Lucas Octane booster?

1998RM250 · Oct 16, 2010

I know you're not supposed to use any octane boosters, and most are gimmicks but i've actually heard the Lucas octane booster works? Is it safe to run in a two stroke, and does anyone have experience with this stuff? I can't find race fuel anywhere so I'm looking for alternatives, thanks again guys.

helio lucas · Oct 16, 2010

1998RM250 said:
i've actually heard the Lucas octane booster works?

one thing i can assure you, if it has LUCAS in the name, WORK is not a word you can apply on the same sentence. i bet that if you try it your bike will be lazy as my computer. :laugh:

_JOE_ · Oct 16, 2010

helio lucas said:
one thing i can assure you, if it has LUCAS in the name, WORK is not a word you can apply on the same sentence. i bet that if you try it your bike will be lazy as my computer. :laugh:

:rotfl: This coming from a fella who'd know a thing or two about the Lucas name!

Chili · Oct 16, 2010

What is it you're trying to accomplish running it? If it's to try to gain performance your wasting your time and money.

Rich Rohrich · Oct 16, 2010

If you look at the Lucas MSDS sheet for the product you'll see that the product is MMT based.

MMT = Methylcyclopentadienyl Manganese Tricarbonyl

It's an organmetallic fuel additive used to replace lead and raise octane (mainly RON). This is important because two-strokes usually need and increase in MON to squelch knock.

MMT has zealots both for and against it. As far as I know it isn't used in pump fuel anywhere in the US, but I believe it is used in parts of Canada. The metallic deposits tend to shorten plug and oxygen sensor life, so in a world of 100,000 mile tune up expectations it's unlikely you'll ever see it in US pump fuel.

MMT tends to be less effective at boosting octane as the percentage used increases, and the deposits get much worse as the percentages increase. So it's definitely a case where more is NOT better.

If you look closely at the pictures attached you'll see the electrode edges are really sharp on the plugs even though the deposits are fairly heavy. All those deposits were built up in just over an hour, running about 2 oz/gallon of high percentage MMT based octane booster in a YZF four-stroke that was jetted sharp.

It's actually a pretty good additive if all you want to do is add a few octane points protect your engine from knocking in a pinch, but it generally makes tuning a total nightmare, and comes with some significant side effects on a two-stroke.

Reading plugs with this in the fuel is next to impossible. In a two-stroke the deposits can easily lead to hot spots in the combustion chamber increasing the chance of pre-ignition.

Here's a thread that has some info on a couple of boosters I tested with for reference: http://www.dirtrider.net/forums3/showthread.php?threadid=15450&referrerid=16241

You would be much better served adding a small percentage of leaded race fuel or even AvGas to your premium pump fuel to raise the octane rather than using an additive like this.

1998RM250 · Oct 17, 2010

Oh wow, well count that out of the question! So what would be a good mix of av fuel and 93 to raise the octane up to around 100 oct, 50/50? I just want to try doing this to confirm the "pinging" that I'm hearing is due to running to low of an octane fuel. After that I'm going to send it back to the guy I paid $100 to jet it and tell him to jet it slightly rich so that it runs on 93 pump without the detonation. He was blaming that detonation noise on my bottom end and even told me he heard it, he should have known better in my opinion!

Rich Rohrich · Oct 17, 2010

1998RM250 said:
Oh wow, well count that out of the question! So what would be a good mix of av fuel and 93 to raise the octane up to around 100 oct, 50/50? I just want to try doing this to confirm the "pinging" that I'm hearing is due to running to low of an octane fuel.

All you can do is TEST and find out what the engine wants. It might be 50/50 but it could easily be something different. 50/50 is a reasonable place to start though.

1998RM250 said:
After that I'm going to send it back to the guy I paid $100 to jet it and tell him to jet it slightly rich so that it runs on 93 pump without the detonation.

I'll say it again just so it's clearer this time . There is no guarantee that making the fuel curve richer in a specific area will kill the knock. If the engine is already running on the rich side and it's knocking then adding more fuel isn't likely to change things.

It's possible that if the combination you are running produces enough pressure and heat you will not be able to kill knock with jetting alone and still make it run properly on pump fuel. If that's the case then you'll have to get the head and possibly the porting and ignition advance changed to achieve the goal.

1998RM250 · Oct 17, 2010

Thanks again Rich, I'm listening to your advice believe me! Sorry, I'm just trying to get it to run right without having more headwork and spending alot of money. I just did some more research on av fuel and have read alot of negative things, as well. I will say that before I put in the wiseco piston and had this guy jet the bike, I never heard it knock or ping when it used to run decent on pump fuel. I think it ran much better on the stock jetting, I was afraid it was even running a bit lean then with the needle clip in the 2nd position!

Ol'89r · Oct 17, 2010

I don't think I would use it. It may cause electrical problems. :whoa: ;) :laugh: :rotfl:

Rich Rohrich · Oct 17, 2010

1998RM250 said:
I will say that before I put in the wiseco piston and had this guy jet the bike, I never heard it knock or ping when it used to run decent on pump fuel.

If the old rings were worn out and leaking pressure from the combustion chamber it would lower the effective compression ratio, similar to what a head mod would accomplish.

