KLX 300 vs. KR 400

Both bikes need suspension work for any agressive rider.

XR 400 Pros: Very good low end power, Honda reliability, usually a good starter.
Cons: Weight, used prices probably higher than KLX

KLX300 Pros: Light weight for a thumper, very good handling, benefits greatly from big bore
Cons: Stock motor is a little weak, lower than normal ground clearance and foot pegs. Modified motors can be hard to start after a crash.

IMO both bikes are good choices for a casual trail rider. The DRZ is probably a better bike than either but is supposed to be a 'red' sticker machine.

The XR400 is tuned for low end power. Therefore, the XR does not rev out like a KLX or DRZ and makes a modest power peak for a 400cc bike.

I am not surprised a modified KLX could make more peak power, especially after increasing displacement with a high compression piston.

My buddy had a Stroker 331 cc KLX w/pumper carb, etc... and it was an excellent trail motor with enough low end grut, but it could rev out very high, requiring less shifting. The modified KLX motor greatly increased the fun factor over stock.

FWIW, another buddy has a virtually stock '00 XR400 - he loves it and absolutely rips no matter where we ride.

It's been a few years since my buddy sold his KLX, so I don't remember all the details about pumper carbs and idler gears. The guys at Stroker Racing are KLXperts and would probably answer any questions your friend has.

We have 2 KLX 300's and my buddy has a XR4 and KLX300 also. I have ridden his 400 and it has more low end "grunt" than the KLX. However I would (and did) choose the KLX. My buddy is shorter (maybe 5'7-5'8 or so) and is often falling down in the technical trails cause he can't reach the ground. The times I have ridden his XR4 I found myself dreading the weight. It is a heavy bike and the extra weight wears too much on me. It just isn't fun after a day of hard technical riding. Wide open whoops and it's a blast. Tight singletrack and I'm beggin for the KLX. Also, the KLX is a blast cause you can really flick it around. The XR isn't for flicking.

Regarding mods. The stroker idler gear for the KLX is about $85. The stock gear is too brittle and can break causing catastrophic damage. Supposedly Kawi says it is OK, but a change to the stroker gear is cheap insurance. Also, many people like to get the stroker shift star. It makes the shift from 1st to 2nd more positive. Less mised shifts. The Honda gearbox is very positive feeling. Both bikes benefit from the usual thumper mods. Toss the airbox lid, remove the butt plug, crankcase breather mods, etc. The KLX really comes to life with a simple header swap. The stroker is a good one and only $140. To really make the KLX rock you can go with a pumper carb. That makes the bike jump when you twist the throttle. Overall the KLX is more of a rever type motor. i call it a 3 stroke. if you really like the slo reving low end grunt the XR4 is it.

Both are solid bikes, but for a shorter smaller person I think you can't go wrong with the KLX. I could go for the XR if it was just 30lbs lighter. Oh well, I love the KLX's.

Because of your friends height, I would go with a 1 - 3 year old KLX that already has all the modifications done. Should be around 2 or 3 thousand bucks. :)