PLEASE HELP -1500 PUZZLE,runs great 1-2-3-4, then flat-spot?

Information and questions on GL1500 Goldwings (1988-2000)
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Location: lake arrowhead, California
Motorcycle: 1997 1500SE Goldwing

PLEASE HELP -1500 PUZZLE,runs great 1-2-3-4, then flat-spot?

Post by CaptainDave » Tue Apr 08, 2014 10:45 pm

please HELP 1500 riders... here is the puzzle:
- 1997 1500 SE 52k miles - bike lives 5200 ft high in the San B mountains of southern CA
- starts good - idles good - goes thru 1-2-3-4 gears just normal and fine ... then in top gear - there is a flat-spot hesitation in the throttle, usually when backing off the throttle a bit on the freeway - all the time a little bit - not horrible - stays running - just seems like a fuel starvation issue ? - doesn't cut out like an electric issue would - seems to run a little better if the choke put on a bit ... runs a bit better it seems while the engine is cooler - once hot and down the mountain - the flat-spot/hesitation persists

- runs worse in the hot heat when riding down the mountain in Riverside - seems to run BETTER once up in the cooler air up high -where there is less air pressure
- idles just fine once off the freeway down the hill and up - runs ok down the exit ramp
- just had the carbs rebuilt with all new stuff inside at dealership

- how about plugs ? - not enough power to the plugs/weak spark ?
- fuel filter ?
- gas tank contamination ?
- or ???????????
---- thanks for reading this PUZZLE - a gift to the man who figures it out (dinner if its a gir who beats all the guysl) ;-)

Captain D - retired

nice to meet you ... all the best ...

- come ride with us up in the beautiful San Bernardino Mountains in sunny southern Calif

Captain D - retired
Lake Arrowhead, CA
Goldwing 1500SE rider

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2002 honda Gl1800

Re: PLEASE HELP -1500 PUZZLE,runs great 1-2-3-4, then flat-s

Post by rescue1042 » Wed Apr 09, 2014 7:19 am

my first guess would be to pull the plugs and see what they look like are they wet dark and sooty??? Do you have a big decrease in gas mileage?
2002 GL1800
I dont always ride!
But when i do it's on a Goldwing!!

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84 GL 1200 I

Re: PLEASE HELP -1500 PUZZLE,runs great 1-2-3-4, then flat-s

Post by virgilmobile » Wed Apr 09, 2014 8:30 am

I'm thinking....seems to me(I run a 88) that the wing has 2 possible areas that may be considered...

Mine has a Altitude sensor that "adjusts" the carbs to compensate for changes in elevation.....
It also has a ambient air temperature sensor for further 'fine tuning'

I'm sure yours would have the same and should be researched for possible problems or modifications for your driving conditions...
I have heard of adding a resistor in parallel with the temp sensor on a 1800 to alleviate some troubles..Perhaps the same ideas apply to your model...

I'm also aware that on mine,the ECM alters the ignition timing when I select 3rd or 4th gear...yours may also..

If you level off in 4th...It does not have this problem.???? Could a PO have switched the 3rd/4th wires that feed the ECM from the selector switch.?? To get the cruise to be able to set faster???

Keep researching...

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Re: PLEASE HELP -1500 PUZZLE,runs great 1-2-3-4, then flat-s

Post by robb » Wed Apr 09, 2014 9:00 am

Sounds like the dealer set up your carbs a little on the lean side. Fuel filter is easy to check and might try removing the fuel cap to see if vent is bad. With all the rain seen the last few months it would be easy to have water in fuel. Was at a Kangaroo Gas on Monday while tanker was filling a ground tank, rain was so hard it was going in tank where hose was dropped.

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