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Flat spot off idle and stalls.

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Hello, I am experiencing a flat spot in the throttle right off of idle. If i'm sitting at idle and accelerate normal it will sometimes stall. Some times I will have to feather the throttle to keep it going, once i'm moving it is fine, only happens off idle. It will also stall at times when comming to a stop. 97 Dr 650, just installed Dyna jet kit and gsxr muffler. Any help would be appreciated.

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+1 If you have your pilot screw set to where DJ recommends... you are way too rich at idle. Unatomized fuel is building up in your intake tract... when you open the throttle all this fuel is picked up and you get an instant choked rich amount of fuel. A more normal pilot screw setting for the DR650 is around 1-1/4 turns out from lightly seated give or take a 1/4 tun.

Pilot circuit adjustment procedure

Edited by mx_rob

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Thanks for the info guys, I'll do that today and post up the results.

FYI, I'm using the 160 jet and set the needle as described in the directions. I filed down one side of the plastic shim as jesse described so the clip is nice and flat. If I recall the directions say to place clip on 3rd slot which is what I did. I followed jesses directions exactly.

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turn your pilot screw in and see what happens.

i have a modified bst but not DJ.

i had that somewhat and now i'm at 1 turn out (@ 7K elevation) when i had 2 before.

no bogging.

clean your carb.

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I used to have the same problem with my DR before it died, and that was the issue, too rich fuel setting.

Used to be real embarrassing too, I'd be waiting at a light for a while, and right when I started to accelerate, it would die, making me look like I stalled it. People would laugh and point their fingers

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Thanks for the info guys, I'll do that today and post up the results.

FYI, I'm using the 160 jet and set the needle as described in the directions. I filed down one side of the plastic shim as jesse described so the clip is nice and flat. If I recall the directions say to place clip on 3rd slot which is what I did. I followed jesses directions exactly.

The normal position for the DJ kit needle is in the 4th position down from the top of the needle. (3rd is OK for higher elevation or if you don't mind a bit less throttle response) If the filed flat spacer is on top of the needle clip you are good. (as the clip is supposed to be at the bottom of the slide height wise) If you have the spacer under the clip you are too rich in the needle setting by the thickness of the spacer. Either move the spacer to the top of the clip or move the clip to a position on the needle that would make up for the thickness of the spacer. The second clip position down would be about right.

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It still stalls at 1 1/4 turns. Is 2 turns too much?

I am on the 4th groove. And I did put the spacer under the clip. The bottom of the slide has notch or flat on the side. Per jesse's instructions you are to file one side of the spacer flat so it drop down level with the flat spot or notch on the inside of the slide so the clip is not just resting on one side.

I will try the 2 turns as soon as I can and post up results.

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If the filed flat spacer is on top of the needle clip you are good.
And I did put the spacer under the clip. .

There's the problem

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+1 Yeah, I know Jesse talked to DJ about this issue and is convinced the spacer goes under the clip with the clip in the 4th position down but I think he talked to an "isle manager" instead of someone with any actual tuning experience on the DR650. Your machine is far too rich set up the way you have it. Since you've already filed the white plastic spacer flat to fit next to the D-shelf in the slide I'd either remove the spacer from the needle and place it on top of the clip or leave the spacer below the clip and move the clip up the appropriate number of clip positions to make up for the thickness of the spacer. I think it's position 2.. may even require a shim to get the exact measurement. The bottom line is the needle height is supposed to be that measurement that equals the clip being in the 4th clip position, counting down from the top, with the clip sitting flat at the very bottom of the slide... how you get to that measurement is up to you but it is where you need to be.

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I have a couple of questions.

1. Is the problem temperature sensitive. better or worst hot or cold?

2. Remove the airfilter. Did it get better or worst?

3. Does the choke/enrichener make it better or worst?

My 2008 DR has the airbox snorkel removed, dj neddle 3rd clip from top no spacer, dj155main and a stock pilot. Idle mixture screw at 1-1/2. Air filter lubed to spec. I'm as close to lean as I can get without any surging or hesitation.

Lean the carb out one circuit at a time till you find a problem. Then richen it up. The lean point is easy to find. Best performance is one or two steps to the rich side of lean. BUT the main jet setting can be lean enough to cause engine damage. Don't go leaner than stock.

One last thought don't remove the side cover from the airbox and go for a ride. Your nuts will fall off.

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+1 Yeah, I know Jesse talked to DJ about this issue and is convinced the spacer goes under the clip with the clip in the 4th position down but I think he talked to an "isle manager" instead of someone with any actual tuning experience on the DR650. Your machine is far too rich set up the way you have it. Since you've already filed the white plastic spacer flat to fit next to the D-shelf in the slide I'd either remove the spacer from the needle and place it on top of the clip or leave the spacer below the clip and move the clip up the appropriate number of clip positions to make up for the thickness of the spacer. I think it's position 2.. may even require a shim to get the exact measurement. The bottom line is the needle height is supposed to be that measurement that equals the clip being in the 4th clip position, counting down from the top, with the clip sitting flat at the very bottom of the slide... how you get to that measurement is up to you but it is where you need to be.

