<div class='quotetop'>QUOTE (BRB @ Feb 8 2007, 06:21 PM)
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Would the method below be accurate enough to check it?
Fill both tanks full and run them down to almost empty, fill them back up again measuring what it takes to top them off. Then divide the units of gas by the same units of oil.[/b]
Yes.
<div class='quotetop'>QUOTE (BRB @ Feb 8 2007, 06:21 PM)
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If I find the oil mixture correct how do I check to see if the jetting in the carbs is right?[/b]
I don't know if BRP lists hp in the brochures, but if they do and both sleds are listed with the same power it's highly likely they're jetted the same. If you have access to parts diagrams & part numbers, you can check the jets used in both sleds. You can also check the e-clip position of the midrange needle, as it may not be indicated in the parts lists. Might be in the shop manual though.
As for checking if jetting's right, spark plug readings, piston wash, and exhaust gast temps are ways to to find out. If both engines are the same, I'd suggest making sure your oil usage & oil pump calibrations are good anyway.
<div class='quotetop'>QUOTE (BRB @ Feb 8 2007, 06:21 PM)
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So, spending $40 for a gallon of synthetic oil does not guarantee anything. Cheap mineral oil might have netted the same results.[/b]
I won't buy Cat oil anymore, because price didn't guarantee it was any better than any other. All I use now is Shell Ultra Advance full synthetic. It's about half the price of the Cat oil when on sale and seems to leave less deposits than the original petroleum oil I started with when the sled was new. I can't say Shell's oil is the best, but it certainly seems like an excellent oil for the money after using it for a few years.
There's a number of factors that can cause carbon build-up. If your fuel/air ratio is too rich, you get lots of carbon anyway... And if your oiling ratio is too rich, it can compound the problem since a too rich fuel /air ratio will burn colder and might cause the oil to not burn completely either.
An easy solution is an oil with high detergency and a lower flashpoint closer to the fuel's flashpoint. Before power valves were common, most oils had far less detergent additives/solvents than they do today. I can tell the difference even on my non-powervalved engine... The exhaust ports & entry point of the pipes barely have any carbon build-up anymore. The new stuff seems to burn off a lot cleaner than the oils I used 10 years ago (15,000 miles ago).
2 stroke oils do have a flashpoint temperature, and that can vary between brands too. Example: If you pre-mixed plain 10w30 with gas at 50:1, your bearings & rings would all be lubricated proplerly. But the 10W30 wouldn't burn very well and cause massive carbon deposits because its flashpoint temperature is so much higher than 2 stroke oil. 2 stroke oil is forumlated to burn, regular oil isn't. 2 stroke oils are designed to burn, but if there's too much oil and the overly rich fuel/air ratio causes a low combustion temp, you're just not going to burn all the oil completely and end up with partially burnt oil... The gummy carbon black goo.
When I used to have the ice racing motorcycles, I tried all kinds of oils. All oils were good, none caused engine damage. If you think about it, there's no way you can buy a bad oil that doesn't have lubrication specs the motor needs... No oil manufacturer is going to put a product out there that doesn't have the required lubricity. I don't think there is such a thing as a bad oil, petrol-based or synthetic.
One of the biggest difference in oils is
the amount of detergent additves. It used to be that exhaust valve certified oils had the required amount of deteregent additives & solvents and the non exhaust valve approved oils didn't have as much of the detergent additives. In my Ice-bike days, there were two oils that left the powervalves clean... Klotz pre-mix & Yamalube 'R'. Most others would show lots of crap on the powervalve after just a couple bottles. The Yamaha bike ran at 32:1. So you could see the differences in oils really quick, after just a few quarts.
You can change your oil to something else if you like, but I doubt there's anything wrong or bad about your oil no matter what the price was. I use BRP's XP oil in my DFI outboard, I re-calibrated the computer to inject oil at 100:1 ratios (WOT) because the oil was made for it and so was the engine. It's expensive oil, but is so good half as much can do the job. So in the end it's slightly less expensive than using the regular outboard oil at 50:1. It's less than double the price of regular oil, but I use half as much. In this case it really is cheaper to use the expensive oil.
So is BRP's oil good? I believe so. Castrol has been making excellent oils for decades, they're the contract supplier for BRP oil products. But trying different oils can't hurt... The biggest differences you see (if any) are usually the differences in amount of detergent & solvent additives.
il ratio? I'm guessing one was richer than the other.
