Fuels and high comp pistons

This may have been covered allready but ive had trouble finding a thread

Here goes anyway I have high comp forged je pistons
a cometic thinner head gasket
ported and polished head
is pump gas enough ? And is ethanol an option

Now pistons alone are 13.5:1 compression so need to calculate for the head gasket also .
Im running shell 98 or v power as much as I can bp 98 on the odd occasion

I understand ethanol has higher octane and also is more corrosive to rubber parts

Imo I shouldn't have to buy race fuel if I can make my own ethanol and blend with 98

And I did read the fuel truths thread im inquiring more about my specific
situation for my compression ratio

How does it run on the 98?

I think VP race fuels have a ratio for comp vs octain , 98 ron pump fuel is more than enough for 13.5 ,95 may be right up the ally for your comp ratio if you want the most .

this is something said buy a world record holder ,PS just tiring to help ..


The goal is to run just enough octane so that you don't kill power. The race gas burns at a highly accelerated rate. Added oxygen to aid the burn. In a 15 to 1 compression engine, Running VP Q16 116 Octane fuel would kill power. Q 16 is rated for 17 to 1 compression or higher motors. My 15.4:1 1427 is running 104 oct. Vp Mrx02.

First Question does it ping ?? if it does
You could try this had some success with the race 2 strokes

http://www.unitedpetroleum.com.au/unite ... remium-100

Thanks for the replies ive been off the road a few days with a leaky radiator
it runs average on 98 it idles a bit wack seems to either miss or knock a little bit and the valves seem slightly loud but that
could be due to heavier springs im searching for a station in qld that sells 100 but it seems ive missed the boat and I will try race fuel except it's my daily so if it has to have race fuel looks like itl be de regoed
has anyone actully had problems with ethanol enriched? And maxiumus I have also read that article hence im chasing anyone whos had experience with australian pump gas or ethanol on similar comp ratio and I havent tried 95 yet tbh im a bit scared to throw it in untill
I've tried the higher octane stuff and sulli thats the station ive been hunting just dont know if qld ones still sell 100

With the pistons & the thin head gasket, make sure the valves aren't kissing the pistons, that makes it sound like valve rattle, as you mentioned.
Elf 100+ would be what I'd be running.

To top it off , how much has the head have shaved ? You may have 14.1 + . Did you find out your actual comp ratio ?
Ps what bike is it, and do you run more timing into it ??

Ethanol is an alcohol so you will need to through it in the bike , with a ratio of fuel vs ethanol you will have to get the ratio's right .

Im picking ill be close to 14 with my head gasket being thinner I went cometic the one slightly above
the thinnest. its in a 636 and with the ethanol im thinking I might try mix my own 100
will have to do some research but cant be too hard to figure out im almost 100 percent sure 100 is 5 percent ethanol so for eg I have a 25 litre tank so I need 23.75 l of 98 and 1.25 l of ethanol
it needs a retune anyhow got sick of the secondry throttle bodies stuffing up so took them out lol so ill get an acurate reading than of the comp ratio. Will look into the elf 100 also

Im picking ill be close to 14 with my head gasket being thinner I went cometic the one slightly above
the thinnest. its in a 636 and with the ethanol im thinking I might try mix my own 100
will have to do some research but cant be too hard to figure out im almost 100 percent sure 100 is 5 percent ethanol so for eg I have a 25 litre tank so I need 23.75 l of 98 and 1.25 l of ethanol
it needs a retune anyhow got sick of the secondry throttle bodies stuffing up so took them out lol so ill get an acurate reading than of the comp ratio. Will look into the elf 100 also

Mate the only way you can check the comp ratio is with the motor apart , ps not trying to put ya down but you have to find out how much area on top dead centre combined with your bore to stroke ratio to get comp ratio ..
To make it easy just go 50/50 fuel/ethanol so you can work out the ratio's ezey ,ethanol runs 9.0 stioch where normal fuel is around 14.64 that cruise mode only ,under power 12.9 for fuel (in the real world) and close to 7.1 for ethanol .You may need bigger injectors thow..

Ahh blast! Well there goes that theory lol hence why I got someone else to build it xD
Just picked up 20 l of 100 from the station 10%ethanol so will be testing that tomorrow will
let you all know how it goes and yes I like the idea of running 50 50 I may need bigger injectors but I do have a power commander hopefully there not at max capacity as im sure there the same as the 1000s are they not?