40:1 vs. 32:1; runs WAY different....

[mele63]

Just curious what you guys think.

2003 KX125 runs ok on 32:1 Amsoil. Then, I add one measley gallon of 40:1 to one gallon of 32:1 already in tank during mid-ride gas-up. Result: runs like crap and fouls the plug.

I'm just amazed that this change would make such a difference. When you average the two gallons, we're at 36:1 vs. 32:1. Does this surprise anyone? More importantly, do you think my bike was already running too rich?

Like I said it runs ok at 32:1, maybe a little rich at mid-throttle, but I'm already running the 2nd clip from top on needle, two sizes smaller main and pilot, and an "8" plug. I trail ride with two twelve-year olds and sometimes forced to ride at low speeds with frequent stops (yes I know the bike's meant to be run hard but these are the facts).

 

[greenman06]

kx

Ive had similar problems with my 04 kx 125. Ive been using 40:1 belray h1r. The bike was running rich so i moved down 1 jet on the main and pilot which seemed to help, but honestly now that im riding the bike harder now and not putting around like i was when i first bought it, which will definately load it up and foul plugs, it seems to run alot better.. :cool:

 

[+30]

I wouldnt be ready to blame the mix ratio of the gas for the plug fouling, if you had been lugging the bike for a part of the ride then you may have a good bit of unburned oil in the crank, thinning the mix out to 36:1 should be fine, should not cause fouling. 40:1 may be a little too thin if you sometimes ride the 125 hard plus your jetted a good bit leaner from stock so I think your doin the right think with the ratio.Was the second tank of gas same quality and age as first tank? To be sure Id drain the bike and start over with a fresh mix, and go from there.

 

[mele63]

.Was the second tank of gas same quality and age as first tank? To be sure Id drain the bike and start over with a fresh mix, and go from there.

Yes I suppose the gas used to mix the second batch constitutes a variable. Good thought. Riding style, temp/humidity, and mechanicals, however, were about as constant as you expect outside of a laboratory.

 

[motoB]

I have a question about this thread?

Reading through Eric Gorr's site if I remember correctly you changed the fuel oil mixture w/ less oil which in turn richened your fuel mixture, now you are running too rich?!

Call me an idiot if need be but there was a thread about this changing of mix ratio awhile back, and been quite a few beers ago.

Brian

 

[mele63]

I have a question about this thread?

Reading through Eric Gorr's site if I remember correctly you changed the fuel oil mixture w/ less oil which in turn richened your fuel mixture, now you are running too rich?!

Call me an idiot if need be but there was a thread about this changing of mix ratio awhile back, and been quite a few beers ago.

Brian

Yes, I understand the jetting/tuning basics; my inquiry concerns the specifics of my particular bike. I realize the mixture was richened by going to 40:1....I was surprised by the dramatic effect on the bike's performance.

 

[Rich Rohrich]

Just curious what you guys think.

2003 KX125 runs ok on 32:1 Amsoil. Then, I add one measley gallon of 40:1 to one gallon of 32:1 already in tank during mid-ride gas-up. Result: runs like crap and fouls the plug.

I'm just amazed that this change would make such a difference.

It wasn't the oil ratio that caused your problems. Adding an extra 0.8 ounce of oil to the mix compared to what you were running would make no noticeable change in performance.

You are dealing with some other issue here.