400ex XC/BX/MX build.

[Baxter]

Best build for more power and Honda reliability. Race beachcross , motocross , cross country and a 8 hour endurance race. Racing everything and everyone , Banshee's to 1000cc Can Ams.

I basically race on any style of racing.

Can you guys help ?

[cheater13]

Either a 416 or a 426 build would do you good. You have a lot of choices. I honestly think my drag build I have would do you good for what you're doing. Excluding the huge intake, tires, and struts.

[DragonGunner]

You got your work cut out for you then, you will be under powered and heavier no matter what you do. With that said go with higher compression, cam, port, carb...I would also mainly work on your suspension, suspension can make you last longer, and go faster. Get a +1 swing arm and re worked rear shock. Go plus 1 or 2 on a arms. I'll say it again, a great suspension set up will help you the most.

[Zakradu398]

I wouldn't worry about displacement. By going from stock to 416, you are gain very MINIMAL power while wasting 3 bore sizes. Keep that in mind.

[Baxter]

You got your work cut out for you then, you will be under powered and heavier no matter what you do. With that said go with higher compression, cam, port, carb...I would also mainly work on your suspension, suspension can make you last longer, and go faster. Get a +1 swing arm and re worked rear shock. Go plus 1 or 2 on a arms. I'll say it again, a great suspension set up will help you the most.

Weight is not an issue, I usually race a 700xx in the same kind of races. The 400ex feels like a 125cc 2 stroke and thats how I ride it. Suspension is on the list but maybe go +3" though and get axle or wider hubs for the rear. Cheers for the info DG.

[Baxter]

Either a 416 or a 426 build would do you good. You have a lot of choices. I honestly think my drag build I have would do you good for what you're doing. Excluding the huge intake, tires, and struts.


I wouldn't worry about displacement. By going from stock to 416, you are gain very MINIMAL power while wasting 3 bore sizes. Keep that in mind.

Not too keen to go bigger bore but might go for stock bore and stroker crank. What's youre thoughts on this ?

[cheater13]

If you go wider rear, get the Tusk axle. Best axle in my opinion.

[DragonGunner]

Weight is not an issue, I usually race a 700xx in the same kind of races. The 400ex feels like a 125cc 2 stroke and thats how I ride it. Suspension is on the list but maybe go +3" though and get axle or wider hubs for the rear. Cheers for the info DG.



Wider axle good to go.....The wider your a arms the harder to turn in tight stuff, great on big open track with sweeping curves. I ran +2 and they worked great, but in tight MX and XC racing I prefer the +1 I have on now. Also you want a stabilizer on for sure with plus a arms. For the price and quality I sternly encourage a CCP stabilizer. My son raced his 450R on a XC type race a few weeks ago, had not got a stabilizer yet, but he just got the CCP like mine and we went to a open practice and hit the same XC trails....he couldn't believe the difference, night and day, gotta have one for any kind of rough course, really saves your arms and wrists.

[Blodg]

Best build for more power and Honda reliability. Race beachcross , motocross , cross country and a 8 hour endurance race. Racing everything and everyone , Banshee's to 1000cc Can Ams.

I basically race on any style of racing.

Can you guys help ?
I am the last one to ever tell someone to get a 450R instead, I love my 416EX and ride faster than most 450's I ride with in the woods and hills. But in this case with the more open racing and unlimited cc class structure I have to wonder why you are not looking at a 450R instead of a 400EX? Especially if you are considering a stroker as those are expensive and you could put the money toward a more race oriented machine.

I chose my 416EX for the type of riding I do but if I was racing anything but cross country I would go with a 450 if it was me.

[Baxter]

If you go wider rear, get the Tusk axle. Best axle in my opinion.

