What to look for in buying a used 400/426?

So after a 8+ year hiatus from riding/racing mx, I have decided that I want to get back into the sport and a yammy 4 stroke is the way to go. I've been looking primarily at the used 400s and 426s due to budgetary constraints.

My question is: What should I be looking for when I go to check these bikes out? Other then the condition, obvious care that was taken, the routine maintenance schedule and any/all replacement parts/upgrades, what should I be looking for? I'm thinking more along the lines of valve adjustments, cam wear and overall engine condition (I think). :D Are there any sure signs of problems that may lay ahead? Having ridden 2 smokes exclusively before, I'm kinda new to the 4 stroke thing and I would hate to pick up a bike I think I found a great deal on only to have hundreds of dollars of repairs within a month.

Also, I have seen prices vary on the 400s greatly, from all the way down to $1500 up to $3000 - what's the deal here? Is there a such thing as a good deal or am I going to get what I pay for?

Any help would be greatly appreciated!

This is a well beaten thread, so search the forums. Basically, the 4 strokes are more complicated internally than a 2 stroke. Perhaps fewer maintenance items each time, but more major (but easily doable) things when the time comes. The reason for the big swing in prices is usually related to the maintenance interval. When buying a thumper, I would be very leary of a bike/owner that was not very conscious of the minimum of oil changes every 300-500 miles, filter changes, and, given the vintage, at least a valve clearance check if not adjustment or valve themselves. You have ridden before, so look at the overall cosmetic appearance beyond the plastic. This is typically a good indicator. Unfortunately, there is no real good way to check on the valve related maintenance other than crackingit open and measuring yourself. Spend more to get a bike that has been well cared for. It will be money WELL spent!

When I bought my WR, the seller was more than willing to pop the valve cover and let me check the valves. Gave me a warm fuzzy. Also, check wheel bearings, particularly the fronts. WR's go thru 'em. Worn ones may be an indication of overall sloppy maintenance.

One thing I would look at besides what has already been stated is the swingarm.

The WR426 upper chain guide behind the front sprocket had a bad fit. It could accumulate dirt and grit under it. As a result it would wear or grind on the swingarm at that point. I have seen pictures of cracks located there. Near a weld if I remember right. My WR had the same problem.

It's a simple fix but something to look for. I glued a pice of a bicycle tube to the swingarm under the chain guide and it solved the problem. I think TM Designworks makes a better fitting guide as well. It's pretty important not let the chain get too loose on the older 426's. It will slap pretty hard.

Here is a link to a search I did.

http://www.thumpertalk.com/forum/showthread.php?t=6049&highlight=swingarm+cracks

I also like to look at the clutch cover (rear brake) and crank cover (shifter) as an indicator to the number of hours/miles on the bike. If the guy says it has very low miles and the clutch cover looks like it has been hit with a ginder, then, you know he is lying. If he is lying about that, he could be lying about the maint. schedule.

If you are patient, you can find very lightly used bikes.

As well as everything already mentioned, I would check headstem/swingarm/linkage bearings/bushes. Hard to see when the bike's intact I know, but try and feel the headstem bearings by slowly turning the 'bars from left to right, and see if you can feel any notchiness, or otherwise 'unsmooth' action. Swingarm/linkage will be harder, you'll have to just try and make sure the rear suspension travels through its motion freely, without squeaking etc. All the bearings are often neglected, as they're a PITA to grease properly. Stuffed bearings/bushes will add a hefty bill to a used bike though, so check 'em out. :D

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