For you feejers at altitude ...

[jimbemotumbo]

I've been using the plain jane high altitude 85 octane in my 06 with nary a problem, until it got hot.

With the temps in the mid 90's all week, and while riding in traffic, I've noticed the occasional detonation on take off. It's very slight, but I'm a notorious motor geek and hear everything. It's there.

Always wondered whether the state was giving us a line when they stated the 85 octane at higher elevations was the same as the 87 at lower ones. Now I know.

 

[joelmoto]

Hi...I'm curious and confussed...this is an interesting topic because I've always believed that standard 85 was ok for my 06 FJR in all conditions. I never noticed any pinging or any anomalies.

Can you notice a difference at sea level between the various grades?? Can you elaborate??

Thanks

 

[Ignacio]

I've always believed that standard 85 was ok for my 06 FJR in all conditions. I never noticed any pinging or any anomalies.

Short answer:

Actually, you understand it perfectly. If it doesn't ping you can use the lower grade. No reason to put a higher grade in as you're wasting money It doesn't get any simpler than that.

Longer answer:

The 85/87 thing comes into play in differences of altitude where compression changes different. An FJR has the same compression ratio, but the overall compression is less with more altitude. The fuel industry has figured out that a car or bike or FJR at sea level that requires 87 octane would only require 85 octane over a certain altitude. 3.5% less compression per 1,000 feet of altitude.

Moving perennial thread to it's new home.