Valve Questions?

[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?

[Bradracer18]

Polaris(or my predator anyways) uses shims and buckets(which are very expensive by the way!).

I heard that adjusting the KTM engine's valves however are very very easy.