2001 YZ426F Top end rebuild cost

[BigTool]

I want to buy a 2001 yz426f a guy has for sale. This thing is a bit ragged and he says it needs new valves and timing chain. I'm pretty mechanically inclined but I've never done a top end before. How difficult is it to do your self? Any special tools req'd? How much would the parts cost me?? The guy wants 1000.00 but I think I can talk him down to 800. I want to supermoto this thing out. Good deal?? Good bike to start out in supermoto? I'm clueless... thanks.

[Wiz636]

You can price out the parts in the Thumpertalk OEM store...they are about the best prices you will find. I just did new piston/rings, valves, seals, etc. on my '06 and it came to about $700

My question is how does the guy know it needs valves and a timing chain? Is it because something bad happened? It might need more than just new valves and timing chain...like a new head, cams, etc.

[BigTool]

It doesn't currently run and thats what the shop told him he doesn't know anything about engines. I assume i need more than just new valves & a chain. I'd refresh the whole top end but I don't know what all I'd need to buy / have machined to get the job done. I'm just looking for a rough estimate of the total cost to see if buying the bike is worthwhile. I have no idea if it needs a new head/cams. Is buying such a bike for 800 too risky?

[Wiz636]

In that case I would plan on spending $1,000 if I was doing the work myself. If it doesn't even run then you might have to deal with the crank and connecting rod...you just don't know. That means $1,800 (at least) for an 01 426. I think I would look for one that is running.

[grayracer513]

That means $1,800 (at least) for an 01 426. I think I would look for one that is running.

OTOH, that would be $1800 for one with a fresh engine, too.

[Birdy426]

I spent about 1500 on mine with a new crank and a luke's racing 444 big bore kit. TT store is by far the best for price. If you take your time and follow the manual (except the part about lapping the valves...send the head off to Eric Gorr or Engine Dynamics and get the seats cut and guides checked), you shouldn't have any problems at all.

[tnl]

It doesn't currently run and thats what the shop told him he doesn't know anything about engines. I assume i need more than just new valves & a chain. I'd refresh the whole top end but I don't know what all I'd need to buy / have machined to get the job done. I'm just looking for a rough estimate of the total cost to see if buying the bike is worthwhile. I have no idea if it needs a new head/cams. Is buying such a bike for 800 too risky?

I think/bet your in for more than just refreshing a top end. A 7 year old bike probably would benefit from more than just the above especially if it won't even run right now. OTOH, it might be ok if your just looking to get it running and aren't serious about riding but it sounds like you are? My 05 had some work done inside the case and I was suprised at how much more it needed just from wear and tear at 70 hours. I need a winning lottery ticket New crank, primary drive gear with clutch parts, cylinder,rings ugh! BTW, what material is the cylinder head made of? Does it have a special coating in the bore? Mine has some scratches but you can't feel them and I was told it can't be honed without re-coating it? It isn't warped either. New cylinder is about $200.

[00YZ426FMRCD]

I want to buy a 2001 yz426f a guy has for sale. This thing is a bit ragged and he says it needs new valves and timing chain. I'm pretty mechanically inclined but I've never done a top end before. How difficult is it to do your self? Any special tools req'd? How much would the parts cost me?? The guy wants 1000.00 but I think I can talk him down to 800. I want to supermoto this thing out. Good deal?? Good bike to start out in supermoto? I'm clueless... thanks.

All depends on the shape of the rest of the bike. Forks, shock, bearings, chain/sprockets, tires, etc... If the bike chassis wise is in excellent shape, probably worthwhile - if not, I wouldn't spend the time, effort and $'s and would look for something else. Lots of good used 450's out there that run.

Something to be said for buying a bike that runs. At least you know it ran at one point in time. When you buy a bike that doesn't run, you never know, it could be a combo of mechanical, cdi or ignition problems that can get really expensive...

PS. $400-500 for a new top-end if you do it all yourself.

- RCD

[grayracer513]

BTW, what material is the cylinder head made of? Does it have a special coating in the bore? Mine has some scratches but you can't feel them and I was told it can't be honed without re-coating it? It isn't warped either. New cylinder is about $200.

The cylinder, or the cylinder head? Both are aluminum, and the cylinder has a plating of Nikasil on it. It can indeed be honed, and should be before re-ringing it, but you should not use a fixed stone hone.

Instead, use a spring-ball hone ("bottle brush" hone) and make 3-4 quick passes up and down the cylinder (down and back up in about one second). This will remove virtually none of the plating, but it will break the glaze, lay a decent cross hatch down, and tell you whether those scratches mean anything or not. If they disappear following the quick honing, they're not important.

[BigTool]

Thanks for the info guys. Looks like I'll pass. I'm such a sucker for these sort of deals, but I usually end up spending more than I should have in the end. Only benefit is knowing my way around the bike better. I really want to try racing supermoto but spending 5k to do it isn't in my budget.

[patcap]

thats exactly how i felt when i saw the ad,craigslist is a problem or a blessing but there is many a slip twixt a cup and a lip (young guns).