Fuel Ratio/Lean or Rich

[Knine]

Dis Regard thus info....I was Confused Bac then...LOL

[Unlimited]

i dont lug it. i know for a fact that my slow jet is too big i need to go down one size. but im holding all re jetting till after the pipe goes on. should be here by the end of the week. i ordered the fmf fatty it gives a nice boost everywhere. coupled with the fmf shorty which produces nice low and mid range gains should be very nice. that combo is fantastic on my kx. so im expecting the same for the CR

[Knine]

More Bad Info!

[CRrider]

hey man. i went riding sunday and crushed in my pipe. i have a 1990 CR250 and was wondering if you had a pipe you wanted to sell so i can go riding!!!

[Knine]

hey man. i went riding sunday and crushed in my pipe. i have a 1990 CR250 and was wondering if you had a pipe you wanted to sell so i can go riding!!!



I made a tele Call...Let's see what he might have , when he calls me bac!

I'll post bac with a Ya or nay!

[Knine]

Nay! ... ...

[1BFC]

Super necro here but I think it's important to clear a common misconception up that can lead people to damaging their 2 strokes. If this is common knowledge for you guys.. well.. just ignore this next bit :)

32:1 im gonna throw a pipe on it and that will lean it out a lil bit then ill jet it after that.

Try 40:1, that will lean it out also! Lugging it all the time will cause it to seem like it running rich!

This is 100% backwards.

40:1 is richer than 32:1 from a Air/Fuel ratio point of view. 40:1 IS leaner from a Gas/Oil ration.

So, on to why the quote is backwards....

32:1 gas/oil mix ratio means: 32 parts gasoline to 1 part oil.

40:1 gas/oil mix ration means (durrr): 40 gas to 1 oil...

Your carb is jetted to let X amount of gas through per unit of air (totally separate from the oil/gas mix ratio). Stoichiometric (http://en.wikipedia.org/wiki/Stoichiometry) air/fuel ratio for most engines running on regularly available gasoline fuels (read: not alcohol, nitro methane, etc..) have a ratio of ~14:1 as the "perfect" ratio. In reality, performance tuned engines under a full load tend towards 12:1 (can vary by application).

So, 12 parts air to 1 part fuel.

If you mix your fuel at 32:1 gas/oil and your carb is jetted so you are at 12:1 air/fuel then you are getting 32 parts of gas and 1 part of oil per that "1" part of air/fuel that gets through the carb. 32 parts gas... remember this.

If you mix at 40:1 gas/oil and your carb is jetted so you are at 12:1 air/fuel then you are getting 40 parts of gas and 1 part of oil per that "1" part of air/fuel that gets through the carb. 40 parts gas....

Now, which is "richer"? 32 parts gas or 40 parts gas?

40 is greater than 32 in my book!

So, when you have that 2 stroke running good finally and you decide one day to "hey, i'm going to mix a little leaner on the oil to save $$ or to help clean up a bog..." well, you are mucking with a bunch of stuff when you do this.

Stick to a ratio you feel comfortable with.... 20:1 was stock on the 80's era Honda 2 strokes. 32:1 is pretty common to use. 40:1 is also fairly common. 32:1 is handy because it's exactly 4 ounces of oil per gallon of fuel. Once you settle on a gas/oil ratio you can then tune the carb for engine performance. Never, ever adjust mix ratio to fix how your engine is running. Even though you can do it, it's seriously the wrong way to go about things.

DISCLAIMER: ALL of these numbers are for general descriptions only. Do not go by these as the rules for your application. Look into it for your application specifically.

[Knine]

I was confuse:tard[1]:..LOL Bac Then!


But, I'll go with this 1 Now:eek:




Pre-mix 101

OK, looks like it's time for a little pre-mix 101. I don't usually get into ratio discussions, because mix ratios are like religions to most people, and they tend to be closed-minded on the subject, but I'll put in my $.02 here anyway.

There is a prevailing myth that less oil is better, and that the oil in the fuel is what lubricates the engine. Both are wrong.

*less oil is better* People think that if they have a plug fouling problem or a lot of spooge, they need to run less oil. Wrong! Both problems are caused by rich jetting, and have nothing to do with the mix ratio.

*the oil in the fuel is what lubricates the engine* The engine is lubricated by the residual oil that builds up in the crankcase. All the oil in the fuel does is replenish this oil.

The best way to determine if you are running enough oil is to check the level of the residual oil in the crankcase. If the ratio you run leaves enough residual oil in the crankcase to cover about 1/8" of the bottom of the crank wheels, then you are fine. If you don't have that much residual oil in your crankcase when you pull the top-end off, you aren't running enough oil for your riding style and conditions.

