    Thanks for that clarification, Trailrider.


    Thanks to all of you for the discussion, it's been really helpful and I'm stocking DR's now on Facebook Marketplace.

    Did anyone happen to have any insights on my seat height question?
    Trailrider200 likes this.
  4. Mr. Fixit

    Mr. Fixit Reevaluating

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    Please explain that to my wife. Before I did the silly installation, the exhaust was eye-burning and throat-irritating. Now it's not. Catalytic converters were standard on cars long before fuel injection or even computer controlled carburetors were common. A large enough cat can work with surprisingly imperfect fuel mixtures.

    It does get hot (as it must to do it's job), but some pretty low-tech insulation and heat shielding seem to be working just fine. The plastic side panel shows no sign of melting or deteriorating.
  5. Trailrider200

    Trailrider200 Long timer

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    first off your carb was running very rich for how u describe what your wife said.

    first cat cars had computer controlled carburetors, cat wouldn't work without them to make and maintain the 14.7:1 fuel ratio which wastes much fuel.
    The model year 1975 brought the advent of the catalytic converter and the need to use unleaded gasoline, because leaded fuel would coat the catalytic material and render it ineffective. Catalytic converters will only work well when they're fed an engine-out air/fuel ratio of 14.7:1. Thus, the need to keep the mixture at that concentration for the majority of engine operating scenarios was recognized as being important.
    During that time, Detroit engineers were also replacing the breaker point distributor with an electronic system. The new design eliminated the wear that the points would normally experience over time, thereby preventing the increase in engine-out emissions that would have come with it.
    All four of the Detroit car companies responded with their own theories and designs for engine management systems that, at first, employed electronic carburetors but eventually morphed into various styles of electronic fuel injection.
    https://www.hemmings.com/stories/article/eec-ing-it-out
  6. Mr. Fixit

    Mr. Fixit Reevaluating

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    If you say so.

    But my first-hand experience was that catalytic converters came around some years before oxygen sensors and electronic fuel controls became ubiquitous, and could be made to work after a fashion, as long as the carb was jetted a bit leaner than in previous times and unleaded fuel was used exclusively. Remember that in that era, 14.7:1 was considered extremely lean, with 12 or 13:1 being the norm and the universal solution to hesitation and off-idle bog was to crank up the accelerator pump shot.
  7. Mr. Fixit

    Mr. Fixit Reevaluating

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    Also, an overly lean mixture also produces unburned hydrocarbons. I had many arguments back in the late '70s with mechanics who insisted that if you could smell the exhaust, the engine HAD to be running rich. Not so. Some of the worst smog was produced by lean mixtures, resulting in eye-burning oxides of nitrogen due to borderline lean misfires and extremely high combustion temperature/pressure conditions. That's why EGR was developed, to dilute and cool the combustion process.
  8. mj15

    mj15 Been here awhile

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    All that aside, a good running DR, according to my onboard wideband, runs best when jetted to show mid 13:1 range through the lower gears, and high 12's as you get into the upper ranges of 5th, while working against wind resistance. At an easy 50 mph cruise in 4th or 5th, I'd see high 13's-low 14's.
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  9. Mr. Fixit

    Mr. Fixit Reevaluating

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    That sounds about right. 14.7 with an old-school air cooled carbureted thumper strikes me as too lean for acceptable driveability.

    And regardless, with the big-ass catalyst from the Enfield 650, according to my butt dyno, my DR200 runs and sounds just about the same as with the factory exhaust (or maybe a bit deeper and mellower), but it doesn't leave a miasma of eye-burning throat-irritating smog in it's wake. Given that I have zero dollars in the conversion, I count it as a successful experiment.

    If the cat gets too hot and burns the bike to the ground, I'll try to post video. But I don't expect that to happen.
  10. Klay

    Klay dreaming adventurer Super Supporter

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    I would make some insulation out of collapsed beer cans to hang over the cat. This worked well with my DR350 which was bored out to 435cc.
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  11. Mr. Fixit

    Mr. Fixit Reevaluating

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    Pretty close. I cut a chunk of the chrome shell of the RE muffler just long enough to cover the cat, and stuffed the gap between it and the cat with the factory insulation. I also used aluminum foil tape and some rock wool house insulation on the inside of the plastic side panel. I've run the bike hard since then, and nothing has melted or caught on fire...or even gotten uncomfortably hot, so I'm counting it as a win for cheap-ass ADV experimentation. I suspect that if I extracted the cat from the RE muffler assembly and stuffed it into a free-flowing lightweight aftermarket muffler, I could rejet and gain as much as 1 horsepower while making the bike obnoxiously loud.
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  12. Klay

    Klay dreaming adventurer Super Supporter

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    That's why I don't try to find more horsepower with the DR200. If I need more power, I use a different bike. My DR200 is perfect for its mission.
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  13. mj15

    mj15 Been here awhile

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    Beer cans are an amazing resource, especially when full, but still very useful even when empty. A manifestation of pure creative of pure genius
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  14. Ductor411

    Ductor411 Adventurer

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    I asked my local engineer/ fabricator to make the same modification, but he is reluctant to do so without knowing from what grade of steel they are made. I would appreciate any information you may have on this point, as I would prefer a ‘cut and shut’ job, rather than his making a custom set from scratch.
  15. mj15

    mj15 Been here awhile

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    Can’t say. I just cut them, took out the section, and Mig’d them back together, using flux-core wire. 30 minute job.
    Not elegant, but they survived 600 miles off road, and the same amount on road, with a 200lb rider
  16. Ductor411

    Ductor411 Adventurer

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    Thanks very much: I’ll pass that information on.
  17. Mr. Fixit

    Mr. Fixit Reevaluating

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    It's an extremely safe bet that the brackets are plain old mild steel such as 1018. 6013 stick welding rod would do just fine, or ER70 for MIG or TIG. The DR200 is basically a cheap utilitarian farm bike made of common materials. That is one of the things that makes it great. It's kinda like the Toyota HiLux of motorcycles. After the zombie apocalypse, the giant mutated cockroaches will be riding DR200s and Yamaha XT225s and the like unless they have found a Mercedes 240D.
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  18. Ductor411

    Ductor411 Adventurer

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    Thanks for the information, which I have passed on to the engineer.
  19. Jodaddy

    Jodaddy Been here awhile

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    Could you bring the DR 435 to Montana so I can borrow it?
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  20. Maxem

    Maxem n00b

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    Hello! I'm a new memeber and hope this is how you make posts here...

    I recently aquired a 2016 dr200s and was doing the oil change on it today when I accidentaly drained the oil from the wrong drain bolt! (The one next to the main drain bolt) I have been trying to find out if it matters or not but can't seem to find the answer. I'm wondering if anyone on here might know if I'm good to just fill up and ride or did I drain out something else that needs to be filled now?