DR650 Stalling at idle and surging at WOT

[RandyC]

I am posting this because it may help someone who had the same problem I did with my DR650. I have a DR650 that I bought new in 2007 and it is completely stock except I had the dealer drill out the plugs on the underside of the carb and richen up the gas.

 

I never had a one problem with this motorcycle until I had to let it sit up for six months due to working out of state. When I got back the battery was dead and after I got the battery charged back up it did not run real good. I figured it was bad gas. I ran the gas out until I had to turn the petcock to reserve. When it was almost out of gas I filled it up and it seemed to run better. The only problem was that it started surging at WOT and it would die at idle at red lights. I turned up the idle and it did not die as much but it still died and it had the surging. I got on this site to see if someone had the same trouble I was having. I found people who had some of the problems but not my exact problem. What I did find out was that was that surging was probably caused by uneven gas flow and the stalling could be the same thing.

 

Here is what I did. I cleaned the inline filter. The filter was not dirty. While I was cleaning the filter I decided to check the flow of gas coming out of the gas tank. When I checked the flow I noticed that the petcock was still on reserve. I did not think it would have mattered. I checked the gas flow in the On position and no gas came out. I checked the gas flow on Prime and gas poured out. I checked the gas on Reserve and no gas come out.

 

I put the filter back in and decided to gave it a test run with the petcock in the Prime position because I knew that gas was flowing through that setting. No surging or stalling in Prime. I switched to On position and again no surging or stalling. I switched to Reserve and it surged and stalled. I switched back to On and it did not surge or stall.

 

Since 2007 when the motorcycle was new I have never used the reserve setting. The petcock must be plugged up in the reserve position. Since the carburetor uses vacuum to pull the gas into the engine this would explain why it was surging and stalling. It seems to me that if the Reserve was plugged up this would starve the engine and cause the surging and stalling. I will get a new Petcock the first chance I get. 

 

RandyC

[Kommando]

 You could also just clean the petcock. I'd try just running some SeaFoam or Techron through it for a bit. The filter screen for the Reserve pipe might be gummed up.

[TN2Wheeler]

I am posting this because it may help someone who had the same problem I did with my DR650. I have a DR650 that I bought new in 2007 and it is completely stock except I had the dealer drill out the plugs on the underside of the carb and richen up the gas.

I never had a one problem with this motorcycle until I had to let it sit up for six months due to working out of state. When I got back the battery was dead and after I got the battery charged back up it did not run real good. I figured it was bad gas. I ran the gas out until I had to turn the petcock to reserve. When it was almost out of gas I filled it up and it seemed to run better. The only problem was that it started surging at WOT and it would die at idle at red lights. I turned up the idle and it did not die as much but it still died and it had the surging. I got on this site to see if someone had the same trouble I was having. I found people who had some of the problems but not my exact problem. What I did find out was that was that surging was probably caused by uneven gas flow and the stalling could be the same thing.

Here is what I did. I cleaned the inline filter. The filter was not dirty. While I was cleaning the filter I decided to check the flow of gas coming out of the gas tank. When I checked the flow I noticed that the petcock was still on reserve. I did not think it would have mattered. I checked the gas flow in the On position and no gas came out. I checked the gas flow on Prime and gas poured out. I checked the gas on Reserve and no gas come out.

I put the filter back in and decided to gave it a test run with the petcock in the Prime position because I knew that gas was flowing through that setting. No surging or stalling in Prime. I switched to On position and again no surging or stalling. I switched to Reserve and it surged and stalled. I switched back to On and it did not surge or stall.

Since 2007 when the motorcycle was new I have never used the reserve setting. The petcock must be plugged up in the reserve position. Since the carburetor uses vacuum to pull the gas into the engine this would explain why it was surging and stalling. It seems to me that if the Reserve was plugged up this would starve the engine and cause the surging and stalling. I will get a new Petcock the first chance I get.

RandyC

I agree the petcock is probably clogged in the reserve position but for the record, the carburetor does not "use vacuum to pull gas into the engine" With the OE petcock manifold vacuum is used to simply open the petcock. Gravity pulls the gas into the float bowl.

Edited September 30, 2013 by TN2Wheeler

[Olmxer]

I have the same problem with the petcock on my 2008 DR650, except that, when I tested it by removing the gas line from the carb,, then removing the vacuum tube from the carb so I could suck a vacuum on the petcock mechanism in order to watch the gas flow, I realized that the reserve went on and off just fine, the prime was free-flowing at all times, but the on position did not flow under any circumstance.  I disassembled the petcock - it was in perfect (looking) shape, and with a small hose I could blow freely through all the orifices. Go figure?? I looked like, if the vacuum works on the reserve, it should work on the on position. But it doesn't. The problem occurred out of no where on the freeway, when the motor quit running like the key had been turned off. Any explanations?