Should I be running 89 or 91 fuel in my 900ss?

[jordan]

After the tragic loss of my VFR, I bought a 99 Ducati 900ss the other day. Damn it's fun to ride! My friend suggested I run 89 fuel instead of 91 becuase of the 9.2:1 compression ratio. Any opinions on this?

Thanks,
J

[afm199]

Run what the manufacturer suggests. Due to combustion chamber and head shape, cam timing, the octane requirement for a 9.2 to 1 may be higher than a 10.5 to 1

[jordan]

Run what the manufacturer suggests.

Hmm the manual states 95-98 RON. so according to this chart (http://www.desmoducati.org/octane.html) I could use 89 or 91?

[afm199]

sounds right to me

[monstermonster]

It's a longstanding debate and you'll get a number of answers, ranging from 87-93. Conventional wisdom says run 87 unless you get pinging. There are plenty of high mileage 2V 900 engines out there that have been runnin' 87 their whole life without nary a problem. OTOH, there are plenty of strong opinions that insist that you HAVE to run 89.

Personally, I ran 87 in my monsters until I installed hi-comps. Now it drinks 91.

[jordan]

sounds right to me

Thanks Afm, I guess I'll just stick with 91

Cheers,
Jordan

[jordan]

It's a longstanding debate and you'll get a number of answers, ranging from 87-93. Conventional wisdom says run 87 unless you get pinging. There are plenty of high mileage 2V 900 engines out there that have been runnin' 87 their whole life without nary a problem. OTOH, there are plenty of strong opinions that insist that you HAVE to run 89.

Personally, I ran 87 in my monsters until I installed hi-comps. Now it drinks 91.

Thanks for the info!

[Aluisious]

You only really need high octane fuel in a racier engine during peak power conditions anyway.

If your bike is marginal on 89/91 and you're just going around town, you'll be fine with the lower rating.

[My900ss]

I have 50k miles on my 1995 900ss SP. I run 89octane and have since I bought it with 12k miles. No fuel related issues at all.

[paunchy]

+1 for 89

20,000 ping-free miles on my '99 900SS with 89 octane (almost exclusively Chevron)

[jordan]

Been running 89, seems fine Ill stick with it.