What mix ratio, factory or leaner

[1SWEETYZ]

Hey guys I have this damn ratio thing thats pissing me off, I have a 01 yz125 and the factory manual says 30:1 but all my boys at the dealer say 40:1 and never mind the book. Would someone please shed some light on this for me. I apologize if its been beaten to death but it's really bothering me. I have a slight bog at low rpm and their telling me I need a leaner mix to get rid of it

Thanx :bang:

 

[IndyMX]

Changing the premix ratio is not the way to fix issues like this.

Yes, it has been beaten to death. Make sure any mechanical issues are addressed, and jet it properly.

Plus, stop listening to that shop. They obviously have no idea what they are talking about.

Yes, you need a leaner mix, you're probably very rich. But not with the oil/gas ratio. But the Fuel/Air ratio.

There is a very detailed carb tuning guide here on the site.. http://justkdx.dirtrider.net/carbtuning.html

Read that, and follow it carefully.

 

[Patman]

It seems like a lot of folks confused the gas/oil ratio and the air fuel ratio just like Indy has pointed out. I previously ran 50:1 when I had a KTM360 but when my son started riding a 2 stroke I knew he needed a bit more lube in the gas so I re-jetted my bike so that we could both use 32:1 fuel and that's pretty much where we run his 125 to this day. A little extra oil isn't going to cause any issue and will help protect things better plus give some better sealing. Rich has done some research on this at ratios in the 16:1 & 20:1 range I believe. All the same setting the carb up for a proper air / fuel ratio WILL cure your problems, messing with the oil ratio to fix a carb tuning issue is not the way to properly fix it. The guys at your shop seem to be lacking in real knowledge so I would no let them anywhere near my bike.

If you are lazy like me the James Dean Carb kit is a great way to get your bike dialed in really well. It sure ain't cheap but it takes a lot of the guess work out of things.

 

[RM_guy]

...If you are lazy like me the James Dean Carb kit is a great way to get your bike dialed in really well. It sure ain't cheap but it takes a lot of the guess work out of things.

It was sure cheap for me when you look at how much time and money I spent on jets, plugs, new silencer packing, etc. Since I've had his kit install I spend zero dollars and time on jetting issues...and my bike actually runs like it should :nod:

 

[brentn]

What does the kit consist of?

 

[RM_guy]

It includes what ever you may need for your bike including main, pilot and a special multi taper needle. The needle is the real beauty. The multi taper really helps clean up the 0 to half throttle carburation.

If you have specific question or there is no kit listed for your bike, give them a call and they will set you on the right path. There was no listing for my bike but the one they sent did the trick :)

 

[whenfoxforks-ruled]

Fast 125 and 85 racers, need even more oil, 25:1 at least. The average water cooled 125 should be good at 32:1. Just look in the bikes manual, it will tell you. Then jet it, after everything else physically checks out. You can not start in the middle, like not knowing exactly the condition of your motor, intake and exhaust, and electrics. Trying to jet a bike, not knowing exactly how everything else is, is worse than playing russian roulette. That slight bog could be, to rich on the pilot, float valve not serviced yearly, float height off, worn top end, oil soaked packing, to name a few. And sure as heck do not take anymore advice from your "shop". They did not try selling you a power now blade for your carb? Thats a good sign! What kind of plug is in it?

 

[TRexRacing]

It can and will be argued until they really do outlaw SI 2 strokes.However more oil in the mix is more power.Just run the bike at what the engineers designed it to run with.Easiest bestest way to go.

 

[1SWEETYZ]

I have a brand new top end and everything else, basically I rebuilt the bike from the bottom up, I believe the carb sat for a long time and I forgot to clean it before i installed it, I'm hoping that may be the problem too

 

[whenfoxforks-ruled]

Yeah the carb thing. Geez, I have a whole box of mikuni parts, like 8 carbs. 2 were able to be salvaged. Clobbered by others, and parts that never get lubricated, and scale that flat out will not come off! There is a filter inside the gas tank also, atop the petcock.

 

[cujet]

All other issues aside, more oil makes more power and reduces wear.

There have been a number of very well instrumented scientific tests on this subject. I was involved in one for Mercury Marine. We settled on 16 to 1, even though 8 to 1 provided more HP, there were other problems with so much oil.

In our testing, 32 to 1 provided all the protection necessary for non racing applications. 50 to 1 did result in slightly higher wear rates.

 

[MXcruiser]

Am I the oly one who likes the smell of 2 stroke oil. My bikes run 32:1 smoke when idling but clean out fast and run great. And nothing like the smell of following a good 2 stroke burn!

 

[1SWEETYZ]

I use that strawberry racing oil, it smells awesome, no more headaches just sweet smelling oil, I have had guys ask me what makes that smell cuz when they are behind me it smells like strawberry. lol :ride:

 

[whenfoxforks-ruled]

927 and ether oxygenated race fuel. Be warned, a little dash on the wifey will make her skin burn/break out. And possibly injure you!