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Discussion Starter #1
well here is the deal...i have a 1993 Yamaha ExciterII it already is pretty fast but i am wandering what else i can do to it...it already has been piped and has had some cluch work done (im not sure what kind of work because it was done when i got it)im wandering also if i ad an Octane additive to my fuel if it will help with power or if the stuff is harmfull to my 2 stroke. i dont really go over 85 so i kind would like to have more accelaration, but i dont want to get rid of the long track. so any advise or hints would be appreciated.

o by the way its a 1993 Yamaha ExciterII 570 Liqued Cooled with a 136 track with 1 inch paddles
 

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If you dont care if you go over 85 you could gear it down a couple of teeth and reclutch it..It will pull alot harder and accelerate faster..
 

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If you want more power DONT USE OCTANE BOOST Higher octane fuel burns cooler than lower octane fuel (you get more BTU's of energy from the lower octane gas) the reason they use high octane fuel is if they have high compression motors they need to disipate the heat quicker which the higher octane fuel does do. It won't ping as easily and burn holes in your pistons if you are running a high performance motor. Run regular old 87 or 88 octane fuel and make sure your jetting is correct and that 570 will pull plenty hard.
Gearing down as RMK says will help the bottom end acceleration but will limit your top end.
 

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Hmmmmm, you've got me thinking now 2000TCMC. I've always run super unleaded in my sled, as do everyone I know around here (Maine). I have had some trouble fouling plugs in the past. So assuming everything else is adjusted and cleaned properly (carbs, jets, throttle and choke cables, etc) then running just reg unleaded (87 octane) would burn hotter, there fore reduce fouling. I think I'm going to give this a shot this winter.

It's a hell of a lot more inexpensive too. So my only question now is, how would you be able to determine if the engine was pinging? I mean its easy enough to hear in your vehical, because its much quieter. But a 2 stroke and a full face helmet would buffer that pinging sound wouldn't it? Could you still hear it? Is there a noticeable loss of performance?
 

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yes. run the lowest octate your engine will withstand. octange is a rating of how volitle the gasline is. higher octane = burns slower.
 

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Discussion Starter #6
cool! thanks for telling me that! right now i kinda want more low end...i LOVE accelaration :D and i dont really go over 85 much...how hard is it to change the gears? and are you talking about the gears in the chain caseon the right hand side? im kinda new to sleds still so if i sound ignorent i am lol...im going from quads to sleds and they are diffrent. and if you are what gear would i be changing? top or bottem...and if so would i have to get a smaller chain, or would it still be able to keep its tention?
 

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yeah, gears in the chaincase. Most likely, you would go with a smaller gear on top, and larger gear on bottom. You need the right combination in order to get the tension right with the proper length chain though... There is a tension adjuster most likely on the side of your chaincase, that holds the correct tension on your chain.
 

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Discussion Starter #8
ok i thought there was but i havnt taken this one apart....i have take one apart on a 440 indy ( my neighbers) but this is still all a little new to me. So when going to lower gears do you go buy the number of teath on a gear?
 

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For those of us that ride in the mountains at high elevations, the air is less dense because the atmospheric pressure is lower. Because the pressure is lower we burn premium gas, even in engines that have not had any work done to alter the compression. You can actually buy 93-94 octane in Revelstoke, BC if you want it. As far as I know, higher octane fuel requires a higher temperature to ignite it (it doesn't burn "hotter"). Conversely, it won't pre-ignite at a relatively low pressure. Now if you burn regular gasoline at high elevations, it will pre-ignite (ie. the temperature in the cylinder chamber causes the air/fuel mixture to ignite prior to the plugs firing) because of the low pressure inside the combustion chamber. Pre-ignition happens before the piston reaches the top of its stroke. If this scenario is bad enough, it can lead to detonation. The explosion caused by the pre-ignition prevents the cylinder from continuing upward, but at the same time the cylinder can't move downward because of the connecting rod. The end result is that the shock waves cause the piston to rattle back and forth...wallah...detonation. Obviously if this goes on long enough, something has to give, and its always the piston.

I really hope I got this right. A guy thinks he knows this stuff until it comes time to explain it to someone...then you quickly find out just how much you know (or don't know...LOL!).
 

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yup, that sounds about right. The only addition i have is that the spark plug nearly always sparks before TDC, but the flame front takes time to travel before the mass explosion takes place. Which is why you set timing in most motors to a few degrees before TDC. You described pre-ignition, which means that something OTHER than the spark plug lit off the combustion process. Detonation is when the spark plug sets it off, but the flame front travels too fast for the spark timing and compression, and the bulk of the explosion happens before TDC...

anyway, i jus thought i'd add that
 

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Discussion Starter #12
so how much does it cost to regear?
 

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A good top sprocket can run from $20-$30..
 

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for gearing, try 20-40 should be a 68 link chain

call coffee's and royal distributing have good deals on sockets, it's an easy job.

if you'r running premium anyways, rather than dropping the grade of fuel, up the compression by shaving your heads or removing head gasket layers.

if you've got any questions Email me, I don't check these boards often
 

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Discussion Starter #15
if i up my compression how much more power would i get?would it be worth it to get more compression and run a less volitile fuel?
 

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more comp[ression will help you out, it's hard to say how much, depends on what you have now which in turn depends on what kind of shape your engine is in, but if you wanna crack the engine open, it's easy enough to do rings, a hone, and a port while you're in there. then you could really bring that sucker to life.
 

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Discussion Starter #17
well the engine is in awsome shape, but i dont have tthe tools to do a hone and port polish.
 

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die grinders are a wonderfull thing : ) pretty good investment for $40 to
 

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Discussion Starter #19
so do you have to change your rings after you hone your sleeves?
 
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