My 2007 Sportster started intermittently coughing/sputtering yesterday after a heavy rain. Coincidentally, before my road trip, I added Sea Foam to the tank. It's never sputtered like that before and it was the first time I added the treatment. It ran fine for several hours before the rain and then after a heavy downpour the sputtering began, mainly at lower RPM's. This lasted for about 75 miles or so then seemed to correct itself after it dried out some. Is there any correlation between the Sea Foam and sputtering or rain and sputtering? Any ideas on what might cause this?

 

I can only assume you followed the directions for the Sea Foam. You didn't add the whole can to your tank? Did you? I have never had a problem using Sea Foam when used properly. Do you have an open style A/C?

 

No seafoam wouldn't have anything to do with sputtering. Sounds like you sucked some water into the breather. Is your air filter exposed such as one of those heavy breathers?? I have a hyper charger on my dyna and heavy rain will soak the air filter and cause a little coughing till things dry up

 

I added the Sea Foam as directed and my air filter is not exposed. I searched before posting and I was seeing lots of issues with exposed air cleaners getting wet. Shouldn't be the case on mine.

 

No it shouldn't but it happens lol. Water has ways of doing miraculous things. You should open up your breather and inspect. Filter may smell a bit " musky" if it's been wet.

If it's all sorted back out and fine now I wouldn't worry.

 

I would lean towards the air filter getting wet then.

 

Ha! Yes you are right. I will inspect it as you suggested. Thank you both!

 

You don't say how many miles the bike has, but it is also possible that. The plug wires need replacing. If moisture is getting in during a rain storm it could cause the same symptom.
Just a thought!

 

Definitely sucked some water into the intake. Water can find it's way into anywhere.

I trailered a bike home to NH from NC once and we got stuck in huge rainstorm. It was a 68 Sprint.
When I got the bike home, and eventually got it started, it blew out a TON of water
out of the exhaust. I shut it off, and looked at the dipstick, the oil looked like it had water in it.
I dumped the oil, and it came out looking like a chocolate milkshake!

Have you checked the oil since?
I would recommend changing the oil, just in case.

 

Put a dab of dielectric grease (NAPA, AUTOZONE) on the ends of the sparkplugs and the ends of the plug wires where the plug ends go into the coil. Just may need to waterproof some connections.