With that said, to have that amount of residual oil in the crankcase at 50:1 (a ratio made popular by magazines and oil bottles), you can't be riding very hard, or your bike is jetted richer than necessary simply to deliver enough oil. I arrived at 26:1 for my bike with my riding style because that is the amount that gives me the proper amount of residual build-up. Small-bore engines require greater oil concentrations than larger engines to achieve the proper amount of residual build-up, because they rev higher and have higher intake velocities. Along the same lines, someone that pushes the engine harder, and keeps the revs higher, also needs to use higher oil concentrations to achieve the proper residual build-up.

To understand why the residual oil is so important, you have to understand what happens to the oil in your fuel when it goes into the engine. While the oil is still suspended in the liquid gasoline, it can not lubricate anything. It has about as much lubricity at that point as straight gasoline. When the gasoline enters the engine, it evaporates, dropping the oil out of suspension. Now that the oil is free, it can lubricate the engine, but it must get to the parts to lubricate them. The way it gets to the bearings and onto the cylinder is by being thrown around as a mist by the spinning crankshaft, and the droplets are distributed by the air currents moving through the engine. Ever wonder why there are two small holes in the transfer port area of the crankcase, right over the main bearings? These are to allow some of the oil droplets being flung around inside the engine to drip down into the main bearing area.

Some of the oil eventually makes it into the combustion chamber, where it is either burned, or passes out the exhaust. If the combustion chamber temps are too low, such as in an engine that is jetted too rich, the oil doesn't burn completely. Instead, some of it hardens into deposits in the combustion chamber, on the piston, and on the power valve assembly. The rest becomes the dreaded "spooge". The key to all of this working in harmony is to jet the bike lean enough to achieve a high enough combustion chamber temperature to burn the oil, but also still be able to supply enough oil to protect the engine. If you use enough oil, you can jet the bike at it's optimum without starving the engine of oil, and have excellent power, with minimal deposits and spooge. At 50:1, you simply can't jet very lean without risking a seized engine due to oil starvation, unless you're just putt-putting around on trails without putting the engine under much load.

With the high oil concentrations that I use, I tend to get far more life from my cranks and rings than most of my friends that run leaner oil ratios. The high oil content also produces better ring sealing, so more of the combustion pressure is retained.

One small point. No one ever broke an engine by using too much oil.


__________________________________________________ _______________________________________________

Pre-mix ratios and power production

I have run Dyno tests on this subject. We used a Dynojet dynamometer, and used a fresh, broken in top-end for each test. We used specially calibrated jets to ensure the fuel flow was identical with each different ratio, and warmed the engine at 3000 rpm for 3 minutes before each run. Our tests were performed in the rpm range of 2500 to 9000 rpm, with the power peak of our test bike (a modifed '86 YZ 250, mine) occuring at 8750 rpm. We tested at 76 degrees F, at 65% relative humidity. We started at 10:1, and went to 100:1. Our results showed that a two-stroke engine makes its best power at 18:1. Any more oil than that, and the engine ran poorly, because we didn't have any jets rich enough to compensate for that much oil in the fuel, and the burn-characteristics of the fuel with that much oil tended to be poor. The power loss from 18:1 to 32:1 was approximately 2 percent. The loss from 18:1 to 50:1 was nearly 9 percent. On a modern 250, that can be as much as 4 horsepower. The loss from 18:1 to 100:1 was nearly 18 percent. The reason for the difference in output is simple. More oil provides a better seal between the ring and the cylinder wall.

Now, I realize that 18:1 is impractical unless you ride your engine all-out, keeping it pinned at all times. But running reasonable ratios no less than 32:1 will produce more power, and give your engine better protection, thus making it perform better for longer.

[Andy9933]

You have a 4 stroke now:crackup::bubbrubb2:The two stroke is building dust now:bubbrubb2:

[Slo Poke]

You have a 4 stroke now:crackup::bubbrubb2:The two stroke is building dust now:bubbrubb2:

just like with wheels.... 4>2.....:devillook:

[shogun323]

just like with wheels.... 4>2.....:devillook:

:crackup::crackup: :goodpost[1]:

[Knine]

You have a 4 stroke now:crackup::bubbrubb2:The two stroke is building dust now:bubbrubb2:



Rode Both Yesterday....and Both Are NICE & SHINY..Today!:rock:

[Ricksta]

knine said he was going to give me his suspension :)

[shogun323]

knine said he was going to give me his suspension :)

Nice!!! Congrats!!!

