What bore kit is best for 440ex??

[z400ex]

I am boring my 400ex to a 440, and would like to know what kit is best? What kit is better in performance and wat kit is better for reliablity???? Thanx for the feedback.......:D

[Nausty]

I would suggest looking into 416 because those are much better for the price and you get get like say 3 angle valve job, port and polish, high comp piston sparks racing cam with the harder springs and rockers and everything else compared to a half *** 440. The only time I say go with 440 is if you really wanna put everything into it. Check out sparksracing.com which is about the best builder out there and then you got tc racing, ct racing, duncan racing, ims, ect there it tons of companies that build kits.

[z400ex]

thanx for the feedback.....but wouldnt the 416 with all the cam , rockers, valvesprings, and valve job cost alot more then a 440kit with a port and polish??? I have also heard that 416 are more reliable wich makes since because its a smaller displacement and runs cooler. How much do 416 kits run as compared to the 440 kits at 220$ 300$, as far as labor my dad pretty much can do everything but the sleeve install...would you happen to no wat those run for also??????thanx

Nausty I would suggest looking into 416 because those are much better for the price and you get get like say 3 angle valve job, port and polish, high comp piston sparks racing cam with the harder springs and rockers and everything else compared to a half *** 440.

And if you call FST or CT or TC or LRD or whoever they will tell you that the above comment is half arsed and the author possibly confused or misled by incorrect comments and heresay.

Sorry Nausty but I am just getting a bit more than ticked off over the misunderstandings of the 416 vs 440 BS. Its gettting way too deep and I dont have my boots on.

If less cc's were the way to go then everyone should invest in a 250X motor and start kicking some butt.

But you are correct that the 416 will be much less expensive than the 440 "done right" but then screwed that up with the suggested mods that would benfit both or any size motor.


Back to the orig question.
You should be ok with any of the major builders or piston mfgs products, and you will find some good info on most of these on the older threads so do a search.

Be sure to check your piston height at TDC in relation to the top of the cyl. as the most prevalant prob with the 440 is a loss of compression due to the piston not being at the correct height (level to the top of the cyl).

Also remember that none of this is going to be working right without the proper cam, exhaust, porting and carb or jet settings.

Basicly the 440 needs to breathe more or move more air than the smaller bores to work properly.

[Nausty]

I didn't read all of ^ but it didn't sound to good, is all I gotta say is go look on sparks web site and look at the price between the 440 and 416 and I think he would be much better of with a sparks 416 over some half arse 440.