reliability, 400ex or 450r

[darkzealot]

What do you think is more reliable ?
400ex with aftermarket exaust, k&n filter, aftermarket cam,bored 416 11:1 compression piston ( lets say JE ) port and polish job and crf450r timing chain OR stock 450R

considering that the 400ex was build correctly...

i have a 400ex right now, and im wondering if i should mod it or simply buy a 450r (used). reliability is an important factor for me. I wouldn't want to have to rebuild the 450r every year...thats why..

thank you

[mic 902]

Considering that most bike manufacturers have got the bottom end of engines worked out most of the reliability of a 4 stroke bike/quad comes from the head. The head in the 400ex is simple and effective, from what i understand the head in the 450r is similar to that in the crf450 and on the bike forums guys with all these new 450's are dropping valves left right and center. The 400ex engine is almost a carbon copy of the xr400 with only a few changes to make it more suitable for a quad, i have never heard of an xr400 with problems, they just keep on running.

Hope that helps. :D

[2004exrider]

^^^ almost impossible to hurt an xr engine!

Jimmy

[darkzealot]

yea it does help !
thx for your answers guy =)

[Wheelie]

A 400ex is absolutely bulletproof, IMO. It's a tough machine to beat from a reliability standpoint.

[F-16Guy]

The 400ex is very reliable IF BUILT CORRECTLY! That would mean a good, straight bore job, HD head studs professionally installed, quality parts, and, if it were me, a FST-style top end cooler. Mine is built as above, and also has a Carrillo rod; it's bullet proof. The 450R is also reliable, but probably won't go as long between rebuilds because of the thin piston and the high revving design (more wear). The valve problems were on the CRF450R bike because the valve material was fairly soft, but had a titanium nitride coating. If the valves weren't maintained on a regular basis, the coating would wear through, and the valves would smash down where they meet the head. Because of the design of the valvetrain, that actually makes the valves tighten up, which causes hard starting, poor performance, and burnt valves. I don't think the 450R uses the coated valves.

[darkzealot]

so anyone know for sure if the 450r use or not these coated valves ?

[F-16Guy]

Do a search in the 450R forum; I think there's been quite a bit of discussion on the subject there.

[darkzealot]

thx...good idea
forgot about that hehe :rolleyes:

Also check out the "It finally happenned to me..." thread in the "Open Frum"

[darkzealot]

very nice tread..a lot on information on there.

450r is not that reliable as i can see even stock ? maybe i should stick with my ex, mod it and have fun. i don't want a problem quad since money is an important factor for me. I just want more power from my quad to do bigger jumps and have more fun in the trails even if i don't do any race. And the price is very high for a used 450r here in quebec canada.....4000$ can for used ex and 7000$ can for the used 450r 2004...you see the diff.

I dont really know what i should do..i would get more power from a stock 450r then a modded ex with the mods listed in the beginning of this thread? But the ex would be more reliable?
if i don't plan doing race with a 450r...would it be a good quad to have anyway or the power of the 450r isnt worth it considering the reliabity for a guy like me ? ( don't worry, i do all necessary maintenance tho )

in fact the question could be...what is the best ratio performance/reliability between a modded 400ex like mentioned before and a stock 450r ( or with exaust) ?

thx you very much for your answers guys ! really appreciated

[krt400ex]

Originally posted by mic 902
Considering that most bike manufacturers have got the bottom end of engines worked out most of the reliability of a 4 stroke bike/quad comes from the head. The head in the 400ex is simple and effective, from what i understand the head in the 450r is similar to that in the crf450 and on the bike forums guys with all these new 450's are dropping valves left right and center. The 400ex engine is almost a carbon copy of the xr400 with only a few changes to make it more suitable for a quad, i have never heard of an xr400 with problems, they just keep on running.

Hope that helps. :D


they r dropping valveson the 250s, those bike rev higher and have a whole different power characteristic. the 450s r reliable.

Seems like alot of guys are running the 416 EX with the strokers.

If you aven't upgraded your suspension, I'd mod up yur EX, get serious about your suspension, and get good enuf where the bike begins to hold you back.

I'd be willing to bet that you'll win ALOT of races with that approach.

Maybe even to the edge of teh pro class.

[F-16Guy]

I agree. Suspension will make your bike much more fun to ride. You can easily outride stock suspension with a stock engine, so you may want to do shocks, arms, and axle first, and then do internal engine stuff. It will take big $$$ to make the same HP numbers as even a mildly modded 450R, but with good suspension and a properly built 416 or 440, the EX can hold it's own. For most types of riding, I actually prefer the EX's power output. It's very linear, instead of the 2-stroke feel you get from the new 450's.

[darkzealot]

don't worry about the suspension, it's not the best but i have 450r front shock revalved and stock 400ex rear revalved.
I just want to have more power to be able to clear bigger jumps at the track of my friend. I dont race but i like to play in the mx tracks, heh...

Originally posted by darkzealot
don't worry about the suspension, it's not the best but i have 450r front shock revalved and stock 400ex rear revalved.
I just want to have more power to be able to clear bigger jumps at the track of my friend. I dont race but i like to play in the mx tracks, heh...

Seat of the pants observation -

Modding ANY motor is gonna place it under stresses the engineers never intended.

Factory 400 EX motor is very dependable.

Modding it to something else can ONLY serve to reduce that reliability.

Same with the 450R. Honda engineers designed it to do certain things. From my reading , changing the 450R piston to a higher compression set up is what is causing it to kaboom.

Higher performance than the factory set -up has a price.

If yer gonna dive into the motor ONCE, you increase the liklihood yer gonna be diving in regularly.

You can't buy a BMW and then expect to get Ford prices on repairs.

[darkzealot]

thx you ! very useful tips =)