[Knine]

knine said he was going to give me his suspension :)


YA! Right! :eek:


Knine Will Give U The # to PRO-ACTION"s Only Franchise In The State Of FL.
http://www.wnyproaction.com/index.html


Contact: Bobby in Lakeland @ (863)412-6630


And This! :)




1. Forks and shocks should be installed according to your
owners manual. Improper installation could result in
improper handling and harshness or even mechanical
failure.
PRO-ACTION FORK SETUP GUIDE :

If you received your forks back from us then they are ready
to bolt on. The oil level is set and the compression and
rebound adjusters should be within two clicks in either
direction. If your forks were sent in for a oil change , seal or
bushing replacement and no revalving work done , the
adjusters will be set where we received them unless
otherwise stated.

If you received your forks through UPS service , they have
been allowed to lay flat. Before installing the forks on the
bike , stand them up and pump them 10 to 12 times each
with caps on. This will force the oil back into the cartridges.

SETTING COMPRESSION :

Step 1 : When riding the forks should flow smoothly. They
should react to all changes in terrain. If the forks seem
harsh on small choppy bumps , lighten the compression
dampening.

Step 2 : With the compression dampening set for smooth
action over small bumps , the forks should work on rougher
terrain. The forks should bottom over the worst obstacles
on the track. If harsh bottoming occurs, increase oil level in
5 mm increments.

SETTING REBOUND :

The rebound dampening is the speed at which the front
wheel returns to the ground. Rebound is not only
responsible for straight line handling but also is the energy
that holds your front wheel in a corner.

Step 1 : Out on the track find a good corner , preferably a
short sweeper. The forks compress to set up for a turn
(providing you ride and apply your front brake correctly).
The speed at which the forks rebound is the energy that
pushes your front end in to the ground. If the forks are
allowed to rebound too quickly , the energy will be used up
to early and the front end will wash or push to the outside.
If the forks rebound too slowly , the front end will tuck
under and turn too soon. Adjust accordingly.

Step 2 : With the forks handling well in the corners , go on
to rougher sections of the track. The fork action should be
smooth and the wheel should return to the ground quickly ,
it should not bounce off jumps or deflect off berms.

Note : If head shake occurs , try lowering the fork legs in
the triple clamps. This will extend your wheel base. If you
have exhausted yourself with tuning and still can't get it
right , you may want to consider our revalving service. If
you are using a set of our revalved forks and are having
problems....CALL US IMMEDIATELY!

PRO-ACTION SHOCK SETUP GUIDE :

Your shock should be ready to bolt on straight out of the
shipping box. It should be within 2 clicks , in either direction
, on your rebound and compression adjusters. Spring
preload is set at 10mm (follow sag setting steps after
installation. ***For shocks with a remote reservoir do not
attempt to loosen the hose to reposition it.***

SETTING SAG :

The sag of your bike is determined by the rate of your
spring and the amount the spring is pre-loaded.

STEP 1 : Put the bike or atv on a stand so the weight is off
the rear wheel(s). Take the measurement from the center
of the axle to a solid point above (seatbolt / fender) and
write this measurement down.

STEP 2 : At this point a second person is needed. Take
the machine off the stand. Place on level ground. Bounce
lightly a couple of times. Position yourself in the neutral
position of the seat directly over the foot pegs. Have your
assistant measure using the same points of your first
measurement. Subtract this measurement from your first
and this is your race sag. Adjust accordingly by adding or
subtracting spring preload until you have between 95 and
100 mm of sag.

STEP 3 : Check static sag with rider off the bike. Bounce
the bike to resettle the suspension. Measure again using
the same 2 points as before. Subtract this from your first
measurement to get static sag. With your race sag set at
95 mm , the proper static sag should be between 15 and 25
mm. If the static sag is less you need a stiffer spring , if it is
more you will need a lighter spring.

SETTING REBOUND :

When the sag is properly set , find a long straight away
with some breaking bumps going in to a corner. Subtract or
soften the rebound until the rear end feels a little springy or
loose , then turn the screw in until that springy sensation
goes away. Find a jump next , the wheel should hit and
absorb but not bounce. If it bounces add rebound. Now go
to a section of whoops or rockers. The bike should track
straight and absorb bumps with the rear wheel returning
quickly enough as not to pack. Packing is caused by the
rear wheel not coming back fast enough to absorb the next
bump. If packing occurs , soften the rebound.

SETTING COMPRESSION :

With the sag and rebound set , find a corner on the track
with choppy acceleration bumps leaving the corner. If the
rear wheel seems to lose traction or bounce over the tops ,
soften the compression (for bikes with high and low speed -
adjust low speed). Next try some g-outs and jumps. You
should bottom on the worst obstacles , but it should not be
bone jarring. You can adjust the high speed adjuster to a
stiffer setting to help with these obstacles.

Note: These tips are starting points and may not be correct
for everyone. If you cant seem to get it right , give us a call.
We are here to help you.
About Us

[Andy9933]

Pro-Action FTW!!!!!!!:bubbrubb2: