Need Professional Opinion (Compression & Octane)

[Aikaru]

I'm currently re-building my top end 80cc engine. I'm installing an expansion chamber exhaust, and one of those square high compression heads. I was planning to run 87 octane on it with a 32:1 ratio of gas and oil. However, with some thinking, I wondered if the new exhaust and the new compression head will cause detonation with 87 octane fuel. Should I go to a higher octane? If so what octane should I go to? I want to make sure this engine performs perfectly. Thank you.

 

[Frogslayer]

You may be just fine with 87. It really depends on what your compression ratio actually is and what plug you run. Is 91 or octane booster available? You'll hear it knocking or pinging if your getting pre detonation.

 

[Aikaru]

You may be just fine with 87. It really depends on what your compression ratio actually is and what plug you run. Is 91 or octane booster available? You'll hear it knocking or pinging if your getting pre detonation.

I can only get 89 or 93. Octane booster is available though. I'm not sure what my compression ratio, but if this helps, I'm using a copper head gasket and torqued the cylinder head bolts to 15 foot pounds. I run an NGK B6RHS with a stage 1 NGK performance CDI system

 

[Chainlube]

When you get it all together, mix your gas and oil 20:1 for break in with some good quality dino oil. Once everything is good and black from the oil, wash it all off with some carb cleaner and then you can change to 32:1.
Watch the young lad on youtube take the alcohol from regular gas and use that for your mix.

 

[DieselTech]

I'm no professional by any means when it comes to these 2 strokes, I run 91 octane or plus due to the fact there's no ethanol in the fuel. 87 & 89 octane in my parts have up to 10% ethanol. The ethanol is very hard on carb seals & gaskets.

 

[Chainlube]

 

[Aikaru]

I use Startron in all my fuels which basically keeps the ethanol from separating from the gas and wreaking havoc on seals and such.

 

[Aikaru]

When you get it all together, mix your gas and oil 20:1 for break in with some good quality dino oil. Once everything is good and black from the oil, wash it all off with some carb cleaner and then you can change to 32:1.
Watch the young lad on youtube take the alcohol from regular gas and use that for your mix.

I’m using some classic STP Dino oil for my break in. I believe my previous break in attempt failed also because the rings did not set properly

 

[Karl Snarl]

87 is what you want, and any oil you wanna use, at any ratio you want. I've used syn, dyno, bean, for break in and it never made a difference. Rings always seat about the same time. Just jet correctly. I sometimes run 24:1 if I plan on beating the snot out of my bike. If not I run 32-40:1. I'll break it in with one tank on a 20-24:1 mix, even used castor to break in with no ill effects. It's how you ride it on break in that counts, the extra oil just flushes the particles out, wets the bearings, coats the inside, and helps seal the rings.

 

[Chainlube]

I use Startron in all my fuels which basically keeps the ethanol from separating from the gas and wreaking havoc on seals and such.

Still better to remove the alcohol than bandaid stabilizer. Besides, water is free.