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Engine running poor after spark plug change


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Hello all, hope you can help and I'm hoping that this is simple, 

I have a 2009 DRZ400sm; I just passed 18,000 Km on her. I bought her at 12,000 Km. The 6,000 Km I put on her have been mainly commuting miles (12 miles into work/12 miles home). She has always run really well; no problems with her. 

I decided to do a 18,000 Km service on her. I changed the coolant. I replaced the oil filter and changed the oil. I replaced the spark plug (that was the first time I have ever replaced an spark plug). The spark plug I removed seemed fine and in good condition. I started her up and briefly ran her after the spark plug change to check I had a good connection. She ran fine. But I only ran her for a few minutes.  I didn't ride her.  Like a fool I threw away the old spark plug.

Finally I removed, inspected, cleaned, and re-oiled the air filter (this was also the first time I have replaced an air filter). 

Whilst the air filter was drying I gave the bike a right good clean and a wash.

I put the air filter back on and started her up and she didn't seem to be running as well. I felt like I need to keep the choke out for longer than previously and that she needed a bit of throttle to keep idling. If I left her unattended she would cut out. I also felt that the exhaust was a bit more smokey. 

I spoke with a friend and he suggested that I had over-oiled the air filter and was starving her. I removed the air filter and started her, but it didn't help. It also seemed like she was getting rougher. The idle was getting poorer and the she was taking more starter cranks to get her going.  I flattened the battery a number of times at this point playing around with her.

I removed the spark plug and checked the gap which was within tolerance. I replace the plug and there was no change. She started poorly, ran rough and would cut out. Smokey exhaust.

I left here alone for the night. The next day I tried again she was worse. Hard to start. Needed full choke. She would cut out with zero choke. Smokey exhaust. There were even few flames firing out of her. This is still with air filter removed. And that is as far as I have got. I'm worried about what I have done. I don't want to ride her the 12 miles to the Mechanic's place because I'm not sure if I will make it or if I am doing her harm .

I've been reading the forums, but I fell I lacking knowledge to understand the solution. My gut feeling is that the combustion is poor for some reason. Is there any other diagnostics people might recommend, anything else I can check. Could I be unlucky and have a bad spark-plug. Have I damaged something -nothing felt like it went wrong when I was replacing the spark-plug. 

If I could just ride it to the mechanics I would be happy.

Regards, hope you can help, 

Fat Robert

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Bermudacat,

Thanks for the response and the advice. Okay. I've just done some reading on fouling on a spark plug. So I understand what you are saying. What might have caused it to foul. All I did was replace it. Could it be that the overly oiled-air filter starved the air, caused a bad burn and then the fouling ran away with it self.

Should I replace or can I try cleaning the plug (trying to avoid waiting until Monday and driving into town)

 

 

R.

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sbmon,

Wait. I think I might be an idiot. There are two pipes on the petcock. I have only been connecting one.  I am doing some reading...

I only had the larger pipe connected, the smaller pipe behind was not connected. Thing is, I don't remember disconnecting it in the first place. Maybe I gave the tank a tug to lift it off and that caused the smaller pipe to be disattached.

Would that explain all my problems

 

Edited by fat robert
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39 minutes ago, fat robert said:

Bermudacat,

Thanks for the response and the advice. Okay. I've just done some reading on fouling on a spark plug. So I understand what you are saying. What might have caused it to foul. All I did was replace it. Could it be that the overly oiled-air filter starved the air, caused a bad burn and then the fouling ran away with it self.

Should I replace or can I try cleaning the plug (trying to avoid waiting until Monday and driving into town)

 

R.

Oil fouled by the air filter. Cleaning them seldom works, and even when it does, they are so much more prone to foul again it isn't worth it.

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The smaller rubber hose you found is the vacuum line that operates the stock petcock.It plugs into the small nipple on the rear of the petcock.When you lifted the tank off to gain access to the spark plug you probably didn't realize that it was attached when you yanked up on the tank.

You should reclean your air filter and only lightly oil it and gently knead it in then cover it with a towel and let it hang in a cool dry place for a little while before installing it.You may need to clean out the carburetor of the air filter oil if it is excessive to keep from fouling the jets.

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Gents,

Thank you so much. That was the problem - I did not connect the vacuum line. I am, without doubt, an idiot. 

- sbmon: thanks for pointing me in the correct direction

- bumtarder: the way you explained it happening is exactly correct.

- Bermudacat: thanks also for pitching in at first.

So pleased. Was really worried about what I had done to my bike. I shall drink to you good health tonight. 

FR.

 

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8 minutes ago, fat robert said:

Gents,

Thank you so much. That was the problem - I did not connect the vacuum line. I am, without doubt, an idiot. 

- sbmon: thanks for pointing me in the correct direction

- bumtarder: the way you explained it happening is exactly correct.

- Bermudacat: thanks also for pitching in at first.

So pleased. Was really worried about what I had done to my bike. I shall drink to you good health tonight. 

FR.

 

No worries, Bro......👍

We all start somewhere.

Next time you'll be helping someone with this exact problem. Meanwhile, you'll be learning how to shim your tappets and re-valve your front forks. :ride:

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