BajaNomad

Tuning a 2 Stroke Carb.

TMW - 7-19-2018 at 08:09 PM

bajatrailrider - 7-20-2018 at 09:22 PM

That is a very well written article . All of my dirt bikes have different carbs on them. My bore and stroked CRf 230 uses a 2 stroke carb to get it perfect we had to solder the pilot jet re drill it and the grind the slide. As the size we need not made.

ehall - 7-21-2018 at 04:58 AM

I just saw that flowchart yesterday. Pretty good stuff and alot is the same for 4 strokes.
Any experience with the smart carbs? Lectron etc.?

ehall - 7-21-2018 at 04:59 AM

I should print this and take it with me. We are riding 9k-13k feet next week in Colorado. Lot of 2 strokes will be there.

ncampion - 7-21-2018 at 12:06 PM

Quote: Originally posted by ehall  
I just saw that flowchart yesterday. Pretty good stuff and alot is the same for 4 strokes.
Any experience with the smart carbs? Lectron etc.?


Been running an Edelbrock on my WR for many years after getting tired of cleaning pilot jets. Very simple, one jet, a flat tapered needle and everything works fine. You can even adjust the needle by hand on the trail.

JZ - 7-21-2018 at 01:18 PM

I'll just take my bikes to my mechanic, thank you very much.

Desertbull - 7-21-2018 at 01:19 PM

Works on my Husqvarna Chainsaws too!

David K - 7-21-2018 at 01:24 PM

Quote: Originally posted by Desertbull  
Works on my Husqvarna Chainsaws too!


How's that gasoline-powered blender doing? 1 million margaritas and going?

TMW - 7-21-2018 at 02:05 PM

Quote: Originally posted by JZ  
I'll just take my bikes to my mechanic, thank you very much.


JZ does he jet your 2 stroke under riding conditions. 4 strokes are very forgiving as to jetting vs 2 strokes. If you find yourself needing to use PEMEX Magna mix it lean.

willardguy - 7-21-2018 at 02:52 PM

Quote: Originally posted by JZ  
I'll just take my bikes to my mechanic, thank you very much.


perfect opportunity to reach into those deep pockets and trade her in on one of the EFI 2smokes! :yes:

JZ - 7-21-2018 at 03:30 PM

Quote: Originally posted by TMW  


JZ does he jet your 2 stroke under riding conditions. 4 strokes are very forgiving as to jetting vs 2 strokes. If you find yourself needing to use PEMEX Magna mix it lean.


What ratio?

ehall - 7-21-2018 at 04:32 PM

I wonder if the new oil injected , efi 2 strokes compensate for pemex fuel. My 4 stroke runs great on it.

JZ - 7-21-2018 at 07:28 PM

I always put Premium in it with some few acceptations. It runs great.

TMW - 7-21-2018 at 08:01 PM

If you are running PEMEX Premium and don't have any problem fouling plugs you are OK with the mix you're using. Most manufactures usually recommend a 32:1 mix. Back in the 90's we ran 40:1 using race gas and syn. oil for racing. We'd mix 32:1 with US premium gas and never had a problem until we put PEMEX in. Usually it was PEMEX magna then we would go to a 50:1and that helped, but careful to not go to full throttle for any distance. The plug should be a light tan color. Any time we changed gas (octane) or mixing oil we would spend time making sure the jetting was correct at all speeds.

We would use 87 octane pump gas racing at Mammoth Mtn. due to the altitude.


[Edited on 7-22-2018 by TMW]

JZ - 7-21-2018 at 08:24 PM

Mines a 2016 KTM 250 XC. The manual says 60 to 1. I always run 50 to 1. Never had a fouled plug. No jetting. Runs perfectly.

TMW - 7-21-2018 at 08:29 PM

Wow the new bikes have come a long ways. With fuel injection everything has changed, I think for the better mostly.

My last bike was a 2004 XR250. I won it at the Off Road Expo in Pamona in 2005 in a raffle drawing at the Checkers booth. I loved that bike. It had enough power for me and the suspension was just to my liking. I had a shaved seat with a grip cover and a lowering link so the seat was 2 inches lower than stock. A 4 gallon gas tank and rewound stator for more light power. A Scott stabilizer keep me straight hitting the rocks. I gave it to my son who's in Colorado. He gave it to his son after buying a new Yamaha 450.

[Edited on 7-22-2018 by TMW]

JZ - 7-21-2018 at 08:41 PM

My kid's 2016 4 stroke has been a lot more problematic.

It randomly overheated twice. First time was out near Tecolete after 10 days of riding. We changed the antifreeze and it was good for several runs. Then it over-heated again when we were in the middle of running the Pioneer Mine trail. Let it cool down and it was fine, but we circled back to the 5 just in case.

I had the mechanic go over it, and turns out a small dent in the radiator from his friend hitting it with his bike was causing the water to not fully circulate (at least that was his theory).

Put a knew radiator on it, and it ran the Seven Sister's flawlessly.

The only issue now, is the Baja Design's light I've got on it is killing the battery, even with a new strator. Gonna try to change the battery and see if it fixes it. Have jump started that thing 20 times. It doesn't have a kick start and is impossible to start it by popping the clutch. Why they made a bike w/o a kick start kills me.

del mar - 7-21-2018 at 08:52 PM

Quote: Originally posted by JZ  
My kid's 2016 4 stroke has been a lot more problematic.

It randomly overheated twice. First time was out near Tecolete after 10 days of riding. We changed the antifreeze and it was good for several runs. Then it over-heated again when we were in the middle of running the Pioneer Mine trail. Let it cool down and it was fine, but we circled back to the 5 just in case.

