1998 Wr400 Complete Rebuild, What Upgrades should I do, have a 2001 Yz426 complete parts bike

I traded a few bikes over the winter to get this 1998 Wr400. The bike wasn't running and later found it to be low on compression. Before this I completely cleaned the carb and found  that the slide in the carb was a two piece design, well the lower part of the thin part of the slide was broke away. I order a new one at $120.00 cleaned the carb. I figured that the missing part of the slide went through the engine which it did. There was small pieces stuck under the valves. At this point, a week ago I decide I was going to keep the bike and rebuilt it to new. I have it completely apart now, order way to much money in new parts, like new piston rings, new valve seals, all new gaskets oil rings and seal, new sprocket and chain, shim kit for the cam, almost all new plastic, and decal kit., I am rebuilding the front and back shocks my self just to have new seals and oil in them, putting all new grease in all the bearing. I sand blasted the frame and all the other painted parts and will be spraying them this weekend, unsure if I am going to OEM purple - blue or changing it to a bright blue metal flake. This bike will be awesome when done in a few weeks. I have a complete 2001 Yzf426 that I am parting out on ebay real soon, any parts that I should keep or use to upgrade? Also what upgrades should I do now that it is a million pieces in my garage? I also have a 1999 running YZ400 at my disposal I just got, FAST bike! I live in the great UP of Michigan and will be trail riding it, But I want to make sure it beats all my friends XR400's when they come up in a few weeks. Will be running stock lighting, all new cables, hardware and tons of other stuff. Just did the same thing to a 2001 Xr80 for my son, it looks better than new

Well i would start by rebuilding and putting the yz426 back together or at least putting the 426 engine in you 98 wr frame, there is defiantly nothing to gain only loose buy using the 98 engine..   You will have no trouble out running a xr400, you could do that on a wr250f :ride:

...you could do that on a WR250R, too....


I would rebuild the 426 way before a WR400......

The 426 has a bad crank that is not rebiuldable, rod locked up which I could do my self, but the sprocket is all worn out also on the crank, also the case has been welded by the sprocket which looks to be a good repair, but I like the idea of have the higher gears that the wr400 has to offer because in the UP of Michigan there is endless fire and logging roads to run, that are more open than tight trails. I bought the 99 yz400 to part out, but that might stay around for a while it is crazy fast. I don't have a title for the 426 and don't really trust the guy I bought it from, I do have the title for the wr400 and yz400, titles are hard to come by in Mi, and you have no way of knowing if a bike is stolen in Mi until your register it (which isn't reqired here,as why no one has a titile) but they will still take your money but a week later the police show up at your door for the bike, great system. The police won't run the numbers before you buy it, or the DMV, so your screwed.

Didn't know if using the cam out of one of the other two bikes was a option for better performance?

I am keeping the exhaust from the yz's to use on my wr for sure, the wr is stock

Is there any ignition modifcations for the wr400?

Kind of funny with the XR400, I have a large collection of xr's but never a 400, I mosty ride my cool 1984 Xr200 with twin carbs, fun bike and very rare. There is a group of friends with about 6 xr400's in it, one is faster than the rest, it was my friends bike but is son took it over, so he is leaving his other xr400 with me when he comes up riding in a few weeks and wants it to beat his sons bike when I am done, looking at a big bore kit, pipe, cam, maybe a pumper carb, he will have over $1500 into it, but has plenty of money so why do I care. I told him he could sell his xr400 and just buy a yamaha 450 and that would beat any xr400, lol.

Edited by upbart

Also like the ability to have lights that the wr offers

Why spend all this time and money on such trashed bikes?


You can get a great condition WR for $2k, which is gonna be what you spend in repairs on a bike that is 10 years older....

I will have about $2000 in it all together, but it will be just like new, really wasn't in bad shape to start with, I could have just fixed the carb and cleaned and adjusted the valves and been ready to ride. You won't find a bike in this condition when I am done, I also enjoy restoring bikes. I didn't have much into the bikes I traded to begin with. I took the engine all apart with the thought in mind if there was any thing major it was going on ebay, and there wasn't I am doing the rebuild so it don't blow up later on and destroy the complete engine, just the way I do things, also my toys never brake down, I have a 2000 mxz sled with over 16,000 miles, never dies

@upbart. Do what makes you happy. I recently acquired a 98 WR 400F had 25 hrs since new. It was in great shape. I put new chain and sprockets and brake pads on it. I had to rebuild the carb and accelerator pump as it had been setting for several years.

I have about $800 in it and it is an awesome ride. I have a couple of newer YZ two strokes but love the sound of the thumper.

If you are determined to keep the wr450 then I would part out the 98 wr chassis and use the 01 chassis. The yamaha made frame changes in 00 to both wr and yz that made them corner and handle better. The steering head was moved back 5mm and the rear shock was lengthened 3 or 4mm. I had a 98 and 01 and could definitely feel the improvement.

Oops, I meant wr400. At the very least use the tank and seat from either yz on the wr. The lack of fuel range is worth the improvement.

I only had about $550 in it with the two bikes I traded, could have just fixed a few issues pretty cheap but wanted a real nice bike so I stripped it, painted it a blue with pearl in the clear coat, didn't need a piston but repalced it just so later on some day hopefully it does fly apart and take out the complete engine, the bike didn't need a lot of things to ride but I like there to be no issues at all with my bikes and them to look nice also, also very picky on having all the proper hardware. I rebuilt the forks and rear shock yesterday, and it is all painted going to start putting it together  tomorrow hoping my big box shows up in the mail. I am thinking of keeping the Wr tank, gas can be difficult to come by up here, in places, but after I ride it I will see, been riding that 1999 yz400, that thing is fast, hate the seat though, loves big bumps, not so smooth on the small ones. If riding with my son I will probably ride my 1984 Xr200, rides smoother down the trail. I am going to be parting out the 2001 Yz426 on ebay as soon as I can get all the pics taken, it's all apart now and all the parts are washed, the 1999 yz400 not sure what I am doing with it, might try to trade it for a very nice newer Blaster for my son, or smaller sled for my son, will for sure will be a skidoo, looking for like a 500 or smaller with electric start and reverse, I don't want to have to start his sled all the time. I have close to 40 dirt bikes at the time, seem to always have xr's for me and my son to ride, just completly restored a 2001 xr80 for him, looks better than new. But I wanted a yamaha as a big bike for my self, feel they have better technolgy over a Xr400. 6 of the bikes are mine and my sons, the rest will be parted out on ebay.

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