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....)

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.

I have heard really good things about union-bay heads. *I would recommend that you look into them. *Also look at chip's site: *http://mxz670.tripod.com/

670's work really well with high compression...

odoa4

PSI single pipe(&#36300) or modify the 'Y' pipe w/stock exhaust (no cost), 501 rotary valve(can cut the stock one to match the 501 at no cost), advance the timing 4 degrees (no cost), and then 'clutching'. Whatever you do, clutch last or you'll just have to doo it over.

I had a 98 670, I installed 501 rotary valve, UFO´s, Ypipe mod, and thunder shift kit on clutch, it worked great really woke it up. You can go to www.dneperf.com for free speed tips.

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)

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!!!!!!

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!

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... :-)

This is were you can find the Y-pipe mod http://dneperf.com/tip_ypipe.html. Claims to give 4 hp.

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! * *

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.

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

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.

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.

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?

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.

It is part #SKI-MXZ-04-96. It Fits 96- 99 MXZ 670. The claim is 'a real 5 hp gain at 7900 RPM' *It is a kit that consists of pipe, silencer, and all the hardware. It created tons of torque over stock. It was a nice fit. It is fairly quiet, buts sounds nice! cost is &#36299.00.

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!!!!!!!!

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

never personally had a pipe on any of my 670's. *Did have a dynoport silencer on a 583 and 670, basically for the weight, and the bark was nice too. *But, it made my 670 a dog! but, the 583 ran like a raped ape?? *who knows why? *Every pipe is different.

No reliability issues for me. Been running the pipe since Jan 99.

I also added a thunder shift kit and geared down my 97 mxz 670. *The sucker would roar out of the hole and out of the corners. *We lined that same 670 up against my MXZ 700 Stock, and my MXZ 800 with a heel clicker clucth. They are all close out of the hole. (unfortunatly for me on my new 800)

Good luck and rock on!

Crank Shop twin trail pipes-( why walk when you could run) For the money go twin or stay stock.

Does anyone know if the DNE Y-pipe mod works on 98's as well, or has Bombardier already incorporated it?

I wouldnt do the y pipe mod, it does give a couple of hp at the sacrifice of less torque down low and a narrower powerband. I recommend the 501 valve set to close at 76 deg, a head cut to give .060-.065 squish and a good clutch setup. 200/350 pri spring, px ramps, 18.5gr pins and a 52/48 helix at 20# (b-6)with the beige spring. These specs apply to mxz's from 96 1/2 to 98. *Pre 98's need to update jetting to aa3 nozzles and 290/310 mains. Dont touch the airbox and pull the limiter straps up, leaving 1 hole showing on the limiter is worth almost 10mph on top over the stock long strap setup, plus it helps control the wheelies that the s chassis mxz is noted for. My experience has shown twin pipes arent worth a damn on the 670 unless the case has been ported and the compression optimized.

But chicks dig the wheelies..... http://www.snowmobileworld.com/forum/style_emoticons/<#EMO_DIR#>/sad.gif *:p *:D

Where do you live? *There is a dealer in Marshal Michigan that will get you a true 12-15 HP out of your motor for about $250-$300 and it will still be reliable as a rock and trailable. *Apparently, the jugs on the pre H.O. 670&#039;s don&#039;t match the case very well. * Alot of grinding along with gutting the airbox and shaving the head really wakes her up. *I had this done to a 98 mxz670 that I once owned and after the work was done, my wife didn&#039;t have a problem keeping up with my buddies H.O. anymore. He did a few other little things as well, played with the rotary valve, re-jetted of course and something with the needles. He might have did something with the timing also. *The best part of the whole thing is this, he does the work himself and is a perfectionist. *When I got the sled back, you couldn&#039;t tell that a wrench had ever been used on the engine until I rode it.

I&#039;d like that info if you don&#039;t mind. Send me an email with the name and the address of the guy and/or shop. http://www.snowmobileworld.com/forum/style_emoticons/<#EMO_DIR#>/biggrin.gif

MightyMach-If you would, copy me on the address also. I only live 25 miles away. *That sounds like cheap HORSEPOWER!!! *Thanks!:D

For anybody else interested, Stanley Lawn and Garden is the Business name, ask for Greg at (616) 781-3951. *Tell him Dan sent ya. *He usually does one sled a week, works all day at regular business stuff, goes home for dinner and comes back later and works on your sled. *He alone does the work except for shaving heads, and as I mentioned, is a perfectionist. *He also rides and knows what to expect from his work. *Last year I was in the UP and ended up riding with some guys in the room next to us. *One of the guys had an older mxz583 that would consistently beat my buddies XC-600. *My buddy asked him what he had done to the sled because a 583 had never beat him before (so he claims). *He said; not really too much, *he took it to a guy in Marshal that he had heard good things about and I piped up and said; Greg Stanley and he looked at me and asked how I knew.

