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Old 08-12-2013, 06:15 PM   #7246
Norm12
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Backfiring into the intake is most commonly because of a lean air-fuel mixture which creates a slow burn in the combustion chamber. In this condition, there is still burning mixture in the combustion chamber when the intake valve opens subsequently and this ignites the air-fuel mixture in the intake passage and carburetor. The resulting increase in temperature/volume expels burning air-fuel from the carb throat and can ignite the air filter in rare cases. Of course a cold engine exascerbates this effect.

Rejetting to reduce the lean mix and not attempting to operate without consideration to enrichener (choke) and throttle avoids this effect.

I haven't bothered to check to see if the reduced restriction improves operation so will simply leave it out as my curiousity is at a low eb.

Norm


Quote:
Originally Posted by Trailrider200 View Post
a fire can only happen it the engine backfires thru the carb, which really can't happen with an electronic ignition, but with a points ignition plus yrs ago with the points ignition the screens where never such a tight mesh as they are today.
epa noise requirements deal also with the intake which really can be louder than the exhaust.
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Old 08-12-2013, 06:24 PM   #7247
Norm12
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Rejet to correct air-fuel mixture, bench mark by running under a repeatable condition, then remove the lid and duplicate. Mine made 7 mph higher speed on the highway with lid off. The noise is daunting so, rather than drilling the lid, I installed spacers to hold the back end of the lid up about an inch to increase intake area. The sound is acceptable but that is an individual assessment, of course.

It is clear that the stock airbox inlet holes are not able to flow sufficient air to match the intake and stock exhaust.

I always admire people who can simply take a bike as it is and just ride it. The improvement bug is always at me such that I think I enjoy improving more than riding and that's either sad or crazy.

HIH

Norm


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Originally Posted by Trailrider200 View Post
the oem holes in the airbox provide more than enough area for airflow to the carb. they have more area than the carb throat.
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Old 08-12-2013, 06:59 PM   #7248
Dual Badger
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carb ?

Hello,
Looking to buy a dr 200 for my girl, it is a 2003 with 1,200 miles.
great shape, but will not idle with the choke push in after warmup just dies.
it has been sitting for awhile any answers? idle screw tighten does not help.
Thank You!
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Old 08-12-2013, 08:08 PM   #7249
Klay
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Quote:
Originally Posted by Dual Badger View Post
Hello,
Looking to buy a dr 200 for my girl, it is a 2003 with 1,200 miles.
great shape, but will not idle with the choke push in after warmup just dies.
it has been sitting for awhile any answers? idle screw tighten does not help.
Thank You!
It's very likely the carb needs a thorough cleaning. Very common problem with the sitting DR200.

I think if you want to richen up the idle, you turn the idle screw out, not in, if I remember correctly.

It's a simple carb, just turn it on its side and take all the jets out and thoroughly clean them.
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Old 08-12-2013, 08:42 PM   #7250
794613
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Quote:
Originally Posted by Andyinhilo View Post
Check the rear brake torque link bolt where it attaches to the brake plate. There is a shoulder that needs to be in both the link and the plate before the nut is on and tightened.
Andyinhilo,

Thank you, you were correct. I could have sworn I tightened it down, but the only thing holding it on was the cotter pin. Sure stops really well now.
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Old 08-12-2013, 09:41 PM   #7251
Dual Badger
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Carb

Quote:
Originally Posted by Klay View Post
It's very likely the carb needs a thorough cleaning. Very common problem with the sitting DR200.

I think if you want to richen up the idle, you turn the idle screw out, not in, if I remember correctly.

It's a simple carb, just turn it on its side and take all the jets out and thoroughly clean them.
thank You !
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Old 08-12-2013, 10:05 PM   #7252
Klay
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thank You !

And clean them again and again. The jets are really small on the DR200 and they can be fussy.
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Old 08-12-2013, 10:06 PM   #7253
Norm12
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If the engine does run and only idling is the complaint, then cleaning the idle circuit seems the obvious but you may find that adjusting the idle mixture screw out may allow a decent idle. If you are not comfortable with removing & cleaning the idle pilot jet, idle mixture screw & idle passages, an adjustment and living with the condition while giving the fuel system a does of Sea Foam may solve the problem if it is gummed up as Klay references as most likely.

