AV Gas vs. Petrol

[cowpoos]

Twostrokes dont need high octain gas what do you think happens when you add oil to gas it lowers the octain 95 or 98

it raises the octane....oil is a very slow burning....much slower than diesel....and deisel is up around [dont quote me on this] about 170-180 octane.

[IronicCapers]

Theres a differrence between diesal and petrol. In diesal engines they use compression to light the fuel, so the diesal engine will detonate every single time hence why diesal engines look bigger than petrol engines of the same size. Petrol burns slowly and it shouldnt detonate at all in the combustion chamber, if it does theres something wrong with your engine or fuel.

Some people mix av gas and 98 octane dont know the ratio but apparently it works nicely. Not sure on performance gains but do you really need it if your just a trail rider or a clubman.

Diesal isn't rated the same way as petrol is there is a different rating because it burns quicker i think. THE HIGHER THE OCTANE THE SLOWER IT BURNS!!!

My advice is to use a good quality 98octane fuel with a good oil i recommend motorex or mobil 1 two stroke mix.

[Krusti]

Years ago the old man had a newish honda accord..filled it up with deisel at the farm by mistake,prob half tank petrol allready in the tank. Car was on LPG as well so he'd start it and warm up on LPG then switch to the tank. Smoked like shit but used it.

That car did 300,000km before he sold it! A true story!

[sugilite:Me]

so u reckon run about 98-101 octane then?

most those bike just need normal pump gas...best run 95 in the summer...and up to u in the winter really....as bike will run cooler anyway...

Yep, I'm really only thinking racing purposes, anything else, just stick with pump gas.
When I supermoto'd the KX500 I learnt the hard way that I needed decent fuel.

Most of my info came from Robert Taylor. He seemed to have a shit load of knowledge on the subject.

[speedpro]

My current bucket is a 2-stroke and revs to 11,000rpm, the sidecar which had a similar 2-stroke ran to 14,000+rpm. They were tuned for 100 octane and would damage pistons in a short time on pump gas. If the compression hadn't been so high we probably could have gotten away with 96. If you want more consistency than pump gas then use either mega $$$ racing fuel or avgas/100octane. If the engine isn't tuned for it don't waste your time or money. Bucket guys with tuned motors using pump gas will every now and again have a piston fizzle away. Even if the motor has previously been just fine. The only variation has been a new can of gas from the petrol station. Ideally you'd want to change your ignition mapping putting in more ignition advance in the midrange. I played round with that on the dyno with good results. Big gains in the midrange with the same top end.

[cheese]

shit, I always thought the higher the octane the better for the bike I'll go back to normal pump stuff.

[vifferman]

shit, I always thought the higher the octane the better for the bike I'll go back to normal pump stuff.

Common misconception.
I guess people go, "Ooh! Higher numbers, must be more powerful!"

[Ivan]

I know of a guy who mixes Methanol with Wairarapa pump fuel 96??? and runs it in his scooter and in his RM250

[MSTRS:Me]

I know of a guy who mixes Methanol with Wairarapa pump fuel 96??? and runs it in his scooter and in his RM250

Hmmmm...never heard of that. Does he have a problem with corrosion esp in his carbie? Methanol is veeery corrosive & has a high water content - not good to leave it sitting in the 'works'

[IronicCapers]

Hmmmm...never heard of that. Does he have a problem with corrosion esp in his carbie? Methanol is veeery corrosive & has a high water content - not good to leave it sitting in the 'works'

For sure. I think metanol has bad effects on rubber hoses and plastic tanks 2(not sure).
And why bother screwing round with the expensive stuff when your engine isn't tuned to it. Cause dam aint fuel fukin expensive.

Funny how the fuel price goes up quickly and stays high but goes down very slow....wait im wrong very very very very very very very very slow. Greedy fukers!!!!

[speedpro]

Methanol "might" mix with the new pump gas but not with the old leaded pump gas and 100 octane without a little help from something like acetone. I think the current pump gas has a lot of toluene/toluol in it which might help blending but even with that in my turbo bikes fuel it still needed about 500ml of acetone for every 20L of mixed fuel for everything to blend properly. It is a total pain in the arse on the race bike mixing it all, I can't imagine why anyone would bother on a road bike. I used to add Toluol to 96 octane and methanol and then blend it with acetone. Mixing methanol and petrol can play merry hell with seals and fuel lines as generally rubber is EITHER methanol OR petrol proof.