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DR200SE takes too long to return to idle

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My wife's 1996 DR200SE takes several seconds to return to idle after closing the throttle. It seems that the higher the idle is set, the longer it takes to come back down to idle when the throttle is closed - i.e., if the idle is set so low that the bike is barely running, the revs will fall much faster once the throttle is closed. Hope I'm making some sense... The bike runs well otherwise and accelerates as well as a DR200 can be expected to. I've looked at the actual throttle cable and it doesn't seem to be binding anywhere, so my uneducated guess is that this may be a jetting issue :) . This condition seems to have developed just recently. Is it possible that the carb is just 'gummed up' since the bike only gets run about once a month?

Also, I noticed that the exhaust header pipe glows red-hot for a couple inches after leaving the cylinder head, even when moving along at 40 mph in cool weather. Is this normal for a small-displacement air cooled engine? Just thin-gauge steel used for the pipe?

The bike is like new with 3,800 miles, and no modifications that I'm aware of (bought it used about a year ago). Any suggestions (before I start taking things apart at random) would be greatly appreciated.

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If it gets red-hot during normal riding, it sounds like the wrong mixture.

You could get the same effect if the choke is left on.

Try the mixture screw, or pilot jet maybe ?

Otherwise there may be a leakage of air somewhere. Maybe the rubber between the carb and engine leaks ? In this case the engina may run to lean, which can lead to higher temperatures, and ultimately breakage..

You could try to spray some start gas around gaskets, and connections from carb to engine and see if the rev changes (if the gas leaks into the engine somewhere)..

/K

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Thank you for the reply, Klas. I'll inspect closely for cracks/air leaks this weekend, and if I find none, I'll start tinkering with the carb.

Anyone know where the mixture screw is on the Mikuni? I know I had to drill out a brass plug on each carb to get at the mixture screws on my SV650, but I don't see anything like that on this little carb. The only obvious screw is near the bottom of the float bowl, and that just seems to operate a drain.

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Insteresting problem. I just test drove a used dr200 at a local dealership today and I noticed the same slow to return to idle problem. It was about 30° out and I assumed the bike was just acting a little cold blooded. How do I check for a lean or rich condition? Same old method of what the plug looks like? Or is there a better way for this bike?

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Yup sounds lean, abnd its going to be worse in the cold.

Some people spray WD40 at the carb boot and see if the idle changes. The idea is the light oil will close up the leak for a while.

Does the bike pop when you back off the gas. If you run it with the choke on a little does the condition correct?

These dr's are sent from the factory borderline lean so a small leak will make a big difference.

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The fuel screw is on the bottom, front, middle, by the engine intake, a longer tube cover by a brass cap. Jessie at Kientech engineering has a fuel screw. Yes horribly lean from the factory. If you cut a hole in the top of the air box with a "door knob" hole saw (get the rubber velocity stack from Jessie at Kientech), go up one on the pilot and the main (you want a 37.5 pilot and 127.5 main) and adjust the fuel screw(after completely warm) by turning in until it hesiates or drops RPMs and come back until it is smooth you will be pleasantly suprised by hom much better the bike runs. If you open up the pipe you will probably have to shim the needle but my wife's bike runs great with this setup and she doesn't want anymore power. Oh and get the replacement allen bolts for the float bowl, again all from Jessie shipped for around $30 I think.

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what he said! This bike opens up dramatically once you make it breathe....I know :) I had a blast with mine for a year and a half!

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My wife's 1996 DR200SE takes several seconds to return to idle after closing the throttle. It seems that the higher the idle is set, the longer it takes to come back down to idle when the throttle is closed - i.e., if the idle is set so low that the bike is barely running, the revs will fall much faster once the throttle is closed. Hope I'm making some sense... The bike runs well otherwise and accelerates as well as a DR200 can be expected to. I've looked at the actual throttle cable and it doesn't seem to be binding anywhere, so my uneducated guess is that this may be a jetting issue :) . This condition seems to have developed just recently. Is it possible that the carb is just 'gummed up' since the bike only gets run about once a month?

Also, I noticed that the exhaust header pipe glows red-hot for a couple inches after leaving the cylinder head, even when moving along at 40 mph in cool weather. Is this normal for a small-displacement air cooled engine? Just thin-gauge steel used for the pipe?

The bike is like new with 3,800 miles, and no modifications that I'm aware of (bought it used about a year ago). Any suggestions (before I start taking things apart at random) would be greatly appreciated.

I'm just learning myself.

red pipes means overheating - could be mixture too lean

ask Jesse at http://www.kientech.com/index.htm he's into DRs

email at the bottom of that page.

like klas said - the choke may be sticking

I think slow returning throttle may be a rich mixture problem at idle and just above. Lean mixtures get better as temperature increases or as the bike's temperature increases because there's less air/oxygen particles in hot air so the leaness compensates for this. Just like there's more air particles in the air in the morning cool.(air is denser). Heard the saying - warm air rises - because cold air has more oxygen in it and oxygen wants to stay closer to the Earth/ground. That's why there's less air up in space.

Maybe the problem is up around half throttle where it might be a tad too rich and it takes a while too be burnt off before it goes back to idle.

The thoery would be as soon as you get off the throttle -at idle- the only fuel getting to the engine is through the pilot jet which up to 50% of that fuel is metered by the pilot fuel screw(mixture screw)at idle. At low throttle cruise up to 25% of the pilot jet's fuel is metered by the fuel screw. It depends on how far out the screw is turned. Wether richness or leaness makes the engine prolong it's reving or fuel burning - I don't know.

There's also the choke system and the starting system ( aswell as the main system - main jet ......and the slow system - pilot jet ...........)

I want a dr200 now....Noel

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A glowing head pipe shows a lean mixture. Most factory set DR's are lean but to make it glow? You said you checked the cable to see if its letting the throttle close and is not sticking. OKif thats not it ckeck for a vacuum leak with carb spray around the gaskets to see if there is a crack while the engine is idling. If a cracked gasket is sucking air,the idle will change when it is sprayed. If all checks out, try backing off on the idle mixture screw 1 turn to richen it up. Then reset the idle speed and I am 99% positive this cure your wandering idle problem. This is the first mod performed in all stages of aftermarket carb kits. Its basic and even some outboard motors can benifit by it. Engines don't like to be lean. Good luck.

Mike.

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