what ratio to premix at?

[Cruiser]

I run the amsoil at 44:1 too, great oil, just started using motul last tank as I was given some buy a factory rep and it works well too.

[GMP]

I'm a beleiver in a little more oil is better, so I run Amsoil Dominator at 36:1. When I pull the top end off, there is always a small puddle in the cases that coats the crank and rod big end. Only smokes a lot on the choke, and the PV parrt are always clean. For the wife's Pampera 250, I just start with my mix and double the fuel for 72:1, as the trials motor is different.

Motul 800 is a very good oil but stupid $$ if you have to buy it, like $13/qt. last time I checked. A gallon of Amsoil is just under $40 to my door.

[jeffd]

I remember guys mixing going with less and less oil in the 70s - thinking more gas and less oil would make for more power. And then cycle magazine did a dyno test showing that more oil actually increased hp output - and they did rejet for each run. Running more oil in the mix - you get better ring seal and you also you get better heat dissipation away from the piston as the oil helps conduct the heat away, and you get better lubrication of the crank bearings (and heat dissipation benefits there too).

Honda recommends 36:1 full synthetic in a CR250 for racing.

GasGas recommends 50:1 full synthetic in an ec250 in the manual. The gasgas must meet european emissions standards and running at 50:1 will reduce smoke and emissions overall.

The question is - if gasgas were spec'ing out oil mixture ratios for solely a racing environment without consideration of the road use of the bike, would they, like honda did for the cr250, have picked 36:1 as the recommended mixture ratio?

jeff

[widebear]

So mixing at a ratio of ,anything -to-one, should be just about right?

[iancp5]

Originally Posted by widebear

So mixing at a ratio of ,anything -to-one, should be just about right?

Yes! Unless you want to spend a lifetime testing.

I think of it this way. Different bikes, different oils, different applications. Might as well use the manufacturer's recommendation.

For example Honday specify 36:1 for a CR250 - when? what oil was that based on. I also assume it was to cover very aggressive use by an expert rider in a moto? Are GG bearings and tolerances the same? All I can say is in my environment 50:1 works well.

[GMP]

Well I'm not going to argue with success. I've taken these bikes apart every year and they look great inside. I should post a photo of a Vertex piston with a season on it. Both friends of mine with my old bikes run the same mix. The '00 had a new crank and mains in '02(from a different problem) and its still fine, as is the '03 with 4 solid seasons on the original lower end.

We just completely rebuilt an '01 XC125. This bike was Jim Cook's demo, then sold and raced by an A rider for a year. My brother and I got it for my nephew, did a top end, and its been running great. Just last fall the ignition side main started to get loose, up until then its just been a new Vertex every winter. Thats outstanding for a 125.

[gasser]

I run Amsoil at 43/1 that's 3 ounces per gallon. Ratios with even ounces make it easy to mix gas in odd amounts. I've used Amsoil's Dominator and their HP Injector(can also be premixed) oils in the past with good results but I'm switching to their Intercepter oil for my new bike because it's their top oil for non-racing applications. - Ken