Silly gasoline question.

Now, I might be mistaken as I don't have the book in front of me right now, but I'd swear that the owners manual I just paid Yamaha $25 for says that the '82 XJ650 is supposed to use *leaded* gas?!

Assuming this is the case and I didn't simply have a brain fart as I was reading, what impact is there on the engine to using standard unleaded at this point? Do I need to be using a lead substitute in my gas? Etc.

Mike

 

No, unleaded is fine.

 

The only reason i burn 87 octane these days is because they dont sell an 83! lol

 

i wish they sold leaded fuel at the pumps! the race fuel we run is heavily leaded, and heavily oxygenated too......but i wont be runnning that in the bike because its $12 per gallon.

what is actually in the "lead" additive bottle that makes it a sufficient leaded fuel substitute? just curious...

 

Biff, your bike should be just fine with unleaded fuel. I and many of our clan have run our machines with it for years with no detrimental effects.
Remember, that owners manual was written back when leaded fuels were commonly available. Your only concern is ensuring that you match the octane rating to manufacturer's specifications. Seeing you are in the US, you should have no problems running 87/89 in your machine. I would avoid E-85.

 

Thanks all - I couldn't remember what purpose the lead served ...

Think I have gotten my carbs all ready, will be able to test tomorrow ... found one enrichment circuit blocked as well as the jet furthest from the float needle blocked in another carb ... I can't wait to get home and finish hooking it up!!!

Michael

 

The lead was added as a way to boost octane rating cheaply. Specifically, it was tetra-ethyl lead that was added to the fuels. It was then noticed that the lead collected on catalytic converters and also seemed to be a bit toxic in high concentrations. Today we have ethanol (and MTBE in some areas) to raise the octane of the fuel and to oxygenate it.

 

Octane is the amount of knock resistance for a given fuel. As mentioned above this was done by adding lead to the fuel. The lead had a second benefit as a lubricant. This was particularly beneficial to the valve seats, which were pretty soft in the old days. Makers of automobiles and motorcycles knew that unleaded fuel was coming long before it went to market and began using hardened valve seats sometime in the early seventies. I used to could tell you when, but it hasn't come up in several years. You should not need to use a lead additive in anything that was made to run on the road after about '73 or '74, even then, only to protect the valve seats. If knocking is the problem, the better solution is a higher octane fuel. Boats that used four stoke engines were very slow to go to hardened seats, and I used to put an additive in the fuel for an old Mercruiser I had because of that.

Incidentally, ethonal has lousy anti knock properties. The first blends that came to market pinged and knocked terribly, and many of the cars at the time ran poorly on it. Computer adjusted timing and knock sensors have alleviated a good part of that along with more intelligent blends.

 

While tuning the 900 filled with regular gas bought from Gulf marked 10%
Ethanol ... I got to a point adjusting the Mixtures where water was pouring-out the Bleed Hole at the head of the silencer.

I'm stepping up a grade of gas and not using regular in my bike.

 

As a rule, always use the lowest octane you can without your engine pinging/knocking UNLESS it states that you need to run Premium. This would typically be in a higher compression automobile engine.

As Mbrew stated above, Octane is a measure of knock resistance of spark ignited fuel. The higher the number, the less likely it is to ignite when compressed. It also seems to take more energy to ignite the fuel. So, if you need to run premium, make sure your electrical system is up to snuff. Or spark as the case may be.

Oxygenated fuel just means that an Alcohol, either ethanol or methanol, has been added to the fuel as a means to increase the Octane rating.

 

Thank you all for your comments.

Mike

 

my seca seems to run way better on 93 octane and sometimes i like to go get some dirt raceing fuel 110 octane it is leaded and the bike runs awesome on that stuff but it is expensive

 

I have no scientific explanation for why it does but ...

Both my bikes run better on Premium Fuel.
Especially the 750 Maxim.

The Max will knock on Mass Regular.