KX500 fans check this out

[KX500]

It does seem extreme but the guy been running his 2004 constantly on it since new.

20:1 far to low, you start throwing into much oil and the bike starts to run rich cause the consistence of "your brew" is to thick and does not run through your carburettor jets as efficiently - great way to seize a motor.

[cs363]

100:1? Best way to fuck your engine in no time. 30:1 is better...20:1 better still. 2 Strokes make more power and torque with more oil in em. Better ring sealing.

Yes, a popular misconception and whilst modern oils have undoubtedly improved since this article was written http://www.bridgestonemotorcycle.com...oilpremix6.pdf the basic premise remains the same. Though like anything there are some exceptions and variations but at the end of the day if your engine calls for 32:1 or 40:1 it's usually best to stick to manufacturers recommendations, or close to them.
Unless of course you enjoy building engines...

[cs363]

It does seem extreme but the guy been running his 2004 constantly on it since new.

20:1 far to low, you start throwing into much oil and the bike starts to run rich cause the consistence of "your brew" is to thick and does not run through your carburettor jets as efficiently - great way to seize a motor.

That's actually another misconception - the amount of oil added to the fuel has very little bearing on whether the bike runs rich or lean, that is handled by the jetting in the carburettor. And in fact the less oil you run the richer (in fuel) the mixture becomes....but we're talking small percentages here.
This explains it better than I could:

http://www.spectro-oils.com/motorcyc...action=v&id=31

[Armitage Shanks]

That's actually another misconception - the amount of oil added to the fuel has very little bearing on whether the bike runs rich or lean, that is handled by the jetting in the carburettor. And in fact the less oil you run the richer (in fuel) the mixture becomes....but we're talking small percentages here.
This explains it better than I could:

http://www.spectro-oils.com/motorcyc...action=v&id=31

Cheers guys, been running Motul 800 since new at 40:1, I could go a leaner mix ( not confusing oil ratio with carb settings ) and it runs fine. Also that's the mix I ran my , bought it new in 97 , KX5 and after about 80 hours I took the barrel in to have it cleaned up before I slipped a new piston in and was told not to bother ... " it's already been done by the looks of it ". And It had'nt been touched .......something about the Nikasil coating, sure, but also something about running good oil at a reasonably generous ratio . Gotta be one of the laziest and most reliable Dirtbike motors made ....or used to be made

[cs363]

Cheers guys, been running Motul 800 since new at 40:1, I could go a leaner mix ( not confusing oil ratio with carb settings ) and it runs fine. Also that's the mix I ran my , bought it new in 97 , KX5 and after about 80 hours I took the barrel in to have it cleaned up before I slipped a new piston in and was told not to bother ... " it's already been done by the looks of it ". And It had'nt been touched .......something about the Nikasil coating, sure, but also something about running good oil at a reasonably generous ratio . Gotta be one of the laziest and most reliable Dirtbike motors made ....or used to be made

40:1 with a good oil like that is probably a good compromise (KTM's are 32:1 correct?) most people I know tend to run around there with good oil. The main point is that the possible extremes like 100:1, given the information regarding lubrication, are probably unlikely to give extended engine life...

[Armitage Shanks]

40:1 with a good oil like that is probably a good compromise (KTM's are 32:1 correct?) most people I know tend to run around there with good oil. The main point is that the possible extremes like 100:1, given the information regarding lubrication, are probably unlikely to give extended engine life...

Not sure about KTM's but my '04 KX5 still has the little white sticker on the rear guard that says " 32:1 " same as my '97 , was gonna peel it off but I can't, it's so cute

For the record my Victa grasschopper runs mineral at 25:1 and 91 octane possibly slightly less compression and I'm not certain whether it has a powervalve ?

[honda_power]

Amsoil is different to normal oil [dont ask me details] and can be run at ratios such as 100:1

[KX500]

I read the lengthy article - cheers for that. Oil technologies changed great deal since 1978 Between crasher and the article I'm going to give 32:1 ago from my usual 40:1 brew.

Yeah amsoil special stuff, ratios could goto 500:1 if there was some super dooper solution invented, fully synthetics probably have very little in common with the stuff that comes out the ground.

Wonder with the K5 being designed around 1990 would a mineral based oil be more appropriate/do the job ?

