440 kit advice

[2002Honda400ex]

I have a 02 400ex with lrd full, kn filter, and dyno jets. I was wandering if i could just put in a 12.5:1 piston, new sleave and hot cams stage 1 or 2 in. Will it last as long as a stock engine? Do i also need to get new valves and springs?

[2004exrider]

From what ive picked up on here from other 440 owners to get a some what reliable 440 you'll need:
Stronger connecting Rod, Cylinder bored and a bigger sleeve installed, alot of people are using the old stage 2 cam (now the stage 3/ stroker cam), bigger head studs, bigger oil cooler and reservoir, and a stronger clutch. Some other things that will help keep it a little cooler will be using a good synthetic oil and running the right octane gas for it. As for the valves and springs, get them checked out and see if they're still usable but your best off just buying new ones. Heck i'll even get you the part numbers to help you out some, prices might be a little off, its an older schematic...

Intake Valve: 14711-kcy-670 $18.27
Exhaust Valve: 14721-kcy-670 $33.85
Outer Valve Spring: 14751-kcy-670 $6.31
Inner Valve Spring: 14761-kgo-003 $3.84

Jimmy

[GPracer2500]

Hmmm. If I had a stockish 400EX (like you) and really wanted more performance, I'd consider selling the bike and buying a used Honda or Yamaha 450. They are leaps and bounds beyond the 400EX. You could easily end up spending more to build up your 400 to what you want than it would take to simply get a higher performance quad.

2004exrider is right. If you run your quad hard (who doesn't?) and expect reliability than it is not as simple as just buying a 440 sleeve and piston and slapping it all together. You'll need to build the whole engine (and don't forget a good carb) and maybe you'll wind up with something that performs like the 450s.

If I were in your shoes, I'd either consider another quad or add a cam, a 416 or 426 piston at 11:1 or less, HD studs, and o-ring the top of the sleeve. Any more internal mods than that (other than maybe porting/valve jobs and blueprinting type work) and looking for another quad starts to make more and more sense.

All of that is assuming that you don't want to invest the time and money to rebuild your engine more than once. Some folks to enjoy that kind of thing in-and-of-itself rather than as a means to and end.

Just my $0.02

[Wheelie]

Stroke it:macho

[GPracer2500]

Originally posted by Wheelie
Stroke it:macho

Now that actually might be a more reliable way to get to 440cc...didn't think of that. I'm not well versed on strokers though so I couldn't say for sure.

[DOHC]

I have a 2001 440ex and its reliable

[2004exrider]

I wonder how the 416 piston with an extra 4mm stroke (also comes out to a 440) would be, reliability wise?

Jimmy

[eganracing]

hd studs r an absolute must. to really wake it up u would need a carb and a port in polish.

[Wheelie]

From what I've read and been told, the 440 Strokers, though more expensive, produce more power/torque and are more reliable. I've heard to many horror stories about 440BB, that's why I went w/ a stroker.

No flame intended.

Hopefully I'll have my crankshaft back next week.:macho