EG YZ144 Jetting

[burgunder]

I am running 35pj, 440mj, 06 needle 2nd clip. I was running sunoco 110 leaded with amsoil dom at 32:1 and still getting goo. Tomorrow I will switch to 50/50 110 and premium pump 93 sunoco. I am hoping the decrease in lead content and will decrease the goo and that the combination will lean me out a hair more that I am looking for. I will let you know how it goes.

 

[Rich Rohrich]

I am hoping the decrease in lead content and will decrease the goo and that the combination will lean me out a hair more that I am looking for. I will let you know how it goes.

The lead content of the fuel doesn't have anything to do with it. Even if the overall fuel curve gets a bit leaner with the addition of pump fuel, the higher temperature components present in average pump fuel won't ever vaporize and will pass through the engine in liquid form and eventually dribble down your swingarm.

In an engine that runs above say 7000 rpm fuel components that vaporize above 240 F or so will pretty much pass through the engine in liquid form. If you look at the Sunoco chart below you'll see the amount of heat necessary to vaporize the Sunoco 110 will only accomplish the job for about 1/2 of the fuel.

Dr. Dave Redszus the blender of FirePower race fuels gave me these numbers as typical values at the refinery for Northern Illinois in the summer (other parts of the country are similar).
10% - 158.0
50% - 250.0
90% - 374.0
End point - 437.0

So adding pump fuel to a race fuel that already has the wrong characteristics, only makes the problem worse.

Remember if the fuel won't vaporize it won't burn, and it ends up making it's way into the expansion chamber as a liquid. Suddenly you're the mayor of SPOOGE CITY even with perfect jetting. Automotive engines have long HOT intake runners and slow turning engines so their is plenty of time and heat to vaporize these high temp heavy ends in pump fuel. There isn't enough time or heat to do it effectively in the average MX race engine.

If you decide to add pump fuel to this mix I'd stock up on Simple Green if I were you. ;)

You have to address the root problem which is the race fuel you are using. It's designed for lower rpm V8s with long intake runners that run at very high temperatures so there is plenty of time and heat available to vaporize the fuel before it hits the combustion chamber.

You engine will never accomplish that. If you look at the chart you'll that all of Sunoco's leaded fuel share similar characteristics. Every point from 10% (this influences throttle response) all the way to the end point are way too high for your use. The exception in this group of fuels is M02X. This fuel has a curve that is pretty close to what you are looking for.

Another example of a proper distillation curve for our use is Chevron TT100ULE (see chart below).

Until you address the fuel issue you won't see the real performance your bike is capable of, and you'll never stop the spooge problem.

 

[burgunder]

Wow, I couldn't ask for a better response.

Now if you can answer me this question I will send you a check for $20. What fuel should I use that is accessable around Pittsburgh, Pa.

 

[_JOE_]

Not to crash this thread, but which VP fuel should I run in my bike? There's a local car performance shop that sells VP but I'm not sure which blend. If I understood Rich's post, running an automotive race fuel isn't really a good idea in a bike. Any input is appreciated.

 

[Rich Rohrich]

Wow, I couldn't ask for a better response.

Now if you can answer me this question I will send you a check for $20. What fuel should I use that is accessable around Pittsburgh, Pa.

Go to your Sunoco dealer and ask for Sunoco 260 GT or Sunoco 260 GT Plus. Both are unleaded fuels and have curves that are a much better match for your application. The standard 260 GT will likely be best based on the way Eric builds these engines.

More info on 260 GT

http://www.sunocoinc.com/Site/Consumer/RaceFuels/UnleadedFuels/Sunoco260GT.htm


For those using VP fuel, C12 is still a very good choice and is very easy to tune for. Stay away from VP Red for the same reasons stated above for Sunoco 110.

 

[whenfoxforks-ruled]

Rich,you are awesome,I wish I could throw some vp on the fire and bench race with you!Isn't firepower available worldwide,and or under another name.And they do ship,don't they?I had a distributor list I found somewhere,and on 4 hours of sleep my memory is worse!Chevron Phillips other fuel I believe is the same and available in europe,damn what is the name http://www.cpchem.com/enu/specialty_chemicals_p_racing_fuels.asp found it!537 and xamax oils,PROPERLY jetted and no mechanical issues=NO SPOOGE!I do not fully understand what the deal is with trying improper fuels or mixing with garbage,I would in my van with 225,000 miles,it still does not spooge and I do not care,but the dirtbike does not require a service station or a 20 gallon fill up a day!

 

[bclapham]

ive run sunoco regular 110 and supreme 110 either straight or mixed 50/50 with pump and get no spooge.

but alas, the 260GT plus is pretty good.

that said, a 440 main jet is way too big for a 38mm carb and you wont be making any power, i was running a 380 main in my high comp rm144 with a 110/gt plus blend...had to go 400 with the straight GT plus but that was at a seriously fast and long sand track.....if the pipe aint blue, then you arent getting the engine hot enough.

