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VP C-12 and a CB 350

815 Views 7 Replies 3 Participants Last post by  jbranson
Has anyone tried running this in a stock CB 350... is it good, bad, or no difference ?


J "not that" D
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I run VP-C12 in our race bikes...both have somewhat higher than stock compression and some pretty radical timing (45-47 BTDC fixed).

Actual compression on stock engines is around 8:1 regardless of what the manuals say. Our race engines are probably in the area of 9.5-9.75:1. So...we don't need the octane of C12 but I like the way it behaves in the bike. It's more forgiving of small jetting errors, it runs more consistantly throughout a race...even when the engine gets very hot. It seems tolerant of just about any weather/atmospheric conditions.
Downside is heavy exhaust valve deposits and it doesn't like to be used if you are just going to putt around. It performs at it's best when you are running the engine very hard. I'm thinking of mixing with some U4 to try to lessen the valve deposits. It's serious race fuel meant for engines that they figure will get torn down pretty often so to them valve deposits are no big deal, as they will be removed every race or two.
I've also used the NHIS track fuel for numerous bikes both almost stock and heavily modified...seems to work decent.
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That's kinda what I was hoping...that mixing with standard race fuel would clear up some of the deposits. But...fuel mixing is strange, and not never know what you'll end up with.

I'd think on a stock engine the best bet would be the trackside fuel. It's leaded, around 108 octane I think. The higher octane may cost you a tiny bit of power, but typically the other additives will help keep the engine alive.
Don't get me wrong...C12 is not going to hurt a stock engine. And might go a ways to protecting the top end. The valve deposits don't become a problem until after a few races...even then it will depend...every engine is a bit different. And by "problem" I mean reducing exhaust gas flow maybe 10-15%....I'm guessing a stock engine has exhaust flow to spare in the port.
Don't worry about it, use it...and you don't have to worry about having decent fuel in the bike, you'll know you have some of the best.
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