WR400: Engine rebuild cost/ Engine swap?

Whoa!!! Been a long time since I posted here. Everything looks different on the site.

After a big accident in '09 where i shattered my knee, I hung the helmet up.... BUT I'M GETTING THE ITCH AGAIN!!!!!

I found a wr400 for really cheap, but sounds like the motor is toast/siezed.

I realize with these older bikes, there is a shallow point of diminishing returns, but I was wondering:

1) What the cost of an engine rebuild is (doing all labor myself)?

2) Are there any other options for engine swaps (WR450)? I prefer this approach if it is feasible...

I am very mechanically inclined, can weld, and have tools/garage.

Is a better option to wait for a 426 engine to come up for sale?

Thanks guys!!

All depends on what it needs...

Rod kit is about $100.00, and $100-$150 in labor to rebuild, true and balance the crank (you can use a 426 rod if you want to go big bore)

Big bore kit (bored, plated honed cylinder, piston, rings, gasket kit, et)c is about $550. If the borte on the 400 is OK, a piston kit and gaskets are about $175

Headwork...here's where there's a bunch of variability. If the cam bearing journals are in good shape, 5 stainless OEM valves, springs, keepers, retainers, etc will run about $150-$175, and about 25 bucks a hole to have the seats ground. If the cam journals are dorked up, another $150-$300 to repair (Engine Dynamics works miracles). Cams are about $300 for the pair. Go hotcams to get auto-decompression.

ABout $150 for bearings to replace all of them, another $125 for gaskets and seals, and probably another benjamin for timing chain, misc clips, seals, o-rings, etc.

Clutch plates and springs are another $100 or so if it needs them (and it probably will)

You can very easily rack up $1500-$1800 just for parts and m,achine work, with no trans parts inthe mix.

A 426 motor is a drop in, but be sure to get the carb and electronics with it as there are some differences between the 400 and 426. The problem for me ith buying a 426 motor to drop in is I would still want to go thru the thing to be sure it wouldn't leave me stranded somewhere...so I would still spend all that money. There area few advantages to the 426 motor, though...carb is way better, clutch is more robust, and the primary drive gear is spined to the crank rather than keyed.

The 450 motor (at least for the steel framed WRs) also looks like it should be a drop in, though I don't know anyone who has done this. You would need to get the 450 subframe, tank, seat and plastics to have a place to put the battery for the e-start. Search in the YZ forum for the details of the plastics swap. You have to fab a couple of brackets for the fuel tank. Again, depending on the age of the motor, you may end up going thru it anyway...I know I would.

ipicked up a seized 400 a few years back for $700.. big end bearing was toast, everything else was fine. i spent another $500 on bits to get it roadwo9rhy again incl the engine bit, gaskets, suspension earings, chain, tyres etc etc. ended up with a really clean bike but ightly more than the market value. factor in the cost of my time and i should have just bought one that was already clean. one intangible benefit was it really i8mpoved my relationship with my old man.. we hadnt done much since he had a stroke and building the engine together was great..

in my experience, every bike that is X dollars cheaper than the average market, ends up having X+ spent on it to bring @i to market value.. there hence arent really any cheap bikes, just ones that you spend either time or money on: buy according to whichever you have in more abundance :bonk:

Yea right i got my 2k wr400 for 700 bucks. Needed a float and float needle and seat. Has been a really strong and fun bike. Just ordered a cam chain because it has recently started a top end knock at mid to high rpm and really under a load or bogging it. Hopefully its the timing chain...idk ill see i guess

Edited by tater1994

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