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reduced acceleration power at lower speeds

952 Views 17 Replies 9 Participants Last post by  wallowaman
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My 1984 Aspencade has 133k miles on it. It just came out of a mechanics shop, where the previous owner was told that they think it has a problem with the coils. "Weak spark to both rear cylinders". Any thoughts on that anyone? :?


It already has new plugs. Been sitting since July of this year. The acceleration is a bit week on the low end but seems to be fine at higher speeds. I was thinking that the carbs may be a bit varnished from sitting. Based upon what this mechanic said, i am thinking of replacing the coil pack. What do you think? I am a new member, and i just bought this bike last Friday. I hope someone has some ideas of what direction to take. I am also planning on running some carb cleaner through it also. Thanks in advance for any help! Cheers! RJ
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Hello, 1200s bikes have 2 coils, one for front cylinders and the other for the rear, yes it could be the coils, but you could test that out by swaping them. it will tell you if are the coils or the carbs. how long was the bike sitting? seafoam could do the job, try a full can of seafoam on half tank of fuel (very high dose but harmless), check air filter, its very well known that mouse love to build their house there.
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Rear cylinders are powered by 1 coil, front by the other. There is a test of the coils outlined in the service manual which can be downloaded from this site.

I'd at least give them a static test before buying new ones.

As far as "down on power"...I'd have to know what rpm you are trying to accelerate from. GL12s make power in the mid and high RPM range. They have some "grunt" compared to older models but still don't like to be lugged.

Carb cleaner won't hurt but the carbs would have to be pretty gunked up for the cleaner to show an improvement in power.
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by swapping them, i am assuming that you mean swap out the wires so that they are powering different cylinders......OK. The bike has been sitting since July of this year.
I just bought it this past Friday. I have already put new plugs in it, and that did make a difference, but still lacking in acceleration.
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You could look around for a spare coil. If you find one at a reasonable price your laughing! I would also pull the carbs, Clean them very throughly to eliminate them as a culprit. Test your accelerator pump for good fuel flow. You might have a small hole in the diaphram.
the plug boots also have a 5k resistor in them that can cause weak spark when they give up. I replaced all 4 on my wing with a huge difference!
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Are you sure its not because you aren't used to the weight of your Aspencade? With all the luggage and the fairing parts it probably comes close to 900lbs. Plus you.
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why was it in the shop to start with and how long had it sat before then.:shock: if it's running good up in the rpms i bet you the seafoam will do the trick. cheap and quick fix. try that first.:action::action::action:course it could be the coil but seafoam it first.
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if seafoam doesn't work, then go through the carbs.
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Thanks. I will try cleaning the carbs first. If that does not take care of it then i will look into the coils. I found a set of used coils locally for $90, supposedly out of a running 84 wing. Do you think i am asking for trouble purchasing a used set of coils?
Thanks again. I appreciate it.
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I am sure that it is not due to the heavier bike vs. my magna, which is fairly heavy too.
Thank you.
Many thanks to everyone that is offering advice. I do really appreciate it. Will try a product similar to sea foam that i have here at work. I will post with results when i am done with this part. Thanks everybody! document.write('/forums/images/emoticons/wink.gif');
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by swaping the coils i mean to swap all the wires.
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Like "Bike ... and Dennis" saiddownload the repair manual and test the coils. If its like my '83 you'll need a three point coil tester and an ohm meter. You probably don't have or will be able to find a three point coil tester and will have to forego that test. Your mechanic might be able to run the test but I wouldn't worry about it. There are three things to worry about on the coils. Make sure the wiring harness is in good shape. Check and clean where the coils plug into the wiring harness and the connections at the coils. Depending on the type of ignition in that bike you may or may not be able to check the voltage at the coils. The manual will tell you if there is a procedure for that. The next check is the resistance in the primary and secondary circuits in the coils. The manual will have the specs for each. The primary will probably be from .5 to 2 ohms and +/- 10%. Most coils can be out as much as25% and work well. I wouldn't replace them unless they are +/- 25%. The secondary circuit will probably be something 15K to 25K ohms +/- 10%. I would also not replace them unless they were outside of +/- 25%. The next thing is the case can crack and sometimes not be visible. To test for this start her up and at idle pour or squirt water on them. If there is a crack it'll cause a bad miss.



