heffergm Posted May 7, 2014 Report Share Posted May 7, 2014 I just bought my first two stroke in a million years, and I'm not quite sure what ratio to mix my fuel. The bike is a '13 Evo 300 2T, and the manual recommends 1.5% if running synthetic premix, 4% if running mineral. I'm using a semi-synth because I have it around (it's motorex), so I'm not sure how to mix... maybe split the difference? Quote Link to comment Share on other sites More sharing options...
dan williams Posted May 7, 2014 Report Share Posted May 7, 2014 70:1 is a super safe bet, I run as high as 100:1 on Bel-Ray HR1 without issues. The low-revving water-cooled electrofusion bore engines are a lot more tolerant than the old aircooled engines. Kinda depends on how you ride, more oil if you're going to be flat out trail riding but less for real trials plonking. Even 80:1 will puddle in the bottom of the crank at trials speed. Quote Link to comment Share on other sites More sharing options...
heffergm Posted May 7, 2014 Author Report Share Posted May 7, 2014 70/1 is ~ 1.5% if I'm not mistaken. I ended up going ahead and mixing at ~4% for this batch... didn't want to under do it, but I guess it's going to be super over oiled. Ah well. Quote Link to comment Share on other sites More sharing options...
dan williams Posted May 7, 2014 Report Share Posted May 7, 2014 Not gonna be a lot of mosquitos in your woods! At least your buddies will know where you are. Quote Link to comment Share on other sites More sharing options...
dadof2 Posted May 7, 2014 Report Share Posted May 7, 2014 This is a subject on which there are a lot of different opinions, I would do a search of past posts, there are many on this subject. As the beta comes jetted for 4% oil you are probably going to have to lean the jetting off a bit if you run at 1.5%. I run at 100cc oil to 3 litres of petrol on semi or fully synthetic. The bikes start easily and run clean. My mix ratio is too rich in many peoples opinion but I regard it as useful insurance against engine damage and wear. Only mix as much fuel as you need for the days riding. It never has been regarded as good practice to use fuel that has been mixed for some time but there is mounting evidence that ethanol in petrol causes fairly rapid deterioration of mixed fuel. Quote Link to comment Share on other sites More sharing options...
slicktop Posted May 8, 2014 Report Share Posted May 8, 2014 (edited) 80:1 is recommended. And there is a reason to run that mix. Unburnt oil collects in the pipe and if the bike is just putted around for a while the build up can be substaintaul. When you do bring the temps up high enough, the oil catches on fire and you will think the bike has seen its last ride. It can burn so hot that the plastics around the pipe could melt and potentcially the airbox. If nothing melts, then the bike is probably gtg but if the mix is correct in the first place you can avoid this hair raising scenario. Edited May 8, 2014 by slicktop Quote Link to comment Share on other sites More sharing options...
mokwepa Posted May 8, 2014 Report Share Posted May 8, 2014 Own the same bike....only difference might be V force reeds, titanium pipe and magnesium crank case. 66:1 or 75ml/5 litres. Works for me and makes me feel good knowing that shes getting lubed properly. Done tons of research on the same matter and settled on the above ratio....a poll was done a while ago. Lots of guys do 80:1 but I play it safe.....I cannot afford to rebuild a top end. Quote Link to comment Share on other sites More sharing options...
mokwepa Posted May 8, 2014 Report Share Posted May 8, 2014 80:1 is recommended. And there is a reason to run that mix. Unburnt oil collects in the pipe and if the bike is just putted around for a while the build up can be substaintaul. When you do bring the temps up high enough, the oil catches on fire and you will think the bike has seen its last ride. It can burn so hot that the plastics around the pipe could melt and potentcially the airbox. If nothing melts, then the bike is probably gtg but if the mix is correct in the first place you can avoid this hair raising scenario. A melted airbox from a slightly richer mixture......WHAT !?! You serious....? 2 strokes would be burning up all over the world. Quote Link to comment Share on other sites More sharing options...
mokwepa Posted May 8, 2014 Report Share Posted May 8, 2014 As dan says....Bel ray H1R is good stuff. You can take Dans word.....he does know a thing or two about Betas Ill be a girl and play it safe (just for my own peace of mind). Quote Link to comment Share on other sites More sharing options...
dan williams Posted May 8, 2014 Report Share Posted May 8, 2014 I have seen pipes loaded with spooge from running a rich mixture of oil get very hot from the oily goo igniting. The pipe get much hotter than in normal operation, smokes like a coal locomotive and has to be dealt with in relatively quick order or surrounding materials suffer. It's a lot rarer now than with the old air-cooled engines but it can happen if your engine isn't tuned properly and you're heavy on the oil and run full blat for a long time. To be honest I can't remember the last time I saw a trials bike fail from lack of lubrication. The engines are just so much better now. Quote Link to comment Share on other sites More sharing options...
slicktop Posted May 9, 2014 Report Share Posted May 9, 2014 A melted airbox from a slightly richer mixture......WHAT !?! You serious....? 2 strokes would be burning up all over the world. I am surprised you would discount my post as dribble. The example given is indeed plausible and has happened to a very accomplished rider as per his account to me (though admittedly on a gasser). The beta top end only requires the recommended mix 80.1 for proper lubrication. Anything more does more harm than good. 1 Quote Link to comment Share on other sites More sharing options...
heffergm Posted May 9, 2014 Author Report Share Posted May 9, 2014 I'm slightly confused where 80:1 came from. My manual says 1.5% on synthetic, 4% on mineral. Quote Link to comment Share on other sites More sharing options...
dan williams Posted May 9, 2014 Report Share Posted May 9, 2014 Just as manufacturers jet on the side of caution they also spec oil mix conservatively. When engines were air cooled and the first synthetics claimed you could mix them at 50:1 the cognoscenti declared it heresy and prophesized a great cataclysm of smoldering wreckage as every engine in the land was simultaneously destroyed. Now engines are water cooled with hard chrome plating directly on the aluminum cylinder with digital ignition curves. The hot spots that used to develop in iron sleeved cylinders simply don't happen and spot thermal runaway that used to require oil as a coolant and lubricant just isn't a problem anymore unless something is drastically wrong. Think about it, a highly stressed MX engine that is running at full throttle a significant amount of time blows most of its oil right out the exhaust. The little bit that sticks to the cylinder wall is sufficient to keep it from sticking solid so in practical terms it's probably getting a lot less oil than that 50:1 number would seem to indicate. On my trials bike running at 100:1 I can putt for a while and after a long fast trip between sections the bike is smoking because it is purging the excess oil that is pooled in the crankcase. 80:1 is sort of a compromise for those who are tired of being the smokey bike but not quite ready to go full lean. All this is academic though because if you are happy the way your bike runs with a higher ratio then use it. I may have the cleanest running bike in the woods but I still get my clock cleaned by guys on twin shocks belching smoke. I just hate to be behind them in line. It's all good. Let's play! Quote Link to comment Share on other sites More sharing options...
heffergm Posted May 9, 2014 Author Report Share Posted May 9, 2014 Cool. Was just curious. I'm just trying to find a baseline and stick with it. This first batch I erred WAAAY on the caution side. I'll slide back towards 80:1. Quote Link to comment Share on other sites More sharing options...
mokwepa Posted May 9, 2014 Report Share Posted May 9, 2014 I am surprised you would discount my post as dribble. The example given is indeed plausible and has happened to a very accomplished rider as per his account to me (though admittedly on a gasser). The beta top end only requires the recommended mix 80.1 for proper lubrication. Anything more does more harm than good. WOw!! My apologies. .......ive just never heard of this happening before. Quote Link to comment Share on other sites More sharing options...
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