Stuttering/misfiring problems after oil change

Bike is an 06 SM, with buncha mods, 440 big bore, FCR 41 mm, full Yoshi exhaust, cams, some others. Relatively new to me (~1,000 miles, 22,000 on the bike) so this was my first oil change.

 

Went riding on Saturday. No problems. Went home and dumped the oil, opened up all the drains (including the frame filter, cleaned that), put in new oil. Bike started right up, like usual (never has much trouble starting), let it warm up, then off for 3 minutes and check the oil per the manual. Oil level was fine.

 

Go out next day to go for a ride. Leave house, go onto main street, gave it some gas, and it just starts sputtering and popping and lurching like it's starving for fuel. WTF? I did nothing that would even remotely cause this! It idles just fine, even goes just fine at partial throttle, but anything past partial throttle and it sputters and lurches.

 

My first thought would be the main jet getting clogged, since it idles just fine but doesn't like partial throttle. But it was literally a before/after event - bike ran fine, changed oil, bike runs like shit. Oil change related, or strange coincidence, something else messed up at just the right time?

Oh yeah, the spark plug looks perfectly fine, no fowling, no carbon, no oil, no crusty build up, perfectly gapped etc. ngk cr9e (i think, oem is an 8 and this is a 9). i wouldn't think throttle position would have anything to do with ignition.

Change the spark plug this morning (knew it wasn't this, but it was cheap and easy), and replaced the carb vacuum line since the old one was looking pretty dry rotted. The spark plug wire felt a little loose, but that seems to be fairly common on this bike. Bike fired right up, idled fine, took it around the block and at first everything was going well, was able to give it some gas. But after a few minutes, things got worse and anything over idle or partial throttle would intermittently result in missing and stumbling.

 

Short of just randomly pulling things like the carb completely apart, I have no idea where to even start.

 

Is it possible that the oil is causing these problems? I've never felt clutch slippage like this before.

Edited by joey stalin

What kind of oil did you use?

I'm thinking that the main jet has loosened up and lying in the bottom of the float bowl.Have you removed the bowl drain plug to see?

I'm thinking that the main jet has loosened up and lying in the bottom of the float bowl.Have you removed the bowl drain plug to see?

 

Interesting...I'll take that into consideration, but getting the carb out looks like a pain in the ass!

 

What kind of oil did you use?

 

Well, honestly at first I used a mish-mash of oils I left around the house, and no filter change. All good oil, all non-energy conserving. Then I bought the right filter and used the Rotella T non-synth 15-40.

Why remove the carburetor??On a FCR you just unscrew the float bowl drain plug.I think it's 17mm.It's that easy.After you drain the bowl first,of course.

Edited by bumtarder

Why remove the carburetor??On a FCR you just unscrew the float bowl drain plug.I think it's 17mm.It's that easy.After you drain the bowl first,of course.

 

I've never worked on this bike before, and the carb is already out! Didn't see anything that is a 17mm wrench on the carb, though...Either event, there is no jet floating around in there. Everything looks fine on first passage. The accelerator jet definitely works, I was thinking that may have been the problem. My plan now is to simply clean it and put it back in.

So for good measure, I drained the fuel tank, and removed and fully cleaned the carb. It wasn't even dirty, but I did it anyway. Reinstalled, and same problem appeared after a few minutes.

 

DEFINITELY engine temp related. I turned it on (fired right up), idled for a minute, then went for a ride in the neighborhood. For the first few minutes, I could go full throttle. Then the hesitations started, and got worse. Now it will do it under zero load, just reving the engine. I noticed that it seems to be worse at higher RPM's.

 

I'm guessing it has something to do with either the CDI unit, or the stator somehow. Any suggestions?

Thoughts:

Vacuum line to petcock should use clamps at each end (snug zip-ties work for me) or the potential for a vac leak is quite real, resulting in poor fuel flow, as it was for me.

The pick-up coil on the stator could also cause similar symptoms.

Edited by shuswap1

Thoughts:

Vacuum line to petcock should use clamps at each end (snug zip-ties work for me) or the potential for a vac leak is quite real, resulting in poor fuel flow, as it was for me.

