Why did Honda ditch the OHC engine in ATV's??

[MudBug]

Just been thinking, with all the trikes and older model quads being over-head cam engines, why do all the ute quads today run on the push rod system? is it superior to OHC, or just more economical?

[gsw902]

less maintenance, no valves to adjust if they use hydraulic lifters.

[MudBug]

How would you adjust them? My friend has one that ticks and im only familiar with the OHC system

[MuckUte]

With hydraulic lifters there is no adjustment, if they are noisy then the lifter needs srevicing or more often replacement. Somtimes different oil can quiet them down also. For solid push rods the adjustment is the same as an over head cam as there is still a rocker in the head that operates the valve.

Pushrod engines have some advantages and disadvantages. The timing chain can be much shorter or even replaced with gears, eliminating problems with chain tensioners and problems with stretched/worn chains but then the pushrods can bend or break.

Overhead cam engines are usualy more complex to work on as the timing chain needs to be removed prior to removal of the head

This doesn't really help with why honda ditched them tho

[MudBug]

good info ^^

I doubt there are hydraulic lifters in this bike. its an 01 Rancher. I dont like the look of those pushrod engines, something strange about them

[Dirtcrasher]

I'm unfamiliar with this pushrod stuff?? (Got any linkns??) Isn't "some" HP lost?? using pushrods?? I hope it was done well... Time will tell, lets hope HONDA gets back on top (Just because I like Honda) ; When Mitch Payton's Kawasaki's took the top 4 spots (I believe) at the final Las Vegas 450CC Supercross race, it sure said SOMETHING!!. Regardless, he knows how to build both a motor AND a wining team........ He's a great man as far as I'm concerned!!

Kevin Windham is so likable, so talented and smooth that I don't cut him out of the chase for 2011 next SX season and 2010 MX soon, I don't think he does as well there though. Lots of guys got real fast when Reed and Stewart lost the championship very early in the season. Reed has a baby now and may not even race the Motocross schedule (Can't blame him) and he's made it obvious that hie preference is SX. They ALL gained confidence and that is KEY!! Even when approaching big jumps on your trike...

SORRY to get off topic, I just follow the entire sport immensely!! They make it appear so EASY, just ask WHYZEE how tough it really is!!

Anyhow, BACK OT!!

I've been told by top notch mechanics, that some new technological improvements are not always the best thing (this may be CR250F or 450F though) that they were talking about.....

It was explained the me that Honda was trying to accomplish FAR too much with the "UNICAM" and also including a rocker arm for the decompression lever. NOT home mechanic type easy...

Again, you may me referring to some other type 4 stroke utility models which may (or may not) benefit from (the statement of never adjusting valves again) or it could be a sh!~t show. Time will tell, I just know that my motors lasted and lasted. Even junk Hondas run with fresh fuel and a carburetor cleaning...

I know at some point they had to make THUMPERS much more competitive, but why change a design on the utility quads to an engine that has run and run and run for 25 years or more!! Hof often do they require a simple valve and timing chain tensioner adjustment??

I guess it's JAPAN and not CHINA, but these pit bikes seem to be basically junk and built CHEAP (hence the low cost); Which is nice to get your kid trying something and then moving on to something such as a Honda TRX70/90 and enjoying it. But lets hope HONDA makes some big changes SOON!!!!!!!! Without reliability issues!

Did I hear that the new YZF450F is a rear facing head?? It won't surprise me as they were always the 4 stroke "pioneer" Makes allot of sense motor wise as far as I'm concerned, I think room may have been an issue before but with EFI up front, we don't need to worry about a huge carburetor right behind the front tire shooting rocks at it b Didn't ROTAX accomplish this years ago??

ALL the big guys have the technology, it's whether they want to implement it or not or bring out bits and pieces each new model year...

THAT is the big question...

Sorry for the book! I wanna see these "pushrods"...

[rdlsz24]

DC, something like this. The cam is in the block, and it moves pushrods up and down to operate the valves. The same as some OHV v8 motors in a car or truck.

Rob

[tecat-z]

Cannondale had the reversed type cylinder/head efi arrangement you speak of in the late 90's on their m/x bikes. It was later adopted to the quad. The pushrod utility engines of Honda are archaeic looking, and make all the power down low. Long term reliability was surely their intent, but in the real world it probably amounts to nothing gained. Since a well designed engine will have durability engineered into it from the start of new engine development. I've said it before, Honda is truly a company that is corrently lost, and can't seem to find it's way. Even though they are a 4stroke ONLY company. Suzuki, Kawasaki, Yamaha, and KTM all still make 2stroke engines. Some are sold here, some not. problem for Honda is that their 4strokes are better than Hondas best effort too. Many local racers i know have given up on Hondas and gone elsewhere for a competition machine. Both atv and M/X. Follow the leader was once Hondas slogan......... Well, now they find themselves, following the "leaders".