Risk of Running Rich or Lean

[Harvo]

Can running rich or lean cause damage to a bike? I know that running too lean for a while can burn up a motor right? But are there concerns with a bike that runs too rich or a little lean for long periods?

[William1]

Too lean on a 2S will destroy the engine. Too lean on a 4S will mostly prevent it from accelerating, rarely any damage. Rich on either will 'clog up the works' but not destroy either.

[Valosity]

Too lean on a 2S will destroy the engine. Too lean on a 4S will mostly prevent it from accelerating, rarely any damage. Rich on either will 'clog up the works' but not destroy either.

On the rich side, your are completely wrong. A rich condition on either kind can be jist as bad as a lean condition. Ive seen huge pistons blown a hole through them from being run rich for too long. Rich causes detonation

[mustards12s]

Depends if you are saying rich in fuel (most use this)

Or rich on air. Given the choice I would rather deal with a rich on fuel bogger than a pinging ready to blow lean..

[William1]

On the rich side, your are completely wrong. A rich condition on either kind can be jist as bad as a lean condition. Ive seen huge pistons blown a hole through them from being run rich for too long. Rich causes detonation

Detonation? No, not from being rich. Wrong fuel causes detonation.

[mlatour]

2 stroke too lean = engine seizure

2 stroke too rich = fouled plug, doesn't run well, spooged exhaust

 

Running extremely rich on a 4 stroke could wash off the oil film on the cylinder wall / piston, and dilute the oil.

Running extremely lean on a 4 stroke will cause high combustion temps, erode the top of the piston, burn the exhaust valve.

 

After adding an engine mod, or all of a sudden your bike isn't runnning right

keep an eye on your sparkplug's colour, could save you a lot of trouble.

[Valosity]

Detonation? No, not from being rich. Wrong fuel causes detonation.

Yes, from too rich air fuel wise. Wrong fuel can, but detonation is when the fuel burns and explodes at the wrong time of the engines cycle

[William1]

Yes, from too rich air fuel wise. Wrong fuel can, but detonation is when the fuel burns and explodes at the wrong time of the engines cycle

???????????????????????

That makes no sense.

 

Detonation is from having a fuel that has too low an octane for a given actual compression ratio. Firing off at the wrong time is either preignition (wrong octane) or mis-timed spark firing off the moix at the incorrect time (which is more or less unheard of in todays electronic ignition engines)

 

 

It has nothing to do withg the A/F ratio. Especially if it is too rich.

A too lean mix can ping but it is often burning a hole in the piston as it pings (pinging is not detonation), though this is nearly exclusive to a 2S. A 4S just fails to rev.

[LovingOffroadPain]

Can running rich or lean cause damage to a bike? I know that running too lean for a while can burn up a motor right? But are there concerns with a bike that runs too rich or a little lean for long periods?

Lean will destroy a motor, it'll blow. Yesterday we went riding in east Texas, the weatherman was proven a liar--it was 35 degrees, not the forecasted 55!! So we were cold every time we stopped til we got warmed back up riding. It was about 40 degrees when we pulled out at the temp' speak if the day.

It was also humid. Lower temps and humidity cause a carb'd bike to run lean, so I could tell it needed rejetting. It wasn't in danger of blowing up but I'll rejet for the next ride if I know the conditions will be like yesterday.

[LovingOffroadPain]

By the way I went riding with Cleaner1--had a blast buddy!! 50+ miles of Barnwell Mtn beat us down.

[Red Mountain Addict]

Lean will destroy a motor, it'll blow. Yesterday we went riding in east Texas, the weatherman was proven a liar--it was 35 degrees, not the forecasted 55!! So we were cold every time we stopped til we got warmed back up riding. It was about 40 degrees when we pulled out at the temp' speak if the day.

It was also humid. Lower temps and humidity cause a carb'd bike to run lean, so I could tell it needed rejetting. It wasn't in danger of blowing up but I'll rejet for the next ride if I know the conditions will be like yesterday.

I went riding last week for a 3 day camp out at Red Mountain CA.  Night temps were in the mid 30's, and no amount of wool could keep me warm enough from having to get up a few times in the middle of the night and fire up the van to get some heat.  Here I'm crying about mid 30's in CA while our riding brothers back east are facing far worse.  So freakishly cold, that it's just turned me off to riding in the winter altogether.  I'm hoping the weather will warm up in the coming months so I can go out again and have the blast I did last weekend, but man, that cold is a real deal breaker.  I thought about getting a Coleman Catalyst burner to keep me warm in that van at night, but I've always been weary about running any kind of burner in an enclosed space like a closed van in fear I'll run out of O2 and die in my sleep.  Got lucky yesterday and found a Coleman (Kawasaki) 800W generator for only $45, needs a little TLC, and with that, I'm hoping I'll be able to run a small electric heater instead and be comfy while I slumber and recoup for the next day of riding.  I wanted very much to stay a 4th night, and my provisions (gas, food, water) were still good, but that freaking cold convinced me, there's no way I'm doing another mid 30's night.  That cold has a way of seeping into you while you sleep, only to rudely awake you to think you've entered an ice age.  I'll be glad when summer comes again.  Even riding in 40/50 with the wind chill factor pretty much took all the fun out of it.  I say I probably got about 4 good hours of riding each day.  Anyone camp out "old school" (meaning tent, van, back of a pickup ~ (certainly not a fancy 40 foot motorhome) and have any good stories to tell about this freaking cold?  Sorry, let me include this to stay on topic, "agree", lean is bad, a lot worse than rich I think.  I rode all three (3) rigs at about 80-1 that weekend and didn't have any problems, but I would rather run rich and foul, than run lean and blow.

