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xs400 what octane level should i use?


socalyamaha
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(octane level)

87?

89?

91?

I've used all 3 and can't tell the difference, so I stick with the cheapest.

handbook just says regular or low lead fuel

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I've used all 3 and can't tell the difference, so I stick with the cheapest.

handbook just says regular or low lead fuel

Well I still have the original sticker under the seat on mine and it states 91 octane minimum. Being as the spark advance is not computer controlled I would suggest that 91 be the minimum used. I personally run the highest I can find and I CAN hear and see/feel the difference. I get some pinging on anything less and gas milage is better with 91 than 87.

Oh, it states leaded regular also, but I have been told that the valve seats are hardened so it can handle unleaded just fine.

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Well I still have the original sticker under the seat on mine and it states 91 octane minimum. Being as the spark advance is not computer controlled I would suggest that 91 be the minimum used. I personally run the highest I can find and I CAN hear and see/feel the difference. I get some pinging on anything less and gas milage is better with 91 than 87.

Oh, it states leaded regular also, but I have been told that the valve seats are hardened so it can handle unleaded just fine.

They are built to use unleaded, must be your locale.

I thrash mine and never get pinging. I regulary do 80+mph on cheshire A/B roads (weather and cameras permitting) and it never fails or throws a wobbler.

I do keep it in tune though

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They are built to use unleaded, must be your locale.

I thrash mine and never get pinging. I regulary do 80+mph on cheshire A/B roads (weather and cameras permitting) and it never fails or throws a wobbler.

I do keep it in tune though

California has garbage gas. They put stuff in it that eats the fuel delivery system. When I put it back together the carbs were it pretty good shape at first, as I had prepped them before storing it.

Then I checked them and put fuel in the tank (after getting everything else ready first) and started her up (started on the third try cranking her) and everything ran fine. Things rapidly went downhill, and I pulled the carbs to check things out and found that the pilot plugs (idle pilots on the 80's have a rubber plug in the bowl and pull fuel around another way) and the plugs were gone.

A bit later (after I jury rigged some plugs) it started flooding and pulled them apart again and the o-rings on the needle valve seats were basically GONE! Turns out the stupid CA gas dissolved them. I got carb kits from Mikes-XS (plugs and all) which are designed for the modern gas and now it runs quite nice although it's still lean and I haven't drilled out the plugs to adjust the mixture yet (but it's running pretty much like it did new so I can't complain to much).

I'm guessing you guys don't have that stupid MTBE in your gas, and that stuff make the gas milage go WAY down (about 25% on my Camaro) and is pretty caustic. Of course I plan on getting new Star 1300 next year, but I'm not getting rid of the XS, I'll just go through and do a proper full restoral so it looks like a new bike. That should be quite fun I'm thinking.

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