Topic: Preignition/Toluene as an octane boost?

[scondon]

     The highest octane pump gas I can find here in California is 91. There are a few 76 stations that sell 100, or so I'm told, but none are close enough to me. I am experiencing pre-ignition and am ready to experiment with higher octane gas. The octane boosters sold at the auto store are not only expensive but confusing as to how much they actually boost the octane. I've read several things online about Toluene and Xylene being used as a "home brew" booster. It is easy to formulate 92,93,94,95....octane using Toluene but figured I'd ask here before giving it a go as most of what I've read concerns cars w/turbo boost. Can anyone give me a good reason not to try this?

http://members.rennlist.com/951_racerx/RocketFuelFAQ.html


     A little background: '78 CB750F.  Engine is a 836 with 10:1 ratio. Head has been decked so I assume that ratio is a little higher. When I open the throttle fully at high speed(80-mph), and in 5th gear travelling uphill, the engine sounds like it has either gravel in it or loose chain and there is diminished power.It is most noticable when the daytime temps are above 90 degrees(F). Plugs have wart-like deposits on the insulators which tells me all is not good.

     All other ranges of riding are great. 1-4 gears pull hard at all throttle ranges, 5th gear is fine on flat or downhill.

     I have been trying richer mixtures(bigger mains, raised needles) and have retarded? the ignition so far that the bike idles like crap. Still no good and I'm ready to try higher octane.

    Other info: D7EA plugs(hot), Dyna S ignition, Dyna 3.0 coils, Megacycle 125/65 cam, 4-1 exhaust w/competiton baffle,oil cooler. Bike is pretty far from stock set-up.

   Any and all input appreciated.

     

[TwoTired]

Why aren't you using D8EA plugs for summer riding?

Cheers,

[Terry in Australia]

It's probably buggered mate, send that engine to me and I'll stick it in my bike for a little while and sort it out for you, ha ha!

But seriously, can you buy "AvGas" legally in California Sean? Most AvGas is 100+ octane, and what the go-fast guys here in Oz use, although we can still buy 100 octane gas at the pump. (not that we can afford it)

If you know the correct mix ratio for toluene/gas then give it a go mate, you're probably running closer to 12 or 13:1 comp with Mikes head and those pistons, so try it out and let us all know, when I get that 1166cc engine together I'll be looking too! Cheers, Terry.

[scondon]

Why aren't you using D8EA plugs for summer riding?

Cheers,

   Should I be running a colder plug at hotter temps? I'm still trying to gain perspective on plug choices. I originally switched to D7's as an attempt to get a cleaner running plug. I had the carbs dialed in to where I was seeing mostly tan but a lot of build up with D8's and was told I should try D7's. I've got both types on the shelf, if you think running D8's would help with the preignition on hot days I'll put'em in tomorrow.

It's probably buggered mate, send that engine to me and I'll stick it in my bike for a little while and sort it out for you, ha ha!

But seriously, can you buy "AvGas" legally in California Sean? Most AvGas is 100+ octane, and what the go-fast guys here in Oz use, although we can still buy 100 octane gas at the pump. (not that we can afford it)

If you know the correct mix ratio for toluene/gas then give it a go mate, you're probably running closer to 12 or 13:1 comp with Mikes head and those pistons, so try it out and let us all know, when I get that 1166cc engine together I'll be looking too! Cheers, Terry.

  There are places I can get the 100 octane but don't feel like keeping a 50 gallon drum in the garage. 100 octane pump gas is super expensive and well out of my way to get. I ride this bike everywhere so am trying to find a more convenient way to run high octane. With the Toluene I could add 1quart per fill-up and though I don't like the idea of having to lug around a quart container it is the best alternative so far.

[MRieck]

Sean...you definitely need a colder plug...I run 9's. You are not above 10.5 with that head. Back off your ignition advance. A Dyna 200o is what you need...believe me. Call Dyna and if you can't a unit let me know. Add some more fuel too and see if it helps.

[MRieck]

It's probably buggered mate, send that engine to me and I'll stick it in my bike for a little while and sort it out for you, ha ha!

But seriously, can you buy "AvGas" legally in California Sean? Most AvGas is 100+ octane, and what the go-fast guys here in Oz use, although we can still buy 100 octane gas at the pump. (not that we can afford it)

If you know the correct mix ratio for toluene/gas then give it a go mate, you're probably running closer to 12 or 13:1 comp with Mikes head and those pistons, so try it out and let us all know, when I get that 1166cc engine together I'll be looking too! Cheers, Terry.

Actually Terry...yours is 16:1.....it'll be just fine on pump.

[scondon]

Sean...you definitely need a colder plug...I run 9's. You are not above 10.5 with that head. Back off your ignition advance. A Dyna 200o is what you need...believe me. Call Dyna and if you can't a unit let me know.

    Figured I was between 10 and 10.5, thanks for the confirmation. The more I ask about hot/cold plugs, the more confused I get   I am ready to follow directions, the 8's go in tomorrow and I'll buy a set of 9's. 

    When you say "back off your ignition advance" do you mean retard it further(later in the compression stroke)? If I back it any further I'll never get the bike started in the morning.

    The bike that's getting your "THE Works" head will be treated to a Dyna 2000 for sure. Don't know if I want to go the expense of getting two. I'll PM ya about unit costs tomorrow,thanks Mike.

[Terry in Australia]

Hey Sean, the more retarded the spark is, the easier it will start mate, so that won't be a problem.

Hey Mike, are you taking the piss? 16:1? Ooooooooh................. Hey if sean was running a 10.5:1 Wiseco 836cc kit, and you milled a mm or two off the head, wouldn't that bump the comp ratio up substantially?

I know I'm supposed to be on the road as I type this, (in case you were wondering) it's a long story, starting with "Once upon a time, there was a big chicken, who was too scared to ride his new bike in the rain...................

[flatblack]

Go get a couple of new five gallon gas cans. Drive out to your local airport and buy some aviation gasoline. It's (slightly) leaded 100 octane gasoline of much higher quality than you can get for autos. It's more expensive, but WTH...

It's what I've been running in my bikes -- no issues.

fb

PS: They may not sell it to you for one reason or another, but it's worth a shot...

[scondon]

Hey Sean, the more retarded the spark is, the easier it will start mate, so that won't be a problem.

    At the moment my ignition is retarded to around halfway between "T" and "F" at idle, and just a hair left of the of the first 1[]4 mark at advance. The bike is already harder to start than when I had the ignition "spot-on" and will die at idle if not fully warmed up. I've got some time on my friends lift tomorrow and am going to do a thorough systems check,synch and tune. Along with some colder plugs, brrrrrrr    

    Then it's off to the paint store for some toluene.

Hey Mike, are you taking the piss? 16:1? Ooooooooh................. Hey if sean was running a 10.5:1 Wiseco 836cc kit, and you milled a mm or two off the head, wouldn't that bump the comp ratio up substantially?

I believe it was .012" deck(.3mm). It's engraved on the head but can't read it unless I remove it. My Wiseco pistons are 10.25/1.

I know I'm supposed to be on the road as I type this, (in case you were wondering) it's a long story, starting with "Once upon a time, there was a big chicken, who was too scared to ride his new bike in the rain...................

Sissy!!!

Go get a couple of new five gallon gas cans. Drive out to your local airport and buy some aviation gasoline. It's (slightly) leaded 100 octane gasoline of much higher quality than you can get for autos. It's more expensive, but WTH...

It's what I've been running in my bikes -- no issues.

fb

PS: They may not sell it to you for one reason or another, but it's worth a shot...

    This is one of my options and the airport is not far. Now if I can just figure how to strap 10 gallons to the bike twice a month     Seriously though, If higher octane improves things for me I will be testing some aviation fuel. My current project bike will not be a daily rider and so will not need to be filled as often.

[Terry in Australia]

You can buy a 44 gallon drum of Avgas Sean, I don't know what the law says about storeing that much fuel in your garage, but Avgas is only about 20% more expensive here than regular gasoline, I ran my BMW R100RS with 12:1 compression on it for years, (we sold it at the gas station I worked at part time) it certainly smoothed the bike out, but remember, the higher the octane rating, the more resistance to ignition, so if it's not starting/idling well on regular gas, it's not gonna get better with high octane rocket fuel! Cheers, Terry. (chicken man)

[joeb]

Hey Sean theres a place down by my house that claims to sell racing fuel its off of Lewelling down by the railroad tracks ,I will be going by there today to drop off some things elsewhere. I will see if they are open and what they have to offer. Give me a call land line about three on Sat.  As you know I am running into the same problems, also need to talk to you about yanking the motor out I reallly want to ride this beast, will paint in the fall.     

[madbunny]

many race tracks and drag strips often sell high octane racing fuel on site as well.
i think hardly anybody in a population center in the US is more 20 miles form an airport or a racetrack.

[TwoTired]

So, I called up the airport fueler for the delivered (to the plane) price of their 100LL avgas;  $4.46/gallon.
My airport (Reid-Hillview) has a credit card self serve pump @ $4.25/gallon.
My Gas station down the street sold me 91 rating for $3.30, yesterday.

Check your Homeowners or Renter policy about storing gas at your dwelling.  Some Ins policies will negate any claims if flame accelerants are stored on premises.

Were, I you, I'd definitely go colder plug.  D9 or D8 and go do a WOT plug chop with the auto premium.  You're probably not going to like the performance during warm up, though.

Plugs have wart-like deposits on the insulators which tells me all is not good.

You're right about that.  Especially if the wart-like deposits have the glint of aluminum.

What is your nearest airport where the "little planes" land?  Hayward?  Oakland?  Concord?  Pleasanton?