Edited February 9, 2014 by YZ490-DEVIL

[Brandt233]

On the rich side, your are completely wrong. A rich condition on either kind can be jist as bad as a lean condition. Ive seen huge pistons blown a hole through them from being run rich for too long. Rich causes detonation

Incorrect. Detonation absolutely cannot be caused by a rich condition.

Leaner mixtures burn faster.

Detonation is combustion that goes too fast: the crankshaft hasn’t turned enough to allow the combustion event to properly push the piston down and rotate the crankshaft. Rich mixtures do not burn too fast obviously.

[Kroynon]

Incorrect. Detonation absolutely cannot be caused by a rich condition.

Leaner mixtures burn faster.

Detonation is combustion that goes too fast: the crankshaft hasn’t turned enough to allow the combustion event to properly push the piston down and rotate the crankshaft. Rich mixtures do not burn too fast obviously.

Also incorrect but i wont bother explaining what detonation is and what can cause it.

Educate yourself.

[Badunit]

Detonation is when a pocket of fuel-air mixture that is not part of the flame front ignites. A rich mixture does not cause detonation.  A rich mixture does not prevent detonation. A rich mixture is less prone to detonation. 

[Brandt233]

Also incorrect but i wont bother explaining what detonation is and what can cause it.

Educate yourself.

Hey. You believe what you want. I tried to give you the layman's version. If you want the technical version here ya go. Educating is tough.

Under normal conditions, the combusting air and fuel mixture inside the combustion chamber ignites in a controlled manner. The mixture is ignited by the spark, normally in the center of the cylinder, and a flame front moves from the spark towards the outside of the cylinder in a controlled burn. Detonation, or engine knock, occurs simply when fuel ignites before the piston reaches scheduled spark ignition. This means that a powerful explosion is trying to expand a cylinder chamber that is shrinking in size, attempting to reverse the direction of the piston and the engine. Causing sudden pressure changes in the cylinder (Up to 10x that normally experienced), and extreme temperature spikes that can be very damaging on engine pistons, rings, rods, gaskets, bearings, and even the cylinder heads. This is exactly what I said in much simpler terms before. I hope you are not an engine builder. LoL.

Edited February 10, 2014 by Brandt233

[Kroynon]

I build turbocharged drag race V8 engines.

Your explanation is partially correct but still technically incorrect. Problem being you may not realize there is a difference between detonation and preignition of which you are combining the two in your explanation but no worries here. Ride on...

[Brandt233]

I build turbocharged drag race V8 engines.

Your explanation is partially correct but still technically incorrect. Problem being you may not realize there is a difference between detonation and preignition of which you are combining the two in your explanation but no worries here. Ride on...

No mix up here. I am very aware of the difference. Pre-ignition is defined as the ignition of the mixture prior to the spark plug firing. Anytime something causes the mixture in the chamber to ignite prior to the spark plug event it is classified as pre-ignition. The two are completely different and abnormal phenomenon.

[Kroynon]

In confident you know your stuff and it's sometimes hard to get across on a forum like this without writing a book. All good. Didn't mean to sound like a know it all or anything.

[Brandt233]

In confident you know your stuff and it's sometimes hard to get across on a forum like this without writing a book. All good. Didn't mean to sound like a know it all or anything.

Oh no worries. Just good discussion. No ill intent. Sometimes text comes across wrong. Didn't mean to sound like a know it all either. All good. ?

[LovingOffroadPain]

Anyone camp out "old school" (meaning tent, van, back of a pickup ~ (certainly not a fancy 40 foot motorhome) and have any good stories to tell about this

I've camped at RedMountain in the winter for riding trips (camped to the west of the Spangler Hills, they are so fun job a freaking CR 500), and we camped in the low teens weather in Oregon as a kid.

The key to cold weather is preparation. Wear sweats and hoodie, wear stocking cap in a sleeping bag rated for sub 40s weather. If you can't justify that expense bring a few thick blankets. Also your bed is very important--even an air mattress gets cold. Put blankets beneath the sleeping bag to insulate yourself, and/or put bed pads or something beneath the air mattress bc the cold floorboards do you no good!

I lived in Victorville for a few years, had a lotta good rides and races at RedMountain. But that place can sneak up on you.. mine holes and occasionally rain ruts. My uncle was an expert racer in his day, we were riding across the southern valley below Spangler Hills and suddenly he... DISAPPEARED. My uncle, bike and all were swallowed by a massive 6' deep rain rut that ran from the mountains. He got freaking lucky.