I had the mechanic go over it, and turns out a small dent in the radiator from his friend hitting it with his bike was causing the water to not fully circulate (at least that was his theory).

Put a knew radiator on it, and it ran the Seven Sister's flawlessly.

The only issue now, is the Baja Design's light I've got on it is killing the battery, even with a new strator. Gonna try to change the battery and see if it fixes it. Have jump started that thing 20 times. It doesn't have a kick start and is impossible to start it by popping the clutch. Why they made a bike w/o a kick start kills me.



Evans coolant and a fan kit.....does it have a Rekluse?

bajatrailrider - 7-22-2018 at 09:49 AM

All the KTM guys I ride with on our super hard trails over heat. With fans Evens coolant and double over flow tanks. The 2 strokes don't over heat of course nobody in there right mind would be there.

TMW - 7-22-2018 at 09:56 AM

Maybe the water pump isn't moving the coolant fast enough.

del mar - 7-22-2018 at 10:20 AM

there's a mod that bypasses the thermostat....that and some Evans should do the trick. already having battery issues you're probably not to keen on the fan kit

[Edited on 7-22-2018 by del mar]

John Harper - 7-22-2018 at 11:38 AM

Quote: Originally posted by JZ  

The only issue now, is the Baja Design's light I've got on it is killing the battery, even with a new stator. Gonna try to change the battery and see if it fixes it. Have jump started that thing 20 times. It doesn't have a kick start and is impossible to start it by popping the clutch. Why they made a bike w/o a kick start kills me.


Do you have a multimeter? You can check battery voltage and stator output with even a cheap/free HF one. How many amps does the new light draw? Does BD certify it for use on your bike? Have the battery checked at a local parts store for it's own condition. What happened to your first stator? Have you checked your regulator/rectifier? Everything grounded well?

John

bajatrailrider - 7-22-2018 at 01:40 PM

Quote: Originally posted by TMW  
Maybe the water pump isn't moving the coolant fast enough. [/rquot They have used the aftermarket water pumps its not like we do normal riding. Burro canyon even caught one KTM on fire . The best to help over heating Bikes only. 100 percent coolant no water no 50 50 mix. Our riders been doing this since 1985 Big help to not over heating. I know you gearheads will say but it runs hotter with no water. Correct slight bit hotter but does not boil over. Witch is better boil over nothing in rad or full of coolant.:)

John Harper - 7-23-2018 at 05:26 AM

Quote: Originally posted by bajatrailrider  
They have used the aftermarket water pumps its not like we do normal riding. Burro canyon even caught one KTM on fire . The best to help over heating Bikes only. 100 percent coolant no water no 50 50 mix. Our riders been doing this since 1985 Big help to not over heating. I know you gearheads will say but it runs hotter with no water. Correct slight bit hotter but does not boil over. Witch is better boil over nothing in rad or full of coolant.:)


I knew a guy with highly modified Camaro drag racer who ran pure antifreeze in his motor. That was way back in the 1970's, have not heard of that since then.

John

bajatrailrider - 7-23-2018 at 06:53 AM

When you run pure antifreeze in your daily driver car or truck it does not work. On a drag racer that runs few mins that's another story. The KTM guys a I ride with also use oversize radiators. Another over heater bike is the Beta 450/500. What is funny some people think water cooled bikes run cooler then air cooled bikes. Not in the real world as air cooled bikes don't boil over. My ex KTM 525 was fine on more flowing speed rides but the hot slow stuff would boil over. My ex KTM 200 2 smoke never over heated.

John Harper - 7-23-2018 at 08:45 AM

Quote: Originally posted by bajatrailrider  
What is funny some people think water cooled bikes run cooler then air cooled bikes.


I thought tight emission standards led to higher engine temps due to leaner fuel mixtures. Hence the need to go to liquid cooling on more and more motorcycles. Or, oil cooled heads, etc.

John

bajatrailrider - 7-24-2018 at 07:07 AM

True John on dirt bikes real world. Most all dirt bikes sold water or air cooled. Are tuned to meet tight emission standards we do not ride them that way. As no power run hot with lean settings. On air cooled bikes re jet richer pilot and main jets. Air box baffle out tiny muffler baffle out. On FI water cooled bikes Retune black box that controls FI air box and filter mod. Or new hi performance black box very expensive. They build them not to ride but pass test. On Yamaha 450s the use a throttle stop you only get less then 1/4 in throttle. You replace throttle stop with one from a YZ450 to gain full power. At the end of the day in my experience the air cooled bike. Less over heating no coolant to lose.

John Harper - 7-24-2018 at 07:16 AM

Quote: Originally posted by bajatrailrider  
True John on dirt bikes real world. Most all dirt bikes sold water or air cooled. Are tuned to meet tight emission standards we do not ride them that way. As no power run hot with lean settings. On air cooled bikes re jet richer pilot and main jets. Air box baffle out tiny muffler baffle out. On FI water cooled bikes Retune black box that controls FI air box and filter mod. Or new hi performance black box very expensive. They build them not to ride but pass test. On Yamaha 450s the use a throttle stop you only get less then 1/4 in throttle. You replace throttle stop with one from a YZ450 to gain full power. At the end of the day in my experience the air cooled bike. Less over heating no coolant to lose.


Yes, I'm familiar with the tuner mods done on FI bikes. On my carbed Sportster, I've richened up both pilot and mainjets as well as intake and exhaust upgrades.

John

[Edited on 7-24-2018 by John Harper]