Stock 86 250R flat out flies with this jet setup

[3Razors]

Hey Zee!

32.1 isn't really that lean. I use the MOTUL in my 88 R & @ 40.1 it rips all the way through and I too have messed with the mixture in the stock ATC's and the factory recomendation is rediculous.

Honda has the factory jetting setup for a 20:1 mixure. If you do change ratios YES you should lean out the jetting for peak performance.

On a side note 20:1 works great in my 250r's. 2 of them are still on the original crankshafts/bearings/piston, and the third is on its first over after 20 something years. The harder you run your machine the more oil it needs to live a long time.

[whyzee]

Ok finally got the chance to take my R to an open field and really hold her wide open in 5th and 6th gear. I noticed a lean bog at around 3/4 throttle to wide open only in 5th and 6th gear tapped out.
Conclusion.... awesome short track , woods setup up through 5th gear mid throttle. If you need to go faster than that or ride in the sand this will be too lean.

Sick bottom through top pull 1st -4th. You need to sit on the tank to keep the front end down

[burnoutboy]

Yeah, you're right, it's not lean, in fact it is rich. The stock 20:1 is lean, more oil and less gas=lean mixture.

20:1 is very rich..20 parts gas to 1 part oil. 40:1 is 40 parts gas to 1 part oil..

[NINJA]

20:1 is very rich..20 parts gas to 1 part oil. 40:1 is 40 parts gas to 1 part oil..

LMAO!
Hmmmmm, why don't you think about that one a little while longer, because, apparently you don't understand how this works. At a 40:1 mixture you now have 50% less oil in your gas as oppossed to a 20:1 mixture. 40:1 equals more gas and less oil, therefore it is a richer mixture. That is why nobody else has argued with me about this. If you ever mix anything with a Ratio Rite you will quickly figure this out. Please don't argue about something if you do not understand how it works.

[stoney420]

At a 40:1 mixture you now have 50% less oil in your gas as oppossed to a 20:1 mixture. 40:1 equals more gas and less oil, therefore it is a richer mixture.

i think its the other way around man, you are right 40:1 equals more gas and less oil as opposed to 20:1 obviously, but i beleive since u have less oil at 40:1 that is a leaner mix isnt it?.. am i missing something here???....

[NOS_350X]

On the stock bikes ive played with i end up around a 160 main. Amazes me how lean you got these things. Im real courious how long that piston will hold up in there. But you also said you arnt getting in 5th or 6th. Out west here we will run in the desert for miles wide open. You defently want it on the rich side here.

[whyzee]

On the stock bikes ive played with i end up around a 160 main. Amazes me how lean you got these things. Im real courious how long that piston will hold up in there. But you also said you arnt getting in 5th or 6th. Out west here we will run in the desert for miles wide open. You defently want it on the rich side here.

definitly. When I finally got it to a field where I could run it wide open in 5th and 6th I could feel the lean bog set in.

This setup I am suggesting is for woods or tight tracks . I am lucky if I have it wide open for 2-3 seconds before shutting it down to make a tight turn.
Wish I had some riding like you have!

[NINJA]

i think its the other way around man, you are right 40:1 equals more gas and less oil as opposed to 20:1 obviously, but i beleive since u have less oil at 40:1 that is a leaner mix isnt it?.. am i missing something here???....

OMG! I am really getting sick of this you guys. Do your effin homework and learn how this works before you argue it! You are missing something here, it's called oxygen. Say you have a 20:1 mix, that's 20 parts gasoline to one part oil. Now, think of that mixture going through the tiny little orifice of a main jet. You've got more oil displacing the gas through that tiny little hole. Now that mixture is pulled up through your main jet and into your emulsion tube where it gets blended with air, that mixture finally gets pulled into your carburetor venturi. Now stay with me here. If you were to mix your gas and oil at 40:1 you would now have more gasoline going through your main jet and into your emulsion tube to mix with the air coming through your main airjet and into the emulsion tube. This mixture would be a richer mixture because it is more gasoline, less oil, and the same amount of air.

[3Razors]

Well put Ninja

[stoney420]

lol damn u got me all confused now, o well i guess thats why i dont have any 2 strokes! sry for the thread highjacking..
~Stoney~

[burnoutboy]

um ok...now im real lost. guess the whole air thing ads a third dimension to fuel to oil ratios. so in another words the more oil i use the leaner it is?

[NINJA]

That is correct, the more oil that is in your gas, the leaner your mixture is going to be going into your engine. That is why the stock 250Rs have such large main jets from the factory, to deal with the factory recommended 20:1 mix. They recommend 20:1 because all that oil will help the machine cope with alot more abuse and last longer. Chainsaws for example commonly use a 16:1 ratio because they get run wide open frequently.

[RedRider_AK]

What people need to learn to do is figure out that "rich" and "lean" can mean two different things. If your "MIX RATIO" is lean, it means that you used less oil in proportion to gas. If you have a lean "mix ratio" (or whatever you want to call it), you have a richer jetting, because of the fact that it's letting more fuel into the cylinder per intake stroke, due to there being less oil in the gasoline premix.

[NOS_350X]

An easy way to put it, the more oil means you will have better lube on the berrings and crank. BUT your piston (combustion) will be running lean so you can fry the pison.
Running less oil, means your combustion will be richer (assuming same jetting) but lube on the berrings and crank will not be as good. (Leading to a possible froze crank)