gpx 250 acting funny

[vindy500]

it seems to lose power and then pick it up again and then lose power and get power and on and on, this happens more at highway speeds but sometimes in town too, just started doing it, any ideas?

[Ragingrob]

Does it seem entirely mechanical, or does the dash and all fade when the "power" cuts out? Could be bad petrol/water in tank, or something nasty like the regulator blown. And probably half a million other things :p. So let's cut it down!

[vindy500]

or does the dash and all fade when the "power" cuts out?

dont think so. in fact confident it doesnt.

[Ragingrob]

Alright well next time it happens just think about whether you're indicating or something to point out that it could be electrical. Even a loose battery terminal does this kinda thing!

On the other hand, there could be fuel blocking somewhere down the line, rust in the tank jamming it up and then freeing itself.

What year is the gpx?

[breakaway]

Sounds like a cylinder stops firing. It would feel exactly as described by the OP.

Change plugs, check connection / condition of HT leads.

[BadCompany]

If it is the plugs, the ones you need are NGK CR8HSA (found at repco and probably super cheap auto and motorcycle shops). Just did mine this weekend, also came across this if you're a do-it-yourself person.

http://pdftown.com/Kawasaki-GPX250-Service-Manual.html

[MSTRS]

GPXs are renowned for rust in the fuel tank (the drainage tube doesn't direct water away from building up over the filler cap, so it gets inside the tank).
It would be my bet that this is your problem and there is a partial fuel blockage in the tap. Enough gets through for the engine to run but not enough to sustain revs for long. When it 'cuts out', the bowls get enough in to fire up again, then repeat....

[vindy500]

GPXs are renowned for rust in the fuel tank (the drainage tube doesn't direct water away from building up over the filler cap, so it gets inside the tank).
It would be my bet that this is your problem and there is a partial fuel blockage in the tap. Enough gets through for the engine to run but not enough to sustain revs for long. When it 'cuts out', the bowls get enough in to fire up again, then repeat....

what do i do if this is the case? i liek the sound of the plugs more... lol



its a 87

[MSTRS]

Basically, you have to completely flush the system to start with. I suggest you first remove the tank, drain it completely and give it a shake - you'll hear if there is any loose material in there, that'll be the rust flakes - then remove the fuel tap and use petrol to flush the crud out - once the tank is clear of crud/loose stuff you may want to try a sealer? - otherwise refit the tap. Now attend to the carbies - open the drain screws on both bowls (or preferably remove the bowls if you can and clean them out) - hopefully this will get rid of anything foreign in there. Before you refit the tank, you should put a filter in the hose. Refit everything, refill with petrol, open the carby drains again to flush residual crud. Now you should be good to go.

[vindy500]

just checked the spark plugs, were quite corroded, gave em a sanding, didnt replace as no shops open at the mo, may do that in near future... anyway one of the ignition leads isnt sealing over when its plugged onto the spark plug, is this a worry?

[BadCompany]

just checked the spark plugs, were quite corroded, gave em a sanding, didnt replace as no shops open at the mo, may do that in near future... anyway one of the ignition leads isnt sealing over when its plugged onto the spark plug, is this a worry?

Your local Repco should have the plugs you need, and they are open to a handy time of 7pm everyday.

[MSTRS]

just checked the spark plugs, were quite corroded, gave em a sanding, didnt replace as no shops open at the mo, may do that in near future... anyway one of the ignition leads isnt sealing over when its plugged onto the spark plug, is this a worry?

Sounds to me that your bike has been a bit neglected over the years. Well past time for a service?
Get new plugs and check for crap in the fuel system as I described before. Hell...go all the way and change the oil and treat your bike to a new oil and air filter.
The plug caps are really long reach similar to the bottom centre picture http://www.totalmotorcycle.com/maintenance/photos/sparkplugcaps.jpg but with a sort of skirt at the top near the bend to seal off the hole in the rocker cover. Not really a problem it it's missing (or not sealing) other than water that gets in will sit around the plug itself and cause corrosion and/or short the plug causing misfires.

[vindy500]

Sounds to me that your bike has been a bit neglected over the years. Well past time for a service?
Get new plugs and check for crap in the fuel system as I described before. Hell...go all the way and change the oil and treat your bike to a new oil and air filter.
The plug caps are really long reach similar to the bottom centre picture http://www.totalmotorcycle.com/maintenance/photos/sparkplugcaps.jpg but with a sort of skirt at the top near the bend to seal off the hole in the rocker cover. Not really a problem it it's missing (or not sealing) other than water that gets in will sit around the plug itself and cause corrosion and/or short the plug causing misfires.


recently had a service at motorad, the guy said he would check the plugs (pretty sure he didnt along with a whole bunch of other things he said he would do) he did change the oil tho... needs new steering bearing and fork seals so going up to my mate whos an engineer in wanganui whos going to do those, might be able to get him to do some more stuff too