Castrol A747

I'd go with the oil manufacturer's recommendation over the manual in this case. If the oil was designed to lubricate at 40:1, it likely will not do so well at a thinner ratio. More oil won't hurt your engine, but not enough certainly will.

That stuff smells lovely !

People use that up to 60:1 no problem. It's super oil. For you I would recommend 50:1.
Keep in mind that manufacturers always say what oil they are talking about when they say to use it as such and such a ratio. That is because each oil has a different viscosity and that is the main factor in determining ratio. So that 40:1 doesn't apply to any other oil than the one they were talking about, most probably Motorex.

Mix to your rpm range, but, at the same time; it’s a 300, so it’s gonna be pulling a ton of fuel, and with that comes a lot of oil, I’ve ran 40:1 in my 2012 250sx with maxima k2 and never fouled a plug, and never smoked excessively, i was also pretty demanding and needed the oil. To put this into perspective, even dfi 2 stroke oil injected sleds at wot will get as rich as 20:1 ratios in some conditions due to the heat build up, and the need to maintain proper lubrication. But sleds are also a twist and hold machine, where dirt bikes will always have a break in the rpm between shifts and corners. Everybody has their theories, as to what works best. But few actually know, manuals only give factory operating specs, and oils they have tested with for the ratios they arrive at, but don’t be deceived, most manufacturers will sell you crap oil to cause wear and tear to sell parts, yamalube R, and stihl are two that do this on purpose for sure, there’s a reason why you gotta mic 32:1 with yamalube, it’s garbage!! Spit would lube more efficiently, and stihl’s “PREMIUM” mix they sell, is quite possibly one of the worst centistoke rated pre-mix’s going.
Try some different ratios, but If your wide open all the time, richer is always a better way to go, like I said, 40:1 K2 in my 250sx and it ran arrrsum zero issues, and the stock YZ250 pistons I ran in that bike, came out clean as can be.

"I’ve ran 40:1 in my 2012 250sx with maxima k2 and never fouled a plug, and never smoked excessively"
Maxima K2 in a water cooled engine reving to 9500 should be used at 52:1 according to my oil ratio calculator so you gave it more oil than that which is fine because its 90% synthetic which is why it still didn't smoke much or foul the plug.

Chad reeds supercross 05 YZ250 ran best at 32:1

Can you show me this calculator for oils?

Why oh why do people quote oil ratios without listing the oil? The ratio only matches the oil. There are no universal ratios. Heavy viscosity synthetics are used much more sparingly than crude petroleum oils.

Sorry, I thought that would have been a no brainer, YZ250, factory ride, hmmmm may be yamalube r?

Something tells me Yamaha isn’t about to go out on someone else’s premix

Did anyone else also hear that PC and HRC used 747 over their oils?

Does your calculator account for a riders weight, skill
Level, elevation, conditions he’s riding in, is he a lugger is he a screamer, does he ride the mid? Has he put different coolant in? Has he adjust the squish? Did he retard or advance ignition timing, If you don’t think these ARENT things to consider when choosing which ratio to run with, then I guess we have zero g here on earth, and everything runs at a constant ambient temperature that never changes, and flash points mean absolutely nothing, the lower the flash point, the quicker your oil will burn out, and clear out, in which case, you cylinder will need more oil to properly lubricate, if you DONT get your cylinder temps up to the point that you reach flashpoint, you engine will load up and be perfectly happy at a leaner ratio with no engine damage what so ever. Trail riders need a lean ratio so the bike doesn’t load, mx riders need lots of oil because of the rpm range they operate at, and since your running a castor oil, you had best be screaming the piss out of it. Because castor oils have the highest Of the flash points, they also have a huuuuge centirstoke rating, and only now are we actually seeing ester synthetics getting anywhere near them,

Also, does your calculator account for centistoke rating? Or Is that gibberish?

Pc has gone with maxima oils for a while, and as far as hrc goes, they used hp2 the scent it gives off is unmistakable, possibly the greatest smelling premix when mixed with race gas, I always wondered what mix that was when I was a kid, who ran it, well, it was honda, and I found out after I got a bottle of it with my 05 cr250, and it would blubber and fart on any other mix, so it’s what I had to run

Damn, I don’t remember where I read that before. “Believe none of what you hear, and only half of what you see” applies to me lol

I can’t see inside your engine, so I don’t think there’s a piston in there..... but it makes noise, I STILL DONT BELIEBER!

HP2 and the old VP MR2 smelled so good. Smelled like a BBQ. Haha

Need to bottle the scent, and sell it as cologne,


MIXED by Ralph Lauren

Smell like you just ate a gate drop