Waking up my mxz 670? - Snowmobile Forum: Your #1 Snowmobile Forum

cvankauwenberg · 12-26-2006, 08:37 PM

What specific mods would wake up my 99' mxz 670? Is there a common setup that everyone uses. The machine is mostly ridin' on the trails. I would also appreciate reliability. I'm running 96 studs, and the machine is stock with 3000 miles on it. I'm looking give my brother-in-laws F7 a run....maybe.

TUGHILLYAMMI · 12-26-2006, 08:50 PM

Very cool idea. Good luck on this project. It is gunna take some tinkering to catch that F-7. Is your sled factory as of right now?

upersleder · 12-26-2006, 09:34 PM

going to have to modify or replace the rotary valve. do some mild porting and some clutching, it really wakes them up.

**smallengineguy** · 12-26-2006, 09:52 PM

Clutching is the most bang for the buck.

skidoomxz670MI · 12-28-2006, 03:24 PM

Is it a HO? It should give the F7 a good run. I would reccomend clutching it and mayber bigger carbs with new reeds. The possibilities are endless.

jagermiester · 12-28-2006, 10:29 PM

Don't know if it's a good comparison or not but I have '03 REV 800 and ran about 50/50 with an F7, both stock. Sometimes he wins, sometimes I win. Sold my brother my '95 Mach 1 670. When we ran the Mach with the REV, I thought I had him smoked, turned to see how bad I beat him and he was only about 60'-70' back at about 90 mph. That was about 8" of snow. Mach=144 studs, 2800mi. REV=96 studs, 3900mi. Since all this, I have added new 1 1/4' ripsaw track w/ new woody's, MBRP can, VF3 reeds and have clutch kit on the way. The 670's are very fast and if you listen to these guys they will have you beating the F7. Don't know about the reeds though, the '95 Mach I had was rotary. The stock pipe should be good. Maybe change duration on the rotary valve, bump ignition timing, re-jet, and like SEG said, clutch kit.

Guess I'll shut up now, rambled on long enough.

cvankauwenberg · 12-28-2006, 11:01 PM

I don't believe it is the HO. It doesn't say HO anywhere on the hood. Thanks for the info. I'll probably just clutch it and let him beat me :-( I don't want really want to mess with the jetting.

jagermiester · 12-29-2006, 07:28 AM

Don't think he will beat you by much.

TUGHILLYAMMI · 12-30-2006, 07:59 PM

Hows it coming, any progress at all. I actually hope you win i luv to see the underdog take it. Just remember if you win by an inch or a mile winning is still winning

98mach1 · 02-22-2007, 11:28 PM

that 670 wont have no issues with an F7 lol low to mid range im sure it will keep up if not surpass the f7

garyc355 · 03-04-2007, 07:13 PM

ON mine I have crank shop pipes the crank shop intake geared it up and cluched it U really half to hold on to her good luck

97Mach1 · 03-05-2007, 10:00 AM

If it's a 1999 MXZ 670, it's a HO. What's the first 4 digits of your VIN #? Should be 1415, 1416, 1417, 1452, 1453, or 1466.

If it is a HO, don't touch anything. Maybe gear it down 1 tooth on the top sprocket, and/or get a clutch kit. You're going to find not much is available for the HO, they were that good from the factory.