KTM 150sx 2018 fuel/oil ratio???

ginger969
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ginger969
Edited Date/Time 4/7/2018 6:52am
this is for the 2018 150SX KTM -

I've now heard everything from 32:1 - 60:1...What gives here?

I'm using the KTM Motorex Cross Power 2T fully syn premix oil

What should I be mixing my fuel to? I'm still getting a bog off the bottom at 60:1 and 50:1, bike is stock jetting aside from the needle position being lowered one spot. I'm at 2600ft elevation, dry climate.

Please help me out here Smile
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kb228
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kb228 3/30/2018 10:12am
3/30/2018 10:12am
Mix what your service manual says and jet accordingly. Compensating bad jetting with mixture changes is only a band aid fix.
seth505
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seth505 3/30/2018 10:55am
3/30/2018 10:55am
I think it says 40:1 right on the bike/manual.
Paw Paw 271
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Paw Paw 271 3/30/2018 11:01am
3/30/2018 11:01am
I think it actually states 60:1 in the manual, but check it. I know Motocross Mag. did a big write up about all this last year and found that the factory mix ration as stated in the book is the best even with a re-jetting. They never got it to run as well as it did with the stock mix ration and jetting.

Paw Paw
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seth505 3/30/2018 11:05am
3/30/2018 11:05am
Paw Paw 271 wrote:
I think it actually states 60:1 in the manual, but check it. I know Motocross Mag. did a big write up about all this last year...
I think it actually states 60:1 in the manual, but check it. I know Motocross Mag. did a big write up about all this last year and found that the factory mix ration as stated in the book is the best even with a re-jetting. They never got it to run as well as it did with the stock mix ration and jetting.

Paw Paw
I thought the 125/150 were 40:1 but you might be correct. My 250 manual says 60:1

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CarlinoJoeVideo
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CarlinoJoeVideo 3/30/2018 11:18am
3/30/2018 11:18am
I’m using on my KTM 125 with JD Jet kit:
VP C12 @ 40:1 50/50 with 91 Pump at 60:1
(Should average about 100 octain and 50:1)


AJ565
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AJ565 3/30/2018 11:26am
3/30/2018 11:26am
The 125/150 mix 40:1. The 250 mixes at 60:1.
Luxon MX
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Luxon MX 3/30/2018 11:52am
3/30/2018 11:52am
Manual says 40:1 for the 125/150. I've been running mine at 36:1 because that's what I always used previously in 125s and never bothered to read the manual Laughing . No issues at this ratio.


ginger969
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ginger969 3/30/2018 11:54am
3/30/2018 11:54am
Luxon MX wrote:
Manual says 40:1 for the 125/150. I've been running mine at 36:1 because that's what I always used previously in 125s and never bothered to read...
Manual says 40:1 for the 125/150. I've been running mine at 36:1 because that's what I always used previously in 125s and never bothered to read the manual Laughing . No issues at this ratio.


No roll on sputter?
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joliver722 3/30/2018 12:19pm
3/30/2018 12:19pm
The fuel is contingent of the equation. Are you using pump gas or a high octane leaded fuel?
Luxon MX
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Luxon MX 3/30/2018 12:35pm
3/30/2018 12:35pm
ginger969 wrote:
No roll on sputter?
Nope, runs great. It's 50/50 91 pump and VP C12, 36:1 with Motul 800 2t. 1.1mm squish, Vforce reed valve, and an FMF pipe/silencer with the Mikuni carb.
ginger969
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ginger969 3/30/2018 12:53pm
3/30/2018 12:53pm
So...Either he's wrong with the Cross Power 2T or? haha SOO many opinions gahhh TPI please...hahaha

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Luxon MX 3/30/2018 2:41pm
3/30/2018 2:41pm
ginger969 wrote:
So...Either he's wrong with the Cross Power 2T or? haha SOO many opinions gahhh TPI please...hahaha

Well, he's wrong in quoting the manual as he did. The manual calls out the 40:1 for 125/150 and 60:1 for the 250. That's the top portion of the image in my post (from the KTM manual). It's also calling out the MINIMUM octane rating for the fuel for each which is a function of compression, timing, etc. that is different for the 125/150 (98 octane) and the 250 and off-road bikes (95 octane).

What he's referencing in the video is the later portion of the manual that's the bottom portion of the image I posted (I combined two parts of the manual into one image), but he's doing it out of context and saying that the ratio depends on the fuel octane, which is wrong.
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Bruneval 3/30/2018 4:29pm
3/30/2018 4:29pm
32:1 on mine with Maxima 927 and leaded race gas. V-Force reed block and FMF pipe with JD jet kit.

