How does KTM get away with 50-60:1 premix ratios?

[KTM-548cc]

it just depends on what you want. 50:1 or even 100:1 is fine, but you'll go through topends a bit quicker as the rings will wear faster with less lube. the upside is a crisper running bike with better throttle response.

i disagree 100% with that comment and ive done my own reasearch to prove it wrong. many other documented tests have been done that found the same results i did. a well tuned bike at 16:1 runs just as crisp and revs every bit as fast.

[adam728]

k, you are right, i worded my self wrong their.but at the end of your day, your motor will still be over oiled. as said befor,oil burns hot. a hot motor dose not make as much HP then an engin running at optimal temp.

86 octain fule makes more "power" then 98, why? because it burns hotter and more vilently.

So which is it? You claim oil burns hot and reduces power, but 87 octane burns hot, increasin power?

Both are wrong, by the way.

[KTM-548cc]

wanted to add something to my earlier comment. im not saying you should use a 16:1 ratio. what im saying is, i did the testing myself, and theres other documented tests as well. your living in a dream world if you think 16:1 makes a bike foul plugs, spooge out the pipe and not run as crisp. assuming everything is tuned well. that goes for any ratio though. probly alot of folks around here with black tar running out of the muffler on a 50:1 ratio

[gravelfreak]

Oil decreases octane rating and thus increases the chances of detonation and runs hotter. Lack of oil is the least of the enemies of a two stroke motor, as long as the supply is constant.

[adam728]

I think it goes without saying that the octane level of the fuel you chose needs to be sufficient to avoid detonation, with whatever oil ratio you decide to use.

Lack of oil is the least of a two strokes enemies? Are you saying 200:1 should be fine?

[JTSmith]

I think I just may try an ounce of oil for every five gallons of gas, that way I can have super awesome throttle response AND my engine will run cooler.

[chadk66]

Oil decreases octane rating and thus increases the chances of detonation and runs hotter. Lack of oil is the least of the enemies of a two stroke motor, as long as the supply is constant.

glad to see somebody here gets it.?

[harrperf]

On cooling:

How is heat transfered on a two stroke piston?

Through the rings - and the skirt.

But the contact patch on the skirt is very small mechanically! That means if you ran it dry of oil very briefly you see the scuff marks on the piston where it contacts the cylinder. This contact patch is small. it's why four strokes have a very small skirt instead of a big skirt (because it cuts weight and the extra area is not needed for contact.

But when running lots of oil - you increase the contact area of skirt to cylinder. The piston actually runs COOLER with more oil. The single hardest stressed part on a two stroke is the PISTON. And the more power a two stroke makes - the harder the piston gets loaded THERMALLY. Ulitmately the power EXCEEDS the thermal limit of the piston - and you can not make more power without piston failure even if you COULD make more power

Then methanol comes in to play!

If heat were an enemy in combustion - why do thermal coating companies exist and claim that increased heat/retained heat in the exhaust gasses are better? Riddle me that!

Also - when a two stroke is run with NO oil - what is the first thing to go? The piston. It builds so much heat it literally MELTS and scrapes off aluminum and bonds to the cylinder on a small level.

Thats the farthest extreme on one side.

What happens when a bike is run with TONS of oil? Say 10:1?

The piston looks great and the never melts unless the user does something incredibly stupid with jetting and even then it wont usually melt a piston.

I'll run more oil, thank you.

[kx450f63]

k, you are right, i worded my self wrong their.but at the end of your day, your motor will still be over oiled. as said befor,oil burns hot. a hot motor dose not make as much HP then an engin running at optimal temp.

86 octain fule makes more "power" then 98, why? because it burns hotter and more vilently.

putting in just the right amount of oil to keep parts moving with the least amount of resistance is all the motor needs.

this is what i have been tought, im not saying you are wrong, im not saying i am write. just what i have been tought. by no means am i trying to start a pissing war.

You have been taught wrong.

[harrperf]

You have been taught wrong.

And you right?

Just curious.

My shop is located near san antonio, VP Race Fuels head quarters..

I will try and see if I can get a break down from one of their guys regarding temperatures and fuels..

But their highest end motocross race fuels are VERY LOW octane rating. I think mrpro5.1 is 86 motor octane rating.

It makes more power than almost any other fuel they offer - regardless of the fact it conforms to current fuel rules.

Their high octane leaded fuels such as c12 makes terribly power in a race four stroke by comparison.

Race fuels do not BURN cooler. Some are designed to pull more heat away as they vaporize - which is critical in a two stroke to also help cool the piston. It's one excellent quality of a good two stroke race fuel such as c12. This may be where the myth of cooler burning came from. The PISTON runs cooler due to the fuels vaporization characteristics - but the combustion process may be hotter.

