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Discussion Starter #1
What determines how far you can go at WOT?

Here's the scenario...I'm running my Mach 1 with 87 octane fuel with enough Klotz octane boost to assure me at least 91 octane (so I've been told by Klotz)...how can I tell if the engine is pinging? What should I hear/ feel? ??? :nervous:
 

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Hey rocket, why don't you just run number 1 fuel [91 octaine] in it . Its probably cheaper in the long run and would be more realiable . When I own a 98 grand touring with a 700 triple triple in it [2 years ago] thats what I used, and I carried the octain booster with me at all times just in case of doughts about the gas [touring in northern ont . in small reg gas only communities ] . Usually , you could tell if you have crappy gas in the first start of the day and your motor doesn't idile good or at all, then pour in the gas line antifreeze then the booster. Still got that mxz for sale? I've got a couple bits on my indy 500 !
 

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Rocketman, if you have a load of questionable gas DON'T run your sled wide open. Octane booster will not raise 87 to 91 maybe to 87.4. I don't know about anyone else, but I start to feeling sorry for my engine after the first mile or so at WOT.
 

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I ride with a guy with a set of EGTs, and he said his sled runs cooler at WOT than mid throttle on the trail. I don't know if this means it's safe to run at WOT or what? ???
 

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Discussion Starter #6
In the area that I ride I may not be able to get 91. Otherwise I would not be thinking about octane boost. The Klotz rep that I talked to assured me that their boost does actually work, unlike the others like VP fuels and 104+ which basically told me I couldn't rely on their product to get what I need.
 

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Someone else made the comment on egt being cooler at wot than 1/2 thorrottle , that is correct. I have been on gogebic lake in U.P. w/ many different sleds over the years and w/ other freinds that have went the entire 14 miles wide open w/ all skidoos and never had one go down. thats wide open all the way and don't even burp them. again these machines are all 100% stock, no jet changes or anything.
 

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This is probably not what you want to hear...it depends!

My guess it that it would depend on 3 major things and maybe a lot of smaller things.

1- Jetting
2- Ignition Timing
3- Ambient Temperature/ Elevation

Without EGT gauges or someother sensors, I would think that the best way would be to perform a "plug read" prior to your marathon run.

If you detect a lean condition, I would limit the run. If your running "fat" go forever.
 

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Rocketman, the key words in your post are Kotz REP, what doo you thing the guy is going to say about the product he is trying to sell? bottom line is, if you don't have the good fuel in your sled dont hold it to the bar for any extened run's. If I was to use a booster it would be V.P fuel's. I don't thing it will raise the octane level any more then the other booster's but it has some good additives that seem to make the unleaded( oxygenated) fuel burn more like the good old leaded stuff. You can get a better read from the plug and piston.
 

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Discussion Starter #10
The guy I talked to answered their technical support number. VP couldn't guarantee me 91 octane. Klotz also has their HITrate, concentrated race fuel. What do you think of that stuff? It is leaded.
 

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The only way to tell if your machine is running rich or lean at WOT is to look! Start by installing the main jets which you think are appropriate for the temperature range you will be riding in. Most stock sleds are jetted way too fat from the factory to keep people from burning up the motor when holding it WOT accross a five mile lake. Typically, most Ski-doos tend to be 1-3 jet sizes too big from the factory, depending on the temps. you run in. The main jet's only job is to meter fuel flow at WOT and near WOT conditions. The larger the jet, the more gas, the smaller, the less gas. The "pinging" you are talking about is called detonation. One cause of detonation is running the motor too lean (not enough gas). It increases the cylinder temperature and can do MAJOR damage if it is bad enough. Detonation is also caused by improper timing, usually from too much ignition advance, and low octane fuel. The detonation is basically when the air/fuel mixture is pre-ignited (before the piston reaches Top Dead Center- TDC) because of any of those reasons. The higher octane fuels are less susceptable to detonation due to their higher octane levels. They can actually lower cylinder temperatures. That is why a stock motor performance will suffer when trying to run "race" gas. Most of todays motors are designed for 87-91 octane.The "pinging" noise is the detonation.

Now that you have your starting point, put in fresh plugs, and go run the thing across a lake or something for a few a while. You can then pull the plugs, and inspect them. The center electrode should be a cardboard brown. If they are black, it is running rich. If they are clean, it is running lean. Also, take a flexible inspection light and stick it down in the cylinders. The piston tops should have the proper amount of "piston wash". They should have a black soot on the middles of the piston domes, and the edges of the pistons should be clean. If they are all black, it is running too rich, and if they are all clean, it is running too lean. From there, you can determine if you want to change jets. Remember, as the temperature changes, the jetting needs to be changed for top performance.

I would always take the side of caution when jetting a trail sled. The last thing you need is to burn the thing down 50 miles from home.
 

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Dito what jiddru says, very good info. SWRules
 

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Ran my MXZ 700 WOT for aprox. 4 miles in Quebec last year. People from this forum said it wouldn't make it with a mod motor (RK TEK/MacDizzy) but I had no issues. The other guys with twins and less mods had to shut down because of high EGT's.

Set up correctly, you can run all day. ronzx9
 

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I suppose it depends on how long of an open stretch you have! I still am careful not to hold it to the bars for too long. I have been riding accross Lake Gogebic (about 20 miles long) at high speeds when two other sleds have burned down. Both times they were small sleds trying to keep up with the big boys. I mean really, what's the difference with riding 20 miles at 90mph, instead of 105! I would rather go 90 and blast back and forth to the top end. But then again, I care more about acceleration than top speed. Top speed goes to whoever has the most money spent on their motors...
 

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It doesnt matter what kind of motor you have, WOT for extended periods of time is bad for any motor.... set up correctly or not.
 

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These two strokes are designed to run wot all the time w/o problems, I,ve held them w/o accross Gogibic w/ alot of other guys many times over the the last 12 years and have never wrecked a motor
 

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;) Geeze,, back in 1968 when I bought my first Ski-Doo (a 10 hp Rotax) Olympic,, ;) or whatever they called them before that,, I HAD TO run it wide open most of the time to keep up with the BIG GUYS running 399's and stuff. I could only go 35 mph or so then, but bring on the deep powder, and I left them laughing! :D I didn't have the power to spin my track, and floated along nicely.

;) I guess considering those memmories, and some others involving a 125cc Sachs two stroke I rode Moto-Cross with for two years, I'd have to disagree that a well set up 2 cycle has to worry about extended WO operation. :p through possible stupidity I did it for several years back then. (1967-1973)
 

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The reason I went with MacDizzy is he builds fast, reliable motors. I sent him the whole motor to look for any potential design weakness before modification. My motor was one of the first if not the first sled motors he did, Kelsey's may have been first. My sled has 1500 hard miles on it + tons of dyno time and still runs great. Was I nervous that first time across 4ish miles of open lake? Darn right, but you gotta test 'em sometime.

Ronzx9.
 

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Jiddru, your plug reading statement is correct, the piston thing is dead wrong., if its all black its meltdown lean, all shiny its rich, I know this doesnt sound right but when its rich the fuel wash`s the piston clean, ideally, for most folks, a little shiney around the ports ( edges) of the piston and black across the rest of the top works good, and obviously that will change the longer you run it wfo. What you posted is actually a common misconception.
 
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