That's great info, thank you very much Rob.

Just to clarify. If I take the spacer out from under the C clip will the needle drop all the way down? Jesse said the needle would be sitting on the D shelf and could cause the needle to "cock" a little. He also said you may be able to rotate the needle a little so the open side of the C clip is facing the D shelf and it would drop down but he was concerned the clip could come off. Your input is always appriciated. I am going to move the spacer to the top of the clip and see how that does, when I do that should I move the fuel screw back in a little?

Thanks again.

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That's great info, thank you very much Rob.

Just to clarify. If I take the spacer out from under the C clip will the needle drop all the way down? Jesse said the needle would be sitting on the D shelf and could cause the needle to "cock" a little. He also said you may be able to rotate the needle a little so the open side of the C clip is facing the D shelf and it would drop down but he was concerned the clip could come off. Your input is always appriciated. I am going to move the spacer to the top of the clip and see how that does, when I do that should I move the fuel screw back in a little?

Thanks again.

No problems with the clip coming off with the open end facing the D-shelf. Never seen anything like that posted. I never had any problems using that method. You do need to do that if you are going to allow the clip to sit on the bottom of the slide though. Jesse is right, even if the needle does not cock it is binding against the side of the hole in the bottom of the slide. The needle needs to be able to self center in the needle jet.

The other option is to move the clip up leaving the filed spacer under the clip. Just make sure the needle height measurement is equal between the two methods. 3mm stainless washers available at you local hardware store are generally 1/2mm thick. :smashpc:

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No problems with the clip coming off with the open end facing the D-shelf. Never seen anything like that posted. I never had any problems using that method. You do need to do that if you are going to allow the clip to sit on the bottom of the slide though. Jesse is right, even if the needle does not cock it is binding against the side of the hole in the bottom of the slide. The needle needs to be able to self center in the needle jet.

The other option is to move the clip up leaving the filed spacer under the clip. Just make sure the needle height measurement is equal between the two methods. 3mm stainless washers available at you local hardware store are generally 1/2mm thick. :smashpc:

Thanks once again for the great info. I will be away untill Monday and will not be able to work on the bike untill then. I'll post up results as soon as i get back and get it done.

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Tonight I took the carb apart, removed the plastic shim completley. The clip is in the 4th slot down with the washer on top. Needle drops all the way down when the open part of the clip is facing the flat shelf in the bottom of the slide. Adjusted the fuel screw 3/4 out. I'll give it a good run in the morning and see what happens.

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Tonight I took the carb apart, removed the plastic shim completley. The clip is in the 4th slot down with the washer on top. Needle drops all the way down when the open part of the clip is facing the flat shelf in the bottom of the slide. Adjusted the fuel screw 3/4 out. I'll give it a good run in the morning and see what happens.

3/4 of a turn out on the pilot screw is going to be pretty lean.... If you set it at 1-1/4 turns out you'll be way closer to the correct pilot circuit adjustment.

👍

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It's been a while since I updated this thread. Today I reset the clip to the 4th slot down, 1 1/4 out on the air screw per Rob's recommendation. So far it seems better but I got a flat and could not ride. The only thing I did notice was a little bit of popping on decel, how much popping is normal.

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With a properly adjusted pilot circuit you will get audible decel popping with a performance exhaust system. Decel popping is a normal lean condition that occurs from high vacuum under closed throttle decel. You can over-richen the pilot circuit to help minimize decel popping but it will lead to off idle rich stumbling if you go too far.

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With a properly adjusted pilot circuit you will get audible decel popping with a performance exhaust system. Decel popping is a normal lean condition that occurs from high vacuum under closed throttle decel. You can over-richen the pilot circuit to help minimize decel popping but it will lead to off idle rich stumbling if you go too far.

Thanks Rob. That makes total sense. After I moved the clip I had the fuel screw at 3/4 out and had a loud back fire (not a pop) after I went to 1 1/4 I only get the popping. Very happy with the jet kit mod.

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Riderskate and mx_rob thank you for the discussion. I had the same problems. I couldn't make sense out of the spacer deal. I couldn't see how the filed spacer would make a difference if it fit next to the "D" shelf. It didn't seem that the "e" circlip would fit next to the "D" shelf. Now I know better.

Additionally, I hope that this helps someone, I had tuning issues when I didn't realize that I lost the little "o" ring and washer when replacing the stock with the extended air screw.

Thanks again fellas.

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