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GPX250 Fuel

Discussion in 'Bling and Appearance' started by EvilUrge, Jan 15, 2006.

  1. Hi Everyone,
    I have just purchased a 93 GPX 250. I was wondering what fuel should I be running in it. I know this question has probably been asked before but I can't find it in the search.

    So do they run alright on regular, or do I need go premium, and if I do need the good(premium) stuff, what should I stay away from?


    Evil Urge

  2. ive read a lot on this.

    some people will swear by it.

    i ran premium for a while and thought it was better, then i went back to normal and didnt think it made any difference.

    a higher octane supposedly means slower combustion which im told not ideal for a high revving 4 cylinder.

    i dont know the specifics of the science, so i cant give a definitive answer. try it, make your own decision as unless you speak to an expert in fuels and combustion then you will get different opinions.

    just dont try diesel.
  3. i think a gpx is a two cylinger four stroke. and i think premium works better on higher compression bikes? dont quote me on that. i put it my cb of all things and can't tell the difference, except for maybe slightly underperforming (if thats possible on a cb)
  4. My 2005 GPX used to stall every half hour or so when I used premium (tried Mobil, BP & Caltex). Once I switched back to regular the problem stopped.
  5. just use regular from a reputable source ie shell. put from a no name place once and the idle speed dropped and would stall when cold.

    so the way i see it is it runs fine on regular so i use regular :)

    just remember have on the gpx its a great bike been serving me well for a year now
  6. Thanks everyone who replied.
    Just to fill out the information, I paid $3k for a 93 GPX with 10 months reg. It has obvously been droped at some point, the right can is scratched, as are the bar ends, but it seems to ride alright and the engine is strong.

  7. That's a decent price. I sold mine for $2500 [93 model], 2 years ago.

    I would recommend regular unlead as well, the bike is not specifically tuned to run on premium. It wont do it harm, it'll just lighten your wallet. :grin:

    Premium's only neccessary for some new bikes which are tuned from the factory to run 95-98 Ron fuel. Sure, u can use the regular stuff, but the power output would be slightly reduced, and so will the responsiveness.

    One of the major factors in using premium fuel is to avoid detonation and pinging, which affects motors that are running lean [due to various factors - high boost, dying fuel pump, high intake temps, injectors maxing out]. Usually, force-induction engines.
  8. My gpx pings at low rpm and high load when using standard petrol. With premium it doesn't as badly, so I run premium. It's a stop gap solution (need to do the valve clearances and balance the carbs) but it's solving it in the short term.

    If your bike runs well on standard, my tip is to use it.

  9. I had a 91 GPX and from memory they have an 11:1 compression ratio which supposedly should show signs of improvement with higher octane fuel (someone correct me if I am wrong). With so few horses to start with the small % increase was barely noticeable (if at all). If your bike has a specific problem premium may be the answer, but a GPX should run OK on regular.
  10. My boyfriend has an 88 or 89 GPX and he put some of the super duper hi octane stuff in it over xmas - it ran really bad... he normally uses normal premium and that is fine.
  11. My 91 Gippie runs fine on 91 RON... 98 premium gives it a bit of zing, which i can feel and so normally i'll put it in if im doing much two-up or country riding...

    I have noticed in the real hot weather 95 and 98 have boiled my coolant but thats not a tested fact just an observation at this point (only happened 3 times in the last 6 months...)

    Rough idling and stuff happens but my carbs are due for a balance so i don't put that down to fuel, but another observation i've had is things seem to always be smoother on BP fuel...
  12. My mechanic adivsed me to switch to premium after we noticed the engine pinging...

    I switched to premium, it stopped the pinging... But the f**er won't start half the time.

    Went back to normal and now it's fine.

    However, in saying that every time I get my bike serviced... It always has problems starting!!!!!
  13. Regular, for sure.

    My GPX ran like an absolute dog on premium, hard to start, stalling, the works. Regular was fine... and cheaper. :)
  14. bizarre? Have been running my '92 gpx 250 on 98 for the last few months (since i bought it) as i am 100kg with all the riding gear on and it runs very well. After reading this will go back to 91 and give it a go. thanks guys!