GL1200 top speed 80MPH

10106 Views 32 Replies 22 Participants Last post by wingsam41, Aug 16, 2011

Jerryk959

Discussion Starter · Oct 12, 2009

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I have hadmy '84 GL1200 Aspyfor 5 years now and I have put lots of miles and spent a fair amount of money fixing, accessorising and maintaining. Since I have owned this bike, I have done a 'poor boy' modification, rebuilt the carbs, replaced fuel filter several times, replaced the fuel pump and timing belts andreplaced spark plugs and wires. My usual route takes me to work and home...about 46 miles round trip. I don't usually do a lot of freeway driving, unless we are on a trip. Speaking of which, while on our way to Eureka Springs last month, we put 1500 miles round trip on the old girl. I was pulling a trailer, but it seemed as if there was no top end power. I would get to about 70-80MPH and that was it. I didn't think anything about it because I was towing a trailer and we were going up and down a lot of hills. Yesterday, as I was about to leave work, I met a man who was riding an 1800. He stopped to look at my bike and said when he had a 1200 he could pop a wheelie. I told him mine would struggle to get to 80 on the freeway. Anyway...

After I rebuild the carbs eariler this year, the bike runs goodfrom idle thru 4th gear. Once I hit 5th gear and open the throttle wide, there is almost no acceleration. I do not hear any unusual noises and the clutch seems ok. I have neverbalanced the carbs though and I was wondering if this could cause a loss of top end power. Any thoughts? Thanks in advance.

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FitzAl

· #2 · Oct 12, 2009

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Balancing the carbs might help, but I'd say it is either the mixture set too weak (what color are the spark plug tips?) or you could even have a slight drag on the brakes.

DaveO430

· #3 · Oct 12, 2009

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Not sure on this, I don't have info on 84 1200s but I think the ignition module has an input from the gear position switch to advance the timing in 5th. If it will run faster in 4th than 5th this is one possibility.
Carb balance has 0 effect at any throttle position over about 1/4.

Jerryk959

Discussion Starter · #4 · Oct 12, 2009

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Thanks guys, I will check the plugs and brakes next Sunday. I put new brake padson it 2 months ago, but the problem has been going on for a long time. I don't normally drive that fast so 70 to 75 MPH is normal for me. I just can't believe that 80 is as fast as this bike can go.

nsjoe

· #5 · Oct 12, 2009

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Jerry, your bike should go MUCH faster than that. I wish I could help you diagnose the problem, but I wouldn't want to steer you in the wrong direction. I'd listen to the gurus. My 1200 would zip past 115 with no problem. Good luck.

William_86

· #6 · Oct 12, 2009

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After running half a can of seafoam through the oil, now the clutch seems to be powerful, a week ago i was riding at the beach boulevard with a girl in the back and i was trying to tease one of my friends with his brand new sporster 883 for some illegal speeding:battle: when he pulled the throttle i released the clutch and the front wheel went off the ground

everyone was like :shock::shock: the old fart bike can wheelie:cheeky1:.

before seafoam when i released the clutch under hard acceleration it would have a delay to fully engage, now she does it like she mean it!!:cooldj:

i've never been past the 110 mph on mine, but she can do even more.

check your air filter, there is also a vacuum hose from the carb/intake of cylinder 4 to the ignition module for the spark advance.

chris in va

· #7 · Oct 12, 2009

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My 83 1100 is the same way. 5th gear is pretty much an overdrive and cranking it open at 70mph does pretty much nothing. A downshift to 4th is called for if I want to get around a car.

Then again 70 is the fastest I feel comfortable doing on the old girl. That huge windshield I have really slows the bike down. If I pull the clutch in at speed, it's like someone threw out a small anchor. I can be on a 9% down grade and it'll drop speed. And no...the brakes aren't dragging.

Bike...and Dennis

· #8 · Oct 12, 2009

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Kind of sounds like it's starving for air, but I'd think that would show in the lower gears as well.

Are there any mods on the bike that could deflect air flow away from the air cleaner at higher speeds? Most crotch rockets now have a scoop that opens at high speed and directs air right where it's needed.

Electrical problems usually show up first at high speed, but they "cut-out" not bog down.

Dave's guess is as good as any. A dirty connection in that system?

Then again, maybe it's your wife dragging her feet.

