Total Motorcycle Community Forums

Hey!
Just joined the forum, looks like theres alot of good information here. I hope you guys can help me out! I just bought an 85 Honda Nighthawk 650 w/ only 14,800 miles on it. The bike runs great overall, although theres a few problems. The bike has been blowing white smoke out of the exhaust just during normal riding, and more so during a good freeway ride. A local mechanic suggested running seafoam through the bike to fix the problem. I followed the directions on the can and from posts on the internet i've found, and put about 1/3 can (or less) of seafoam through the PCV vacuum line that connects to all 4 carbs. The engine stumbled and died after about a minute. I let the bike sit for about 5 minutes, per directions, and then tried to fire it up. The bike did not want to start at all, until I changed all the plugs w/ fresh ones. (they were soaked!!). The bike then took a couple tries, and then finally fired up with alot of white smoke (i was expecting that from the directions on the can). The bike ran for about 2 minutes, then died. It would barely crank over, as the battery was almost dead. (from a ton of tries to start it..does the bike need a charged battery to continue to run? I've heard this bike will not charge the battery below 3k RPMs.) I then hooked the bike battery up to my car battery and tried to start it for awhile. It only started a couple times, with the choke on full, but even with the choke, would only idle at 1k RPMs, and would die if you touched the gas or backed off the choke. Now I can't get it started at all.

I have the bike sitting overnight now, charging up w/ my battery tender. What did seafoam do to my bike? I followed the directions!!! Help please!!


Also, should I run this seafoam in my gas tank instead when I get it running again? Should i run it in the crankcase oil? I'm reasonably experienced working on bikes, although mainly on 2 strokes and dirt bikes. I'm not afraid to get my hands dirty. I've got a shop manual coming tomorrow, as I have to replace the fork seals, which are shot. The cam chain tensioner is also making alot of noise on this bike.

Why would my bike be smoking in the first place with only 14k miles on it??

Thanks for the help, its much appreciated!!!

Evan

My '91 Nissan Stanza smoked for a good five minutes after sucking up a can through the brake booster vacuum line. That stuff really loosens up a lot of crud which ends up getting burned. Sounds like your bike is pretty congested at this point, but I doubt any damage has befallen it.

ZooTech,
hey man thanks for the quick reply!!! I'm really hoping thats the case. So what would you reccommend? Should I just let it sit overnight and give it a shot tomorrow. Is there anything I should do to get it cleaned out?

Thanks!!

Evan

I know you just changed them, but the plugs may be fouled again. Even a mere two minutes of firing in that smoky mess would be enough to ruin any plug. Check 'em again and clean if necessary. If they check out okay, the carbs may need to be removed and cleaned by hand.

If you're bike is blowing a whitish colored smoke, isn't that most likely oil? I had an old beater that used to do this because the rings and valve seals were shot. It would spew a huge white cloud in initial start, then less while riding, unless I went hard on the throttle. I was constantly having to pull the plugs because they were oil fouled.

Your bike just has a lot of gunk in the cumbustion chambers. You probably fed it too much Seafoam with too little throttle, causing the plugs to foul. Then you cranked the bike until the battery dead, which wouldn't do anything since the plugs were shot.

So new plugs, charged battery and you should be just fine. The bike WILL be grumpy for a bit but should clear itself up just fine. I'd try putting it under load (ride it!) and let the smokescreen fly behind ya.

I doubt the carbs need cleaning. Just a charged battery and clean plugs, then once you get it started, you're gonna have to keep that throttle open for a bit to clean all the crap out.

As for the rest of the can, I'd put it in the gas tank. It should work as a pretty good cleaner that's safe for all the fuel line parts. For a cheaper alternative for fuel treatment, I've found Marvel Mystery Oil works quite well.

My Seafoam tale: Put some in my Rad when it hit about 25k miles. Let it die, didn't put out too much white smoke. Let it sit for about 10 minutes while buddies showed up, then we went off on a group ride, with me in the lead. We'll just say I had cagers 1/2 mile back slowing down from the smoke. Didn't seem to make the bike run any smoother, though.

Hey thanks so much for the quick replies everybody! Please keep them coming if you have anything to add. I'm going to let the bike sit overnight and charge. I'll try and start it in the the morning, and if its still not working I'll replace the plugs again.

To clarify though, I put the seafoam in with the original plugs (the plugs on the bike when i got them...no idea how old). Then it died on me and didnt restart until I put in brand new plugs. The old plugs were soaking wet from the seafoam i'm assuming. It did run with the new ones, until the battery died. Should the bike run with a dead battery?

Thanks for the help already. I'm replacing the fork seals next week, any tips/info on that job?

Evan

fadingfastsd wrote:Hey thanks so much for the quick replies everybody! Please keep them coming if you have anything to add. I'm going to let the bike sit overnight and charge. I'll try and start it in the the morning, and if its still not working I'll replace the plugs again.

To clarify though, I put the seafoam in with the original plugs (the plugs on the bike when i got them...no idea how old). Then it died on me and didnt restart until I put in brand new plugs. The old plugs were soaking wet from the seafoam i'm assuming. It did run with the new ones, until the battery died. Should the bike run with a dead battery?

If it's running, a dead or low-charge battery shouldn't matter. It'll put extra, un-needed strain on your charging system but your bike shouldn't die. It probably fouled the plugs again from excessive Seafoam in there. Keep those revs up and it *should* be fine, though...

fadingfastsd wrote:Thanks for the help already. I'm replacing the fork seals next week, any tips/info on that job?

Make sure you realize how much force those springs are putting out, when you're unbolting the spring cap. There's quite a bit of zip on those, keep yourself safe and wear eye protection!

Hey everybody,

thanks for all the replies, you guys were alot of help. Got an update for you.... I replaced the plugs again, charged the bike up, and it still wouldnt start. I drained the fuel in all the carb float bowls, and noticed there was hardly any gas in them. Turns out, when I had slid the gas tank back to change the plugs, the vacuum line on the fuel valve came off where it attaches to the carbs. I noticed this and looked it up in my manual, and the fuel valve is vacuum operated to prevent leaks when the bike isnt running. With the vac line disconnected, the bike wasnt getting any gas!! So I replaced the vac line, cranked the bike for 2 minutes straight...it coughed a little and fired up with the biggest cloud of smoke you've ever seen. I ran it for awhile, and its still smoking a little out of both pipes, but its running like a champ. I used a little more seafoam mixed with a fulll tank of gas, so I'll run that through there to clean everything out.

Now on to replacing the fork seals, and figuring out how to the fix the cam-chain buzz/rattle that wont go away. Any tips on doing that?


Thanks again!

Evan

Glad the bike is running good again. Love them manuals, eh? Handy as pockets in yer underware, they are.

Your camchain noise could be as simple as a sticky auto-adjuster(if your bike has one) or a quick adjustment to the manual adjuster if that's what you got. Your manual will tell you what's what there. If the auto-adjust is sticky, you just need to take it out, give it a quick clean and re-install and set-up.

Or the chain coud be worn out. Or the cam-chain guides could be worn. Both problems mean a bit more work, a bit more money for parts and gaskets, too. Let's hope it's the adjuster.

Good luck.