Octane Booster

[Jpn]

I've only been able to find 87 octane ethanol free fuel where I live. I want to stick with ethanol free fuel so, is 87 octane good enough to prevent detonation during hot weather riding? Or should I add and octane booster chemical?

[RPM - Robert]

Should be fine stock compression is only 9.5:1 depending if you have the timing mod or nor.

[Pat Conlon]

For storage I run 87 ethanol free (clear) gas in my 1380 with 10.5-1 compression. It runs fine for short around town warm up rides. Long rides, hot weather I run 91 E10 gas, no problem....the E10 only plays havoc when I store my bike....I then drain the tank and go back to 87 clear gas if the bike sits for 2 weeks or more. 

With a stock FJ, the owners manual specifies using regular 87 gas. You should be fine.

Stock FJ factory jetting runs lean, when you get a chance remove the #37.5 pilot jets and put in #40 or #42.5 pilot jets and bump your mains from #110 to 115 or 117.5.
 Your bike will run cooler in the hot summer thin air high altitude Colorado locales.

Cheers

Pat

[Jpn]

Hi Pat,

After I bought the bike last spring I overhauled the carbs and installed a dynojet stage 3 Kit with 120 main jets and 144 pilot jets then tuned the carbs accordingly. Bike runs good as far as I can tell but don't have anything to compare it to. I havent checked plug color yet...

Would you suggest reverting to your recommendations?

Regarding octane I was running 91 on hot days and never had any pinging and wasnt sure if E free 87 was ok.

[Pat Conlon]

Hey John, Dynojet has their own proprietary jet sizes so disregard my Mikuni jet sizes.

I thought you had stock jetting. I think your Dynojet jetting should be fine.

Storing your bike with 87 octane ethanol free gas is fine. Short rides are fine.

On a hot summer day @ 5,500' the air density in Lakewood is low, meaning air flow for our engine cooling cooling is less, so in my opinion, I would avoid riding in summer stop and go traffic with 87 octane gas. Perhaps I'm being overly cautious.
Other folks can chime in....

If you want to do a plug reading, be sure to disconnect and cap off, the vacuum advance, pop in fresh plugs then ride to get the plugs to the proper color.

With the vacuum advance connected, you will find your plugs are white.... not an accurate color reading.

More info on the vacuum advance: https://fjowners.com/index.php?topic=11690.0

Cheers Pat

[Firehawk068]

I never had any issue running 87, or even 85 octane in my 1200.
I rarely ever ran 91 in it. Never noticed any difference in the way it ran with regular fuel or higher octane fuel, even in the summertime.
5600-feet here in Aurora.
Compression is a bunch lower at altitude, so you can run lower octane fuels.

I always stored it with "Ethanol-Free" fuel though........Makes a difference.

[Pat Conlon]

Thanks Alan!

[filsurs]

For storage I run 87 ethanol free (clear) gas in my 1380 with 10.5-1 compression. It runs fine for short around town warm up rides. Long rides, hot weather I run 91 E10 gas, no problem....the E10 only plays havoc when I store my bike....I then drain the tank and go back to 87 clear gas if the bike sits for 2 weeks or more. 

With a stock FJ, the owners manual specifies using regular 87 gas. You should be fine.

Stock FJ factory jetting runs lean, when you get a chance remove the #37.5 pilot jets and put in #40 or #42.5 pilot jets and bump your mains from #110 to 115 or 117.5.
 Your bike will run cooler in the hot summer thin air high altitude Colorado locales.

Cheers

Pat

I always use E95, no problems even after 6 weeks. Never had problems also with my BMW R1100RT,  Ducati 750 ss ie, suzuki  gs 750(1978), Honda vfr 1000 f and a suzuki 700 intruder. I would say, just use it

[Pat Conlon]

I always use E95, no problems even after 6 weeks. Never had problems also with my BMW R1100RT,  Ducati 750 ss ie, suzuki  gs 750(1978), Honda vfr 1000 f and a suzuki 700 intruder. I would say, just use it

Be careful of your terms. You are not running E95 95% ethanol in your bikes

You are using Euro 95 (E10), which is 95-octane gasoline with 10% ethanol added for standard petrol vehicles

Apples and oranges

[Billy Bananahead]

E10 has up to 10% ethanol while E5 has up to 5% ethanol here in the UK.
Most of the lads over here use E5 over E10 because it doesn't mess with the carbs rubber parts as much.
It is a bit more expensive but why use E10 when it causes problems.
I've left E5 in my tanks and carbs all winter without any problems though i do regularly fire the bikes up to stop any crystallisation in the carbs.