Cheers,

[Bodi]

Around here, with the terrrorist terror and all, even the flying clubs have a secure area and there's basically zero chance of me getting to the avgas pump with either a jerry can or a motorcycle.
I think a proper war on terrorism would mean not being in constant terror. The powers that be don't agree, and keep telling me I should be more afraid.

[scondon]

Many thanks for the excellent and timely advice guys

     After reading TT's and Mikes posts on colder plugs I entered "hot spark cold spark" into Google and came up with enough information that I finally understand the "how's and why's" of choosing the correct temp range. Originally, I was doing plug chops to determine the best jet sizing and clip position for my setup and had narrowed down to a decent point but the plugs looked "too cold" (tan tip surrounded by black) using D8's. Changing to D7's helped clean up the black area but the "wart like" deposits on the insulator grew(they were slightly present on the D8's). No glints of aluminum and when I tore the motor down earlier this year I did not see any pitting on the pistons so I'm hoping that I am changing back in time. My quest for the perfect burn continues, but not with hot plugs

     My knowledge of carbs, ignition timing, electrics, and their effects on performance has grown considerably this year(from nothing to something,haha) thanks to you all

[MRieck]

Hey Sean, the more retarded the spark is, the easier it will start mate, so that won't be a problem.

Hey Mike, are you taking the piss? 16:1? Ooooooooh................. Hey if sean was running a 10.5:1 Wiseco 836cc kit, and you milled a mm or two off the head, wouldn't that bump the comp ratio up substantially?

I know I'm supposed to be on the road as I type this, (in case you were wondering) it's a long story, starting with "Once upon a time, there was a big chicken, who was too scared to ride his new bike in the rain...................

For Godsakes man.....a mm off the head! Just enough to get it to what I want.....nothing crazy. Except when it comes to your #$%*.

[Terry in Australia]

Ha ha, sorry Mike, I tend to compare everything to my magnificent stage 3 head, and forgot that Seans is a bit milder. Also I just finished reading David Vizards book on modifying Ford SOHC 4 engines, and a couple of mm off those heads is nothing, talk about under-developed!

I went thru my race piston collection last night, I've got 5 different sets in a box, from high comp 61mm thru to high comp 65mm (and Sean tells me that my 72mm MTC pistons have arrived in sunny Oakland, so I guess that makes 6 sets) and it's interesting how each each piston manufacturer has had a slightly different design brief on the optimum shape for a piston crown in one of our engines, it's really quite fascinating! Cheers, Terry.  

[MRieck]

Ha ha, sorry Mike, I tend to compare everything to my magnificent stage 3 head, and forgot that Seans is a bit milder. Also I just finished reading David Vizards book on modifying Ford SOHC 4 engines, and a couple of mm off those heads is nothing, talk about under-developed!

I went thru my race piston collection last night, I've got 5 different sets in a box, from high comp 61mm thru to high comp 65mm (and Sean tells me that my 72mm MTC pistons have arrived in sunny Oakland, so I guess that makes 6 sets) and it's interesting how each each piston manufacturer has had a slightly different design brief on the optimum shape for a piston crown in one of our engines, it's really quite fascinating! Cheers, Terry.  

Sean's head is pretty nice if I remember correctly. He certainly didn't cheap out!!

[scondon]

Ha ha, sorry Mike, I tend to compare everything to my magnificent stage 3 head, and forgot that Seans is a bit milder. Also I just finished reading David Vizards book on modifying Ford SOHC 4 engines, and a couple of mm off those heads is nothing, talk about under-developed!

I went thru my race piston collection last night, I've got 5 different sets in a box, from high comp 61mm thru to high comp 65mm (and Sean tells me that my 72mm MTC pistons have arrived in sunny Oakland, so I guess that makes 6 sets) and it's interesting how each each piston manufacturer has had a slightly different design brief on the optimum shape for a piston crown in one of our engines, it's really quite fascinating! Cheers, Terry.  

Sean's head is pretty nice if I remember correctly. He certainly didn't cheap out!!

The first one you sent(the one I'm running right now) didn't get the "works" and is still quite enough for my Daily Rider. The last one you sent is sitting on a pedestal in my living room, in front of a puddle of drool. When I get THAT motor together and in the bike I plan on shipping it Down Under and giving Terry a good ol' American "What For" on the road of his choosing,haha.

[Terry in Australia]

Whoa back there, boys, fold up that American flag and put your "Yankee Doodle Dandy" CD away, I remember that Sean's first head is, as he says, fairly mild compared to the one you did for me Mike, I certainly didn't infer that Sean had "cheaped out", ha ha!

Bring your bike over though Sean, it'll be good to ride with another trick 750, but beware, we have a lot more corners here in Oz, so you better stay off the freeways for awhile, or you'll go home in a cast, ha ha! Cheers, Terry.    

[Hop on a Honda]

Hey, give the poor enging a go, use the new ?NGK Aridium ones.
They made mine simply GO go.
Dave