Runs okay, but I plan on adjusting the powervalve as a next step.
CarlinoJoeVideo
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CarlinoJoeVideo 3/30/2018 5:51pm
3/30/2018 5:51pm
I’m not sure what’s wrong with following the manuals recommendations, why run more oil than what KTM says?
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Bruneval 3/30/2018 7:48pm
3/30/2018 7:48pm
CarlinoJoeVideo wrote:
I’m not sure what’s wrong with following the manuals recommendations, why run more oil than what KTM says?
Because I have run 32:1 for 25 years and never had a single oil related problem - it’s just my default setting that has proven to work for me on the tracks I ride back in Europe which are mainly sand.

I only have 2 hours on my ‘18 150sx so far but might try using a little less oil when I finish the batch I have mixed-up. Still setting the thing up to be honest.
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BobPA 3/30/2018 8:37pm
3/30/2018 8:37pm
CarlinoJoeVideo wrote:
I’m not sure what’s wrong with following the manuals recommendations, why run more oil than what KTM says?
Because two strokes make more horsepower when used with more oil. It also protects internal engine parts. My old man raced sleds for Arctic Cat in the 70's and they did all kinds of dyno work. Engines always made more horsepower at 20:1 than they did at 40:1. Oils are much better today, so there is no need to go down to 20:1 for MX, especially for 250's and up. Karting guys run as low as 16:1, but they are pounding the shit of their engines for long periods of time. Do a quick search and you will see that two strokes like oil.

That being said.....I say pick an oil, choose your fuel, pick a ratio, jet your bike, and stick with it. If you can, keep everything consistent and do not go changing fuels or ratios...it will throw your jetting off.

I am sure modern, quality, synthetic oils are fine at 60:1...But oil is cheaper than engine work.
CarlinoJoeVideo
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CarlinoJoeVideo 3/30/2018 9:22pm
3/30/2018 9:22pm
CarlinoJoeVideo wrote:
I’m not sure what’s wrong with following the manuals recommendations, why run more oil than what KTM says?
BobPA wrote:
Because two strokes make more horsepower when used with more oil. It also protects internal engine parts. My old man raced sleds for Arctic Cat in...
Because two strokes make more horsepower when used with more oil. It also protects internal engine parts. My old man raced sleds for Arctic Cat in the 70's and they did all kinds of dyno work. Engines always made more horsepower at 20:1 than they did at 40:1. Oils are much better today, so there is no need to go down to 20:1 for MX, especially for 250's and up. Karting guys run as low as 16:1, but they are pounding the shit of their engines for long periods of time. Do a quick search and you will see that two strokes like oil.

That being said.....I say pick an oil, choose your fuel, pick a ratio, jet your bike, and stick with it. If you can, keep everything consistent and do not go changing fuels or ratios...it will throw your jetting off.

I am sure modern, quality, synthetic oils are fine at 60:1...But oil is cheaper than engine work.
Very interesting!

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689
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689 3/31/2018 3:31am
3/31/2018 3:31am
The Mikuni carb will always have roll on splutter unless you jet it super lean before and after the rich spot. Tried a heap of different needles, and my bike would never run correct with that carb. Ditched it and runs correctly with the Keihin.
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RockyRider 3/31/2018 7:12pm
3/31/2018 7:12pm
The oil ratio ain't causing your bogging, sounds like you need to do some jetting work
ginger969
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ginger969 3/31/2018 7:14pm
3/31/2018 7:14pm
RockyRider wrote:
The oil ratio ain't causing your bogging, sounds like you need to do some jetting work
Yeah I've started that path now haha you're prob 100% right too...new carb to arrive on the 5th tho! that'll help too Smile
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macz400 4/3/2018 3:16pm
4/3/2018 3:16pm
Bruce372 wrote:
Vp T2 is 40.1 and runs amazing in our tc125
Just got 2 jugs of this myself. Ran T2 in my CR125 and was great. Since the 18 150SX reccomends 40:1 anyway, I figured I'd keep running it in the KTM.
theycallmeebryan 4/3/2018 7:40pm
4/3/2018 7:40pm
I always run 125's at 32:1 on 100octane. 4oz of oil to 1 gal of fuel. Very easy to measure and remember.

For 250's, i would run 3oz of oil to 1 gal of fuel, which equates to 42.6:1 ratio.
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racerx317 4/4/2018 7:46pm
4/4/2018 7:46pm
The KTM manual is pretty spot on with their jetting suggestions based on elevation etc... go to manufacturer specs at 40:1 with a 98 motor octane non ethanol fuel and you should be spot on minus a little minor air screw adjustment. That said, I do use VP T2 myself and it is awesome stuff. Motor octane on T2 is within range at 101 octane and it’s premixed at 40:1, however it’s oxygenated so you’ll need to go up on the main from the manual if you use it. My suggestion, if you go to T2 fuel, would be to go up 2 mains to start and come back down as needed so you don’t run too lean.
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Asimo 4/6/2018 12:08pm
4/6/2018 12:08pm Edited Date/Time 4/6/2018 12:08pm
They recommend ratios for emissions, not engine longevity.

