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ktm 250 sx ?s
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Only $10 for all 2024 SX, MX, and SMX series (regularly $30).
Tell him to run what he's comfortable running, and don't use pump gas.
I usually just run 93 octane from a busy gas station..... But I'll splash some race hooch in every now and then
The Shop
The catch is that running the Lectron carb, the bike uses way less fuel, therefore it's getting way less oil too.
If you are running leaner than the 32:1 - 40:1 oil range, you are losing power, have less piston seal and have greater potential for engine failure.
The only exception to this is some of the smaller engines need a leaner mixture. We ran our KTM 65s at 44:1, anything richer and the powervalve would not work well (we ran Maxima 927)
927 smells awesome... But have fun getting the carbon out of the power valve!
BVM - I have always used 927 and trust me, after blowing 2 cranks by switching to Yamaha 2r, I will never switch again. But I have never had "carbon" on my powervalves. I have carbon on the top of my pistons and usually black splooge on the PVs but it has never been a problem.
What I run 927 for is next time you do a top end, look down at the crank journals, with 927 they will be covered in oil. This is the only oil I have tried that leaves this much oil on the crank and for this reason, I have never lost a crank using 927.
I always ran 927 in my 85-98 CR 125's and 250's until I switched to Kawasaki in 1999 and it just gummed it up and crusted the sub port valves so bad I scrapped for hours to clean them. I switched to K2 and never had that issue again, and now after 12 years off the bike I started riding again with my 2006 KX250 this year I started running Mutol, just pulled the cylinder off and the power valve is spotless and free without any noticeable carbon build up and there seems to be plenty of oil in the bottom end to me. I'm not trying to convince anyone one way is better or another but I have been very satisfied with the full synthetics... I do miss the castor bean smell from the exhaust with C12 there is nothing better!
Pit Row
Who knows.
That's why different oils have a different ratio recommendation, some oils are concentrated more and need less of it to achieve the same fuel air ratio without changing physical jetting specs.
Example...on a cold night when the two strokes are running crisper and snappier compared to a hot day, some guys would go "man i better run a bit more oil so i don't burn the motor up" when in fact, that's wrong. The cold air is denser (more oxygen) so you have more oxygen available per unit of fuel, adding more oil only makes the mixture leaner yet. If you have MORE oxygen available, you need to have MORE fuel available to mix with that oxygen, so you need LESS oil per unit of fuel.
Seems confusing, but it's not really, you just have to think about how much fuel is available to a given amount of incoming air (oxygen).
Also, in a perfect world, none of the oil would burn. Most of it doesn't actually. What happens is when the mixture of oil and fuel pass through the carb, the temperature of the mixture is very cool in relation to the inside of the cylinder. When that cool mixture enters the engine via the intake ports, it "sees" the hot environment, the fuel is much lighter (vaporized) while the oil is heavy/thick, so the oil drops (separates) out of the suspension and sticks to the sides of the cylinder and crank parts, providing lubrication. Some of it burns of course as it is exposed to the combustion environment. Most of it is deposited on internal engine parts, such as hot power valves and expansion chambers, where it forms carbon deposits. So ideally, a concentrated oil can be run at higher mixture ratios (50:1 or higher even) so that there are less deposits on the motor which means less maintenance, as opposed to a 32:1 mixture which dumps more physical oil amounts in the engine.
But for a backyard fix on a cold night, as a teenager when I didn't have jetting parts available, we would just tweak our mixtures via premix to get closer hahah.
lol, when my dad bought me my first race bike ('97 CR80) it came with the bike!! I've been working out of it ever since.
It says 'Graydon Proline' on the lid.
Here is the case with jets.... Kinda pricy.... http://m.ebay.com.au/itm?itemId=170494670315
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