[sugilite:Me]

Been down the octane route before...bear in mind that I was road racing my 500 at the time which stresses the motor way more than dirt riding. Here is the info I previously posted....

finally tracked down a article i did for supermoto.co.nz
My 500 had blown up and i went to the master of octane info, Robert Taylor.
heres the article...

The other Weekend my KX500 came to a grinding halt whilst racing at Manfield. After a top end tear down, the electrosil was found to have flaked off the barrel. Not good as I had not long just got it back from the platers. Turns out it was due to detonation. I was running BP Ultimate 98, so I was surprised to find that it had been detonating that badly. A respected motorcycle figure did some research on BP98 by contacting BP themselves. Guess what, you can forget NZ petrol octane ratings as they are quite misleading. Read on....

Here are some of the details supplied to me on the matter. (In italics)
The specs for BP98 are alarming. I don't know whether you are aware of same but all "pump" petrols (98 is a 'pump' petrol as such) have their octane ratings listed as the RON or research octane method. This is a little misleading and is not the information that racers really require.
Looking at the attached spec sheet the MON or motor octane rating of this fuel is in fact only 84. The MON number is always lower but not by such a huge amount.

Note that as a comparison the MON number of 91' pump petrol is 82, not a lot different.
Would you run your motor on straight 91'?
The respective anti knock index ratings are also not that encouraging.
Note that although the spec sheet is written / itemized a little differently for No. 1 / Avgas, but in fact the RON number is typically within 105 - 110
even though they don't rate Avgas in this way. The MON number is 100 or more, which is exactly the "territory" you need for your motor.
Note that BP "Ultimate 98" is an "Environmental" fuel, it is not marketed as a racing fuel as such and has low benzene count.

So there you go
folks, always be very aware of the octane sensitivity of your racing 2 stroke. Some motors may run happily on pump fuels but many are very sensitive and can detonate quite readily due to a whole host of variables.
Many of the late model highly tuned 2 stroke MX based bikes require at least
a 50% concentration of Avgas and 50% 96. Those most sensitive to detonation will require an even higher concentration and so on. As Avgas has a slower burn speed it is popular to use "cock tailed" with pump fuel to raise the burn speed for decent
engine response.

The flip side is that with very high concentrations of Avgas, reed petal life becomes shortened."

The other factor to be aware of is that in the autumn months fuel companies change the volatility of their fuel for easier starting in cold weather. "The fire lights easier" and burns more rapidly. This is no problem for your average passenger car, which accounts for 99% of the fuel company's market.
However, this can very often can be detrimental to a highly tuned racing motor, engine problems can suddenly appear in the
autumn months that weren't there during the warmer months.

By law of averages we are just a small minority and a relatively small annoyance to fuel companies who are only concerned about a bigger picture.
Nothing is ever as simple as it seems......................


I find it interesting that when approached at a technical level, BP say they market 98 as an environmental fuel, but in actuality, looking at the adverts for it at their stations, they seem to market it as a "fuel for performance vehicles"

[KX500]

Interesting stuff ! Cheerz

I asked the proverbial octane question on a KX site and got following link as the reply http://vpracingfuels.com/vp_fuelprop.html

[KX500]

(but in fact the RON number is typically within 105 - 110) Is that for 91 or Avgas ? Any idea of the RON number for 91 if not ?

Yep they advertise the 98 like its the performance pump fuel of all pump fuel.

[KX500]

Like the last scene in American Graffiti "Yep will take em all"

http://www.youtube.com/watch?v=JpxfF...eature=related

Spot the one having the most fun

http://www.youtube.com/watch?v=4ZvjRWJjPn0


Was looking at getting a TL1000s, after watching first video might stick to original plan and get the dirty 5 road registered

[KX500]

Anyone for fishing ? (classic K5 Vid)

http://www.youtube.com/watch?v=XKrNlGhtLpA

[kezzafish]

(but in fact the RON number is typically within 105 - 110) Is that for 91 or Avgas ? Any idea of the RON number for 91 if not ?

Yep they advertise the 98 like its the performance pump fuel of all pump fuel.

ha ha haaa LMAO the 105-110 is for av gas. The RON for 91 is... surprise, surprise... 91

[KX500]

You forgot the F - lololllol got me MON's and RON's mixed up