if these bikes are ment to run on 95% fuel in the land of the jap and we run 92%... then maybe that why they bog down alittle after 8 000 then boost off after 10 000 rpm bp has a premium that 95% im gonna run it for afew tanks and see how it goes im thinking it will be better!!!
lol, not %, octane, also depends on what the bike has been tuned to, my bike on arriving in aust. was tuned for 92 octane unleaded fuel so ran perfectly on that, as soon as i put 95 octane it ran rich but im assuming cleaner? most jap bikes would be tuned to 95 / 96 octane fuel as thats their standard fuel base i am told, so that would suggest that 95 octane fuel would make your bike perform better., sorry for this post if it sounds weird i am a little smashed
i take it you didnt understand the % i ment %octane was just being lazy did you bring the bike in yourself how would you be able to tell what the bikes tuned for
Can't remember who posted that link to the Shell petrol link, but I think it was there that said the bikes are initially tuned to 95RON, but over time and deterioration, the octane rating drops and by the time it comes here as an import, it tunes itself to 92RON?
yeah i heard that but just thought id give it ago because... well that sounds abit out there i dont see how a bike thats riden on 95 and serviced on 95 is then ship hear and all of a sudden its tuned for 92 i now what was said came from some one that well i would say had more know all about bike since i know fuk all but till theres abit of proff posted up hear im not to shore about it all
I think that was me who mentioned the natural adaptation to lower RON fuel due to deterioration of the carbs and fuelling system. Whilst getting carbs running perfectly is part science and part black arts, getting them running moderately well is really just a matter of understanding what they're doing. The point is that when a fuelling system is designed it has a particular RON timing specified for it to operate at peak efficiency. Over time ALL fuelling systems become clogged with junk so jets, needles & even EFI systems don't flow properly and end up either over or under fuelling the engine; quite often both at different points in the rev range (generally rich down low and lean up high). When your little FZR250 was manufactured in ~1990 it had it's fuelling and timing set based on ~95RON fuel. The simple fact is that even when it rolled off the factory floor it probably could easily run on 91RON fuel just it would be a little bit lean. By the same token it could also run on 98RON fuel just run slightly rich. Over time as the needles and emulsion tubes in your bike have worn, they are now supplying more fuel (richer mixture) which means you can easily run a lower RON fuel with no adverse results... possibly even positive results. Again, there is no hard and fast science to getting carbs running moderately well, and given that we're talking about tuning an inline-4 250 we're not talking about tuning it to absolute perfect A/F ratios. In a perfect world where money is no object and we could easily source carb parts for our bikes, i'd recommend everyone tune their bikes for 98RON (0% ethanol) fuel by replacing the needles with ones allowing slightly less fuel in. This means that your providing the optimum amount of fuel for perfect combustion whilst actually using volumetrically less of it; resulting in better fuel economy and longer range. In a real world scenario, you could tune your bike for 98RON fuel by approximating the different density and changing the circlip position on the carb needles; BUT when it comes down to it the bike more likely to end up running a richer mixture at a lower RON rating. Anything i missed? <!-- s --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="" title="Very Happy" /><!-- s -->
Considering that a carbie engine is all mechanical (as opposed to electrically driven), general wear and tear as koma described sounds very likely..
Even in an electrical system the injectors wear out their nozzles meaning that the fuel dispersion isn't as thorough as it originally was when the bike was built, meaning generally the ECU will compensate by richening the mixture.
That's what I was thinking, as the ECU will make up for it, hence keeping it still running at the appropriate RON level (or close enough to it). Unless I've completely noobed it and got it wrong! <!-- s:rofl: --><img src="{SMILIES_PATH}/icon_razz.gif" alt=":rofl:" title="Rofl" /><!-- s:rofl: -->
i new some one with more no all about bikes put that up i wasnt shore if it was koma or dave but back to the topic what your saying sounds like it would be right but like you said not perfict so maybe the bikes not worn as bad as it could be maybe it should be 94% but in about a week ill start puttin 95% in( when this tank runs out) and ill let you know how it goes
Yep, thats about the best way to do it if your not into dyno tuning your bike. Just fill up with 95 or 98 for a week or two and see which one gives you the best 'feel' from your engine. Like many others on this forum, i tried using 95 and 98 in the FZR250 but ended up just going back to 91 as there was no difference in performance and i was still using the same amount of fuel as i hadnt changed the jetting.
Thanks for the insite koma. Anyway I've been using 95 PULP ever since I got my bike and its only had 91 ULP a few times which I could count on one hand. My main reason for using PULP would be that i'm probably guaranteed of having an ethanol-free blend, which probably isn't a very good thing for a small carbie engine, right? When I got the bike to I used 98 octane petrol (Shell Optimax), but I stopped soon after as the bike ran quite badly. I took it to the mechanics and he said that the petrol had partially clogged up my carbies, and that Optimax wasn't well suited to older engines.
Not likely. Ethanol has a higher RON than your standard petroleum distillate. The oil companies can blend anything up to 10% before having to advertise the fact by law.
