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Anyone put 111 octane in their older bike? I have a CB750K5 and someone was telling me to run the race fuel in there. They are not mechanic but they do work in the auto industry.

Any thoughts about it from this fourm?

I have put it in my WR250F and it makes a difference.

If I put it in the CB, would that change the carb tuning?

Thanks
 

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The higher the octane, the more the piston can compress the fuel before it ignition by the spark plug. If your fuel is going bang before the ignition fires off the fuel - that's call pre-ignition which is harmful to your engine. Since the cb750 engine is low compression to begin with and you don't have pre-ignition happening then it would be a waste to spend that kind of money on the fuel. High octane will not do anything for a cb750 operation.
 

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in addition, some race fuels are extremely hard on seals and seats too. I know that the ultimate 4 stuff from VP, you are supposed to drain your tank and carb after use, and run some 93 octane pump gas through it (just at idle) before you store the bike. The ultimate 4 will literally eat your carb. A good rule of thumb is, stock motor, stock gas.
 

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SOHC cb750s were built when bikes were a usefull tool not a high performance machine only. They have fairly low compression (9:1) and run excellent off 87 octane (provided the weather is not to hot). Honda knew that this bike had to run in all markets where premium fuel would not be available.

I run regular in my K5 whenever the weather is below 72 degrees F and I am not going into heavy traffic. If I know there is a posibility that the engine will run hot (like manhattan stop and go) I will run premium (92 or 93) to stave off detonation.

Anyway, running 111 octane in your honda will not help performance, it will only hurt your bike. 111 octane is a leaded fuel and a lot of old car guys think that because something was made in the 1970s you must run leaded fuel (because the lead helps harden the valve seats). With honda bikes unleaded fuel is the way to go and leaded fuel has no real positive effect.

Tell your buddy he should stick to cars.
 

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I have a '70 CB750. Bone stock. I was riding it to work etc. I looked ithe tank one day as I was getting readyy to go to work and saw it was close to empty. I dumped a couple of gallons of VP C12 into it and took off. It hated the C12. 12.5 miles each way to work. On the way home it fouled a plug. Dumped the gas and went back to regular and no problems.
 

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I ran C12 in my RC51 once....same deal, fouled the plugs (Iridium) so bad I had to replace them.
Race fuel is that....race fuel. I use C12 in the race bikes and they love it, they don't need all the octane...but they seem to like the temperature stability, consistancy etc.
JohnnyB
 

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"I know that the ultimate 4 stuff from VP, you are supposed to drain your tank and carb after use, and run some 93 octane pump gas through it (just at idle) before you store the bike. The ultimate 4 will literally eat your carb."

i never had any problems with it leaving it in my carbs.....now this was the original formulation and not the new stuff. i was/am too lazy after the last race of the year to go through the extra steps. always ran fine in the springtime.

tex
 
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