 

[whenfoxforks-ruled]

Thats good Bclapham,but,In my opinion I will stand on a blue pipe means a flame in the pipe,NORMALLY ASPIRATED engines this means rich and or nasty fuel!But why bother with the mixing fuels,good base fuel then mess with the oxygen!That reminds me,I need more boost,road trip to Dr.Daves'!

 

[burgunder]

What do you mean mess with the oxygen. Is there an 02 additive?

 

[steve125]

Pete just had an 05 144 on the dyno, not my bike I just happened to be in the shop at the time of the dyno.

The bike had an FMF pipe and shorty, running MO2x. Optimal main jet for that day around 80 degrees and that fuel, was a 390.

 

[burgunder]

Wow, I am running a 440 in 80*f weather. I know it is not the same bike or weather, but it makes me think.

 

[whenfoxforks-ruled]

Firepower 537 comes with like 2.7 percent Oxygenate,ether.The boost is a 20 percent oxygenate,use it to boost oxygenate.Somewhere I seen a dyno run on the different levels and around 8 advances the ignition.Other companies boast levels of 10 percent,but calm it down with high end distillates,watered down.A few ounces in a GLASS measuring cup per gallon really makes this fuel insane!And there is the smell

 

[rpm12505]

very easy to tune for. Stay away from VP Red for the same reasons stated above for Sunoco 110.

Damn. I thought Sunoco 110 was the bomb. The bike runs good and no spooge. Just found found it for less than $7/gal. Thought leaded fuel was better also. I'm so mis-informed :bang:

 

[whenfoxforks-ruled]

The only thing lead does is act as a catalyst to the oxygenate.Misinformation means money in some slackers pocket!

 

[Rich Rohrich]

Damn. I thought Sunoco 110 was the bomb. The bike runs good and no spooge.

If you are happy with the results then run it.

 

[rpm12505]

If you are happy with the results then run it.

My son is really pissing off some of the 4s riders. I thought maybe we could add a few more :laugh:

 

[burgunder]

My sunoco dealer has the 110 leaded in a pump and do not do specific orders for different fuels. I would have to find another brand of fuel. I have called many different places looking for gas, but I have only found the sunoco 110 (red cam2.) If lead is a catalyst to oxygen, would I find any benefit in the oxygen boost that whenfoxforks-ruled mensioned, and if so were do i find it.

Rich thank you for the help and NO I am not happy with the goo all over the bike.

 

[whenfoxforks-ruled]

http://www.precisionautoresearch.com/page4.html This is the man with the answers!This is where I shop.This product is made by the Chevron Phillips Company,they also market,http://www.cpchem.com/enu/specialty_chemicals_a_racing_fuels_application.asp All their oxygenates are ether based,not alcohol.If I did not use this I would recommend the other company,Sunoco.

 

[Rich Rohrich]

If lead is a catalyst to oxygen, would I find any benefit in the oxygen boost that whenfoxforks-ruled mensioned, and if so were do i find it.

You could make the Sunoco fuel more workable after some trial and error tuning, but at $20/liter (plus shipping) for the additive the cost would likely outweigh the benefits.

Your money is likely better spent tracking down a consistent source of proper fuel.

 

[burgunder]

Rich,
In your previous post you mensioned boiling points and that the gt was closer to what I am looking for. What range am I looking for?

 

[bclapham]

What range am I looking for?

dude, you need to look for a smaller main jet before anything else.

 

[burgunder]

I don't disagree that I need to now start leaning out the main, but if I am running the wrong fuel for my application, I need to take care of that 1st. There is no point on jetting for the wrong fuel. I would have to make jetting changes after I switch fuels anyway.

 

[SpDyKen]

burgunder,

Your being too cautious. Make the jetting change. See what it does. Then, decide what you want to do next.

Learning from your own trial & error is the only way to become experienced. Do the work; answer as many of your own questions as you possibly can. Then share the results, here.

See how well you can make it run on the fuel you have, then see if you can make it run better with some other fuel.

Good luck! Ken

 

[Rich Rohrich]

Rich,
In your previous post you mensioned boiling points and that the gt was closer to what I am looking for. What range am I looking for?

Read the posts again. I provided all the info you need.

But bclapham is right. If you aren't going to take the time to jet correctly then none of this stuff means jack.

 

[bclapham]

anything that has an endpoint below 260 is great- thats where the sunoco name GT260 comes from. the 10% point like Rich says is for throttle response, but any race fuel is gonna be infinately better than pump.

right now, your problem is jetting- if its off, it wont matter what fuel you are using, once the bike is running properly, changing from fuel to fuel will only need small jetting changes if any.....dont worry about throttle reponse since if its too fat, it wont have any anyway nor will it be making the best power.