Anyone tested a D-Max 770 in their RS Options

[Ski-B]

Wow that 770 stage II looks very good. I wonder if a guy could sneak on past the tech guys on the sno-x track.

Sure is nice trq for a shorter stroke motor!!!

[adamadam]

For the past several years we had all been riding race chassis's of some type with bigger motors transplanted in for better power. When the Polaris IQR came out with the long stroke crank we biult an 800 conversion for it and it worked very well. Others dropped in a complete 800CFI and had a nightmare install with many continuing issues.
With the 600RS we were looking along the same lines. Something simple, light, powerful and reliable. At the time we were developing and testing the 800R motor very extensively and I just wasn't crazy with the results. The motor is bigger, heavier seems to have significant vibration issues and isn't making the power eveybody thinks it is.
I wanted to take the best parts of each setup. We were sick of having the failure crank issues that have always followed the 75.7mm stroke 800 crank (this same crank is in the 800R motor). I bieleve the 73mm stroke crank that we use from the 600RS will be much better than the 800 crank over the long term with less gyro effect for a lighter more nimble feel to the sled.
The best part of the 800 has always been the top end. With good pistons it will run great for many thousands of miles. I love the lighter twin TMX carb setup with the auto powerjet. My sled ran flawlessly all winter and spring with the same jetting. No bigger bulkier 800R wiring harness.
I also prefer my lighter race clutch as the 800R has vibration issues BRP recomends that the 800R retains the additional weight of the electric start ring gear even with no electric start to help with vibration. The RS clutching works great with a little additional pin weight for these 770's.
Don't get me wrong i have nothing against the 800R motor. I just think it's not the best option for a ditch banger flying through the air or a light race sled that you want to whip around. I have the option of riding anything that we biuld of course and my favorite slde to ride hands down is a 770 stage2. That's a stock motor with twin pipes. It has plenty of power for low elevation riding, handles and sounds great. I can leave an 800R panting in the bumps and inch away across a lake.
Don't forget for $3000 you get a complete 770 stage2 Pistons, cylinders, gaskets, billet head with domes, valves and twin exhaust system no jetting required and just add pin weight and your clutching is done. Many other RS big bores run $2000 with no exhaust and use the stock head or 800R $2500 with no exhaust system and your maxed out on power.
The 770 stage2 is still a stock motor with 10 - 15hp left in it.

Thats all got me sold, around here there is no help with engine tuning or anything like that, no dyno's. so a kit like this is the ultimate upgrade, its got me more than sold, i've started to save towards one, might even try to get my sled to the shop in the summer maybe!

Reading that it don't get much more bolt on and go!! and spare parts, i'd leave them on a shelf in the garage just to look cool like.

the stage 1 is all i'd go with most likely, fuel millage is sadly a concern for me.

[Dmax]

Does anyone have experiance the a ported 770 w/twins based off the RS 600 motor?
Please fill me in if you have or know of someone who has.
Thanks.
Winter.

Hey Winter, As you know the stage3 770 has not been released yet. From our experience with that Port arrangement will show about 12 hp increase over the stock cylinder port arrangements. We'll be pounding the miles on that stage3 setup this winter and will release it as soon as we have verified that it is as bullet proof in this as it has been in other motors.

[DudeB]

Seems nice kit! Is it done with modified 800HO cylinders/pistons and head?