Lets talk ktm 300 xc

[summitboy]

The PC pipe is garbage in my opinion. Id go with the FMF.

 

[relentless rider]

Thanks for all the info mtn-doo, looks like I need to get busy just a question, what ratio do you premix your gas?

I mix Klotz at 32/1

 

[snocattin]

Klotz 28:1

two hard seasons of motocross at Spokane track,
two hard seasons as snowbike,
pulled piston out, no where on the (stock) piston can you not still see factory machine marks.
Rings were weak though, a bit of blow by, but still ran strong.

Oh, and the complete re-build cost $138.00, nice.

Love my YZ 250.

The Camo Extreme 2 1/2 paddle track will be a nice addition this year.

 

[somepunk22]

50:1 Amsoil Dominator non ethanol premium for my 300 and all my other 2t.

Went through a lot of different oils on my 200, and this seemed to keep the power valve the cleanest. Never had a fouled plug. Piston at 160hrs on the 200 looked good enough to put back in. EFI oil injected sleds run much less oil than 50:1. So I don't worry about long WOT runs on my 3 huny.

A lot of different opinions on oils and ratios. Try a few, and choose what is best for you.

 

[somepunk22]

Anyways this thread needs more 300 pics, because this is all about the snow 300 right?

 

[mtn-doo]

A general statement regarding ratio's. Example; Looooong wide open pulls on a sled. I mean long. Soooo long you're starting to feel guilty. You have most likely felt a soft "fade", then thought, "yikes", and backed off and pumped the throttle a few times. We all or most all have experienced this. Two oil Tech's from Klotx and Maxima both explained the exact situation. Good info. On those extended WOT pulls, your cylinder burns any excess oil and becomes dry. The result leads to reduced ring sea, a dry cylinder and "fade". The remedy is more oil. Increase from those light ratio's to 32 or 28 to 1 and the problem goes away. It works. I have never forgotten it. Be aware though, adding oil will lean you out a little. You may have to jet up slightly.

 

[relentless rider]

Mtn doo , ive got the stock airbox and the wire cage with the snow filter on (like yours on your 450 build) and than got air filter foam in the side panel vents,how well does this work in deep powder and for it getting enough air?

 

[Guitarman]

2013 KTM 300 XC-W

Want to thank everyone for sharing their knowledge on the 300. It helps greatly. I am putting mine together as we speak. I have my new Billet Smartcarb! Knarly pipe and silencer. I will order the 250 sx cdi shortly. Might not have time before snow flies to get it ported. Too excited to get this on the snow. I have the ST kit. Headed for Washington Sunday to meet Allen and Jason at the Washington State Snow expo in Puyallup. Let's Ride!

 

[relentless rider]

We just need snow now, my yard has taken a beating this week .

 

[backcountryislife]

A general statement regarding ratio's. Example; Looooong wide open pulls on a sled. I mean long. Soooo long you're starting to feel guilty. You have most likely felt a soft "fade", then thought, "yikes", and backed off and pumped the throttle a few times. We all or most all have experienced this. Two oil Tech's from Klotx and Maxima both explained the exact situation. Good info. On those extended WOT pulls, your cylinder burns any excess oil and becomes dry. The result leads to reduced ring sea, a dry cylinder and "fade". The remedy is more oil. Increase from those light ratio's to 32 or 28 to 1 and the problem goes away. It works. I have never forgotten it. Be aware though, adding oil will lean you out a little. You may have to jet up slightly.

Also, I have yet to test a single sled that showed a 50:1 ratio. Most cats are in the 20's, even my new etec is in the 30's despite people claiming it uses WAY less oil. Oil helps increase dynamic compression, compression is power.
Depends on how you ride though, if you tool around at low to mid throttle, you'll get spooge at 32, and if you're hammering nonstop you'll wish for the 20's. I'd think due to the increased load on a snowbike compared to dirt, you'd want to up yourself from your normal summer mix, since there's not really much coasting on snow, and you're working it much harder.

There's enough snow to ride around here now... I'm ready to go play!!!

 

[mtn-doo]

Mtn doo , ive got the stock airbox and the wire cage with the snow filter on (like yours on your 450 build) and than got air filter foam in the side panel vents,how well does this work in deep powder and for it getting enough air?

It does pretty good in keeping things clean, it also flows a lot of air. Will run well as long as your box doesn't start filling up. The best way to keep that darn box from filling on cold, dry pow days is to give the snow a place to fall through. Opening up the bottom of your air box. The KTM is so easy to access the filter, I would run it like you have it for a while. Pop the side off and take a peek once in a while.

 

[relentless rider]

How long of a wait for the apt carb for you guys that have pre ordered one?

 

[relentless rider]

a article on premix

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.*

 

[mtn-doo]

That was awesome. Glad you had the nards to speak it. Like you said, it's like politics or religion. You have obviously done your homework. Thanks

Good point folks struggle with. More oil, equals less gas, equals lean. Run higher oil ratio's, you need to jet "up" a little. The oil displaces fuel and and the result goes lean. Add some oil and go up a jet size! Your engine will love you for it. A lot of folks believe "rich" means too much oil. It has nothing to do with your oil ratio. Well, I guess you started it... We'll stick with it. If it helps others, it's well worth the discussion. Thanks

 

[relentless rider]

Haha mtn-doo, I have done my homework, I live and breath this stuff
but there are alot of old timers out there schooling us younger folks, I did alittle cutting and pasting on that one from other forms out there , the bike that this guy dyno on was made when I was 2 lol I sure did lean alot from this article, and thought id share

 

[dooman92]

Ratios

Relentless, thanks for the oil ratio post. Great info. I've been playing with two strokes for 40 years and could not agree more with the info. Almost did not buy etec because of the the inability to adjust oil. The increased oil also aids in cooling/heat transfer. Thank again

 

[ktmrider714a]

Wow lots of great information has come of this. I have been mixing 28:1 golden spectro and actually bumped it down to 26:1 when I was on the snowbike nervous I was pushing it too hard but this info is excellent. Thanks!

 

[byeatts]

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.*

Good read. Its important to use oils with the correct flashpoint to burn rather than spooge and carbon up valves. IE single track riding and the engine seldom sees over 1/2 throttle. I use different oils for singletrack with low flashpoint than my sleds designed to be held WOT.

 

[Rush44]

The 300's are coming!

 

[summitboy]

Nice ! I'd like to see it in 3 ft as well !