[kx450f63]

And you right?

Just curious.

My shop is located near san antonio, VP Race Fuels head quarters..

I will try and see if I can get a break down from one of their guys regarding temperatures and fuels..

But their highest end motocross race fuels are VERY LOW octane rating. I think mrpro5.1 is 86 motor octane rating.

It makes more power than almost any other fuel they offer - regardless of the fact it conforms to current fuel rules.

Their high octane leaded fuels such as c12 makes terribly power in a race four stroke by comparison.

Race fuels do not BURN cooler. Some are designed to pull more heat away as they vaporize - which is critical in a two stroke to also help cool the piston. It's one excellent quality of a good two stroke race fuel such as c12. This may be where the myth of cooler burning came from. The PISTON runs cooler due to the fuels vaporization characteristics - but the combustion process may be hotter.

I think we both know a lot more goes into fuel than just what the rating is. Rite now I am just entertaining myself while watching lap times in L.A. but for debating purposes go to your local fuel station and buy their lowest RON fuel and let me know how much HP you make in your modern 4 stroke race bike and for how long.

So when you talk to your buddy at VP ask him if the number 86 rated fuel is RON or MON. If 86 is the RON rating then I certainly am way behind on the tech. for fuel these days and the chemists are making leaps and bounds in the right direction.

[mdkcrf250r]

I can say for a FACT that more oil makes more power and typically castor oils perform the best.

There are draw backs to more oil in plug life - and sometimes cleanliness (with a castor especially) but it flat out performs better in the HP deparment.

And, surprise, it helps parts longevity too.

So why does KTM spec 50:1? I have no idea! It may be just like honda specs 10 or 15 hour oil change intervals on their 250f but they also suggest top ends every 15 hours...

Often times the engineers dont write the service manual - believe it or not.

So do what you wish! But I promise you this: The fastest engine builders and the fastest engines in the two stroke world are running LOTS of oil.

Then why arent (or werent rather) top level 2 strokes such as GNCC and MX/SX bikes smoking at all or ever had any silencer drip on the silencer? Now I understand they are ridden harder then I ever could but if there running lots of oil as you suggest there would have to be some evidence of it right?

[The Spanky]

I can say for a FACT that more oil makes more power and typically castor oils perform the best.

There are draw backs to more oil in plug life - and sometimes cleanliness (with a castor especially) but it flat out performs better in the HP deparment.

And, surprise, it helps parts longevity too.

So why does KTM spec 50:1? I have no idea! It may be just like honda specs 10 or 15 hour oil change intervals on their 250f but they also suggest top ends every 15 hours...

Often times the engineers dont write the service manual - believe it or not.

So do what you wish! But I promise you this: The fastest engine builders and the fastest engines in the two stroke world are running LOTS of oil.

Yep. ? Dyno testing (my own included) PROVES that more oil will make more power in a two-stroke. And yet people will still argue this point.

86 octain fule makes more "power" then 98, why? because it burns hotter and more vilently.

.

That's a purely ignorant post. Octane rating has absolutely nothing to do with burn rates or combustion temperatures. And the energy available from a fuel is determined by its btu content, not it's ability to resist detonation. All pump gasoline has the same btu content, except for ethanol blends as they aren't pure gasoline.

[The Spanky]

And you right?

Just curious.

My shop is located near san antonio, VP Race Fuels head quarters..

I will try and see if I can get a break down from one of their guys regarding temperatures and fuels..

But their highest end motocross race fuels are VERY LOW octane rating. I think mrpro5.1 is 86 motor octane rating.

It makes more power than almost any other fuel they offer - regardless of the fact it conforms to current fuel rules.

Their high octane leaded fuels such as c12 makes terribly power in a race four stroke by comparison.

Race fuels do not BURN cooler. Some are designed to pull more heat away as they vaporize - which is critical in a two stroke to also help cool the piston. It's one excellent quality of a good two stroke race fuel such as c12. This may be where the myth of cooler burning came from. The PISTON runs cooler due to the fuels vaporization characteristics - but the combustion process may be hotter.

While you are correct, your wording is misleading, and may reinforce the false belief that lower octane fuels make more power.

The mrpro5.1 makes more power than C12 because it is blended with components that have a higher btu content than the C12. Not because it has a lower octane.

And you can't directly compare MON octane with the (RON+MON)/2 rating used for pump fuels. The 86 MON rating of the mrpro5.1 is very likely a point or two higher than the MON rating of most if not all pump fuels.

Not arguing with you, as I said you are correct, just clarifying it for those that will take your post as "proof" that lower octane makes more power...?

[The Spanky]

Then why arent (or werent rather) top level 2 strokes such as GNCC and MX/SX bikes smoking at all or ever had any silencer drip on the silencer? Now I understand they are ridden harder then I ever could but if there running lots of oil as you suggest there would have to be some evidence of it right?

