Stumbling, weak power and backfires upon acceleration.

Everything in-between the gas cap to the carbs.
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Triangles
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Stumbling, weak power and backfires upon acceleration.

Postby Triangles » Mon Sep 19, 2016 4:02 pm

I've been busy and have neglected my poor EN500C lately. She has been unused for far too long. A few days ago everything seemed normal when I first started her up then a mile or so down the road she started backfiring like crazy and acting like she was out of fuel or running on 1 cylinder or running very lean or some combination thereof. Basically what the subject describes and somewhat similar to how another carbed bike I had ran when I decided to try E85 not knowing any better. WOT and barely accelerating past 40mph. I'd back the throttle off and then it was like the second cylinder would kick in and would stay that was as long as I didn't go on the throttle too much. I initially suspected a my carb was gummed up from sitting too long. Then I thought I had an ignition system problem. Last night I added a few ounces of acetone to about a 1/3 full tank. Acetone being a strong solvent I'd hoped would help disolve gunk in the carb and get things flowing right again. I then went on a 40 mile ride mostly 45-70mph. At first I stayed in 3rd or 4th gear to keep the revs up(6K+) and varied the throttle to provide varying amounts of suction to hopefully help suck the gunk out that is mucking up the carb. It took about 3-4 miles till it was "running on both cylinders" I put that in quotes because I really don't know what it was doing it just felt like that. After It felt normal at least some of the time I brought the revs down and used the higher gears. By the end of my 40 mile ride it was almost back to normal. Today it's still acting up but is much better. So I'm fairly certain it's just my carbs gummed up and hopefully running enough gas thru the carbs will dissolve the gunk. I'm contemplating putting some 110 octane racing fuel in it to see if that helps because that is the only fuel I can find that is ethanol free around here. Hopefully this or just running more gas thru the carbs will remedy this and I won't have to take apart and clean my carbs.
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Triangles
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Re: Stumbling, weak power and backfires upon acceleration.

Postby Triangles » Mon Sep 19, 2016 10:30 pm

I added some STA-BIL fuel stabilizer (I didn't have any carb cleaner handy) to the last gallon or so in my tank and started it to get it into the carbs. Then an hour or two later I went for a brief ride down the freeway and by the time I got home it was running normal again. I topped off the tank with some fresh gas and all is well again. :D
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bikerbill
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I ride: 1997 Vulcan 500LTD named Hidalgo

Re: Stumbling, weak power and backfires upon acceleration.

Postby bikerbill » Tue Sep 20, 2016 7:01 pm

I wonder if the spark plugs were starting to foul because of something in the old fuel? Which plug do you use? DR9EA or DR8EA?
--
'Biker' Bill
'97 EN500LTD 'Hidalgo'
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Triangles
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Re: Stumbling, weak power and backfires upon acceleration.

Postby Triangles » Wed Sep 21, 2016 1:16 pm

It went back to stumbling just off idle until I got the RPMs up or eased back on the throttle reaching my desired speed. Still not as bad as before though. I dumped 3/4 of a bottle of carb cleaner in with the fresh gas and went for a ride and it only hiccuped once. I can't believe it worked that good that fast :? It must be a coincidence. I went for two rides today so far and it's running fine.

Bill, I'm using the Autolite XS4164 iridium plugs. According to this chart It is a hot plug. XS4164=hot, XS4163=medium, XS4162=cold. I don't pretend to know what the temperature range is all about or when to use what. the "hot" XS4164 plug is what was recommended for our engine. I don't recall ever checking the plug I had been planning on waiting until my 30K maintenance to check the plugs. I figured running lean from gummed carbs would negate any value in reading the plugs. I've never touched the carbs so they should be as they left the factory. I also possibly thought it might be chunks of the inner pipes falling off and plugging things up. I remember you posting something about that a while back. However I don't feel reduced exhaust flow coming out either muffler. I've been running on broken inner pipes for about 6-7K miles. I did weld over the vent holes so all the exhaust goes out the mufflers and as a bonus it sounds better. Eventually I was going to take a stab and fabbing my own pipes but my metal working and welding skills have a long way to go before that happens.
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