Changing the parts likely raised the working pressure and unveiled a problem that was always there with pump fuel.

In most cases, unless you specifically modify the engine to run on the wretched swill that passes as pump premium today you will have to half-ass it with overly rich jetting and retarded ignition timing. So you learn to live with the crappy response that comes with those compromises or you buy decent fuel for it.

For most people modding the engine to run properly on pump fuel is the smartest and cheapest approach.

Ol'89r said:
I don't think I would use it. It may cause electrical problems.

Hopefully I'm not the only one who finds this incredibly funny. :cool:

helio lucas · Oct 17, 2010

Ol'89r said:
I don't think I would use it. It may cause electrical problems. :whoa: ;) :laugh: :rotfl:

i hear you!!! :yell:

another variable is if the piston you put on the bike is slightly higher or has a larger dome it effectively increases the compression ratio.
i have write this on your other thread: increasing the thickness of the base gasket on the cylinder (not the head gasket because it has o´rings i think) is a wise move to check if the noise you hear is indeed detonation.

1998RM250 · Oct 17, 2010

Ah I see, so many variables... I Put fresh rings in it as soon as I got it, but still had the oem piston. I'm wondering if the wiseco has a bit more compression as well? Previous owner ran nothing but race fuel as it was readily available, but that gas station closed this past year unfortunately. I love how all the "hardcore" racers in the area have no idea where to get race fuel, and I'm a big iffy on the AV fuel.

EDIT: I found a dealer for Dragon Racing fuel 114 oct here in Port Charlotte FL, going to call tomorrow and hope they still carry it! Quick question, the mixture screw on a 38mm pwk carb, if you turn it in it richen's the mix right? Also race fuel, from my knowledge it makes the bike run a bit richer since it lowers combustions temps correct? I've been reading otherwise for both concerns on the web... anyone? :whoa:

whenfoxforks-ruled · Oct 17, 2010

It will take less effort to pull up your sleeves and jet your bike your self, than plundering the internet for what ever it is that you REALLY want to hear. Well, maybe not but I liked it! Fact is, its worth about 100 dollars. And the "pro" mechanic, what if he is correct about 1 thing, your bottom end is toast? When the gas does not fix it, (your version of a ping?) then what?

ellandoh · Oct 17, 2010

Vintage Bob

Rich Rohrich · Oct 17, 2010

1998RM250 said:
Also race fuel, from my knowledge it makes the bike run a bit richer since it lowers combustions temps correct?

Incorrect.

1998RM250 · Oct 17, 2010

Yeah I understand the whole two headgasket thing, but I think It can be tuned to run on pump fuel. If worst comes to worst I found a place that sells race fuel locally, but it would more then double my riding expenses. So race fuel doesn't make the jetting richer? I'm going to mess with the jetting myself, I just want to make sure I know exactly what I'm doing so I dont fry this piston from detonation in the meantime! I highly doubt it's my bottom end, wouldn't it be making noises at all rpm's? It definately sounds like a pinging noise to me and its coming from the top I'm pretty sure. Especially with the head work done to the motor and the previous owner used to only run race fuel (used to be readily available at sunoco cheap). I just need someone to advise me on the jetting,and besides you guys helping me I'm on my own.

_JOE_ · Oct 18, 2010

You've had several of us give you advise on jetting and fuel. Reread you threads and stop posting.....then get the toolbox out and fix the bike.

jsantapau · Oct 18, 2010

Rich Rohrich said:
Hopefully I'm not the only one who finds this incredibly funny. :cool:[/QUOTE

as a previous owner of a sunbeam alpine I found it incredibley painful

dirt bike dave · Oct 18, 2010

Rich Rohrich said:
Hopefully I'm not the only one who finds this incredibly funny. :cool:

I lol'd.

Then I realized it put me in the small percentage of dirt riders old enough catch a reference to the Prince of Darkness.

1998RM250 · Oct 18, 2010

One last thing then I'm done asking questions for now...
What is the stock jetting on my 2001 RM250? I was told 162 main,
48 pilot, and n3wk needle, clip 3rd position by numberous people
but the guy who jetted my bike keeps saying that's not the stock jetting
and getting mad at me!

Patman · Oct 18, 2010

Maybe you shouldn't worry about what the stock jetting is and worry about what your jetting SHOULD be. Good night you need to quit PAYING somebody to do things to your bike that are both easy to do but perhaps a bit time consuming even though in the long run they will give you a vastly better idea of how things really work and how the changes will effect the big picture. Or you could just keep up with the million questions thing and toss Rich & '89er a few bucks per answer :laugh:

Rich Rohrich · Oct 18, 2010

Your service manual will list the correct factory jetting as well as the OEM suggested option jets.

1998RM250 · Oct 18, 2010

Yeah I only have one for a 2003 RM250 which is the same bike with a few minor changes...

whenfoxforks-ruled · Oct 19, 2010

If you look carefully at a microfiche online for your bike, you can view the stock jets there, or buy the 30.00 dollar priceless book.

helio lucas · Oct 19, 2010

on a previous i gave you some links to check the jetting specs from fmf, pro circuit and boyesen. they have it on theire website, or what fiftyage bob as said... ;)

Lucas Octane booster?

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