The video guy above is Clueless as to why various ratios are listed and obviously knows nothing about oil migration times or engine CC requirements.

If you ran a kart 125 at 40:1, you'd probably seize it or at least get a lot of ring wear if it was built loose enough.
More oil isnt going to hurt anything as long as you're burning it off. At worst, you get more exhaust carbon.

For example, JS7 on a 125 needs more oil that your granddad riding the same bike around the back yard.

Outdoors pros need more oil than the same guy racing a SX.

Also if the oil is for both Premix AND Injection, run the next richer step 40:1 go to say 36 or 32:1. Injection oil is pre-diluted and a tad thinner than an oil only for premix.



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slipdog 4/6/2018 4:27pm
4/6/2018 4:27pm
Asimo wrote:
They recommend ratios for emissions, not engine longevity. The video guy above is Clueless as to why various ratios are listed and obviously knows nothing about...
They recommend ratios for emissions, not engine longevity.

The video guy above is Clueless as to why various ratios are listed and obviously knows nothing about oil migration times or engine CC requirements.

If you ran a kart 125 at 40:1, you'd probably seize it or at least get a lot of ring wear if it was built loose enough.
More oil isnt going to hurt anything as long as you're burning it off. At worst, you get more exhaust carbon.

For example, JS7 on a 125 needs more oil that your granddad riding the same bike around the back yard.

Outdoors pros need more oil than the same guy racing a SX.

Also if the oil is for both Premix AND Injection, run the next richer step 40:1 go to say 36 or 32:1. Injection oil is pre-diluted and a tad thinner than an oil only for premix.



Weird because I got a couple top 20 finishes running 64:1 in my 125 with no engine failures....
BobPA
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BobPA 4/6/2018 5:24pm
4/6/2018 5:24pm
Asimo wrote:
They recommend ratios for emissions, not engine longevity. The video guy above is Clueless as to why various ratios are listed and obviously knows nothing about...
They recommend ratios for emissions, not engine longevity.

The video guy above is Clueless as to why various ratios are listed and obviously knows nothing about oil migration times or engine CC requirements.

If you ran a kart 125 at 40:1, you'd probably seize it or at least get a lot of ring wear if it was built loose enough.
More oil isnt going to hurt anything as long as you're burning it off. At worst, you get more exhaust carbon.

For example, JS7 on a 125 needs more oil that your granddad riding the same bike around the back yard.

Outdoors pros need more oil than the same guy racing a SX.

Also if the oil is for both Premix AND Injection, run the next richer step 40:1 go to say 36 or 32:1. Injection oil is pre-diluted and a tad thinner than an oil only for premix.



slipdog wrote:
Weird because I got a couple top 20 finishes running 64:1 in my 125 with no engine failures....
Any reason why you run so lean on oil?
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Jrewing 4/7/2018 2:40am
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Asimo wrote:
They recommend ratios for emissions, not engine longevity. The video guy above is Clueless as to why various ratios are listed and obviously knows nothing about...
They recommend ratios for emissions, not engine longevity.

The video guy above is Clueless as to why various ratios are listed and obviously knows nothing about oil migration times or engine CC requirements.

If you ran a kart 125 at 40:1, you'd probably seize it or at least get a lot of ring wear if it was built loose enough.
More oil isnt going to hurt anything as long as you're burning it off. At worst, you get more exhaust carbon.

For example, JS7 on a 125 needs more oil that your granddad riding the same bike around the back yard.

Outdoors pros need more oil than the same guy racing a SX.

Also if the oil is for both Premix AND Injection, run the next richer step 40:1 go to say 36 or 32:1. Injection oil is pre-diluted and a tad thinner than an oil only for premix.



slipdog wrote:
Weird because I got a couple top 20 finishes running 64:1 in my 125 with no engine failures....
Coulda got top 16 with more oil Derrr!!!
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slipdog 4/7/2018 6:51am
4/7/2018 6:51am
BobPA wrote:
Any reason why you run so lean on oil?
I ran what the motor builder said to run, as did several other guys racing the nationals at the time. The only lower end failure I can recall was from any of his guys was at an SX and was found to be from a machining fuck up, but lower end lubrication and engine hp was never an issue at 64:1

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