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Discussion Starter · #1 ·
I am not a 2 stroke motor head so forgive me if this seems obvious or ridiculous. I posted this over on Dootalk but it quickly got bumped down because it had something to do with an intelligent conversation about snowmobiles. Anyway, you guys seem more level headed over here and even though I observed this in a Rotax engine I think the same would apply to the Suzuki engines as well.

I have had two 500SS sleds. One was a 2005 Trail and the current one is a 2005 Adrenaline. Both sleds used the same model engine. I used the BRP fully synthetic oil in both since new (talked into it by my dealer to help the RAVE valves) and I have some observations to share.

The Adrenaline engine has far more carbon build up on the RAVE valves than the Trail engine did using the same oil. The Adrenaline engine from the get go ran a lot stronger than the Trail engine did. So, could the Adrenaline engine be running leaner (and hotter) than the the Trail engine did resulting in more power but also more carbon build up?

Could the the brand, type and cost of injection oil have less to do with a clean engine than the fuel mixture and combustion temperatures?

What do you guys think?


Thanks
 

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I think you answered your own question. To me, it seems like one sled is running leaner than the other. At any time, with both sleds, did you run a fuel:eek:il ratio? I'm guessing one was richer than the other.

However, I also wonder about other factors. You say the two engines are identical, yet performance wasn't. Is the stock clutching on the two models identical? Assuming both are SDI and computer dependent, do they run the same mappings for fuel delivery? My guess would be "yes", but I really don't know.

But like I said earlier, I think you're on to something with the fuel:eek:il delivery/ratio.
 

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Could it be oil pump calibrations?

The more oil you add to the fuel, the leaner the fuel/air ratio becomes.

Example: A 50:1 fuel:eek:il ratio means 2% leaner fuel:air ratio than straight gas (no oil).

So more oil can mean leaner fuel:air ratio, which should burn hotter and hopefully burn off all the oil... But too much oil can still mean too much unburned oil will gum things up.

It's not always obvious when trying to unravel this balancing act between all the mixing going on.

Does one sled get better fuel mileage than the other?
 

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Discussion Starter · #4 ·
Just to be clear both models are identical (in theory) except for shocks and graphics. Both have carbs and are not EFI. I am assuming that they are jetted the same but I do not know for sure. The newer Adrenaline sled does get better fuel mileage than the the older sled. Also when I would shut down the older sled it would almost always back fire which I was told was from being a little rich and the unburned fuel was igniting in the expansion chamber.

I didn't think about the fuel/oil ratio causing the lean condition.

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.

I will do this just to see if the oil pump needs adjusting.

If I find the oil mixture correct how do I check to see if the jetting in the carbs is right?

So, spending $40 for a gallon of synthetic oil does not guarantee anything. Cheap mineral oil might have netted the same results. The sled has 1900 miles on it and this was the first time I checked the valves and they weren't horrible just worse than the other sled I had.
 

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In my expierence a good synthetic oil ( and I believe the Doo synthetic is a great oil) doesn't cause carbon buildup. The buildup you describe sounds like one engine running leaner than the other. Oil will always cause a buildup, but I've seen people ( and done it myself ) running a ton of oil without a noticeable increase in the buildup.
 

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I also have a 2005 Ski doo mxz trail 500ss.

It has only had the SKI doo synthetic oil in it since we bought it new in 2004, I do have 2 gallons of Klotz waiting to go into it, but still have some xps oil to use up.

I have not noticed any back firing issues with this sled, ever, the engine has been bullet proof.
It would seem that the adrenaline is probably where it should be, but your trail sounds like its running too rich.

I would put two new sets of plugs in each sled and run them both under similar conditions, pull the plugs and check the difference between them.
Both sleds are the same exact motors, carbs. are the same, only the suspension shocks differ between them, so the plugs should be very similar in color.

From there, if you find that the trail plugs are darker and wetter then the adrenaline is, then I would adjust your jetting a bit leaner on the trail.
 

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<div class='quotetop'>QUOTE (BRB @ Feb 8 2007, 06:21 PM) <{POST_SNAPBACK}></div>
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) <{POST_SNAPBACK}></div>
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) <{POST_SNAPBACK}></div>
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.
 

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I believe it a oil ratio problem

this is what I would do

run both sled same distance

say 300miles

and see which one uses more oil

also if one sled is on the throttle more it will also see less build up

+ you can should check compression on both sleds

<div class='quotetop'>QUOTE </div>
Could the the brand, type and cost of injection oil have less to do with a clean engine than the fuel mixture and combustion temperatures?

What do you guys think?[/b]
BINGO,those are my thought exactly

I run Castrol regular in my 583 with RAVE 17,000+km still 140psi each side and the valves had little build up

Guy in my club uses Amsoil same engine as my ZR and his valves are gummed up all the time and I use regular Bardahl and my valves never gum up

Reason why,he use more oil then me

I am sure Amsoil is a great oil but if your oil ratio is too high you will carbon up
 

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hmm, sounds like i need to lean out my cr250's air/fuel mixture.
 

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Discussion Starter · #10 ·
Well I checked the fuel/oil ratio this weekend and it is almost exactly 31:1 so it is using way to much oil. I also checked the mileage again (haven't done that since it was new) and it is still getting 15 mpg. The sled now has 2,200 miles so I used approximately 150 gallons of gas and I should have used about 3 gallons of oil but I have used 5 gallons (x $40/gallon..ouch).

I will find out how to change the oil setting and make some adjustments.

When I bought a new sled I never thought it would be off that much.

If the power valves are gumming up what is happening to the rings? Should I tare it down after the season or with the mileage being fairly low will it be OK?


Thanks guys.
 
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