URGENT - What fuel to use? Bored-out Honda GB single?

[sammcj]

Hi All,

I'm taking part in the Mods vs Rockers event here in CHCH tomorrow.

I have a 1986 Honda GB that I've taken out to 600cc+ and I'm not sure what fuel I should be using.

Kev at KG motorcycles who did the work on the engine said to run 95/98 or better. but I've heard elsewhere to always run it on 91'.

I understand the effects of octane in the combustion cycle but I'm still unsure what to run the 'big single' on, some times it feels better on 98 some times on 91 (perhaps this is more to do with the new carb having 'happy days' and 'sad days'.

What do you think I should put in it tomorrow morning before we head out on the ride, I need as much pep as I can squeeze out of her!

And any other tips / 5 min mods to make tonight?

-Sam.

[MSTRS:Me]

Rule of thumb...high compression/advanced ignition = high/er octane.
I think.

[onearmedbandit]

Running 95/98 won't damage your bike, and if that's what the engine builder suggests I'd go with that. If per chance you did do some damage by running 91 (say excessive detonation) and took it back to him upset and he asks you what fuel you ran, how much sympathy do you think he'll have when you tell him you went against his recommendations because you 'heard elswehere'?

[sammcj]

Thanks for the advice,

The engine builder himself did not seem too sure (which worried me a bit, but he's meant to be very good).
I've got a 1/3 91' tank left, so I'll fill the rest up with 98 unless I hear otherwise.

[gothavealaugh]

Got to agree go BP 98 do not run the Gull stuff as it has ethonal which can cause problems. Maybe try to find some AV Gas

[CookMySock]

Kev at KG motorcycles who did the work on the engine said to run 95/98 or better. but I've heard elsewhere to always run it on 91'.[/B]

Always follow the instructions from your engine builder, particularly if it has its' compression raised somewhat. 91 shouldn't hurt it though.

Don't use the ethanol blends, and dont put avgas in it, although a 100:1 mix of avgas and castor oil will add a great feeling to the event. Though I wouldn't thrash it running on avgas.

Only mods I'd do to it is spend all afternoon polishing it. Yum. Get some Turtlewax Ice.

Steve

[one fast tl1ooo]

50/50 av and 91