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82 GL500, 78 CX500
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Discussion Starter · #1 ·
Got an 82 GL500 Interstate that I've had for about five years now. Been running into a peculiar problem for awhile. With the engine cold, choke on all the way, press start, the engine starts and then revs upward to around 3K rpm until I push the choke inward and the revs drop down. Then engine begins to bog and die and I pull the choke back out again. The engine revs back up to 3K rpm or so. This goes on until the engine warms enough such that I don't have to play with the choke anymore. I have rebuilt the carbs and made sure all the jets and ports were clear including the low speed jets (removed and cleaned them). Still the problem persist. I am going to check the timing and valve adjustments along with the throttle and choke cables again and post the results. In the meantime, if anyone has had a similar situation, let me know what you found and did to eliminate the problem.
 

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Have you tried adjusting the throttle nudger?
Once the bike starts are you pushing the choke in all the way or only partially?
 

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What kind of shape is the rubber on your intake manifolds? It sounds like a possible vacuum leak. Try spaying starting fluid or carb cleaner around the intakes. Could also be the o ring between the intake and head.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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There's a linkage on the choke that slightly opens the throttle. As above, it's possible that your idle speed adjustment just needs to be increased.
 

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You have good advise already.....one question tho....does it sit steady at the higher revs or fluctuate....this may give you a clue to the cause...
 

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one more more question that's very related to the advice about adjusting the idle speed.
Once it's warm, what is the current idle speed? I run mine at ~1200. Below that and it seems like the vtwin is lugging. Even my shiny new Guzzi 1400 with a modern FI system wants to idle at 1200+
 

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'84 CX650E that is evolving into a GL500
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The "nudger" mentioned is called the fast idle adjustment in the FSM. Its purpose is to open the throttle to increase the engine RPM while the engine warms up without having to hold the throttle open manually or increase the warmed up idle RPM .

3000 RPM is on the faster end of the acceptable range for fast idle but not excessive (my GoldWing will run about that fast if I give ti full choke).
The choke isn't an on/off switch so you should be able to set the knob somewhere between pulled fully out and pushed in where the engine runs at about 2000 RPM until it is warmed up enough to run at normal idle in the 1100 RPM range.

RE 1100 vs 1200 RPM, note that according to the FSM Honda didn't consider the tachs supplied on bikes to be accurate enough to rely on when adjusting the carbs so it wouldn't be surprising if the tach on a bike read 100 RPM high or low at idle. Unless you are using a good external tach when setting the idle RPM it is better to set it to what feels best.
FWIW, I sometimes set Eccles' idle at about 1300-1400 (according to the bike's tach) in the coldest part of winter when it takes a long time to warm up (this isn't necessary when it is above freezing).
 

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82 GL500, 78 CX500
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Discussion Starter · #8 ·
Thanks for the input. It took a little while for me to connect the dots, so to speak. It is the fast idle setting that is causing the engine to go really high on the RPM with the choke pulled out. I had to really read the instructions on the adjustment. For some reason when it stated to have the idle stop completely closed, I didn't unscrew it so that the carbs were completely closed. When I tried to adjust it according to the measurement, I set it too high. So, it was pushing the idle up way too much. I readjusted it, but will have to wait until probably Friday to test. I'll let you know how it goes.
Gas Auto part Nut Machine Metal

Also, I am looking for a portable digital tach I can connect to adjust the engine speed a little more accurately. Does anyone know of a good meter that is not too expensive? Also, if you've used one, how did you connect it to get an accurate reading?
 
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