440 big bore

[Got_Mort03]

I am installing a 440 kit in my 400 and i am wandering about any problems i will encounter i am also installing a hot cam stage 1..... has there been any known problems with this kit it will have 11:1 comp. also, are they reliable, etc. will it put out some serious horse power with this done, i already have a cobra pipe,(just for loudness), also have a white brothers pipe, a K+N filter too. any help would be great.

[TC426EX]

With the 440 kit it is a good idea to heli coil or your headstuds or get a heavy duty head stud kit from Eastcoast atv. This is for added reliability on that bore size even though you didnt go with the maximum compression on it. Also, getting some Port work done along the line somewhere will help you get more of the full potential out of the mods. The bike will be noticeably faster largely due to the cam and the piston. If you werent putting the cam in you would only see a minimal difference. To help the motor breathe and make some good useable power, do yourself a favor and eventualy get RID of that Cobra exhaust, especially if it is just a slip on. Those pipes are usually not very good at all and only produce a gain in one part of the powerband if at all. Lastly, you can increase the reliability just by making sure it is done right and taking your time. Make sure you take the time to break in everything properly when you are done!! I know there will be a temptation to go out and start ripping your new motor kit, but trust me, youll save yourself alot of headaches if you just take the time to break those rings and cam in properly (dont forget to check your valve clearance before AND after running it through the break in time.) Also, look into removing the choke from your stock carb if you are still running it so you get a little smoother flow of air and fuel to your motor, it makes a difference. Good luck with the job and PM me with where you are in OH and if you plan on starting racing or not...

[airheadedduner]

Make sure you don't overheat it. It is easy to crack the sleeve.

[FAST400JE]

When building the engine go over everything, from top to bottom and replace anything that needs it, better to do it while its apart. I built the same identicle motor, w/ porting and a WB R4 pipe, it really rips!!! REPLACE THE CAM CHAIN AND CHECK THE TENSIONER!!!! I broke my motor in and noticed a tapping noise coming from the right hand side, didn't think anything of it and the damn cam tensioner colapsed and the timing jumped and dropped the intake valves into the piston, luckly it was idling!!! The engine does like to run hot!!! Jetting is fun too, i ended up from a 148 to a 168 on the main and played w/ the idle air a little and that seemed to do the trick, it all depends on where you ride. Run w/ the airbox lid off and its a whole differnt bike!! Over all if you take your time and go over it well, double check even triple check everything and you will love the engine!!! It really pulls hard 3rd through 5th when she's pinned!!!!! Enjoy and good luck!!