DR 650 Stumbles, Bogs, Cuts Out...Help!

I hate to write a novel here but I am at my whits end and I don't have a mechanic withing 40 miles or so. I'm going to give all the information I can think of in hopes of someone having a viable suggestion for solving my problem...

Help. I have an 04 DR650 with a stumble, Bog, cutout problem. (Clark tank, SuperTrapp IDS2, Air Box Cover was removed, have since relaced the cover and cutout the top as per Pro Cycle instructions. The problems started this winter when I decided to solve a high speed full throttle bog/stumble that appeared last fall. I was in the process of routine maintinence (new break pads, valve adjustment, new chain & sprockets) and I bought a carb kit from Pro Cycle (o-rings, etc.) and took the carb appart to clean it.

I cleaned the carb with gumout and compressed air, made sure of the float bowl spec., and reinstalled it with new o-rings, etc. The problem with the bog still persisted and actually became a stumble and moved into the midrange. I found the inline filter where it sits in the carb intake pipe and cleaned it (VERY dirty). I thought that was it...NOT!

Since I bought the bike with 1K on it and the 1st owner had installed a jet kit (it appeared to be a DJ) I was at a loss. I bought new Mikuni jets and installed a 155 replacing the 170 that was in the carb. Checked the needle

valve...e-clip in 4th slot no spacer with 1 washer on top of e-clip. Everything was to spec. In the interm I thought I'd clean my K&N filter. Someone told me that it was cool to clean it with dishwashing detergent and oil it with 10W40. So I did. Then I read in a forum that this was NOT a good thing. So I bought the K&N recharge kit. (Only $11 so what was I thinking in the first place?). I recleaned the filter and reoiled it with the proper oil. I added this because someone said that his K&N was causing this same problem until he removed his and it ran great...I removed mine and it changed nothing.

Now when I (try to) ride it and shift slowly and at low rpm's the bike runs well. But if I jump on it at all there is a significat stumble from first to second gear. If I hit it hard at all in third it will stumble hard, come back on, stumble again, etc. I was just crusing intown at 30-35 with a constant throttle and it stumbled and kept it up. No motion of my throttle either up or down gave a response. Then it completely cutout locking my rear wheel and probably giving the driver behind me an anxious moment.

As an added piece to the puzzle. I was installing LED lights to enhance the brighness of the mini-dash. They are wedge base type bulbs and they an be put in backwards and henceforth not have the proper polarity. When I put in the signal light bulb it shorted something and blew the fuse. I replaced the 15amp fuse but on of the signal lights (right or left) although works does not show as blinking on the mini dash. Can this cause an electrical problem that would cause what's happening to my bike? (If I knew I wouldn't be writing this novel in a desparate cry for HELP!)

What kind of breather does your tank have? Maybe it's clogged and creating a vacuum.

The first thing I would check is the bypass ports. There are two at the bottom of the carb throat. One is blocked by the throttle plate when closed and the other is not. One of the o-ringed tubes for the float cage sits on top of these two little ports. Make sure they are clean and clear of obstruction. Then check and set your float adjustment.

The dirt in the carb thing has been addressed. I think, on 4 different occasions in the last 3 days. The last time I cleaned it I went to a friends auto repair garage and blew out all the orifices with an air gun that had a rubber tip so it sealed really well.

After sleeping on this problem it almost seems to be electrical. Back in the 70's when my car acted like this it turned out to be the voltage regulator. Hmmmm. And I did have that shortout when replacing a bulb. I'll check.

Oh, and every time the carb has been appart I have checked the float level with a caliper gage.

Thanks for everyone's help. The carb turned out fine. The voltage regulator was the problem.

Hey, thanks for the follow-up. Without it, no one would know where to look next.

Yes, thanks for posting on finding the problem. That could save a lot of time (I think) for myself and others in diagnosing a "symptom". How did you narrow it down to the voltage regulator? An 04 seems to be a fairly newer bike. Anyway, glad you got it figured out and hopefully it's running as it should.:thumbsup:


I'm only 90% about the rectifier. I did an ohm test across the terminals and it reads a consistant 11-12 ohms when it specs out at 1-10 ohms. It still charges at the battery terminals and the + to - ohm resistance is within spec being 10 where the spec is 1-20. I guess I am hoping that it is the problem. It definitely seems to be electric in nature and acts like on of my old 60's-70's cars did with a bad rectifier.

