SRX RUNS FANTASTIC!!!! but....

tomseal6

tomseal6

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May 25, 2003
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Location
Brevort, MI
Im in northern Indiana at my cousins. Got to ride around at his farm in the corn fields with good snow but heavy and wet.

My sled is running smooth and cluches feel so much better but the DCS light is coming on alot....

I duct taped the holes that were drilled in the air box and it seemed to help alot but light may stil come on. It is 30 degrees out.

My jets are 150 PTO 148.8 center and mag with a mrviper ported motor. Needles on the middle clip with shims on the bottom.

I dont know if I need to go richer on the mains to like 152.5 or its because the wet heavy snow where my track is spinning fast but the sled is not going fast.
 

just leave it alone, the wet heavy snow is loading the motor alot more, just leave it alone till you get into good conditions.
 
I had to go up another jet size before mine would stop going out. Are you hitting your correct rpm?? Good fuel?? I remember last winter tomseal you were helping me with my dcs problem but i finally got it nailed down, hopefully you can do the same. Its a great system lol but i get a little leary if i see the old light flashin
 
How much (est hp) will the engine make?
Are the heads modified?
What is your clucth set up?
 
thos are stock '01 jets for a stock motor, wouldn't a ported motor move
more air through it thus needs richer mix(more fuel), if DCS is coming on in 30deg.temps you'll be in truble when it gets colder..

loading the motor will couse more det. for sure,but still, i'd go up

what grade of preimium you running
 
TOM, JUST A EXPERIMENT. TRY, JUST FOR BALLS MIXING 110 50/50 WITH PUMP. EVEN 60/40. JUST CURIOUS. MY DCS HAS NOT GIV,IN ME FLACK IN THREE YEARS RUNNING 100 OCTANE. AND AT 1/2 MILE WOT. 3:16 (yammie tony)
i do agree with don though conditions probley helped this problem
 
Got my SRX running real good today,same thing with the weatherer,mild out ,
0 Celcius today,and the snow is loose and soft.Spinning out a lot but my wot rpm is basically 8500-8600.Higher because of spinning,but once on the way stays at 8500.DCS only came on once today,when I pinned it hard from a standstill. Man them HC's sure do put the power to the track.Instant and that track will spin right out even if going 50 mph.If I had studs on,it would be awesome then.When it gets colder will like to see how I am doing then.Right now I am pleased the way my SRX performed today in these conditions.My DCS really is not an issue anymore.Last year it was flashing all the time.
 
Ill wait till I get to good trail conditions. packed down and hard.

I am going to pick up the next size jets.

MRviper, How does snow conditions "loading the motor alot more have an effect on detonation?

I remember when the sled came out and Yamaha said they tested it in the heaviest snow conditions on the hoteest day but I dont understand why it would detonate at 30 degrees.
 
tomseal6 said:
MRviper, How does snow conditions "loading the motor alot more have an effect on detonation?
Click to expand...
Like a manual pick up in to high of a gear, it'll spark knock when load
on the motor and you give it more throttle

at 30 deg she should be rich
 
I am picking up the next jet size tomorrow in bloomington michigan to have......... "JUST INCASE"
 
Last edited:
the more you load the engine the more you create heat in the head thats why sometime it produce detonation.....so the more you ask the sled to pull hard at a certain point it will detonated... the easier the sled move less heat it produce
 
"Just in case" I would get more than one jet size bigger.

Yes it's true, loading the engine more will create more heat and possibly put the motor into detonation, but it was also like 30 degrees so if you were jetted correctly for say 0, you should have been OK.

The other problem is you're going up to the UP, and it's not the best place to buy good fuel so I would get some bigger jets and jet it accordingly when you get up there. While, it may run fine on 100 oct like Tony said, but when you're riding 250mi. a day in the UP that's not a realistic way to tune your sled, for your use.

Why don't you go about it the other way, rather than sneak up on it from lean to rich, go rich to lean, jets are easier to change than pistons, and while the DCS is nice to have it's not always going to save the engine.

Want me to send an assortment of jets to your Uncles?
 