Before taking any action, including attempted idle mixture adjustment, try draining the float bowl by means of the drain screw. You may drain dirt, water and nesting water fowl which are creating the symptoms.

Sea Foam can be very effective in removing lacquers, gums and varnish deposits from old fuel. One can either treat the fuel in the tank according to the recommended percentage or drain the carb and fill the carb by means of a small funnel fitted into the fuel hose.

Let it stew over night, drain the bowl and give it a try with fresh fuel. There have been a number of credible reports of fouled spark plugs due to over concentrations of Sea Foam so one should not lose one's perspective in adding. Using it as a cleaner, however, and then draining is often effective.

Cleaning a carb without resort to high pressure shop air is often less satisfactory.

It will be likely that you cannot adjust the idle mixture by virtue of the fact that the idle mixture screw is located in the bottom of a plugged well. The brass plug blocking the well can usually be drilled and then a small tap used to thread the hole and then, bottoming, push out the plug.

Klay's recollection that the idle mixture screw is turned out in order to enrichen the mixture. If you need to turn out more than 2-1/2 turns it is likely that the idle pilot jet is restricted or too small.

Good luck with the carb clean. As Klay referenced, these are a very simple and reliable carb so likley just a cleaning will get things right (as they say in Oz).
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Old 08-12-2013, 10:09 PM   #7254
Klay
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Look out for Seafoam...it can dissolve varnish inside the gas tank and send it down to clog the jets in the carb. I've used it, but just be careful with it.
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Old 08-12-2013, 10:44 PM   #7255
Norm12
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Any fuel system additive can have this effect and Klay was kind to offer the caution. Of course, if one has goo deposits in the tank, one is well advised to remove them rather than to allow them the opportunity to choose the time. A flash light inspection of one's tank from time to time is always well advised, and this is particularly so for a newly acquired ride.

Funny that I do this as a matter of routine but never seem to think to suggest...

HIH

Norm


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Originally Posted by Klay View Post
Look out for Seafoam...it can dissolve varnish inside the gas tank and send it down to clog the jets in the carb. I've used it, but just be careful with it.
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Old 08-12-2013, 10:52 PM   #7256
Dual Badger
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Carb

Where is the idle mixture screw?
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Old 08-12-2013, 10:57 PM   #7257
Klay
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Originally Posted by Dual Badger View Post
Where is the idle mixture screw?
It's behind a brass plug between the carb and the intake manifold. You don't have to take the float bowl off to see it, if I remember.
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Old 08-12-2013, 11:29 PM   #7258
Norm12
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It is in a tubular extension which protrudes downward from the carburetor, just ahead of the float bowl and just behind the rubber connector leading to the cylinder head. The bore in the tubular extension is plugged by a brass plug of about 5 or 6 mm.

Easiest way to study it is to loosen the two hose clamps which secure the rubber connectors (cylinder head and air box), then rotate the carb's bottom to the right side. Take care not to over do this and damage the throttle cable, but no problem in rotating far enough to access the plug for drilling. The removal has been described here and in the manual. A definite "must do" IMO. A carb adjustment tool or nimble fingers are desireable for making adjustments. In a pinch, turn the idle mixture screw out one full turn more and try that.

HIH

Norm


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Originally Posted by Klay View Post
It's behind a brass plug between the carb and the intake manifold. You don't have to take the float bowl off to see it, if I remember.
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Old 08-12-2013, 11:41 PM   #7259
Dual Badger
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carb

Thank You for the advice !!!
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Old 08-12-2013, 11:57 PM   #7260
suseuser
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Quote:
Originally Posted by Norm12 View Post
It is in a tubular extension which protrudes downward from the carburetor, just ahead of the float bowl and just behind the rubber connector leading to the cylinder head. The bore in the tubular extension is plugged by a brass plug of about 5 or 6 mm.

Easiest way to study it is to loosen the two hose clamps which secure the rubber connectors (cylinder head and air box), then rotate the carb's bottom to the right side. Take care not to over do this and damage the throttle cable, but no problem in rotating far enough to access the plug for drilling. The removal has been described here and in the manual. A definite "must do" IMO. A carb adjustment tool or nimble fingers are desireable for making adjustments. In a pinch, turn the idle mixture screw out one full turn more and try that.

HIH

Norm
What is the standard adjustment on the mixture screw? I mean how many turns out after seating the screw?
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