ok.. I havent been using higher octane gas and I should ???

[roger86200x]

I put a 10.25:1 compression wiseco piston (.020 over), stock compression is 9.5:1 , in my 86 200x.... I havent been using higher octane gas.... just 87, what will happen if I dont change? also, what are some symptoms that it is being damaged?

[TimSr]

If your octane is too low, you should be able to hear it knocking and pinging, most obvious at low RPMs under load.

[roger86200x]

yah i hear it pinging lol but I thought it was there before but louder now... just kinda ignored it :oops: lol but how much damage will it do? and why?

[AirManCam]

It will probably cause a rebuild :(

[roger86200x]

that would SUCK... I just got it together! (again) lol I will hav to buy 93 octane gas.... should I run any higher? or will octane booster do with 87 gas instead of 93 gas?

[AirManCam]

Buck it! Run her till she dies!

[bbechtel16]

Is pinging an obvious not good noise to someone like me who isn't really experienced with actually working on engines and stuff but I know a lot about them and could rebuild mine (top end) by myself probably? That sounded kinda dumb but yeah... I'm running 87 on my SX with a 10.5:1 and haven't noticed any pinging but then again I dont really know what I'm listening for.

[MR ATC]

93 octane is sufficant for 10.25:1 compression

[Manny55]

Man i only put unleaded in mine but i need to start putting premium in my R because its starting to ping and knocking noises.

[200x Basket]

as MR ATC said run 93. if you run higher then needed octane you will actually lose performance. my race car fell off .1 sec in the 1/8th mile when i went from 104 to 112 octane. this was on the same night. i ran out of gas and all i could get was 112

[AirManCam]

93 Is super right?

[bbechtel16]

93 Is super right?

Yes, the top grade of the 3 main pump grades.

I think my SX is pinging, or might be, it could also be my intake valve clearance (I've already done exhaust), the timing very well could be off a tooth (Me and James Cobaugh did time it.), or my carbration is screwing it up (no choke cable installed which alows extra air through the carb but if I cover the hole it runs crazy mad rich so I'm leaving it go till I figure out what I wanna do. I'm thinking 350X carb? Good idea or bad?)

[AirManCam]

I wouldnt go for a 350x carb

[86waterpumper]

why not go for a 350x stock carb? He could always jet it down some. They are reasonably cheap, and aren't the 250sx carbs the same style as the bigreds? If so, then they are the same style carb as the 350x anyway. With the mods he has, it should help the power a good bit. I say do it! I see carbs go for 30 bucks or less all the time, and if it didn't work good, he could always throw it on ebay.

Oh, and I'd definately NOT be running 87 octane with a 10.5:1 piston. I mean it's only a few cents higher to buy the 93, and it's alot cheaper in the long run when you don't blow your motor LOL, and you're not really going to get the power out of that piston that you ought to be getting with the meager gas!

[AirManCam]

Yeah I would run 93 in everthing.

[bbechtel16]

why not go for a 350x stock carb? He could always jet it down some. They are reasonably cheap, and aren't the 250sx carbs the same style as the bigreds? If so, then they are the same style carb as the 350x anyway. With the mods he has, it should help the power a good bit. I say do it! I see carbs go for 30 bucks or less all the time, and if it didn't work good, he could always throw it on ebay.

Oh, and I'd definately NOT be running 87 octane with a 10.5:1 piston. I mean it's only a few cents higher to buy the 93, and it's alot cheaper in the long run when you don't blow your motor LOL, and you're not really going to get the power out of that piston that you ought to be getting with the meager gas!

Thanks for the info man. Here's another one for w/e is listening. I want to take my airbox out of the equation and replace it with a K&N universal cone with one of their precleaner slip cover things on top of it. I have no idea how large of a cone will be big enough that it won't cause any restriction and what size/shape/style would fit the SX well. I am also considering maybe putting a single sheet splash gaurd of sorts under the filter, or possibly 3 sides, any thoughts on if this is nessasary with the precleaner (not sure if its water resistant of not) and/or how to do it?

[ATC crazy]

Try some 100LL gas :D ;)

[AirManCam]

Are you getting lippy again crazy? ;)