Ethanol corrodes the aluminum inside the carbs, especially the bowl. You probably won't notice it if you run the bike regularly, but its best to use ethanol-free petrol if the bike will not be run for months at a time. Otherwise, its best to drain the fuel out of the carby. Word of caution - draining the carby works fine as long as the bowl is clean. Any debris left in the bowl will most likely form deposits in the fuel passages at the bottom of the bowl when it dries.
ethanol fuel in any tank should always be treated with a product like Star Tron especially if you like ridin' better than wrenchin'. If ethanol sits too long it collects together like flies on s#%t. Half the bikes in the shop have had my hands in them chipping out this political blunder of a fuel from tank to jet- Corn should only be used for tortillas and feeding hogs.
My 2 cents
Excellent advice from the guys. I would also add that ethanol appears to increase rate of breakdown of rubber/nylon etc seals. That is our experience with 3 TTRs (1999, 2004, 2005/6) in family. But all bikes bought secondhand so not sure of their maintenance history.
I like TexasT's comment about "tortillas and hogs" 😬
I've kept away from E10 fuel in my 1999 TTR.
Give me good old mineral-based petroleum/gasoline any day.
Cheers
Jeff