Everyone thinks the main jets are the culprit of the DCS and its not always so, Are the needles shimmed with both shims under the clip? Have you actually taken them out and looked? yes, thats what they are supposed to be stock but I have found on more then one occasion that the shims will be both on top and below the clip right from the factory, you need them both on the underside of the clip. Tom, you also were given a jetting set up for colder weather, but if you run any sled in 30-40 degree temps in wet heavy snow it will run hotter simply due to the weight of the snow, its alot heavier and placing more load on the engine and clutchs, it takes alot more throttle to move the same 40mph as it does when its better conditions out. With taller gearing your also loading the motor more. You can put 170 mains in it and the light could still go off if the gas needed to cool the piston is in the midrange, all the carb circuits overlap, thats why a bigger pilot jet say 45 and 1.5-1.75 out on the fuel screws, 1/2 shimmed needles helps these DCS sleds, your adding fuel from start to finish. You actually have to go quite a distance to be pulling soley from the main, and even at WOT you still see 2-3% of fuel flow from the pilot!
As Tony mentioned, Gas quality ALWAYS has alot to do with it, if your running sammy quickstop 91, that could be your problem, rememeber me telling you to buy some octane booster to keep in the trunk when you go on trips???, its cheap insurance, octane booster wont raise 87 to 94 but it will help whatever your getting out of the premium pump that isnt so "premium". dump a good half bottle in per tank.
 
Here is something else to consider when your buying gas now, i found this post from "Hammer" on the 4 stroke side, but it pertains to the 2 stroke evry bit:

Example of fuel requirements with a carburated snowmobile if an ethanol blend fuel is used: Increase main jet by 2 sizes ... Raise needle clip 0.5

Ethanol (E100) consumption in an engine is approximately 34% higher than that of gasoline (the energy per volume unit is 34% lower) since the energy content is lower a larger volume of ethanol fuel would be required to produce the same amount of energy as gasoline. All vehicles have a fuel economy rating. It is directly proportional to energy content. Using E10 (10% ethanol and 90% gasoline), the effect is small, approximately 3.4% when compared to conventional gasoline, down to 1-2% when compared to oxygenated and reformulated blends of gasolines. As for E85 (85% ethanol) the effect becomes significant. E85 will produce lower mileage than gasoline unless the vehicle is setup specifically to run this fuel (compression, timing, etc). It must be noted that E85 is a high performance fuel and should be compared to high performance premium gasoline. In one estimate the US retail price for E85 ethanol was 2.62 US dollar per gallon or 3.71 dollar corrected for energy equivalency compared to a gallon of gasoline priced at 3.03 dollar.

This is why I choose to run VP C10, non-oxygenated, 100-octane in my supercharger application. I do blend an oxygenated mixture when temperatures are below 20*F for it's improved cold starting characteristics.
_________________
 
I RUN 100 OCTANE IN FOUR SLEDS. ITS MADE BY SUNOCO AND ITS CALL UNLEADED GT. I RUN IT STRAIT IN BOTH MY VMAX 4,s AND STRAIT IN MY 2002 SRX BECAUSE DCS WAS A PAIN. I DID CUT IT BACK IN MY 2000 SRX FOR GRASS RACING WITH PUMP PREM. WORKED GREAT. I WILL ALWAYS HAVE SOME IN MY GAS TANKS AT SOME CAPACITY. EITHER MIXED OR STRAIT. NOW AGAIN I REALIZE PEOPLE CAN,T DO THIS, BUT READ THAT INFO ABOUT GAS DON POSTED. I REALLY BELIEVE ITS THE ONLY OPTION. 3:16 (yammie tony)
 
as don said, i dont know about you region, but over here we only have petro-canada 94 available. When i leave for a ride i always make sure my tank is full of 94 plus add half a bottle of octane booster. I have found from testing with cars equipped with egt's and wideband 02's that even tho you buy 94 octane fuel, the quality between every time you varies alot. I had built a civic with direct port 80hp nitrous kit.It ran strong for 2 years then all the sudden the guy filled his tank with the same 94 as usual and the first pull on nitrous he did he melted 2 plugs. could not figure it out. The same week i was doing another kit for another customer, same kit, same jets. Guess what i filled the tank the same place ( i always go to the same gas station) and the first pass on the juice i melted a plug, then i understood... started doing testing and found the gas quality to be very inconsitent. The same car can be running nice egt's and fill up the tank the same place a week after and the egts would climb quite a bit. So even if youre using the best gas available, always pour a half a can of octane booster, its cheap insurrance. Btw i sure miss when we had sunoco ultra 94 available over here, it was way better stuff and constitant than the cheap petro canada stuff whe are stuck with now...
 
OK

heres the deal..

I ran 152.5 mains straight across.. It helped greatly The DCS light still comes on if I hold it wide open for about 3/4 mile to 1 mile.

Maim rode my sled. He is alot heavier than I am and the DCS light came on for him in about 1/4 mile wide open

I was thinking about 155 mains straight across for next year
 
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