[joevibe]

seems to run fine - seems a bit more "boosty" in the colder weather as well - throttle response, peppy


any issues?

[riddler9]

Are you asking if it is okay to run 98 octane? If so, as long as you are not running leaded fuel then higher octane is fine. Octane does not increase power, so unless you are trying to combat pre-ignition or ethanol, you may not need it.

How are you getting the higher octane? If you are using a formula from a bottle that says use X to increase by Y, then you should consider that boosters will only take the octane so far. If I remember what I have read in the past, 98 starting from 92 octane with a high quality booster is on the upper end of the scale, maybe even past it.

[crfsonly]

do you have a high compression piston installed?

[crazybrother]

If he is blending High Distillates, he may very well ruin his engine... It can get to hot, with the higher Octanes, the burn is longer and Hotter... I.E. the piston and valves will melt!

[mxracer76]

OMG!

Over the years I have been on and off a few web forums and it still surprises just how many people have no idea what they are talking about when it comes to fuel octane.

Now I am NOT a fuel expert by any means but adding higher octane fuel than what your bike, car, truck, sled and or lawnmower requires will absolutely not add any power what so ever. In fact, you are more than likely to lose power with excessive octane!
And no, your bike will not run hotter and melt your piston and or valves with higher octane! In fact, higher octane can cause lower temps due to the fuel not fully burning.
Do yourself a favor, save your money and run what is required!

[mxracer76]

Also, just because you add a high compression piston does not always mean you need higher octane.

Compression is only one piece of the puzzle. Ignition timing and your cam can also dictate what octane your engine will require.

A few years ago I found a huge write up on engines and octane requirements from everything from lawnmowers to diesel engines in military tanks as well as all forms of racing from go carts to dragsters. I will try to find it again and post the link.

It will suprise most people!

[crazybrother]

What I meant was, if he is making his own... He might be in trouble. Now if he is buying 98 Octane, he'll probably be just fine other than wasting his money. I have seen several instances of this happening. When the Octane rating RON/MON in not managed correctly it does get ugly High and Low it can cause severe damage to the engine.

[riddler9]

What I meant was, if he is making his own... He might be in trouble. Now if he is buying 98 Octane, he'll probably be just fine other than wasting his money. I have seen several instances of this happening. When the Octane rating RON/MON in not managed correctly it does get ugly High and Low it can cause severe damage to the engine.

Make his own as in using Toluene? I would hope like crazy that if he was making his own he would not be asking if it has issues - being able to do the calculation required to know you hit 98 with your own mix pretty much implies you know if your going to waste your valves.

Octane, like a "cooler" plug decreases combustion chamber temps, which is why you sometimes need to do both (increase octane, and run a cooler plug) if you increase compression enough. Regardless, 98 simply is not that high. Bike may run like crap (he said it does not), but its not going to hurt. 10% Ethanol is worse than 98 octane. Get above 105-110 and yeah, maybe.

I have seen several tests by magazines and speed shops that show a properly tuned engine on pump gas (91-92) produces more hp and torque than the same engine running higher octane (formulated or with boosters).

If all you did was swap to a higher compression piston, read the plug to see if you have pre-ignition. If you do, run a cooler plug and you will probably get better results than anything else on a FI bike. If it still suffers, then look at adding a booster.

[crfsonly]

i asked the op about the piston being higher compression because i haven't been able to find any after market higher compression pistons for the 250L. if anyone has information on one please let me know.

ken