I agree with flinmxzstyle if you want more than what he said it will cost you $$$$ and gas milage.

I too own a 97 670 and this is whay I did. Short intake boots, 501 rotary valve, 44mm carbs, milled head and thicker base gasket, cut rotary valve plate to match 44 carbs, called Dyno Port "Rich Daily" he has modified silencer for those listed modifications and I bought that silencer. Tried pipe but I couldnt keep it Dialed in so I kept the stock pipe...I didnt know about the "Y" pipe deal maybe I will try it. I put 50degree roller clutch in, 168 woodys studs. Still playing with all these mods but this sled rocks. No lie...I would like to know more about the "Y" pipe!!!!!!!!!

So basically you built yourself a 97 MXZ 670 HO?? http://www.snowmobileworld.com/forum/style_emoticons/<#EMO_DIR#>/tounge.gif

I sure enjoy all this info on the 670&#039;s.... On my 98 F z 670, I have the shorty boots (but if you measure them you&#039;ll find there not a whole lot shorter than the stock ones ..anyway) *I have a 501 rotor, and changed to the *yellow spring in the clutch, and changed the ramps to 280&#039;s. *I did not note a significant change on the bottom, but the sled *seems to breath *better with the 501 and runs better on the top. I don&#039;t think my gas mileage dropped all that much maybe a mile per gallon or so.... This year I just finished the Y pipe mod, and were going to bump the timing up 4 degrees, and we&#039;ll see what happens..... *I&#039;ve not gotten in to the porting, or head milling yet, *I didn&#039;t want to mess with the "bullet proof" reputation this motor has gained over the years... but there&#039;s always next year!!! *Thanks DooZ http://www.snowmobileworld.com/forum/style_emoticons/<#EMO_DIR#>/smile.gif

if you want the big power for cheap in a 670 ho ask the bragger he posted a couple of things in the racing forum that&#039;s where you can locate him. if not i have his email. this guy is going to forget more about the 670 than most know.

send me that email address if you don&#039;t mind Paul. Thanks

Hey 670 riders lets wait for the snow to fly and the lakes freeze, Post your top M.P.H. on radar, lets see who has the fastest 670 on this fourm.

rocketman, the braggers email address is dstbmac@aol.com i am sure. this guy is a true technical wizard and i have seen where he has told others with 670&#039;s not to spend big money. seems he knows where to spend the least and get the most.

Thanks Paul. I appreciate your help.

Let us know what you find out Rocketman.
* * * * * * * * * * * Ryan

Sure. No Problem

Ok. I basically told bragger what I had going on my sled ( shorties, 501, clutch kit and silencer) He said to leave the ignition timing stock, because I&#039;m running the stock pipe. He suggested that going to a 25/44 gearing might not be a bad idea, especially because of my weight ( I like my grandma&#039;s cooking...what can I say ???
* * *Overall he said I was on my way to a pretty quick 670. (I lost a few marks for not having 192 studs on my .91" track though)
* * * So that&#039;s about it. I guess I am ready to go for this winter! http://www.snowmobileworld.com/forum/style_emoticons/<#EMO_DIR#>/biggrin.gif *:D

Mr670.

Thats sounds good.I will be running my 670HO and 600 skidoo race chasis at Double D testing and racing radar runs this winter.I expect to be in the 120&#039;s with both of them(2000 feet).
I will be leaving the forum for a month or two.But i will post my speeds through Speedzone.

ROTAX POWER ALL THE WAY

Great info, I am very interested in the y pipe mods,
but seem to be having trouble getting to the
dneperf.com website. Any help would be appreciated.

http://www.snowmobileworld.com/forum/style_emoticons/<#EMO_DIR#>/biggrin.gif *:D

can&#39;t believe this topic keeps coming back...
DNE&#39;s website is down..has been for a while...

You can switch to a 99 X pipe and get the same gains as a PSI single which is the best single out there, if you do some porting than switch to twins. Here&#39;s what works on the 670.
Massive tunnel porting including opening the intakes, matching the cylinders to the cases, install 44 MM carbs, or bore the stock to 42 MM, match the shorty boots to the carbs than match the boots to the enlarged intake, 501 rotary valve, clean up the transfers and raise the exhaust .040, enlarge the small exhaust ports and raise them to within 1 MM of the main exhaust, cut the cylinder skirt like the X models, take a squish reading and have the head cut to .055 if you can guarantee high quality gas, or .060 if you can run 90 octain, cut 1/2" off the y pipe, or switch to twins, than match the exhaust to the cylinders making sure non of the gasket is cutting down the opening.. If your into drag racing go with titanium arms. Any mod that tells you that you have to jet down is not a mod but a sham. Do not use K&N filters they just make more noise, gut the air box and remove all foam. Now test test and more testing untill you come up with the best clutching. Sound like a lot of work and money, yes, its easier to buy a 800. Good luck I had a lot of fun with my 670 and its a great engine. Below is my 99 X