Change pre-mix ratio, or jetting?

43Duc748 · May 23, 2005

I recenlty bought my 91 KDX250 and found it running rich when I bought it. The bike had a full tank of gas that was 40:1 w/ yamalub and 91 octane pump gas. The owner admitted he never changed the jetting after replacing the pipe and silencer and so it was spitting some goo from the pipe connections. Anyway, I leaned it out with by changing the jets. I did not do the who plug-chop trick as I have nowhere to do it (the burbs). I based my jetting on advise from other threads on this forum. So, the bike ran great with the changes I made and the goo stopped. Yeah for me. Sooooo.... I wanted to use a different pre-mix that I could find at more shops, so I switched to Bel-Ray MC1 which recommends a 50:1 ratio. Well, I mixed it 40:1 as the previous owner said that's what the bike's been running.

Sooooo.... I ran the gas that came in the bike out, and put then new mix in and I ended up w/ a large amount of spooge coming out of the joints. The bike seemed to run fine and started every time.

The question is, do I chase jetting? Or do I mix the MC1 at 50:1? Or do I just go back to 40:1 Yamalube?

Any advice would be appreciated!

ellandoh · May 23, 2005

id pick my oil 40:1 whatever it may be, personally its golden spectro stick to it and jet for that

was there a temp or humidity change between your results

Jaybird · May 23, 2005

There is spooge in the pipe from it previously being way rich. That spooge will continue to come out even when you have the jetting spot-on. You should consider having the pipe cleaned out.

Although the ratio can give you another avenue to tune from, unless you are up on jetting technique you should probably stick to the 40:1 and find the closest correct jetting. Remember that atmospheric conditions create the greatest need for jet tweeking. That is why ellandoh asked about temp and humidity.

ellandoh · May 23, 2005

jay i had the same problem, can i just put some kerosene in the pipe shake it up to clean it out . also i was thinking to put a small piece of chain or rope and swirling it around.....would this work???????

Quailchaser · May 24, 2005

43Duc748 said:
Sooooo.... I ran the gas that came in the bike out, and put then new mix in and I ended up w/ a large amount of spooge coming out of the joints. The bike seemed to run fine and started every time.

The question is, do I chase jetting? Or do I mix the MC1 at 50:1? Or do I just go back to 40:1 Yamalube?

Any advice would be appreciated!

Yes. Maybe. Not if you don't want to.

First thing is that if you are running rich and you change your ratio from 40:1 to 50:1...you now have made you mixture even more rich. 50:1 is more fuel to oil than 40:1...which means that there will be more fuel to air as well. Do a search on this and you'll find all kinds of technical talk that explains this in great detail.

My suggestion would be to run whatever oil you want and mix it at what ever you want (ie. 32:1, 40:1, 50:1, 45:1...) and then stay with that and jet according to this and the environmetal issues.

I would also say that it is way hotter this last few weeks here in the Southwest than it was in prior weeks. My bike ran way richer this weekend (110 degrees) than it did two weeks ago. Looks like it's finally time to go to summer jet sets.

Later
Robb

John Harris · May 24, 2005

The school or experience suggests that you use all synthetic oils mixed at your choice of 40 to 50 to one. Then jet for that mixture and your conditions. Do not jet by what comes out of the tail pipe! However, that said i have always gotten the jetting right and then just let the exaust gasses flush out all the bad content of the exhaust system. Again if your pipe is really bad you might search here and find that others have used radiator shops, etc. to clean them out. Cheers John

bikepilot · May 24, 2005

All synthetic oils are not the same, some are designed to be mixed at different raitos than others. The MC1 is very thick and concentrated and should be mixed at 50+:1 . The yamalube is much thinner and should be mixed at 40:1 (for a 250). With clean jetting and yamalube at 40:1 my KDX ran really strong, didn't spooge and the plugs came out perfect. Plus, the top end and kips valves will stay cleaner with the yamalube than the MC1, I have used both and speak from experence.

good luck

CaptainObvious · May 24, 2005

before you start rejetting, make sure you:

