Getting very close to pulling the engine out of my 08 and going to bump up the power, but not sure which way to go. I am a leaning towards a std bore kit from fst. I am running carbs with muzzy pro exhaust and cdi and vf john's clutch set up. i just hear too many complaints from the 840 guys on here. I guess is what i am asking is will i be disapointed with the std bore kit vs the 840? I also want what everyone else wants; Reliable power, no overheating, and dont want to work on it all the time.
Is the std bore kit enough power to really feel it in the seat?

Thanks for the input

The FST standerd bore kits rocks !!! talk to mickey he will set you up. I have one I have 180 hrs on it and it rips. 69 mph at 9200 with 26" tires and about 76 mph with 28" mudlites. you will not be disapointed at all. Put some tpi valves in the air box and a k&n filter or whatever filter you want and let her buck.

Chris

My bone stocker overheated....I only run in the sand and load the motor pretty hard,so,naturally,my 840 overheated,but not any more....I can cool it down to 175 degrees with 95 degree ambient,.....so,how much power do you want.......I havn't had a stock bore get even close

Boy I have heard this question many times and even was the one asking it one time, but I was like you at onetime leaning towards standard bore you get alot of different opinions but after talking to several different builders I decided on an AMR840 which I am still in the process of right now along with many other mods but I just can't get into it right now with 103 temps in Louisianna but the answer I kept getting is that the standard bore was awsome and would be amazed at the power in the seat as long as I didn't ride an 840 so I think you might have to make your own mind up, I even heard some saying that a standard bore would out run a big bore because it would turn more rpm only problem is I could never find anybody that could prove that they had out run a big bore except on a dyno and a piece of paper so you see which way I went but it seems that most everybody is happy with the standard bore or the big bore and also happy with either builders kit but I just have heard very little problem out of either and as for as the temp issue I think that it is like someone else said the heating issue has been more of a condition more than the size of the engine wether it be stock or big bore and in saying all of this I really have not helped you decision at all, oh well just go for it I bet you will be happy either way.

i am happy with my 840 and i have had not one overheating problem yet....i have 650 miles on the 840..i did have some tuning issues though i beleive i have them squared away for now.i say go for the 840 its only 500 more.you wont be disappointed.

You will overheat a standard bore too. My stock 08 would overheat in 90deg temps. I have put in an oversized waterpump impellor and engine ice coolant and now have no problems keeping my engine temp down. I would value poflo's opinion.. I think he might have the oldest 840 around.

thanks for the info. I do have tpi valves from hw, but need a good filter.

We have good filters too!! LOL

As far as the main question, I won't even try and reply I will get blasted!! LOL

840 ALL THE WAY!! I have no heating issues at all, I run evans coolant and run a switch on the fan so its on all the time. Ive ridden with stockers that overheated and mine didnt!!

I think you should go by what kind of riding u do. The way i look at it is, if u ride dunes and open area's get the 840, If u ride tight and small area where u can't get top speeds get the std bore. I'm still on stock setup but I'm debating on what to get also. I like racing around in trails so I;m thinking of getting the std bore.