Jerryk959

Discussion Starter · #9 · Oct 13, 2009

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nsjoe, Thanks for the encouragement.

William_86, on our Eureka Springs trip, I added 1/3 bottle of marvel mystery oil to the crankcase and I swear it helped. Seemed like there was more power. I'll check the air filter, ect when I finally get a day off. Thanks.

Chris in va, if you find out anything, be sure to let me know if you resolve the problem. Thanks.

Bike....and Dennis, no mods to the air intake. I did have to relocate the radiator about 1 inch forward during the poorboy install. The alternator is 55 watt Geo Metro one and it has been working flawlessly. I tried replacing several electrical items such as the coils, plug wires and installed platnium plugs about 3000 miles ago. I 'll try checking some of the electrical connections when I get a chance. Thanks.

Dadoo

· #10 · Oct 13, 2009

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Have you replaced your cam belts? If they were fitted just one tooth off, high speed power would be dramatically reduced. 1200s should easily accelerate briskly above 80. Let us know what you find.

John

Jerryk959

Discussion Starter · #11 · Oct 13, 2009

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Hey John, thanks for the reply. Cam belts? Is that the same as timing belts? I did replace the timing belts and it is possible that I may have put them on wrong.... Interesting. How would I check that?

Bike...and Dennis

· #12 · Oct 14, 2009

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Hi again Jerry,

If you have 1 belt, off 1 tooth, you'd know it. The bike would sound like a helicopter.

Anyway, when mine had a belt 1 tooth off, it would still go way faster than 80.

Dave's idea is a good one.

Wolfman

· #13 · Oct 14, 2009

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How does it accelerate? Does it seem to lack power in the higher rpm's? Does it seem like it accelerates better in 5th gear than it does in 4th gear?

My 1200 did that, it seemed slow to get up to speed, and it seemed like I had more passing power if I stayed in 5th gear than I did if I down shifted to 4th.

If that sounds like yours, check the throttle valve diaphragms. Mine were all ripped.

Mine were already like that when I bought the bike, and it was my first Goldwing. It was still smooth as silk, so I never realized anything was wrong. Just a lack of power, and I didn't have anything to compare it to, until someone told me that it wasn't right.

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tracker

· #14 · Oct 14, 2009

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i would try for the air filter,here in quebec we have a lot of leaves in autumn,one got caught in my air intake on the filter lost half my power because it wasnt getting enough air in the filter.

4evermetric

· #15 · Oct 14, 2009

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Fuel filter?

Jerryk959

Discussion Starter · #16 · Oct 14, 2009

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Hey Wolfman,

You are right about not having anything to compare to.

I fall into the catagory of someone telling me that it's not right. The bike runs great (as far as I can tell), smooth, good acceleration thru 4th and even into 5th. When it reaches 65-70 the throttle flattens out and there is little or no acceleration after that. The fastest I have had it up to is 80. I ride comfortably at that speed, but there has been a few times when I needed to get away from a cage and I couldn't do it. I'll check out those valves...thanks!

Tracker4x44,

Thanks, I'll check that as well. I know I need to replace the filter, it's been about 8k miles since I changed it.

AZgl1800

· #17 · Oct 14, 2009

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Jerry,

There is something amiss with your bike.

I owned a 1200 also, and the thing that amazed me was how fast that thing would climb from 65-70 to 115+ and it would do it in the short space of time it took to pass a car!

In 5th gear, acceleration was there, but modest.
In 4th gear, acceleration was awesome, it would red line the tach in a heart beat and be over 115 heading for 125 now.

johnc

· #18 · Oct 14, 2009

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Hello Jerry,
This is just a thought as you have had many good suggestions already. I was wondering if your speedo is accurate? Best of luck with it. John

wexy

· #19 · Oct 14, 2009

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Check and see if the bike was a californian spec ,There may be washers in the exhaust down pipes,that will will stop it reaching its maximun power , Just a thought , Ciaran

Jerryk959

Discussion Starter · #20 · Oct 14, 2009

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4evermetric,

The fuel filter is fairly new...about 6 months old.

Azgl1500,

Now that's what I'd like to see!!!:action:

Johnc,

According to my GPS, the speedo is about 4 MPH slower than actual speed. Also when riding with my wife, we have compared speed with her bike and found the speedometer to be close. Of course, she can walk away from me on her Harley 1200 at freeway speeds.

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