1) install a clean air filter;
2) Repack the silencer and clean the pipe (I like oven cleaner);
3) Install a fresh plug;
4) Choose an oil and ratio
5) Make sure there aren't any other underlying problems

cr250can · May 24, 2005

when ever I change any thing to do with my bikes fuel charge I always make sure I have a clean air filter and a new plug. then after I ride it for say an hour or so I pull the plug and see what it looks like. If black or wet = rich. if white or light brown = lean. if choclate brown = good. the only time i worry about spooge is if it is comming out of where the pipe and silence meet, where the pipe connects to the cylinder (these tell me I have a bad seal and can cause spooge even if fuel charge is right) or out the tail pipe if it excessive after many rides.

Jaybird · May 24, 2005

Like John and the Capt stated, you can use Eazy-Off oven cleaner for the spooge in the pipe, however use caution with the stuff as it is a harsh caustic.
If you want, you can also pay a radiator shop to boil the pipe out. Probably $30-50

Just my opinion...but I would never run ANY two stroke oil with less than 32:1. I don't care what viscosity the oil is. You are mixing for volume for protection of your parts. Jet appropriately from there.

43Duc748 · May 24, 2005

Thanks for all the info. I'm going to head down to the store and spend some money.... I'm going to re-pack my silencer, clean out my pipe, replace the plug and switch back to Yamalube since it seemed to like that better.

I pulled the plug after running the latest mixture and it was jet black and moist. It was much lighter when I ran the Yamalube through. And, since the spooge was coming from the pipe joint, I can only assume my silencer packing is a mess as well.

Now I just have to find some containers that I can put the MC-1 gas mix into so I can take it to the disposal center... If anybody in OC wants 4 gallons of MC1 / 91 octane at 50:1, speak now!

Thanks again everyone!

Rhodester · May 24, 2005

Use it to clean parts.

CaptainObvious · May 24, 2005

Put the pre-mix in your truck or car. No problems, with a full tank it will be at 1000:1.

Green Hornet · May 25, 2005

Jaybird said:
Like John and the Capt stated, you can use Eazy-Off oven cleaner for the spooge in the pipe, however use caution with the stuff as it is a harsh caustic.
If you want, you can also pay a radiator shop to boil the pipe out. Probably $30-50

Just my opinion...but I would never run ANY two stroke oil with less than 32:1. I don't care what viscosity the oil is. You are mixing for volume for protection of your parts. Jet appropriately from there.

I've been using Gold Spectrum for 20yrs @ 32:1. Bottle recommends 52:1 for opt performance, 40:1 for heavy load & 50:1. I e-mailed the company w/the year & model of my bike 05 KDX220 & they said"most KDXer's use a 50:1 Ratio. I'm curious and thinking about a 40:1 mixture which is a small change from 32:1. How many people rading this are using a 40:1 ratio?
Jack

John Harris · May 25, 2005

If it is 100% synthetic oil--I would run it at 40 to one or more. Everything does better--KIPS, spark plugs, etc.

Run what you don't use or gets old in your car or truck--Good for it and like above it is a 1000 to one or something when in your vehicle. Gasoline is too expensive to waste plus hard to dispose of properly.

Ride Safe---John

Green Hornet · May 25, 2005

John-By 40:1 or more you mean 40:1 or 32:1

Makeshoes · May 25, 2005

Green Hornet said:
I've been using Gold Spectrum for 20yrs @ 32:1. Bottle recommends 52:1 for opt performance, 40:1 for heavy load & 50:1. I e-mailed the company w/the year & model of my bike 05 KDX220 & they said"most KDXer's use a 50:1 Ratio. I'm curious and thinking about a 40:1 mixture which is a small change from 32:1. How many people rading this are using a 40:1 ratio?
Jack

I started this year running 42:1 to 44:1 and like what I see. (16oz to 5 3/8 gal). Good plug reading and a lot less spooge coming out the pipe. I agree that synthetic can be ran in the 40 to 50 to 1 ratio. That 32:1 sticker is for petroleum based oils. My riding buddies have me convinced.

