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Discussion Starter · #1 ·
hi guys,

for those of you running 1216 or other big street engine kits, do you have to run race gas or can premium pump gas be used without detonation problems?

thanks,

dum dum
 

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I don't have a 1216 in mine, but the size of the motor doesn't mean `nuttin when it comes to what kinda fuel to use... it all depends on how much compression you're runnin'. Most of the people that I speak with agree that 11.5:1 or perhaps 12:1 is about the limit for pump-gas on the oldskool motors.
 

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Fastcat's right (as usual) in the fact of Displacement has nothing to do with Race fuel. In high compression engines you need Octaine to reduce detonation. High octaine can be found in some race fuels but not all. I have been running my high compression 1216 in my 90 at 5 to 1 (5gal of supreme with 1 gal of Nutec) Nutec race fuel is not high octaine but has unique additives (and at 225.00 for 15 gal in Alaska it better) but the 90 has never run better. I am planning to switch heads to get the compression down to 11.5 or 12 to 1.
Bones
 

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Originally posted by FastCat:
the size of the motor doesn't mean `nuttin when it comes to what kinda fuel to use... it all depends on how much compression you're runnin'. Most of the people that I speak with agree that 11.5:1 or perhaps 12:1 is about the limit for pump-gas on the oldskool motors.
<font size="2" face="Verdana, Arial">DITTO You said it all
 

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yeah but you guys didn't even hit on total timing advance and that jazz. You can get away with it even in the higher compression motors in an emergency if you have adjustable advance ignition like Dyna,shnitz. But ditto the other posts keep the comp. down to 12:1 or less and premium should be fine. I wouldn't suggest any thing less than c16 if you plan on adding NOS.
 

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Discussion Starter · #6 ·
i agree that displacement has no correlation with compression and therefore octane requirement. i haven't done any research into the 1216 kits and just assumed (apparently incorrectly) that the bigger displacement kit pistons might be higher compression by design. i guess from what you are saying, this is not necessarily the case.

wild bill, are you saying that a high compression motor with adjustable ignition could work on pump gas in a pinch? is that by increasing or backing off the advance?
 

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Now that we've gotten the opinions out of the way, maybe we can address your actual question
... I've run my B12 as 1157cc x 11:1, 1216cc x 10.6:1, and 1216 x 12.2:1.

The stock-bore 11:1 and 1216 x 10.6:1 combinations were perfectly happy on pump 89 and pump 93 using the stock spark box with a +5° reluctor... I don't know what the total timing was with that setup. The 1216 x 12.2:1 combo ran pump 93 with no audible pinging with both the stock spark box/stock reluctor and with a Dyna2000 set at 35° total.

The 12.2:1 setup would tolerate pump 89 in a pinch but you had to be gentle with the throttle... I only did this a couple of times out of sheer necessity, and topped up with 93 as soon as it was available. If I let the 12.2:1 combo get too hot in traffic it'd **** a bit until the temp came back down.

Camshaft profile is an important factor in whether you can run pump gas with a high CR... the 12.2:1 cams were fairly lively and set up with quite a bit of overlap; I dunno if I'd have been able to run as easily with pump 93 on GSXR cams or the very mild OEM B12 grinds.

Running C12 in the 10.6:1 bike cost me 3 to 4 mph in quarter-mile trap speed compared to passes on pump 93... I didn't get the chance to make the same test with the bike set up at 12.2:1.
 

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That's some weird shit.. I typed the word "p-i-n-g" above, and got a row of asterisks in the post. ****
<font size="2" face="Verdana, Arial">Oh, that's nothing, it just means I will be abducted by aliens again on Monday.
 

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I'm at 12.7:1 and run 91 premium. I can get away with this because of the altitude, I'm at 5280ft. If I go to say Phoenix / Vegas it's strictly race fuel. I have Yosh stage 2 cams stock 91 box(V&H but it is all set to stock) 2deg advance at the crank.

[ 11-02-2002, 11:43 PM: Message edited by: Yosh ]
 

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i had a je 1216 kit in my old bike. it was a 12:5:1 kit from ape. it would run fine on 93 octane. but i ran it with 108 vp racing fuel and pump 93 mix.
 

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i had a 1216 and ran it on only sunoco gold 94...i put 35000 kms on that bike...bulletproof i say!!!!
 
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