What about octane????

[sandpuppi101]

This is kinda a runoff from another thread ,where trike mike was having carb problems,but in the thread we bumped the subject of octane.My particular setup is a '85 250R ,pjk 39mm carb,rad valve,FMF fatty,port job,and a k&n filter with no airbox.Mostly I run a BR9es plug and about 110-117 octane.{Turbo Blue with nos additive}Let me tell ya in the summer it dont take long and she is hot.I guess my question is what octane do you all run in your hot rod 2-strokers and what kind of setups do you have for running your particular octane.Not so much with the alchy burners with lectron carbs but the souped up R's and Z's and tecates.I think this could be very interesting!

[nate b]

why do you run 117 octane fuel?
my 85r runs just fine on 93 octane and i have almost 200 psi cold compression.

[sandpuppi101]

There is a couple of reasons that I run the 117,First off being that me and some riding pals pitch in on quite a bit ,several times a year and that it it easily accesible for us to get it.It is 110 then we put in the nitrous additive.Second would be that I can tell that with the higher octane I use,the throttle response is more crisp,real snappy.The lower 93 or 97 octane is fine in my R but I can tell the difference.Its kinda like I gotta keep up with the Jone's!LOL I don't want to get beatup by Banshee Boys!

[hrc85250r]

hahaha, banshees dont have a chance dude...you know you can smoke them :cool:, i run cam2 mixed with ultra and its around 104 octane or around there, i have 210 static psi and i dont know if i need that much octane, but id rather be safe than to have a piston in pieces in my expensive motor....my motor has about the same mods as yurs sandpuppi but i shaved and reshaped my head and i run the cr gasket too, that were i get the extra psi i think...

[HRC1]

Has the head been shaved at all? Or are you running a thinner head gasket?
All octane is, is a resistance to detonation /pre ignition under comp. And the less octane you can run in a motor, the easier it is for the motor to burn it. You actually loose HP with race gas unless you need it. I run 87 0ct in my 85 250r with 0 problems, and it has a fresh piston. Stock compression is only like 8:1 or 8.5:1 if i remember correctly. Unless it's spark nocking, i'd use premium at max.

[Dammit!]

Is there anything to watch for on your spark plug that will tell you if the octane you're running is too high or too low?

[nate b]

my head has been milled, I also have access to 110 octane right at the pump about 5 min from my house. dont get me wrong I LOVE the smell, but you wont gain any power by running it. alot of my buddies always go fill up with it before a race.

[nate b]

Is there anything to watch for on your spark plug that will tell you if the octane you're running is too high or too low?

aluminum would be a bad sign, but i believe that you go by the ground strap, where it changes color. it should be close to the bend.

[1984kxtTECATE]

I usally run 93 octane, I got my sprocket and chain put on with my extended swinger and let me tell you, 1st gear I was burning out on the asphault, occasionaly I will run NOS octane booster, but 93 seems to do fine with my port work and other motor mods I have. If your spark plug is all white your running hot and lean, if it is black you are running rich, the ideal spark plug will be dark brown in color.

[asc180]

My Z is ported & poslished, head shaved .020, and bored 80 over and I have ran race gas and premium in the same day and have not noticed a difference other than my pocket was a little lighter after the 2.99 a gallon race gas.

[sandpuppi101]

When I am running the high octane fuel I always play the plug game,as I call it.I do sand hill climbs with it and am about 210 so I need all I can get.LOL.I usually make about 3 runs and then shut her down,check the plug and let her cool down.I always look for the golden tan to light brown,and I lean the oil mixture also ,at @ 2oz per gallon which would be about 56:1 or in that ballpark.I have raced with the lower octane fuels 93-97 or so and I seem to loose the toppend at the top so much that I have to dump it a gear, but not so on the good stuff at the same mixture!

[HRC1]

Is there anything to watch for on your spark plug that will tell you if the octane you're running is too high or too low?


Try this link, he is the god of small engines. http://www.strappe.com/plugs.html

[shudup]

My Z is ported & poslished, head shaved .020, and bored 80 over and I have ran race gas and premium in the same day and have not noticed a difference other than my pocket was a little lighter after the 2.99 a gallon race gas.
where are you getting the gas that cheap? and what octane is it?
I mostly buy mine at post drive gas station on my way home from GR
its 3.59 for 104 nolead and 110 leaded

[Dan Tenn]

It is 110 then we put in the nitrous additive..


Could you explain this nitrous additive, and your calculations for getting 110 out of 117 octane? :wondering

[asc180]

I only buy it at Silver Lake and that was last summer so I am sure it has went up at least 60% by now just like all the other stuff. Where you live at in Michigan?

[asc180]

Never mind I remember now by Morley.

[sandpuppi101]

The nitrous additive is an octane boost product actually put out by NOS,I dont have the ratio offhand on how to mix it but ,I think its about 12 oz's of the additive to 5 gallons give 7 more octane per gallon.And that is mixed in with 110 turbo blue.The additive can be found at speed shops that is where we get ours from.On a more serious note I see that many of you with the hot rod 2-strokers stick with the lower 93-97 octane fuels,and occasionally use the 104 and higher .How many using the higher octane fuels can tell a more crisp,raspy throttle response.And if you can't tell the difference ,Why use it!I probably would'nt use it if I rode with people who also did'nt but the yo-yo's I ride with are always trying to outdo on another, I can't get beatup by Banshees! I need to ride with my own kind{3 wheels}!!

[dizasterzrfun69]

Is it better to run a higher or lower octane gas in a 4 stroke? Does it matter? I have a '85 200x and i was just curious if it mattered or if one was better than the other. Right now i'm running plain ol 87 octane.

[Mr. Sandman]

There is a couple of reasons that I run the 117,First off being that me and some riding pals pitch in on quite a bit ,several times a year and that it it easily accesible for us to get it.It is 110 then we put in the nitrous additive.Second would be that I can tell that with the higher octane I use,the throttle response is more crisp,real snappy.The lower 93 or 97 octane is fine in my R but I can tell the difference.Its kinda like I gotta keep up with the Jone's!LOL I don't want to get beatup by Banshee Boys!

I'm not the octane guru, but I do know that higher octane does not equal more power nor will it increase throttle response/make it snappier. High octane fuel is used to prevent detonation/pinging on high compression motors.

If you think you feel more power and crisper throttle response, it could be that you are experiencing detonation with lower octane fuel and the high octane fuel cures that and you feel the difference and equate it to having more power. If you are not detonating and run the high octane mix just to keep up with the Jones's, you should save your money and use it on some other mods that will actually give you more power.

[sandpuppi101]

Yeah I see your point sandman,makes sense!But seriously running the high juice I deffintly can tell.The reason I can agree so easily is that I have noticed pinging at times,like when it starts to pull and I have too dump a gear.On the lower octane fuels.I also agree that I could get some goodies with what I spend on the high dollar stuff.