Green Hornet · May 25, 2005

Thanks, I'm gonna give it a shot at 40:1. Can I mix it into the gas tank with the remainder of the 32:1 mix or should I run the tank down and then add. Also, this would make the mixture richer correct. I use a BR7ES instead of the BR8ES, because my riding tends to be more technical that wide open riding. So should I go back to the BR8 & check the color & then a BR7 if I don't like the color. My jetting is pretty close & I lowered the needle last month for a fine adjustment and I started getting a LEAN BOG. The plug looks cleaner running the BR7
Later
Jack

04kdx200 · May 25, 2005

I mix Amsoil @ 40:1 and run a B8ES plug, the "BR" is a resistor plug that reduces electrical noise, and i don't know anyone who has a cd player on their bike. I ride tight-tight woods, and yet to have any problem..... with the bike that is.

John Harris · May 25, 2005

I mean run 40 to one or 50 to one or somewhere between. I would suggest the 8 heat range plug and jet correctly with that. Seven range is pretty hot for a KDX and not often, but sometimes riders have holed a piston with that hot of a plug. No Fun at all.
Discard all your old gas (put it in your car or truck) even the gas in your KDX tank and start completely over when you change oils or mixture ratios! That way you will learn pretty fast what you are doing and what changes need to be made.

cicone · May 25, 2005

43Duc748 said:
Thanks for all the info. I'm going to head down to the store and spend some money.... I'm going to re-pack my silencer, clean out my pipe, replace the plug and switch back to Yamalube since it seemed to like that better.
QUOTE]
Don't forget to slather a generous amount of red RTV on the end of the pipe on reinstall. No air leaks and no dripping.
my $.02

Makeshoes · May 26, 2005

Green Hornet said:
Thanks, I'm gonna give it a shot at 40:1. Can I mix it into the gas tank with the remainder of the 32:1 mix or should I run the tank down and then add. Also, this would make the mixture richer correct. I use a BR7ES instead of the BR8ES, because my riding tends to be more technical that wide open riding. So should I go back to the BR8 & check the color & then a BR7 if I don't like the color. My jetting is pretty close & I lowered the needle last month for a fine adjustment and I started getting a LEAN BOG. The plug looks cleaner running the BR7
Later
Jack

I run 43:1 and do use a BR7. It is nice tan colored. It does have a little hesitation in it for just a couple of minutes if the engine is not fully warmed but once warmed up no hesistation at all. My riding too is more of the technical variety and less of the full (or 3/4) throttle versions. Try either plug and see what it looks like. Good Luck

19Brendan81 · May 26, 2005

"Again if your pipe is really bad you might search here and find that others have used radiator shops, etc. to clean them out"

I took mine to a head rebuilder (engine rebuilders will do too) and got it dipped in the hot tank / pickle tank. It was a stock pipe that was mighty full of carbon (I was doing this whilst gutting the pipe of the sound deadener as per the KDX home page). It is now virtually bare metal, not a trace of carbon in it. And the price? Nothing. It seems there still are some good blokes left in the world.

Green Hornet · May 27, 2005

Recommendation from Jeff Fredette

I spoke w/Jeff today after placing an order and he stated the following to me by phone & e-mail. Attention Golden Spectro Synthetic users
"golden spectro synthetic we run at 50:1 and have for 20 years. jeff"
Many of you may already know, but for those of you like me who are experimenting w/different ratios, this is from the horses mouth. Mix what ever the oil manufacter recommends on the bottle.
TTFN-Jack

Change pre-mix ratio, or jetting?

43Duc748

ellandoh

dismount art student

Jaybird

Apprentice Goon

ellandoh

dismount art student

Quailchaser

John Harris

bikepilot

CaptainObvious

Formally known as RV6Junkie

cr250can

Jaybird

Apprentice Goon

43Duc748

Rhodester

CaptainObvious

Formally known as RV6Junkie

Green Hornet

John Harris

Green Hornet

Makeshoes

Green Hornet

04kdx200

John Harris

cicone

Makeshoes

19Brendan81

Green Hornet

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Change pre-mix ratio, or jetting?

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