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Discussion Starter #1
CAN ANYONE LIST THE DIFFERENCES BETWEEN THE H.O. AND THE STANDARD 670? ALSO THE IGNITION TIMING IS .126 BTDC ON THE H.O. THE STANDARD 670 IS AROUND .076. WHAT IS THE REASON FOR THIS? WHERE CAN I FIND TECHNICAL DATA FOR THE H.O.?
 

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Well I don't know much about it, but I figure this might get the topic rolling.  I believe the 670 H.O. comes Ported from the Factory.  I don't know about the other differences, maybe something with the clutching too?  I may be wrong, but I'm sure somebody will correct me if I am.

-Josh
 

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Actually the pipe and muffler are the same as the regular 670. What is different is the y-pipe, it has the mod done to it from the factory. It also has 44mm's, different porting, flat top pistons and a different head causing higher compression so you have to run 91 octane.
 

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Discussion Starter #5
WHAT ARE H.P., TORQUE, AND RPM FOR THE H.O.? WORKHORSES PLEASE, NOT SHOW PONIES. I JUST BOUGHT ONE AND I NEED ALL THE ACCURATE INFO I CAN GET MY HANDS ON. I WOULD LIKE TO RUN IT IN NORTH BAY ONTARIO NEXT YEAR LORD WILLING. DOUBLE D TESTING SEEMS TO HAVE A GOOD THING GOING ON WITH THEIR RADAR RUNS.
 

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sorry to chime in on this subject, but just for history's sake, i am a proud owner of the most powerfull stock 670-700cc ski-doo twin ever to come out from the factory, and that is my 1995 mach 1. this motor was only made in 1995 and 1996 for the mach 1 f-chassis. It has factory twin pipes, 44mm carbs, special high comp head (has a "1" stamped at the top of the head, as it fits only these two year motors) special rotory valve timing and porting. stock horsepower is 125 or better. clutch engaugement was factory set at 5k, and with the best drag race rear suspension of all time (improved c-7) and picks, nothing could touch this era of ski-doo's (along with the f111 and machz with same chassis and suspension) at the drags.
These mid-nineties f-chassis with the improved c-7 suspensions were the best stock oval race, drag race suspensions to ever come stock from any manufacturer. yes, they were heavy by comparison, but mainly because of the stock hood, skiis, muffler and air box  which can be easily remedied. if you go back and look at oval and drag racing results in the mid to later nineties, ski-doo just dominated everywhere. just ask guy parquette!

just a little history for the newer sledheads out there!  


if you ever find one of these gems, you would have one heck of a sleeper if you could stick it into a lightweight zx chassis.
 

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Something else i've learned from wrenching on my HO is that the motor mounts are from a mxzx 440!   If anyone has pulled the tra off thier HO, they would notice that the engine sits a little lower than a regular 670.  It's a pain in the @ss because the clutch puller bottoms out on the access hole in the side of the belly pan.  I had to modify my access hole a little to give myself some more room.   HRP claims they loosen the front motor mounts to lift the motor up a little to get better access..  All that just to take the TRA off!
 

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yeah robert you are a little off on your info. The 670H.O. is the most powerful stock 670 ever produced. It is supposed to be putting out upwards of 129 horsepower and 130 lbs of torque. Horses come at 8000 but I'm not sure where the torque is at.
 

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Discussion Starter #11
DITTO RAVE! DO THE MATH. THE H.O. MAKES ALMOST 85 FT LBS. AT 8000 RPM IF MY MATH IS CORRECT. AS FOR THE GUY WITH THE 95-96 MACH COMMENTS... THOSE ARE COOL SLEDS BUT I THINK THE S CHASSIS ARE BETTER AERODAMICALLY. I RAN A 95 SS IN THE RADAR RUNS FOR 4 YEARS. THE S CHASSIS SEEMS TO BE A BIT BETTER FOR TOP SPEED.
 
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