Because they are jetted correctly. If you know how to jet you can run any amount of oil you want with no smoke or spooge once the engine is at full operating temperature. I ran 24:1 for years, and my bikes always have a dry tail pipe. Why? I know how to jet correctly.

Barring any mechanical issues such as leaking crank seals or bad reeds, if your bike smokes or spooges once up to full operating temperature you have a jetting issue.

[grayracer513]

The mrpro5.1 makes more power than C12 because it is blended with components that have a higher btu content than the C12. Not because it has a lower octane.

And you can't directly compare MON octane with the (RON+MON)/2 rating used for pump fuels. The 86 MON rating of the mrpro5.1 is very likely a point or two higher than the MON rating of most if not all pump fuels.

On the power output issue, you're absolutely correct that octane number is totally unrelated to it in any way whatever except in the most indirect manner; that being that in some fuels the chemistry used to raise the octane may increase or decrease the overall energy content of the blend.

But an MON of 86-87 is just about equal to the 91 octane anti-knock index (AKI) listed on the gas pump. The equivalent RON will be around 95-96. Difficult to compare directly, though, as you say.

[JoeMcLaughlin]

The 32:1 oil mixture is a safe bet by any manufacturer. At that mixture it is hard to fry a top end. I've used 50:1 for many years with no ill affects. For 2010 I picked up new left over bikes: 2007 KTM 125SX and a 2008 KTM 144SX. My son and I ran the Grand Prix series, some Cross Country races and the 24 hour race. Austin also ran the 6 hour ironman. Through all that racing we did not have one single problem with the engines. I got into using Dumonde Tech back in my jetski racing days and still use it. It has nothing to do with KTM because I had favorable results running 50:1 in Yamaha and Bombardier watercraft.

Joe..........

http://www.hookit.com/members/austinmclaughlin/

http://www.hookit.com/members/joemclaughlin/

[harrperf]

My post is not to say low octane rating fuels MAKE more power - just to say the best fuel for power from VP IS a low motor octane fuel - and research octane rating on it is too.

I DO know in my talks with them that for formula one type engines that rev to 18k - octane rating has ZERO significance. To combustion process literally outruns detonation...

One side note: Kevin walker ran 87 pump gas in his Loretta' Lynn championship winning bike. He runs it year round - and has no issues with reliability. Of course he rides a yamaha -which does not push the edge in ignition timing as much as other bikes (kawi) but just food for thought.

Anyways - my current race two strokes and all of my customers are running from 20:1 - 28:1 depending on application and engine type.

All silencer outlets of each are perfectly dry with a grey tinge from the leaded race fuels I run and they run.

The only way you will ever tell from the outside their bikes run more oil is if you watched them mix the gas.

For trail riding and slow mx riders - there is no need to run so much oil - and you will see signs of too much in spooge, no doubt about it.

Maxima published a brilliant paper - well a summary of their research - using radioactive tracers in a running engine. This allowed them to see just how much oil was where under varying conditions.

Conclusions: The amount of oil needed purely depends on RPM ceiling and percentage of time spent at or close to WOT. The harder the use, the more the quantity of oil needs to be increased. For screamers their suggestion was around 18:1 to provide sufficient lubrication of the piston skirt.

For real light use ratio's of 40-50:1 were perfectly fine. The point was that the actual amount of oil IN the engine was the same between the two ratio's - because the running conditions dictate how much oil migrates through the engine.

I hope that makes sense - just be logical about this and I think the conclusions are clear - you would not start up your four stroke with no oil - and not many people would risk running them with 50 CC's only! It' just not enough oil for complete coverage of all the parts that need oil - and that's the point.

[NemadjiMan]

I'm wondering why KTM suggests running their bikes on such little oil ratios. I cant imagine their being anything different engine wise to tolerate such little oil therefore it must be the oil they suggest is just better than what the Japs are recommending at the 30:1 ratio. So I should be able to run the same oil at the same ratio as KTM suggests in any other bike with out seizing anything right? If what everyone says about more premix oil equating to better ring seal and ultimately more power than why did KTM go the other way?

You can tell this is the internet due to the large amount of information and mis-information in this thread. ?

I believe that I have the answer to the poster's question. It's because KTM is more interested in selling spare pistons than the other manufacturers are!!

[SDet]

You can tell this is the internet due to the large amount of information and mis-information in this thread. ?

I believe that I have the answer to the poster's question. It's because KTM is more interested in selling spare pistons than the other manufacturers are!!

I don't know. 1986 MXC 500 always 50:1 original piston and rings. Still looks like new inside and has enough compression to keep you up in the air when you're on the kicker.