Like "Hatchetman" said the plug wires and boots can rob spark. You can check the boots with the ohm meter. If they aren't 5K then there is a screw in connector in the spark plug end. Take it out and you'll get a resistor and spring out. Clean it up reassemble and retry. If you can't get 5K then I'd buy a new set. The NGKs are good and readily available for about $5.00 each.



My experience with poor low end acceleration tells me that your coils, wires and plugs probably aren't the problem. You may have a vacuum and centrifical advance. I can't remember which one is more responsible for low end advance but I'd check them both. The vacuum advance if you have one can be checked by removing the line from the carbs at idle,plugging the barb at the carb and then adding vacuum to the line with a vac pump. I don't know if you can suck on the line hard enough to advance the spark. If the idle speed increases then the vacuum advance is OK. The centrifical advance if you have one is normally tested by examination. There will be a cam bolted to the center that is held at rest by springs. You must be able to turn the cam with a finger grip and feel a little spring tension. It has to return to its original position when its released.



I'd then take a look at the accelerator pump. You should get a squirt of gas into the carb throat when you pump the accelerator. Its pretty faint but can be heard. Let the bike idle for a minute or so, turn her offand then remove the air filter cover and air filter and twist the grip quickly. You should be able the hear the squirt in the carbs.



My local recycler just sold a me a coil for $25.00. If you want me to check with him send me a PM. LOL!!!
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wallowaman wrote:
I am sure that it is not due to the heavier bike vs. my magna, which is fairly heavy too.
Honda's V-4 engines made lots of power. What model Magna did you have?

You have to keep in mind that these bikes ran on par with 750cc bikes in their day. That day passed over 20 years ago. Any current 600cc machine will be quicker and faster than your GoldWing. That doesn't mean the 'Wing is running poorly.

And don't forget, a 26 year-old machine with 133k miles on it most likely won't be as strong as it was when it was new.
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Hey Dennis. My Magna is a V65 - 1100. Like you said, lots of power! I hear what you are saying on your comparison, older vs. newer. I understand that it won't be as strong, it just needs some tlc.
The Wing Has been sitting since July. The previous owner stopped riding it because it wasn't running at full power and he self admittedly is no mechanic. Lost his job and had no $ to fix it. What is your opinion on a set of USED coils?
I just know that when i accelerate from a complete stop that the engine seems to bog down (sluggish, but engine not misfiring) a bit, however it seems to do fine when i am up to higher speeds. From all the responses from everyone here (THANK YOU ALL!)document.write('/forums/images/emoticons/smile.gif');
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I will perform a fuel additive/treatment and go from there.
Any other insight will gladly be accepted. Thank you.
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My opinion on the coils is...static test them, or, and this is way more work, pull the false tank and swap the coils to see if the front cylinders become the weak ones.

If you buy some coils and the problem is something else you are just tossing the money. If you want to toss money, let me give you my address...:action:
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wrote:
...
the plug boots also have a 5k resistor in them that can cause weak spark when they give up. I replaced all 4 on my wing with a huge difference!
wallowaman, Don't overlook this by hatchetman!!!



As posted the rear two holes share a coil - so they'd both "spark" at the same time (one cylinderwill be on a compression stroke while the other is on an exhaust stroke). If either of these resistive caps has a tiny crak or carbon foul, or if either of the two plug has a carbon track BOTH plugs will have weak spark.



That little 5K-ohm resistor in there (for RF suppression by the way) has really taken a beating over the years (fires each revolution of the engine - think of 5-thousand sparks for each 100-miles -- assumes 3krpm @60 and all highway) -- but still -- they DO fail, and the caps drop power all the time.



As above (also), haning this on a coil that you can't verify as being good is just a shotgun approach as well... Testing the coils isn't hard - running a fuel cleaner is even easier, the caps are a no brainer, and probably will still be a good use of $20...
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I will check that also. Thank you! I do appreciate the help.
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Well to Finally close this post....sorry for the delay.....i did as many of you suggested and used an additive, and that did take care of this problem. It runs fine now. Thanks to everyone!document.write('/forums/images/emoticons/smile.gif');
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