im thinking about a bigbore for my 400 but i am in a bit of a dilema. ive heard both good and bad about both kits but i would like a little advice on which is better

 

From what I've heard, a 416 will be a lot more reliable, plus, it supposedly revs faster.

 

I know very little about this but according to Mickey Dunlap the reason people think 416's are faster is because it is cheaper to get the most out of them. He claims it takes more to get the most out of a 440 kit which is more expensive and requires a port and polish to get the most out of it. I would also guess that having a new cylinder sleeve versus making the stock sleeve thinner would be more reliable but then again see the above disclaimer about me knowing very little.

 

Now people, tell me why a 416 would have more potential than a 440?
Then, if thats true... why bore to a 416, why not just keep the "rev crazy" 400 bore?

More CC = more power. Thats the reason people bore in the first place, isnt it?


"he claims it takes more to get the most out of a 440 kit which is more expensive and requires a port and polish to get the most out of it"

To get the MOST out of ANY motor, you need to open up those ports, not just the 440.

Just like the Raptor has more HP potential than the 400EX, the 440 has more power potential than the 416. Plain and simple common sense.

Reliability: The 440 has more ring contacting the bore, so its going to generate more heat. It also has a thicker sleeve than the stock steeve'd 416. Keep it rich, and make sure you dont overheat it and it will run great. Mine did.

-Matt

 

Yep, what Mr350x said.... It's silly to say a 416 has more potential than a 440.

 

I think what Micky Dunlop is trying to say is, you get the most bang for your buck out of the 416. The cylinder head on the EX has a little bit of a flow rate problem as the cylinder bore size increases. Once past about 420cc the ports won't flow enough air to fill the cylinder enough to make decent top end HP. The flow rate flattens out to the point where it feels flat from the midrange up. That's why all these people with the 426 and 440 kits say they have excellent bottom end but it doesn't like to rev out, even after installing a high performance cam. For instance, installing our Stage 1 cam on a 440 would only magnify the low and midrange and may MARGINALLY help on top. Once the head has been ported and polished and bigger valves installed they run much better. Like Mr350x said in so many words, "There is no replacement for displacement". As far as torque and hp are concerned, there are no truer words spoken, you just need to make the size be efficient with what you have by giving it the ability to fill the combustion chamber effectively for the displacement.

Tony

 

My brother should get his 440 kits finished by this weekend. I want to make sure that the shop that is doing the work has it jetted right. His mods are as follows:

440 bore
head work(nothing radical, just cleaned up)
Cams(mid to top range) not sure if they are WEB or Hotcam.
Yoshi "full" exhaust


Ok, that should cover it, Now he is using the stock carb, SO what would be good Jets sizes to start at(1200 ft. elevation).


Thanks,

Biggerisbetter.

 

more cc=more power, thats not true, how come a 250r can stomp a 300ex? just food for the thought

 

My fully built 416 will kill a poorly built 440. If you plan on going all out do a 440. Either way do a 440. Im stepping up this winter to a 440..

 

You can't compare apples to oranges. Thats like saying how can a 4 cylinder turbo motor make mor power than a naturally aspirated V8.

Power increases with volumetric efficiency. A well built 440ex will make more power compared to a well built 416ex. Reliability and expense may be the tradeoff.