83 1100I power loss at 4K+


Information and questions on GL1100 Goldwings (1980-1983)
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marcsac
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Motorcycle: 1983 GL 1100I Interstate
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1984 GL 1100I

83 1100I power loss at 4K+

Postby marcsac » Thu Mar 21, 2013 8:17 pm



I have got my 83 1100 Interstate back in good running condition (i thought) until I notice a new issue. Bike runs like it should under most all conditions, with the exception of when I rap on the throttle at about 4K+. If i bring it up slow past 4K it seems ok. Its only when I accelerate quickly does the engine "sputter". No backfiring. I had the carbs rebuilt by the guys at the honda dealer and they said it an old bike...there is nothing wrong with the carbs....then suggested I put some Magic Mystery Oil in the gas in case one of the slides is hanging up. I tried it once with no change (4oz with a full tank of fuel). Also changed gas lines and fuel filter w/ carb rebuild.

I don't buy the "it's an old bike theory". Anybody ever had a similar problem....I'm out of ideas!

Marc


Most motorcycle problems are caused by the nut that connects the handlebars to the saddle :)

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virgilmobile
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Re: 83 1100I power loss at 4K+

Postby virgilmobile » Thu Mar 21, 2013 8:52 pm

marvel mystery oil will not help the slides.
That bike should pull to red line with no trouble...mine did.
I also had a 4k drag...it was in fact a sticking slide.
Only disassemble,detailed cleaning and bench shop vacuum test resolved it.
The secret is in the slides.
On inspection,one had just a spot of oxidation in the cap...another needed the cap rotated 180°........thus the need to bench test first.

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marcsac
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1984 GL 1100I

Re: 83 1100I power loss at 4K+

Postby marcsac » Fri Mar 22, 2013 4:36 am

Thanks for the quick reply! I didn't mention that there is no drag above 4K when starting with engine at idle. It only seems to happen when riding (engine under load). Also, I not sure what the dealer guys did when they rebuilt the carbs.....you would think they would see any oxidation on cap or slide.. Not sure what you mean that you "rotated the cap 180 degress. I thought they screw on. Also how would I bench test?


Thanks again!

Marc
Most motorcycle problems are caused by the nut that connects the handlebars to the saddle :)

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virgilmobile
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Re: 83 1100I power loss at 4K+

Postby virgilmobile » Fri Mar 22, 2013 7:42 am

I also could accelerate fine,however,during hard acceleration it would bog down a bit around 4k.
I also "rebuilt" my carbs (not my first time) but I didn't bench test them (my bad).I just assumed they would be perfect.Stupid mistake.
I identified the sticking slide by using a angled mirror in the plenum and watching each slide bounce as I rapped the throttle....One didn't move much.

The spot of oxidation was about the size of a pencil eraser and just visible...but just enough to catch the piston when it tried to rise.

Bench testing.......I have a small shop vac..the little 1 gallon one......
I simply secured the carbs to the bench(wood bench/one screw) and held the hose on the tube that bolts to the engine.
With the vac running,I operated the throttle and watched each slide rise.They won't go all the way up but they do move at least half way.....one would stick just as it started to move.
Another moved very slow...it too was dragging.
I'm simulating a running engine with the shop vac.
I re-cleaned and polished everything till they moved butter smooth in the cap and tested again.
Read this post...viewtopic.php?f=4&t=8928

One was still sticking so I removed the 2 screws and rotated the cap 180* and bolted it back down..That fixed it.
Test again and mechanically adjusted the throttle valves for a pre sync....Final sync on the engine and my 1200 wouldn't even keep up with it.
Sync tool...viewtopic.php?t=8994&p=40711
And another type...viewtopic.php?f=3&t=14210

Both work very well..

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marcsac
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1984 GL 1100I

Re: 83 1100I power loss at 4K+

Postby marcsac » Fri Mar 22, 2013 8:13 am

Ok I'm convinced! I was going to try to remove the slides (clean and polish them) without removing the entire carb body from the frame. After reading that last post and watching your "sticky slide" video from old....looks like I found the only correct answer to my problem. Make sure they are working properly before you bolt them back on!

