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Discussion Starter #1
I am thinking abou tgetting a litle more out of my 97 MXZ 670, and I would appreciate any do's and don'ts some people may have experienced. What would be the best thing to do, for someone who isn't all that comfortable with tuning as far as compromising reliability. Some pointers would be appreciated.

OH yeah....and the pocketbook is pretty shallow if you get my (snow)drift....)
 

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I'm getting my engine "tunned" from my mxz670 1996. Should have it in 2 weeks. Bored carbs, head shaved, y-pipe mod, porting, rv plate modified, clutch calibrated, gutted air box, new set of piston + new crank. In other words, the works! I'll let you know how it works out. Heard that it can keep up with 800 twin.
 

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Discussion Starter #6
How do you modify your Y-pipe? And what do you mean when you say you gutted your airbox?
What does modifying your Y-pipe do?
Do these things require jetting changes (I am already leaner that factory).
How does your fuel economy change after putting on that 501 Rave valve?

Just went to the DNE website..great site! Does anyone use their silencers? Is that something worth spending money on?

(Edited by Rocketman at 8:17 am on Sep. 25, 2001)
 

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here's the deal man. Don't touch the pipe!!! it will go slower, trust me. cheapest thing to do.  501 rotary valve from a 96' Mach1.  Shorty intake boots, take off the Y pipe and clean the slag out of it. and a pair of K&N filters(always re-jet). do this you should gain about 5 horse for about &#3650, pretty good huh. see what you think , then you can always clutch. Remember, keep those RAVE valves clean, and DO NOT PUT A PIPE ON THAT SLED!!!!!!
 

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This is the formula that I use for my 670's and they just plain right fly!!!
Cut Y pipe (check the DNR site on how),Put a 0.08mm base gasket in,then check your squish it will be in the 0.075-0.080th range .take the head to a automotive performance shop and have it milled so the squish is in the 0.065th range,
I also do my owen base porting and enlarge the transfer ports ,but I would not recommend doing this yourself unless you have some experance doing so.
All of this together should net you a good 10-15hp increase.
My 93 mach-1(there 100Ibs heavier than nthe newer sleds) has a mill done up like this and will give any 2001 700cc more than it can handle.
If you have any other questions just ask!
 

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Discussion Starter #9
Yeah I heard that putting a pipe in doesn't pay....Thought about kickass filters (who's are better.Kickass or K&N?) might still go that route.
What about just a silencer though? I wouldn't mind my sled having a different sound to it an a little more guts...less like a generator...
But again....does that 501 rotary valve change my fuel mileage?...I only get about 90 miles to a tank as it is. (I'm a heavy load... :)
 

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I think that what  flyinmxzstyle is trying to say is that when HE put a pipe on, it didn't go as fast as before.  What he should say is what pipe he used, what he tried to make it work better, and list solid results and let you make the decision. Installing a pipe or doing any major mod usually requires jetting and/or clutching changes. If that is not done you will no doubt lose performance. The 501 does not have to be out of a '96 mach 1. A 501 is a 501. (part #420 9245 01) I'm not familiar with how the 'Y' pipe mod works because I put on a PSI single pipe (and it's still on) It created more torque which is what you need being a heavier fella. We're all just trying to help, but I think that the facts should be presented and backed up with data if necessary and let you make your own decision.

Good Luck____I'm out!    
 

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Hi there Rocketman, on my 98-670, I noticed a small increase in fuel millage with the 501 valve . I believe the valve only makes about 1-2hp. After I installed the ufo´sI got back the fuel milage.With the 501 valve the intake duration is open longer.
 

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Great info guys, but I still have couple simple questions. Does the 501 valve hurt your gas mileage and if so how much. And the 670 in my 98 FZ is the same as that in an MXZ right?
             Thanks for all your help,
                                        Ryan
 

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Rocketman,  I purchased a silencer from dne and was not impressed.  The same silencer can go on the 583 or 670.  I first put in on my 97 583 and didn't notice a single performance gain or loss.  I then tried it on my wifes 96 670 and noticed a loss in power!  I admit it was nice to have a different sound, but not worth 2 bills!  And keep this in mind.  I truly believe my fuel miliage got worse with the silencer because i was always spanking it to hear the noise.....

however, if you are still interested i will selll you mine.  I bought it half way through last season and maybe has 300 or 400 miles on it.
 

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i put on the dne silencer on my 583 and i lost 5mph Then i try it on the 1997 mxz 670 and it gain a couple mph just by changing mufflers.
 

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Discussion Starter #16
Hey idooski....which PSI pipe did you put on? I heard about one that gives you a broad range of increase in horsepower. Is that the one that comes with its own silencer?
 

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Just goes to show that every sled is different.  MXZ583 got his to work on his 670, mine didn't. Glad to hear it worked for him, I wish mine would haved.  It boils down too, you need to test with your own machine.
 

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after working at a ski-doo dealership for 5 years i've found that thereare pipes out there that will give you decent power, but when you look at the coin you spend on them, and the  other work you have to do to really get all you can out of that pipe....it's tough. I've found the 501 valve won't help your milage, but then again, it really won't hurt it.  If you want a fast 670, may I suggest a HO.Now we're talking speed!!!!!!!!
 

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Discussion Starter #20
I will be looking into that....
How is your reliability after putting that on? What gauges do you have?
 
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