Author Topic: Intermittent power problem.  (Read 146 times)

Offline RedMark

  • Trade Count: (0)
  • AMA Supersport Racer
  • **
  • Posts: 54
  • Karma: +0/-0
Intermittent power problem.
« on: November 06, 2019, 05:33:36 AM »
Hi guys, I have a 2002 GS500 and for some reason it loses pretty much all power sometimes. It starts, turns over and runs, but it's like the power is being sapped somewhere. I replaced the battery and plugs, thinking that might sort it. That didn't seem to work, so I tried draining the carburetors.

Doesn't seem to be an air problem.
Doesn't seem to be a spark problem.
It might be a fuel problem.

At a loss what to do next. I'm not sure whether it's fuel being cut to both or just one cylinder.

Offline Bluesmudge

  • Trade Count: (+4)
  • World Superbike Racer
  • *****
  • Posts: 1897
  • Karma: +30/-0
Re: Intermittent power problem.
« Reply #1 on: November 06, 2019, 05:30:03 PM »
Can you be more specific? Is the power loss at all rpms? Does choke effect it? Does it run ok sometimes? What jetting and air filter do you have (or is it all stock)? How many miles on the bike and has it been sitting recently? How long have you owned it?
« Last Edit: November 06, 2019, 05:30:51 PM by Bluesmudge »

Offline RedMark

  • Trade Count: (0)
  • AMA Supersport Racer
  • **
  • Posts: 54
  • Karma: +0/-0
Re: Intermittent power problem.
« Reply #2 on: November 07, 2019, 01:00:34 AM »
Power loss at all RPMs. Choke doesn't seem to do anything on my bike except flood it.

Runs no problems most of the time.

It's been jetted for K&N filter.

78,000KMs and it runs pretty much every day.

I've had it since 2013, and it does this from time to time, but it's been getting worse lately.

I also just recently remembered about fuel tank vacuum, but haven't had a chance to test.

Offline RedMark

  • Trade Count: (0)
  • AMA Supersport Racer
  • **
  • Posts: 54
  • Karma: +0/-0
Re: Intermittent power problem.
« Reply #3 on: November 07, 2019, 09:14:35 AM »
Attempted to go for a ride and it played up again. Tried opening the fuel tank in case of vacuum and that didn't help.

Offline herennow

  • Trade Count: (0)
  • Formula Extreme Racer
  • ***
  • Posts: 207
  • Karma: +3/-0
Re: Intermittent power problem.
« Reply #4 on: November 07, 2019, 12:05:49 PM »
if choke floos it rather than raising revs you are too rich.

Check float height, probably a sticking needle lettign in too much fuel.

Offline The Buddha

  • The guru Ba-moo-derator
  • Administrator
  • Trade Count: (+52)
  • Motorcycle God!
  • *****
  • Posts: 26007
  • Karma: +110/-0
Re: Intermittent power problem.
« Reply #5 on: November 07, 2019, 04:24:14 PM »
I'm having this on mine too, and a startup and take off problem which I suspect is a leaking vacuum diaphragm at the petcock. Which may or may not cause my higher rpm loss of power.
I dunno, I cant get to it for a while though. Maybe after thanksgiving break.
Cool.
Buddha.
-----------------------------------------------------------------
I run a business based on other people's junk.
-----------------------------------------------------------------

Offline RedMark

  • Trade Count: (0)
  • AMA Supersport Racer
  • **
  • Posts: 54
  • Karma: +0/-0
Re: Intermittent power problem.
« Reply #6 on: November 10, 2019, 04:11:03 AM »
I did a little bit of experimenting, and the engine sounds the exact same as when you unplug one of the spark plugs, so now I'm guessing it's either fuel or spark being cut off to one of the cylinders, but I'm not sure how to figure out what to fix from here.

Offline Bluesmudge

  • Trade Count: (+4)
  • World Superbike Racer
  • *****
  • Posts: 1897
  • Karma: +30/-0
Re: Intermittent power problem.
« Reply #7 on: November 10, 2019, 10:28:25 PM »
Next time it happens you could pull the spark plug, ground it, and press the starter to confirm if you have spark or not out of both plugs.
If not, its likely that one of your spark plug coils is bad. These bikes have a reputation for short-lived electrical components.

Offline RedMark

  • Trade Count: (0)
  • AMA Supersport Racer
  • **
  • Posts: 54
  • Karma: +0/-0
Re: Intermittent power problem.
« Reply #8 on: November 10, 2019, 11:53:07 PM »
Yeh, that was my next plan. Thanks for your advice.

Is part number 33410-01D00 the coil?
« Last Edit: November 10, 2019, 11:59:58 PM by RedMark »

Offline RedMark

  • Trade Count: (0)
  • AMA Supersport Racer
  • **
  • Posts: 54
  • Karma: +0/-0
Re: Intermittent power problem.
« Reply #9 on: November 11, 2019, 11:42:21 PM »
It played up again, so I tried pulling the spark plug connectors one at a time to see if it would make a difference. Didn't seem to do anything, but the bike started working properly after I reconnected them. So my next guess is the exposed wiring at the front of the bike might have a problem.