Questions about Valves!!!

[07trx400ex]

Do all of the 450 sport quads have the shims/bucket type valves?

What about the Outlaw 525?

The Raptor 700's have the same style as the 400ex right?

I am getting a new quad and I enjoy doing my own maintenance, so I don't want to get something that hard, and something that needs to be adjusted so frequently, but still want it to rip.

Thanks guys!

[GPracer2500]

The Raptor700 and the Outlaw 525 both have screw/tappet valve adjusters like a 400ex. No cam removal or shim replacement required for adjustment.

[07trx400ex]

Thanks, I sent you a pm about combustion chemistry.

Did you get it?

Also, would the 450MXR have the same type of valves as the 525 since it is the same engine design?

Does anyone know about the other 450's, I know the trx is the shims/bucket type.

[GPracer2500]

I did and I wrote a mid-length email last night. Then my e-mail program crashed before I could send it. Do'h!!

I'll send another with some docs but it may not have my commentary (which you may not want anyway). Look for it later.

[wilkin250r]

Hey, I want combustion chemisty!!!

wilkin250r@msn.com


(I also deleted the other thread copy)

[07trx400ex]

Yes, I would appreciate your insight (ALWAYS very helpful). (GPracer2500)- Thank you.

I found out that all the KTM based engines in the Outlaw are the "screw/tappet" style.

Still don't know about all the other 450's other than Honda, Polaris, and KTM.

I think this is a much easier system for the average consumer, like myself, to service regularly.

I have not done research to support this statement, but it would seem as if the screw/tappet system are less likely to go out spec than the shim/bucket style.

So what would be the advantage of the shim/bucket style?
The KTM and Polaris both make great hp #'s, so what is the drawback?

[GPracer2500]

The DS450, YFZ450, and LT-R450 all have shim/bucket valve actuation.

AFAIK, as a practical matter that style is no more likely to need adjustments than screw/tappets. Any differences there may be in service intervals for those two styles is likely to be overshadowed by other differences between engines. For an extreme example, a stock TRX90 might need a valve adjustment a few times in its long life (maybe). A TRX450 might need a whole bunch and will probably need a whole refurb of the valvetrain before the rest of the machine wears out. But that difference has more to do with the differences in the entire machines vs. the differences in they way they move their valves. In other words, it would be very tough to say that either shims/buckets or screws/tappets require more adjustments than the other by sole virtue of their valve design. It's just too hard to separate the valve actuation style from the rest of the machine. IMO, of course.



Shim/bucket styles are more involved to adjust and require swapping out shims if a clearance change is needed. That could mean trips to the dealer every time a change is needed or the purchase of a shim kit from Hotcams or elsewhere. So if you're looking for the easiest maintenance options, screw/tappet adjusters are where it's at. I personally don't think it's that big a deal though. I'm no less likely to stick to my service regime because I have to buy a $100 shim kit and take 3x as long to adjust my valves. That's me though. I can understand where plenty of folks could really care about and benefit from the friendlier nature of screws n' tappets.

$0.02

[pro-rider46]

the yamaha uses shims, but none of the shim and buckets are hard to adjust, i can tear it down to do it and then put it together and ride all in a little over a hour

[GPracer2500]

Originally posted by wilkin250r
Hey, I want combustion chemisty!!!

wilkin250r@msn.com


(I also deleted the other thread copy)

You got it. Prolly later tonight.

[07trx400ex]

There must be a reason that most of the 450's use shims/bucket style.

Why would most of the 450's use this system?

It seems as if the answer would correlate to the use of a "slipper piston".

A quick overview of the Bore/Stroke of the 450's revealed that they all have a substantially larger bore than they do stroke, except for the KTM and Polaris.

This makes me draw the conclusion that the Bore/Stroke dictates the type of valves used.

Bore/Stroke and type of valve actuation:

Honda TRX450r: 96x62 / shims/bucket
Suzuki LTR450R: 95.5x62.8 / shims/bucket
Yamaha YFZ450: 95.0x63.4 / shims/bucket
KTM 450 XC: 89x72 / screws/tappet

Does anyone have anymore info on this?

[F-16Guy]

Originally posted by 07trx400ex
There must be a reason that most of the 450's use shims/bucket style.

Why would most of the 450's use this system?


Fewer moving parts = less drag/friction = less heat = more power and reliability. I don't necessarily think the problem of more frequent valve adjustments is caused by the the shim-under-bucket design. The cause is actually a few things working together. You have a more radical cam profile, an engine that typically turns more rpms than a 400ex, and for the sake of weight savings, a valve made of a very light and much softer material that has a very thin layer of hard coating to prevent wear. Valve adjustments will probably be slightly more frequent than something like a 400ex just due to the nature of the engine, but if you neglect the adjustment or get it too loose one time, you can beat that thin coating off of the face of the valve. Once that happens, they won't stay adjusted no matter what. The most common solution is to install stronger (and heavier) stainless valves. You'll also have to install heavier springs to compensate for the additional mass.

[witech]

Its about the rpm . A small bucket is much lighter than a cam lever with a bolt and screw setup on it. When your regularly turning 7,000 to 8,000 rpm in the lower performance engines the lever system works fine. The new 450's and other high performance engines have jacked the rev range up well in excess of 10,000 where every gram of extra weight requires a heavier valve springs to close the valves at speed.
Also the strain on the system is less with the lighter parts.
Its the same deal with pistons. The shorter the stroke the higher you can rev a motor safely.

[07trx400ex]

Thank you guys. That is great information and makes sense.

In retrospect, I should have thought about that intuitively.

I am trying to look at every possible angle of my next machine and this is very interesting.

[Knoxy]

gettin into this a little late... but would i be able to get the combustion chemistry document too?
thanks again!

ryanknox69@hotmail.com

[GPracer2500]

Originally posted by Knoxy
gettin into this a little late... but would i be able to get the combustion chemistry document too?
thanks again!

ryanknox69@hotmail.com

sent

[Knoxy]

thank you very much kind sir.. very informative and insightful!

[07trx400ex]

Thank you, that was very informative, I got through the article on engine knock in record time.

Very easy to understand also.

If you stumble upon anymore good reads don't hesitate to let me know.

Thanks,
Charles