Sudden loss of revs + backfire GPX 250

[LeonJW]

Hi there,

I have a 1989 GPX 250. When i was riding to work yesterday doing about 90 ks at 7500 revs bike suddenly lost all revs for a few seconds then kicked back in. A few seconds later it did the same thing but not as bad but it also backfired, i rode a few more seconds then loss of revs + another backfire. I pulled over and idled for a few mins, nothing seemed to be wrong so i continued on my way to work and did not have any more problems. It has occasionally had a sudden loss of revs before usually on high revs after a flogging.

I think the problem lies in the fuel system perhaps a blockage somewhere or i need to change the fuel filter. Any suggestions would be great cheers

[House]

Could also be your ignition system.

Sounds like it could be losing spark for a second, then igniting all the unburnt air/fuel mix in the exhaust when it starts firing again.

[LeonJW]

Yeah thats true, i changed the spark plugs about a month ago maybe i did something then, might be worth having a look.

[Kingkezza]

Could also be your ignition system.

Sounds like it could be losing spark for a second, then igniting all the unburnt air/fuel mix in the exhaust when it starts firing again.

^^^this. Had an old car that used to do it intermittently. The excessive unburnt fuel then causes a backfire. Turned out to be a certain component of the distributor.

Check plugs, leads, coil(s).

[smokeymatt]

Yea check plugs are properly seated and plugged on, also coil to plug leads can harden and split so check them. Also check and clean out fuses. I dont know if the gpx has a cut out swith on the side stand if it does that could be a problem too.

[Creme]

If it happens again, you could always try robbo's technique:

[Dargonk]

bugger leon. i think its time that you got a professional mechanic to do a full service on your bike instead of your constant half fixes

[smokeymatt]

How about you bring it over my house late next week and we'll give it a good going over?

[LeonJW]

bugger leon. i think its time that you got a professional mechanic to do a full service on your bike instead of your constant half fixes

lol christmas has already gone so i can't get my folks to pay for it as a present hey i've only done full fixes with the GPX, its the neon that suffers lol

[LeonJW]

Sounds good matt, i think thursday will be a good bike fixing day, cheers for the help everyone, I might take a look at the leads, distributer, coils etc tonight or on the weekend.