What's next after 93-octane pump gas?

[caboteria]

Over the winter I bought an SV650 former race bike* that has a motor that's had some work done to it. I've done about 6 track days this year and it has run like a top and is a lot of fun. The most recent track day was seriously hot, like 90+ degrees and I think I heard some pinging towards the end of the afternoon sessions so I'd go in early to give the bike (and me) a break. I was running 93 octane pump gas.

So if it runs fine on 93 except when it's hot, what do I do when it's hot? I don't think that I want to run the race gas that you get at the track, since I'd have to fog the motor after each day, right? Can I buy gas that's like street gas, but maybe 95-96 octane? I see many "octane boosters" on Amazon, are any known to be especially good or bad, or are they all going to make my motor explode?

Thanks!

* http://www.nestreetriders.com/forum/...-sv-650-a.html

[Kurlon]

Skip the octane boosters, they're junk.

I'd wager you've got something else going, mayhaps a touch lean or you timing is a tad too advanced? Get it on a dyno and add some fuel, also check the condition of your cooling system.

[01xj]

94

[DroFiveOh]

94

[sedanman]

E-85 but you'll need a ton of mods to run it. As others have said, might be other problems that need addressing.

[bbhzx10]

When all else fails try 87.
Any idea what was done to the motor?

[Rambunctous]

Fogging before long storage. Cam 2 mixed about 5 parts 93 to 1 part Cam 2.

[Rambunctous]

Motors don't explode from too much octane but self destruct from too little octane.

[sedanman]

And running a higher octane does not give you more power. If your engine runs and doesn't knock on 87 run 87 if you have higher compression or an otherwise high performance engine, run higher octane.

[Kurlon]

Also - Not all fuels need to be flushed / etc. The non-oxygenated race fuels are normally safer for long term sitting in the bike, some safer than pump gas even. VP C12, Sunoco Supreme for example are both VERY high octane (approx 110) fuels with no oxygenators. They're very long term stable and not corrosive. But, they'll also make your bike sluggish and slow if not built for them. As noted, you can also mix fuels to hit a desired octane target.

That said, your bike was built for pump gas, find out why it's no longer pump tolerant.

[xsiliconkid]

Also - Not all fuels need to be flushed / etc. The non-oxygenated race fuels are normally safer for long term sitting in the bike, some safer than pump gas even. VP C12, Sunoco Supreme for example are both VERY high octane (approx 110) fuels with no oxygenators. They're very long term stable and not corrosive. But, they'll also make your bike sluggish and slow if not built for them. As noted, you can also mix fuels to hit a desired octane target.

That said, your bike was built for pump gas, find out why it's no longer pump tolerant.

The likes of C12 etc while not having the corrosive additives of more exotic oxygenated fuels.... they don't have any lubricants in the fuel (pump gas does) so the internal metal parts are scoured (by hydrocarbons) of any deposits that delay metal corrosion. Do need to be treated with fogging oil too.
Take a look at the cylinder walls with a borescope in an engine sitting for 1 week after using C12... there will be a light rust starting on the cylinder walls.

[CEO]

Huh i almost bought that bike a while ago, the one you linked... seemed like a nice guy. and that's a lot of bike for the money he wanted... esp. with the carrozeria wheels. I wasn't sure i wanted to deal with a built motor though.

The likes of C12 etc while not having the corrosive additives of more exotic oxygenated fuels.... they don't have any lubricants in the fuel (pump gas does) so the internal metal parts are scoured (by hydrocarbons) of any deposits that delay metal corrosion. Do need to be treated with fogging oil too.
Take a look at the cylinder walls with a borescope in an engine sitting for 1 week after using C12... there will be a light rust starting on the cylinder walls.

I thought since c12 is leaded that it helps to lubricate... an engine builder told me that is a reason to run it. And it burns cooler. was he wrong?

[Kurlon]

The likes of C12 etc while not having the corrosive additives of more exotic oxygenated fuels.... they don't have any lubricants in the fuel (pump gas does) so the internal metal parts are scoured (by hydrocarbons) of any deposits that delay metal corrosion. Do need to be treated with fogging oil too.
Take a look at the cylinder walls with a borescope in an engine sitting for 1 week after using C12... there will be a light rust starting on the cylinder walls.

Interesting, now I want a borescope, and I would be planning to fog my 250 if I wasn't going to be ripping the top end off this week. Thank you for the tip!

[caboteria]

Thanks, folks, that gives me a lot to look into. The bike has a power commander so it should be pretty straightforward to make the fuel/air mixture richer. Not sure what the options are for changing spark timing on a gen2 SV, though. Seems like there are a bunch of things to look at before going to higher-octane gas.

94

OK, but what's after that?

[Rambunctous]

The likes of C12 etc while not having the corrosive additives of more exotic oxygenated fuels.... they don't have any lubricants in the fuel (pump gas does) so the internal metal parts are scoured (by hydrocarbons) of any deposits that delay metal corrosion. Do need to be treated with fogging oil too.
Take a look at the cylinder walls with a borescope in an engine sitting for 1 week after using C12... there will be a light rust starting on the cylinder walls.

All the more reason to be on a two stroke. Already fogged.