Before I tested the rectifier it would accelerate in fairly hard in first, second and third but would cutout, surge and backfire (loud) when I hit forth. Also, when crusing along a city street at 30 mph or so it started to flutter and then completely cutout and locked up the rear wheel. Sometimes I can catch it by pulling the clutch and pumping (twisting) the throttle.

I have enlisted the help of a certified machanic so I'll keep updating this thread if things change.

I would check into fuel delivery as well. Check to make sure the tank is venting properly and make sure the petcock is not gummed up. Have you tried running the bike with the petcock int the prime and reserve positions? Also open the tank and ride the bike. If the problem persists, it is not the tank vent.

I have a Clarke tank on the bike that uses a vent hose. The vent hose is free of obstruction. I have run the bike in both the prime and run positions with no difference in the problem. I have not checked the petcock for varnish and/or gum but I did install a clear gas hose and the fuel appears to flow in a normal matter. Yesterday I took off the float bowl (for the 11th time) and checked to see if the float was in any was sticking. It appeared to move normally with no hitches or binds. I have finally left the bike at a mechanics' house. (He was the head mechanic for the local MC shop that is no longer in business). He's going to look at the bke soon. I drove by his house when the bike "acted up" and he heard the bike backfire and studder. He feels that it's an electrical issue...intermittent spark from a bad ground or something similar. (I am almost useless tracing wires). I'll definitely post the outcome.

I had a similar problem caused by my IMS tank cap. I filled the tank with fuel to the brim and the cap sucked fuel into the carb through the vaccum hose. It would barely start, ran like crap and backfired a lot.

Eventually, things improved as the fuel cleared out and it ran like it should.

It could be the regulater because they are classic symtoms of a undercharging system. If it is it should act the same in ever gear. Check the battery voltage then start it up. It should be 12.5 to 13 volts. Then rev it up and the volts should climb to around 13.5-14. If it's over 14 when at about 3,000 rpm's or under around 13 it's the regulater. I've had a lot of regulaters go on older suzukis. Every Gs model I had whent bad and if it's not cought in time it they burn out the stater. If your volt are good there's no need to check ohms or the voltage at the legs of the stater.

I was partially right. It turned out to be an electrical problem. After replacing the main jet with a 145, a 150, a 155 and a 160 mikuni jet. After raising and lowering the e-clip on every position for every different jet. After cleaning the carb four times and soaking it twice. After checking and rechecking the valves. After using a multimeter on every electrical component I could think of I was about to loose my mind. It still stumbled and backfired...HARD. It even cutout completely while coasting downhill on a back road.

I had the bike up on a lift in my driveway, looking at it and wondering what could be causing this problem...when my eyes drifted to my kickstand. It was barely closing the cutoff switch. So I bent the tang on the stand to close the switch. Cleaned and greased all the components and went for a ride......IT WORKED!!!!!!!!! No cutout, no backfire just a smooth running DR with the cleanest carb in the State of New York. BTW...The carb is now jetted with a 170 DJ jet (inbetween a 157.5 and a 160 mikuni jet size) with the e-clip in the third position from the bottom. The Fuel screw is out + or - 2.5 turns. I could care less about mileage. It's better than my V8 Jeep and it will raise the front wheel about a foot just by quick shifting into second. Happy, Happy....Happy!

Doh! Sometimes its the simplest cause that gets overlooked. At least its fixed now, and good job figuring it out! Maybe your post will help someone else in the future.

I disabled my kickstand and clutch switches like a lot of other DR owners. A lot of people just assume that these have been bypassed. That might be the reason why nobody mentioned it earlier.

You may want to consider disabling these swithes. I think most people are fine without them, but some people like having the kickstand switch functional for safety reasons. The clutch switch is easy, just plug the leads to each other. The kickstand switch can be: a) closed permanently by various mechanical means, :smirk: wires cut and connected, or c) you can bypass the relay. I chose the last option. Relays are generally reliable, but they can still fail.

Happy, Happy....Happy

Excellent well done and you know the carbie inside out.

This is the reason behind posting issues that come up AND the resolution.  After reading through this thread, I checked and adjusted my side stand contact tab and my high rpm stumble is now gone!


Thanks and hope this thread helps someone else as well.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now