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I have a 1984 gl1200a that will not go over 70 miles per hour it is stuck at 4000 rpm at full throtle. I dont understand because when parked the bike can rev way past 4000 rpm. can any one help????:(
 

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Hi Hector, and welcome to the zoo.

There are plenty of guys on here that can help you. Unfortunately I can't but stick around, they'll be along.
 

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hector wrote:
I have a 1984 gl1200a that will not go over 70 miles per hour it is stuck at 4000 rpm at full throtle. I dont understand because when parked the bike can rev way past 4000 rpm. can any one help????:(
Some of the California GL1100s had exhaust restrictions, a washer welded in the header a couple inches down from the exhaust port end. These bikes wouldn't go over 75mph. I don't think they put restrictions in the 1200s but can't say for sure. A little more information would be helpful to determine what's wrong.

What kind of gas mileage are you getting?

How well is the engine running when you get to 70? Smooth, missing?

Have you looked at the spark plugs to check the color?

Is the bike using oil?

How about the intake air filter, clean?

Some of the guys here that are more knowledgeable about the carbureted 1200s will probably give you a hand soon but any additional info you can provide will help a lot.
 

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hector wrote:
I have a 1984 gl1200a that will not go over 70 miles per hour it is stuck at 4000 rpm at full throttle. I dont understand because when parked the bike can rev way past 4000 rpm. can any one help????:(
Hector, see if it will go over 4000 RPM in 4th gear? If so, you have either a fuel flow problem like a failing fuel pump or a plugging fuel filter, or a restriction at the tank petcock, or plugging screens in the carb inlet needles.. OR, you could have dragging brakes (jack the bike up & check that).. OR, you have an air flow problem to the carbs (look for a plugged air cleaner).. OR, you have misadjusted throttle cables not allowing full carb opening (twist the throttle wide open with the engine off & look to see that the carbs are opening all the way).

You could also have other problems like malfunctioning ignition box, or failing pulse generators, or low coil voltage, or failing coils but the most likely cause is either mis-adjusted throttle cables or lack of fuel flow. Maybe try a new fuel filter first as that is the usual cause of low top speed & make sure you have good fuel flow from the tank petcock.

If you can pin it down to one of the above systems post back & we can help you repair that area.

Twisty
 

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Be aware that in the main needle slides are stuck down/close you will have a have hard time accelerating. The fuel milage will be poor too.

This is the only problem with the 82 Sabre for sale... The main needle have rubber diaphrams and they torn... So the maximum speed is about 60-65 MPH WOT...
 

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I had a similar problem with the '84 GL1200A I bought in March. The thing would start and run fine at low speed, but had very poor acceleration and wouldn't go above 75 on a straight road. The RPMs stayed low while driving just like yours. I checked all the obvious stuff like fuel & air filters, vacuum hoses, etc. I finally gave up and took it to a local mechanic. It turned out that the vacuum slides in two of the carbs had torn diaphragms and another one had the diaphragm out of position. I think he also found a couple of hoses switched around and synched the carbs.
After the new slides were installed the thing ran great, hard to believe it was the same bike! The only downside is the gas mileage decreased. Before the fix I could get over 50mpg, now it's down to 38-44 depending on conditions & my driving. I am not upset about the tradeoff at all!
Good luck on your problem.
 

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Take off the governor
 

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Thanks for all the help guys I will check on the simple stuff frist. Like the fuel filter and the air filter, and the plugs before I move on to the carbs. I canget the bike to go up to 6500 rpm just fine reving it up in the drive way before the red lite bar starts coming on. I just don't get it.
 

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hector wrote:
I can get the bike to go up to 6500 rpm just fine reving it up in the drive way before the red lite bar starts coming on. I just don't get it.
Hector, it takes VERY LITTLE fuel or throttle opening to free rev to 6500 RPMS. In fact it will do that on the idle circuits.

Check the easy stuff first like throttle cable adjustment & fuel filter but the suggestions above about the carb slides not lifting is a very good observation & could very possibly be your problem.

Twisty
 

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Mine ran like a dog when I first bought it, then I cleaned out the carbs, replaced the spark plugs, and (most importantly) balanced the carbs. What a difference! If you don't have them balanced, a couple cylinders aren't doing their job! Give it a try! Worked for me.
 

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I don't think the GL1200s were ever restricted. This only happened to the GL1100. I know the California models can be a bit slower than the 49 staters and European ones, but only by a couple of mph. I would be suspecting fuel or carb problems as well.
 

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The bike has 106493 miles on it it runs very smood thru all the gears no missing or poping. I have put some seafoam in the gas tank and will run it some more. I took a look into the carbs they look very clean but you never know. The bike does has a clean air filter, and does great on the oil the oil filter is new and clean. I do need to check the spark plugs they might be ready for replacements. The fuel filter is another thing will have to check. I said the bike runs great right upto 70 mph at 4000 rpm.
 

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I had the very same problem on my 84 1200. pull the slides out and check the diaphrams for tears or holes. I,ll bet an ice cold bud thats the problem.
 

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Take a note of the condition and colour of the spark plugs so we can look further into it Hector.
 

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:DWell I changed the spark plugs, fuel fliter, and the air fliter today and what a diffrance. The bike feels like a diffrent animal now she pulls real good of the line there is no hesitation. I have not taken her on run yet as I just finished about 5 minutes ago but I can all ready tell on a small ride around the block. I will see if I can get her past 70 mph now. I am of to Galveston to see what she can do now.

Thanks for all the help guys I can not tell you how much pride it gives me to be able to do all this mechanic work with your help and keeping this old bike out of the hands super expensive shops around here. With the price of oil going skyhigh every body seems to have jackup their prices for every little thing. Thanks again...
 

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Don't forget to check the brakes for binding. Motorcycle brakes calipers seize much easier than they do on cars. After a short run, check that the wheels spin easily and also check for excessive heat on the brake discs, which usually indicates dragging brakes.
 
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