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B1akebm

Engine bogs past 1/4 throttle - 1993 DR650SE

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Posted (edited)

I just picked up this bike yesterday. She’s in really good shape for her age. I rode it basically all day yesterday with no problems. Later last night I was cruising around and I suddenly lost power when I was getting on the highway. It seemed like the engine was getting starved of fuel. The bike would idle just fine, but anything past 1/2 throttle just bogs the engine down and it backfires really bad. I was able to limp it home at 30mph. I pulled the carb, removed the jets, and shot carb cleaner through them. The inside of the carb looked really clean, but I thought this would fix it. Any ideas? I’m thinking electrical, but I’d better give the carb a better clean first. It seems odd that it would run fine all day then suddenly have this happen.

Edited by B1akebm

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Just cleaned the carb again. This time I soaked it. Bike starts up and idles perfectly, but does the same thing when I give it throttle.

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I solved the problem in a weird way. The air filter that came on the bike was falling apart. I grabbed a similar UNI filter and threw it on. Bogging is gone. This leads me to believe that it’s jetted a little lean. The only way I can get it to not spitter/bog is to run with an oiled filter.

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Yep, just added that the filter was oiled to reduce any confusion.

I’m going to try a Dyno jet kit and see if I can get anywhere with that.

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On 4/24/2020 at 9:54 AM, B1akebm said:

Yep, just added that the filter was oiled to reduce any confusion.

I’m going to try a Dyno jet kit and see if I can get anywhere with that.

Is your airbox cut open, or stock ?

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On 4/24/2020 at 9:54 AM, B1akebm said:

Yep, just added that the filter was oiled to reduce any confusion.

I’m going to try a Dyno jet kit and see if I can get anywhere with that.

Get a JD (James Dean) kit if you can. I think they're better, DynoJet instructions are not the greatest. 

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I actually already installed the DynoJet kit. Haven’t run the bike yet. Went with the 155 main jet

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14 minutes ago, B1akebm said:

I actually already installed the DynoJet kit. Haven’t run the bike yet. Went with the 155 main jet

From my past experiences with DynoJet, they're spot-on with the needle setting. Buy way off on the main jet.

I'd start with the stock Mikuni main jet. Did the instructions say clip#4 for the needle ?

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15 minutes ago, B1akebm said:

Yep, clip #4. I think stock jet was a 138

Ok, and did the instructions say to 'omit' the plastic spacer? I filed a flat spot on mine & re-installed it on the needle.

I did the DynoJet kit too, but mine's a 2020. Not sure how different they are. Hope it works out for you.👍

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Posted (edited)

Bike is running again. Had to wait on some gaskets which took forever. Anyway she runs great at mid-full throttle but the idle is super erratic. There’s also a dead spot right when you open the throttle, then it kinda lurches and has tons of power. When I go to adjust the air/fuel screw, as I turn it in the idle seems to go up, not down. Started at 2 turns out, doesn’t seem like there’s any good setting for it. I should also mention that when I let off the throttle, the revs hang for a bit then it settles back down to idle in about 2 seconds.

Edited by B1akebm

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Turning fuel screw In = leaner. Try 3 turns out? Clogged pilot jet? If all that checks out, might try 1 size up on pilot jet.

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Posted (edited)

you said you think its electrical at the beginning but no idea if you ever checked ignition wise. Would check the CDI

Edited by turboguzzi

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3 turns out on the screw gives the same results. Would the rev hang and erratic idle be caused by a lean pilot setting?

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Posted (edited)
21 hours ago, B1akebm said:

3 turns out on the screw gives the same results. Would the rev hang and erratic idle be caused by a lean pilot setting?

Yes, try +1 size pilot.

Edited by Diverdown

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