I am waiting for a piston set in mail to rebuild my rear master cylinder....I guess I'll tackle it all at once. At least I can still ride it for a week or so till the parts get here. South Florida weather is great this time of year!

One more quick question.....don't you think the guys at the honda dealership should be checking for proper slide operation before putting the carbs back the bike?

Thanks a bunch!

Marc
Most motorcycle problems are caused by the nut that connects the handlebars to the saddle :)

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virgilmobile
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Re: 83 1100I power loss at 4K+

Postby virgilmobile » Fri Mar 22, 2013 8:55 am

One more quick question.....don't you think the guys at the honda dealership should be checking for proper slide operation before putting the carbs back the bike?


In their mind....."why bother bench testing.....it's not in the factory training and not 'by the book'...I'm not gonna get paid for the extra time...etc,etc"

In my mind...."this is old equipment that has significant use and I better test it so I don't look stupid if it doesn't work and have to make up lame excuses to a customer and hope he isn't smarter than me"

It's all a mater of money....get as much as you can for the minimum amount of effort.The Dealer way....not necessarily the mechanics way.
Many times I've been stopped short on a project just to "finish up" the project and get the billing done.....and then told.."well take care of the fine tuning later"...for a extra charge of course.

It's common work ethics...or lack thereof.

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marcsac
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1984 GL 1100I

Re: 83 1100I power loss at 4K+

Postby marcsac » Thu Mar 28, 2013 4:41 pm

Sorry about the delay in reponse to your last post and I really appreciated the help. Well I took the bike back to the dealer who did the carbs and he tried the "sell" me the same BS after he took it for a ride....."I cant find anything wrong"...then... "your in the wrong gear that's why you have power loss"...etc. This time I was ready for it and "educated him" with some of the info you gave me! Especially the bench test. That shut him up quick and he said he would remove the slides.

Talked to them today and he said the carbs are on the bench and he sees nothing wrong with the slides and they are operating normally. Not sure where it will go from here ......he is looking for an answer since they have figured out I'm not going away!
Most motorcycle problems are caused by the nut that connects the handlebars to the saddle :)

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virgilmobile
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83 GL1100 I
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84 GL 1200 I

Re: 83 1100I power loss at 4K+

Postby virgilmobile » Thu Mar 28, 2013 7:13 pm

I also thought my slides operated normal till I actually looked at them while running the engine.Even tho I could manually lift the slide, it just was sticking when I rapped the throttle. Thus my idea of using a shop vac on each one to confirm that air flow would in fact lift the slides equally.
This is the reason to put a mirror in the plenum and look first before taking them apart.

If they do slide butter smooth,the only other avenue to explore is the timing advance system.The bike has 2 of them,a mechanical and a vacuum type but I don't really think it would cause you bike to fall off at 4k.
There are posts about this too.
I hope you get this resolved and no it is not normal.
My 1000,1100,1200,1500 all pull from a idle with increasing torque till red line.None of them fall flat at any rpm.Each have a different torque curve but they don't flatten out where I have to baby it past it.

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SteveB123
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Re: 83 1100I power loss at 4K+

Postby SteveB123 » Thu Mar 28, 2013 7:29 pm

The dealer that tells you to add something to the fuel to release a stuck slide is clueless.

The slide are vacuum powered, so only air, not fuel or mixture, touches them.
Current:82 GL1100 Interstate, 60 Amp Poorboy, MSD coil
Previous: 93 GSX1100F Katana
82 GL500 Silverwing

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virgilmobile
Posts: 7647
Joined: Sun Sep 19, 2010 5:39 pm
Location: Denham Springs,La.
Motorcycle: 1988 GL1500 I
Previously owned
78 GL1000
81 GL1100
82 GL1100 I
83 GL1100 I
83 GL1100 standard
84 GL 1200 I

Re: 83 1100I power loss at 4K+

Postby virgilmobile » Fri Mar 29, 2013 10:13 am

This is true.Air flow across a port created a vacuum and lofts the slides.It's a pretty delicate balance between the slide weight,spring force,port size.Change anything and the fuel mixture changes too.
At 4k the engine is really starting to need a bunch more fuel.the power curve kicks in in that area.




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