720 bigbore on a 600

[byeatts]

Anyone done this Big Bore.I hear it will make a solid 140hp on the sled 600 HO? I,m a new hawker and appreciate any advice.looks like I will go with a 2.5 X144 and drop the gearing by going to 7 tooth Avids. all I do is back country riding .Also where can I get rail extensions?

[General007]

I've seen a few 660 kits on Polaris 600ho but not the 720 the 660 will make it feel more like a 700 and the sled can remain pretty much stock meaning you wont have to pipe it or have work done to the crank. I've heard with the bigger bore kits there more picky on jetting and altitude but I'm just going off hearsay

[byeatts]

Originally Posted by General007

I've seen a few 660 kits on Polaris 600ho but not the 720 the 660 will make it feel more like a 700 and the sled can remain pretty much stock meaning you wont have to pipe it or have work done to the crank. I've heard with the bigger bore kits there more picky on jetting and altitude but I'm just going off hearsay

Spoke with sled Head racing and spi pistons w/700 jugs I believe. I will be getting more info. Will be stronger than a stock 800

[Thunderhawk]

RKTek has a 738 kit for the 600. I think they claim around 150hp.

I would think you'd want to change the 2 core heat exchanger from the 600 to an 3 core from an 800 as part of it. Total cost would be around $2,000 to buy 30hp.

[Hawkster]

I was worried about adding the 3 core heat exchanger when I switched out my 600 for the 800 and it had completely the opposite affect, it runs way cooler. I did not add an ATTEC so I'm running 380 mains, so far. I think theres a guy on here that makes the extensions and I think I also got Boivin's last set of turned up rail extensions , stands right on it's tail when you need it and it has a smaller foot print on the hard pack. SOOOOO MANY OPTIONS.

[byeatts]

Originally Posted by Hawkster

I was worried about adding the 3 core heat exchanger when I switched out my 600 for the 800 and it had completely the opposite affect, it runs way cooler. I did not add an ATTEC so I'm running 380 mains, so far. I think theres a guy on here that makes the extensions and I think I also got Boivin's last set of turned up rail extensions , stands right on it's tail when you need it and it has a smaller foot print on the hard pack. SOOOOO MANY OPTIONS.

Why does everyone change out to a 800, The BB 720 pumps more HP than a stock 800,Around 150 ponies, The bottom end is the same as the 800 so no advantage there ,Its a bore- Dual ring piston /porting and head using the stock 600 cylinders.I,m just trying to learn more about the Why - What to do.....Why does the belt get switched to chain drive, What advantage is there ?

[J&L Snowhawk]

I'm not sure why everyone thinks they need an 800 or even big bore a 600. I think it is mostly because you can and think you need to have more than the next guy. As far as the belt drive to chain drive, I changed mine mostly because of a tree incident that took my belt off on the side of the MTn. The durability of the chain drive is way better and you can change the gearing way easy.

[byeatts]

Originally Posted by J&L Snowhawk

I'm not sure why everyone thinks they need an 800 or even big bore a 600. I think it is mostly because you can and think you need to have more than the next guy. As far as the belt drive to chain drive, I changed mine mostly because of a tree incident that took my belt off on the side of the MTn. The durability of the chain drive is way better and you can change the gearing way easy.

Thanks I come from a Mod sled background where the strongest setup is to remove the chain and install a belt drive to handle more HP. I do understand the advantage for gear changing.

r

[Thunderhawk]

Moutian riding is harder on a machine than trail riding, so I hope I never see these problems, but here's what I've heard.

The path that the drive belt travels on the 800 is odd in that it turns in and out at sharp angles. This was done to take up the slack of the belt they used because a better size was not available. The stresses on belt cause it to wear faster than it should and the stresses on the tensioning pulley can crack the frame at it's mounting point. The cost of a couple of belt replacements equals the cost of the chain drive conversion. With the chain drive, the gears sit much closer to the frame, reducing the stresses on the mounting point. Several people here make chain drive conversion kits. TLKD makes a chain guard and cover as well. A 600 is probably fine as is, but if you up the HP much it becomes something to consider.

Like wise with either the 800 or a modded 600, there's enough torque that the bolts between the frame and engine mounting plate can losen. TLKD makes an engine torque bracket for that.

Just as you said you're from a modded sled background, many of the people that have gravitated to Hawks come from a modding background.

[off road rider]

Originally Posted by byeatts

.Also where can I get rail extensions?

Contact sleader2 here on this forum. He makes some sweet rail extentions, Im sure he can also do the tilt ups if that what you want..1st class products and service.
If I had a 600 I would most likely be happy for several years without feeling I needed more HP.. But like everyone always thinks "bigger is better". some know better.