99 Aspencade RPM flux


Information and questions on GL1500 Goldwings (1988-2000)
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Sawdust62
Posts: 27
Joined: Thu May 07, 2015 7:27 am
Location: Dallas, GA - USA
Motorcycle: 1999 Honda GL1500A Aspencade (Not for Sale!)
1999 Kawasaki ZG1000 Concours (Sold) missing it already...:(
2004 Kawasaki VN1500 Vulcan
1982 Honda CB900C (Sold)

99 Aspencade RPM flux

Postby Sawdust62 » Fri Jul 31, 2015 1:07 pm



I bought my first wing in May and drove it for about three weeks before taking a nail to the rear tire. while I had the bike on the center stand I took the time to change the sub-air filter, cruise filter, fuel filter, rear brake pads, and cleaned the air filter. when I got the bike all back together my first test drive went fine except some dragging of the rear brake pads due to pitting of the pistons not letting it retract. Once that was cleaned up, I took if for another test drive and had a very bad RPM flux in idle and low speeds. With the advice of some on here and my local mechanic, I pulled all the spark plugs one at a time and made sure they were all arcing when the ignition was on. I also verified the fuel filter was in correctly and the air cleaner cover had no gaps. Nothing helped. I ended up taking the carbs off and taking them to a garage to be cleaned, then put them back on; no help. I changed the spark plugs because one of them had some light fouling and was wet when I removed it to test the spark; no help. It may have been wet because I wasn't letting the bike start while checking the spark, just turning it over with the choke off, I don't know. I've changed the fuel with a fresh tank; no help. Let me tell you exactly what it is doing. When started cold, I have to leave the choke on so it idles at about 2000 rpm for 3-5 minutes, then I can slowly lower the choke until it idles at about 1200 for another 3-5 minutes. during this time, the rpm fluxes up and down from about 900-1500 rpm. Once the bike is hot, needle in the normal temp range, I can turn the choke all the way off and it idles at about 1000 rpm. With the temp in the normal range I can ride the bike and it runs smooth above 1500 rpm. when I stop it idles at 1000 for three seconds then jumps to 1250 and settles back to 1000 over about a two second span. three seconds later it jumps to 1250 and settles back to 1000 over a two second span. it repeats this two second jump every three seconds. One thing I noticed when filling the tank today the gas cap made a Fissssshhhhhh noise when I cracked it loose. I've read about vapor lock on several other threads, is the tank supposed to be positive pressure while running, or no pressure? I checked that the vent hose is not blocked by blowing through it using a scrap piece of plastic tubing and a fitting to the vent line. Any suggestions about the fluxing rpm? Bike has 44,000 miles on it. The guy who cleaned the carbs suggested either a pneumatic hose leak or the carbs need to be tuned to the cost of about $300.



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wingman12
Posts: 610
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Location: Land of Lincoln
Motorcycle: 1999 gl1500 se

Re: 99 Aspencade RMP flux

Postby wingman12 » Fri Jul 31, 2015 2:07 pm

there are a lot of vacuum hoses on the 99 1500. you can use starting fluid or wd 40 or brake clean any flammable spray to check for leaks in the vacuum system. start the bike, let it warm up and lightly spray every where and see if the engine changes rpm. this will let you know if you have a leak and where it is at immediately. the 99 1500 is easy to syn the carbs. it takes longer to get the plastic out of the way than it does to sync. and if sounds like yours carbs need to be calibrated. I thought there was a how to do article on this forum, but I could not find it. you will probably have to google ( how to sync carbs on 1999 gl 1500) and get your instructions.
concerning the vapor lock issue, once you have all of the side plastic off to sync your carbs there should be a rubber sheet that covers the exhaust manifolds and is under the plug wires, this shield if to reduce the amount of intense heat from causing your carbs to overheat and cause vapor lock. it also helps protect your wiring and vacuum hoses that run across the top of the engine. good luck and please keep us posted. :D :D

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ct1500
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Re: 99 Aspencade RMP flux

Postby ct1500 » Fri Jul 31, 2015 5:43 pm

Vapor lock is the least of your worries and not responsible for your engine surging.

First off the bike should idle at 800RPM setting higher can compound existing problems. Your engine is running lean due to vacuum leaks or more likely carburetor problems. Unfortunately there are probably a couple dozen different trouble spots that need to be investigated.

When pulling plug wires for a poor running engine you are doing so diagnostically looking for a uniform RPM drop absent the spark among the cylinders not just for the presence of a spark.
This is what I do
Local and need repair help with your 1500, Valkyrie or ST please PM

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Bluewaterhooker0
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Location: Tampa, Fl
Motorcycle: 1997 Goldwing GL 1500 SE

Re: 99 Aspencade RMP flux

Postby Bluewaterhooker0 » Fri Jul 31, 2015 7:42 pm

I'm much less of a mechanic than the previous posters, but I can tell you that I had a very similar problem when I got my '97, 3 years ago. My idle fluctuated from a set point of about 800 rpm to 1200 rpm and back, as you describe. On advice from the forums, I ran a full can of Seafoam through a tank of gas, with a large portion of that tank spent idling. My understanding is that the low speed jets get partially 'gummed' or blocked, and need to be cleared out. The problem was much improved after that first tank, and I repeated the process again with 1/2 can of Seafoam in the next tank. The problem was then gone. After a few tanks of untreated gas had gone through the bike I, again had the beginnings of the idle fluctuation, so I treated it again. Since that time, I actually run a few ounces of Seafoam in every tank of gas. I have had no re-occurrence of the issue since. I also got in the habit of adding an ounce of so of TCW-3 two-stroke oil to every tank of gas. It seems to run a bit smoother with the oil mixture, or maybe it's just my skewed perception, but I figure it can only help to lubricate the fuel pump, prevent rust in the tank, maybe add a tad more lubrication to the upper cylinders, and certainly seems to do no harm. Anyway, it's a cheap fix if it works. If not, you're no worse off.

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Sawdust62
Posts: 27
Joined: Thu May 07, 2015 7:27 am
Location: Dallas, GA - USA
Motorcycle: 1999 Honda GL1500A Aspencade (Not for Sale!)
1999 Kawasaki ZG1000 Concours (Sold) missing it already...:(
2004 Kawasaki VN1500 Vulcan
1982 Honda CB900C (Sold)

Re: 99 Aspencade RMP flux

Postby Sawdust62 » Fri Jul 31, 2015 9:21 pm

I'm going to definitely try the starter fluid method and I've got a can of seafoam that I will use in the fuel tank. I also found this How-to article and video from a link on Youtube. Youtube also had a video from a guy who filmed his bike doing exactly what my bike is doing. His fix was a vacuum leak on a hose under the carb, and several other viewers posted comments on his video that had similar vacuum leaks that caused similar problems. Thanks for the help, I'll keep everyone posted on my success, or failure. I'm leaving for Florida on Sunday so I may not post an update for a week or more.

http://www.goldwingfacts.com/1500balancecarbs.htm




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wingman12
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Motorcycle: 1999 gl1500 se

Re: 99 Aspencade RMP flux

Postby wingman12 » Fri Jul 31, 2015 9:25 pm

Excellent news. Best of luck with finding and solving your vacuum leak. Ride safe to fla. :D :D




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