After riding around on fuel-injected sport bikes for years, I told myself that I would never go back to carburetors, but I miss tinkering around with antiques, and I am back to where I started from. I recently acquired a 1982 GL500 Interstate. The bike is running poorly and I believe the problem can be found in the factory carburetors. The GL500 starts and runs, however, when I twist the throttle, the revs go up and stay around 3 or 4 thousand for about 20 seconds. I am beginning to believe the 40 year old carbs need rebuilt. I do not know much about these old carbs but it seems that the carbs are "out of sync." My gas tank is rust free and I am positive that the plastic throttle tube or metal cable is in good condition. I plan to buy Murray's carbs and toss the factory equipment in the trash and never look back. Does anyone have any suggestions that do not include rebuilding the carburetors. Do out of balance carburetors share similar symptoms? Thank you in advance.
Carb trouble
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Welcome! Does the Prince reference reveal a Minnesota connection?
You can probably get get by with a good carb cleaning. If you're local to me, I'll be happy to help with that.
You can probably get get by with a good carb cleaning. If you're local to me, I'll be happy to help with that.
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Check that the throttle cables are routed as in the factory service manual, available to download from the wiki which is linked in my signature. I had similar symptoms on my bike, corrected by rerouting the cables.
Thank you very much for your reply. I will check the cable and look for vacuums leaks. Thanks again!
Thanks for the reply. Sorry for not being clear enough. I purchased a complete "fully dressed" bike with 30,000 miles last summer and the throttle was stuck. I sprayed starting fluid in the air box and the engine started. I transported the GL500 home and lubed the cable and replaced the throttle tube. Before lubing the cable the throttle would not budge. After the cable was lubed the throttle began to move and now the tube 'snaps back' as intended. After the cable was lubed, I started bike and let the engine idle. After a minute or so of idling, I twisted the throttle and the engine accelerated. Sometimes the engine would settle down to idle after twisting the throttle and other times the revolutions would stay around 3 or 4 thousand. Recently, I decided to test the bike and rode about 70 feet. The engine speed increased during the ride, but the bike did not go any faster.
After the first ride and after I observed the engine running on several occasions, I removed the air box and cut the subframe. So, simply, the motor was running poorly before I removed a single item from the bike. At this point the bike is sitting in my garage without an air box or h-pipe. It is important to note that on my bike the symptoms are the same with or without an air box. The bike was running poorly before I removed the air box and the h-pipe.
No connection. I am a fan of some of the musicians that came out of Minnesota in the early 80's. I affectionately refer to my GL500 as 'purple rain' because the bike was sporting a full interstate fairing when purchased. The bike is currently blue with a slight black fade that faints gradually as it approaches the bottom of the gas tank. After a bit of research, I am fairly confident that the bike was painted in the factory and the original owner faded the tank black. I was planning to paint the entire tank black if I managed to get the bike road worthy, but I am beginning to like the blue and black fade.
There was no blue from the factory.
The engine speed increasing without a corresponding change at the wheel would be clutch slippage. Did you service the clutch cable as you did the throttle?
Failure to idle down is typical of running lean. Completely stripping the carbs and a good ultrasonic cleaning will likely resolve it. Look for Larry Cargill's book on the subject.
Unless the rubber parts are hard, you won't need kits. The bowl gaskets are most likely to need replacement, and they can be bought individually. If the Air Cutoff Valve diaphragms are leaking, they can be bypassed.
The engine speed increasing without a corresponding change at the wheel would be clutch slippage. Did you service the clutch cable as you did the throttle?
Failure to idle down is typical of running lean. Completely stripping the carbs and a good ultrasonic cleaning will likely resolve it. Look for Larry Cargill's book on the subject.
Unless the rubber parts are hard, you won't need kits. The bowl gaskets are most likely to need replacement, and they can be bought individually. If the Air Cutoff Valve diaphragms are leaking, they can be bypassed.
Thank you. I did not know that there were no light blue GL500's painted in the factory. I recently saw a blue GL1100 from the 80's and the blue paint looked similar. I just assumed that since the color of my bike was nearly identical to a GL1100 that I saw on social marketplace, my blue paint was original.
I did not service the clutch cable. The pull is surprisingly smooth, and I have tons of cable up front because the front fairing was removed. While I do believe a strippiIng/rebuild of the carbs will get the GL up and out on the road again, I am extremely busy and do not have time to research literature on the subject. I understand the engineers may have worked tirelessly to perfect the GL carbs, and I would like to learn how to restore them to working order, but my schedule will not allow it. Thank you for your help and suggestions, however, I am leaning towards buying a new carb set and devoting my time and energy to other issues unrelated to carburetion..I feel bad for giving up on the old Kline, but I would rather move on. I am unsure if the new carbs will fix the issues that I am having with the bike. If the new carbs will help the engine run better and the fuel system allows me to ride the bike comfortably across town a time or two, I will consider the carb modification a success, and I will start focusing my attention on other mechanical issues.
I am unsure of my next step. I guess I will weld the hoop, find a suitable seat and ponder my next move.
If the blue is only on the fairing, it could be stock paint. The GL500I had the same Hondaline fairing as the GL1100 Interstate.
The tank and the fairing are both blue with a black fade towards the bottom. The blue on the tank matches the fairing.
This sounds a lot like a problem I had a few years ago. Most of the time it would return to idle when I let go of the twistgrip but occasionally tie RPM would sit at about 3K. In my case it turned out that there was rust on the accelerator pump rod and it would hang up and prevent the throttle linkage from returning to idle. After I cleaned the rust off and rubbed silicone grease into the rod it worked normally again.
Thank you for your help. I am curious as to what could be the problem. I plan to buy a new set of vm34's, but I think at this point I am obligated to remove the carbs and take a look inside. After sleeping on the issue, I decided that I am willing to learn a tad bit of information. I am plan to search a few posts on carb removal and take one side apart.
Removing the carbs is clearly described in the FSM that I mentioned downloading in your New Member thread.
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