The pick-up coil on the stator could also cause similar symptoms.

 

Vacuum line is brand new and very tight.

 

Are stator/pickup problems common on this bike?

Vacuum line is brand new and very tight.

 

Are stator/pickup problems common on this bike?

 

stator flame out is pretty standard, 22000k, can't complain.

Mine didn't make it that far.

About a week ago I had a similar situation....riding on road ....started to hesitate and missfire on acceleration.... switched to reserve ...no change...it would clear up for a while and then start acting up again.

I pulled the plug on the bottom of the bowl...checked for dirt or debre..could npt see any.

Gave it a little blast of carb cleaner and then air (with carb on) just in case.

Has not had so much as a hick up since...so definitely something got past the screen and was floating around in the carb.

Stator/pick-up coils are quite well-known issues with the DRZ and I have one in my parts kit, ready to go.

Why does he have one on standby, you may ask? Because I didn't check carefully enough to see if that was the actual issue before ordering one, that's why.

 

A search on this topic will horrify you!!

 

Keep us posted!

Edited by shuswap1

Shuswap, I was thinking of doing the same thing, I havent fully diagnosed the electrical system but stators are pretty cheap on ebay and if it is a stator pickup problem at least I'll have the parts on hand.

I'm just po'ed because bike worked fine all winter, then we get to the perfect 75 degree spring riding weather and it takes a crap on me!

damn this &%$#@!ing bike. Did the checks outlined in the service manual for checking ignition, everything seems fine. Cleaned the grounds on the battery, everything fine there. Hooked up an LED voltmeter on the bike, and took it for a spin. Still have the same sputtering problems but the output reads a strong and steady 14.3 volts anywhere above idle.

The problem is definitely temperature related, because when cold it doesn't do it, and it gets progressively worse as the bike heats up.

The carb is spotless, as is the petcock and the tank. I cleaned the shit out of all of them, with no change in bike's condition.

I don't understand it, the bike has spark, it has fuel, and it has air, why doesn't it work, after a &%$#@!ing oil change?

damn this &%$#@!ing bike. Did the checks outlined in the service manual for checking ignition, everything seems fine. Cleaned the grounds on the battery, everything fine there. Hooked up an LED voltmeter on the bike, and took it for a spin. Still have the same sputtering problems but the output reads a strong and steady 14.3 volts anywhere above idle.

The problem is definitely temperature related, because when cold it doesn't do it, and it gets progressively worse as the bike heats up.

The carb is spotless, as is the petcock and the tank. I cleaned the shit out of all of them, with no change in bike's condition.

I don't understand it, the bike has spark, it has fuel, and it has air, why doesn't it work, after a &%$#@!ing oil change?

Replace the spark plug and if there is someone close handy, maybe you could swap out and try their coil before you buy one. Or a second hand one from a wrecker/dismantler.

Could be pick up coils as already mentioned.

Edited by Black_DRZ

Replace the spark plug and if there is someone close handy, maybe you could swap out and try their coil before you buy one. Or a second hand one from a wrecker/dismantler.

Could be pick up coils as already mentioned.

 

I ordered a stator/pickup coil/ignition coil assembly from Ebay (was like 80 bucks), just for good measure. But is it possible that the pickup coil would malfunction dependent upon temperature and throttle position?

I ordered a stator/pickup coil/ignition coil assembly from Ebay (was like 80 bucks), just for good measure. But is it possible that the pickup coil would malfunction dependent upon temperature and throttle position?

It *is* possible for it to feel like the throttle is part of the issue, but you should do the checks outlined in the FAQ at the top of the page, I have less faith in what the Clymer manual says.

 

Gents like Erik Marquez and Noble have put together excellent how-to's

Well lookee what I found when removing the left crankcase cover...

IMG_1302.JPG

IMG_1303.JPG

(if not apparent, the exposed copper in the pickup coil wire)

Do you think that might have been a source of an intermittent electrical short in the ignition system, causing sporadic sputtering? mwink.gif I sure hope so, cause I'd like to get back to riding...

Now the next question is, the pickup wire is supposed to fit into that channel, I don't know if it was from the beginning, but if it was done correctly and came back out, how to prevent that from happening in the future?

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