which octane grad is best for the max?

[firefly]

When I bought my new 03 max I naturally wanted to put the best fuel available so I filled it with 98 octane or the highest available, but after asking the service manager at Yamaha I was surprised that he recommended the lowest grad 87 octane.
So I did some research and found out the following.
1- Octane is to prevent pre-ignition in which the fuel ignites prematurely as its being compressed while the piston is ascending, so octane delays that combustion until the piston is all the way up and the spark strikes, this kind of high octane is usually recommended for high compression engines which a stock max is not.

2- The 87 octane is the grade to use for a stock engine max, it actually ignites faster than the higher octane gas
Now if you have a modified engine with high compression use higher octane otherwise a high octane grade will make your max run like shit, and I experienced that first hand
firefly
________
herbal vaporizers

 

[KRL0215]

yeah 87. Plus its cheaper too!

 

[Calimus]

I toss in a tank of premium every great while just to treat the bike a bit. However, I have found that the max seems to like the Chevron Techron fuel a bit more. I've had the same results with my VW's as well. Techron seems to clean aid my older cars a bit.

Still mpg on the max always very's depending on the input from the right hand.

 

[one2dmax]

I toss in a tank of premium every great while just to treat the bike a bit. However, I have found that the max seems to like the Chevron Techron fuel a bit more. I've had the same results with my VW's as well. Techron seems to clean aid my older cars a bit.

Still mpg on the max always very's depending on the input from the right hand.

There is absolutely no reason to "treat" the bike with higher octane. You essentually are giving it gas that is harder to ignite and thus creating more carbon deposits on your valves and pistons.

Run the lowest octane fuel you can run without experiencing detonation. 87 is the lowest most will find though 85 will work even better. Even my higher compression bored out engines run fine on 87 gas.

If you get into power adders than the additinal octane can give you a safety buffer for rapid changes in cylinder conditions and the extra unbuned fuel creates a cooling effect. But, economy and long life aren't the goals in those applications.

Techron is a very good additive (comes in the fuel aready but sold seperately) that cleans the carbon crap off. It and the product Seafoam are very worth running through your tank occasionally.

With proper tuing 40+ mpg is well withing reach.

Sean Morley

 

[mabchewy]

I can get 40+ mpg out of my 2000 on 87 with no problem!

 

[Waylander]

Glad I found this thread before riding my max some 1,600 miles or so to get it home...

Though lowest octane I've seen available down here is 91.

 

[Rusty McNeil]

My guess is that due to the fact that bikes are so light the load is relatively very little compared to what the compression ratio would normally call for in a car.
This would allow a much lower octane to be run without detonation.
11 to 1 in a 3500 lb car would need high octane but 11 to 1 in a 600lb motorcycle would not.
My observation has always been that max power is made when right on the ragged edge of detonation whther it's due to higher compression, lower octane or more advanced timing.
octane is a combustion inhibitor that slows down the burn to stop detonation.
The faster gas burns the more power it's going to make.

These are just my opinions though

 

[one2dmax]

Weight has nothing to do with it. Timing, Ignition, Quench, and other factors have a lot to do with it. These engines much like many made similarly (aluminum heads and good cooling systems) can handle lower octane simply due to the lower cylinder temperatures that tend to make fuel spontaneously ignite which is what causes the loss in power and eventualy component failure.

Many properly setup car engines (including big blocks) can run lower octane and higer comp ratios with the right setup. You would be suprised at how high you can run the comp ratio on these engines with even just pump gas.

Now, if you really want to get the ratio up there (or advance the timing and cam profiles) you can set the engine up to rin the new E-85 which has a rougly 110 motor octane rating. Of course you wouldn't be able to swap back and forth without re-jetting each time.

Sean Morley

 

[mkunert]

I'd love to run the lower octane, but only the premium gas has no ethanol in MN.