Bore kit recommendations ?

thetruck454 said:

what kind of power are you picking up by going to 10:1 or 11:1? High compression usually picks up some snap down low too.

Click to expand...

I was told you'll get more bottom end snap with the 11:1, but as far as power #'s, don't quote me on this, but I was reading some threads where people were arguing over compression ratios, and someone spit out that it's roughly a 5hp jump per every point of compression. (Ie. 10:1 - 11:1). I'm not sure if that's accurate or not, if so, that's a little over a 10% increase. Someone that knows more about this can chime in.

My rational behind doing the standard bore HC Piston over the 734 was for a couple reasons... ( I initially wanted to do the 734 BBK ).

http://www.grizzlycentral.com/forum/showthread.php?t=92561

1. I figured I'd start low and if the HC 11:1 my the other clutch mods I'm doing with it didn't give me what I needed, I can always step up to the 734 kit.

2. I didn't want to mix gas. They make 12:1 + but I don't have access to good fuel here.

3. After talking to some of the really big bore guys, once you start crossing the line of the 734 kits, the reliability goes out the window and there's a lot of down time and things get pretty expensive. Head work is required and other things far beyond my skill set and pocket book.

The 734, is a good kit, and I probably wouldn't do anything bigger than that. If I needed more than that, it would probably be time to buy a bigger bike. Overheating can become a big issue, especially on the bigger bores and well as wet clutches getting destroyed.

My plan with this 11:1 was to pair it with a more aggressive cam to help offset what i would have gained with a BBK. Problem is, no one that I've found makes a drop in Cam for 2014's-2015's (Hot Cams or Web Cams). Web Cam will custom make one, but it's 278 bucks and 3 weeks of down time. Eric at EHS, I was told, might make them now for those years, but I haven't been able to get a hold of him yet to verify that.

Anyways this is my starting point. I may join the 734 club, may not. If I can whip my heavy 30" paddle tires around in the deep snow to my liking with this setup, then that's where I'll probably stay. Good luck with your build though. It's fun to get new stuff in the mail haha

I had great luck with my 734 bbk with a raptor stg 3 cam "griz stg2" and barkers. (until it went BOOM that is but i take the blame for that not the grizz's fault) I didnt have overheat issues till i moved into the 778 after exploded my CP piston in my 734. I now run a 3 core radiator with 2 high speed spal fans. The secondary one runs all the time and i've removed my thermostat altogether. I'd have to check my build threads but had the 734 with barkers and hotcam running strong for about 5k miles. I have about 2k maybe little over on my 778 and i've only had mild issues. Both setups had 105.5 CP 11-1 piston's in them and i found if you're running anything over 4k elevation you wont have issues with 87 octane even. I still try to always run 91 non-eth but in a pinch but i've never had an issue with 87 when running higher elevations. What ever you guys do if you start adding to the motor get a real tuner not just a bullet box. i fought and fought with that till i finally bought a good tuner and never looked back. I have several build threads with full pics and how-tos for complete motor tear down. A 734 bbk top end or just piston swap with cam swap can be done in a day pretty easy. Full motor ground up took me a bit longer.

Spheno said:

How'd you end up blowing the CP in the 734?

Click to expand...

Well weird thing about that day it was kinda the perfect storm. Started the day with deep snow so was pretty pinned. Hit steep deep snow hill climbs where the razors made it up to but then got stuck. I followed to help them out with the winch and ended up after full throttle setting the grizzly on its back rack tilting down hill backward. i rolled off of it thinking the grizz was going to continue to summersalt down hill a few times. Luckily it just sunk and sat in the snow she didnt roll down hill. We tipped it back up right and got everyone unstuck and tried to go further up trail.. "=pinned throttle in a few feet of snow" I wasn't easy on the grizz by any means that day jumping every drift i could find that was deeper than the actual trail. Farther down the hill after deciding we couldnt take the high route we took the low route we ended up in a beaver pond. Everyone made it but 1 guy that took a deeper route through it to show popo could make it well he got stuck right in the middle. No one jumped in to help him so i cranked the grizz up and jumped in the creek. i hooked up the tow strap and gave hell pulling out a stalled popo 850 that ended up getting water in the cylinders and pulled it to semi dry dirt. Once we pulled his wheeler apart and cranked it a bunch blowing water out the cylinders it did end up firing up we headed back to the truck. About 10 miles from the truck we found a huge open field were i ended up doing like 100yrd 4 wheel drive pin'd throttle figure'8's on top of 2 ft of snow. Once you get the grizz on top you dont let down so i just had her nailed. As i was drifting for the second or third round of 15 minutes straight.. there was a huge BOOM come from the motor. I later on found that the airbox had a ton of oil in it from almost rolling the grizz up on the snowy climbs earlier when i stood'er up right and even backwards down hill. So i know she was low on oil at that point and me being fully pinned for so long 4x4 pulling a pretty good load across the snow.. its my fault not to take it a bit easier at that point.. being low on oil and pinned for so long i'm sure had i toll on the after math.

After tearing the motor down here's a vid of my CP piston cracked in half..