Cheers for that , good price too ! :)

[Baxter]

I am the last one to ever tell someone to get a 450R instead, I love my 416EX and ride faster than most 450's I ride with in the woods and hills. But in this case with the more open racing and unlimited cc class structure I have to wonder why you are not looking at a 450R instead of a 400EX? Especially if you are considering a stroker as those are expensive and you could put the money toward a more race oriented machine.

I chose my 416EX for the type of riding I do but if I was racing anything but cross country I would go with a 450 if it was me.

I had one , bought it brand new in 2004 and spent a fortune on it and results at best were so so. Nearly quit quad racing all together and go back to dirt bikes. On a whim I bought a TRX700xx and was probably the best decision I made. Faster on the 700xx in every way but mx.

Could never get the 450 to handle right without changing my riding style which took all the fun out of racing.
The 700 and 400ex suit my riding style ways better and there a blast to race. I found riding the right bike is better than riding what you "should" be riding.

[DragonGunner]

I had one , bought it brand new in 2004 and spent a fortune on it and results at best were so so. Nearly quit quad racing all together and go back to dirt bikes. On a whim I bought a TRX700xx and was probably the best decision I made. Faster on the 700xx in every way but mx.

Could never get the 450 to handle right without changing my riding style which took all the fun out of racing.
The 700 and 400ex suit my riding style ways better and there a blast to race. I found riding the right bike is better than riding what you "should" be riding.


I have rode the 450R too and just didn't like it either. Some do great on them, and others do great on the YFZ. After riding others I liked the 400EX I had built better for myself, just lacked power.....so I fabbed a KTM motor into the frame. Still handles and feels the same but has lots more smooth power.

[Baxter]

I have rode the 450R too and just didn't like it either. Some do great on them, and others do great on the YFZ. After riding others I liked the 400EX I had built better for myself, just lacked power.....so I fabbed a KTM motor into the frame. Still handles and feels the same but has lots more smooth power.

Got me a XR650R motor , cheap for the next one ! :devil:

[Blodg]

I had one , bought it brand new in 2004 and spent a fortune on it and results at best were so so. Nearly quit quad racing all together and go back to dirt bikes. On a whim I bought a TRX700xx and was probably the best decision I made. Faster on the 700xx in every way but mx.

Could never get the 450 to handle right without changing my riding style which took all the fun out of racing.
The 700 and 400ex suit my riding style ways better and there a blast to race. I found riding the right bike is better than riding what you "should" be riding.
Great answer to my question! I love the fact that you want to ride what you are comfortable on and not what everyone else thinks. I am the same way and love the 400EX and do everything my buddies do on 450's even though most people think it is for beginners or for their girlfriend.

But I will say since I have never owned a 450 I still want to buy one to try it myself but if I do I am keeping my 416EX. I have owned several 250R's and a 500cc hybrid and like the EX better. I have never ridden a fully built 450 but the mild builds I have ridden don't feel much different than my 416. Just last weekend I rode a KFX450 with a DASA exhaust, FCI intake, and Fuel Commander and it had more top end than my 416 but in the midrange where we spend 90% of our time riding it felt very similar to my 416. For the hill climbing I am doing the big difference is I have to use 2nd gear when they are in 1st gear on the same hill.

[samm3020]

I love my 400ex for trail riding and most of the time it has plenty of smooth power, but I have to say I have a 2005 built 450 (pipe, intake, cam, 13.5:1, ported +1 valves, 42.5 fcr) and the difference in power is not even in the same world. Provided my 400 isn't as built as the 450 but when you build a 400 you start looking at heat issues, its heavy, braking system isn't up to par, the 450 doesn't have heat issues, also on my built 450 motor I've got alot of hours with nothing but oil changes.

Having said that the 450 has so much power in tight sections it can wear you out from holding on, but when you get it on a mx track or out in the sand I wouldn't want any less power.

[Baxter]

Entered a 8 hour race with a friend. Put 700xx stem,spindles, etc . manged to do 5 hrs . finished 23rd outta 58. My frame seems to be really bent though. Steering stem doesn't fit !