Octane? Timing?

[HardLuck]

So tonight I change my sprocket from a 14t to a 13t after taking off the side case off I found out my bike has a timing plate and its set at +5.....The guy I bought it from knew nothing about what was done to the bike so I'm slowly finding out the details of it....Question is the bike has a K&T cool head, aftermarket carbs, +5 timing.....What octane should I run in the bike? I don't know what size domes it has yet cuz I haven't taken the head off..........Any help will be great!

 

Thanks!

[GrMeyer]

What was ran before for oct?

[Profilact]

Do a comoression test to be sure....

[baker]

the timing shouldnt afect what octane ya run, its all in the dome size or compression,150 or lower pump gas, 150 id run a 50/50 race to pump, over 150 race fuel all the way

[bansheesandrider]

Timing will affect what octane you should run. Advanced timing can lead to preignition and higher octane fuel will prevent that. Higher compression lead to detonation and higher octane will also prevent that.

[sleeper06]

Timing most certanly afeects it

[firebanshee]

I would set the timing at +4 unless you want more for a specific reason, +4 seems to be the sweet spot for pump gas.

[HardLuck]

Thanks guys....So far I've only rode about a half a tank of 91 threw it but I did notice while climbing hills there was a slight pinging but only while climbing....So I'm gonna do a compression test today and may go get some 100octane