UK - Project - WR400 Supermoto Conversion

8 replies to this topic
  • rossonza

Posted April 05, 2014 - 09:17 AM


Hi guys, Im Ross, Im from the West Midlands in the UK. This morning me and some friends drove up to Nottingham to pick up my new bike. I got her off an ebay add last week.


Here she stands - 1999 (first regged 03) Yamaha WR400




As you can see theres quite a few missing parts (mainly the barrel and cylinder head), However she has YZF450 Cams and ive been told was over 52hp when she blew. (the barrel cracked so the guy started to break her)


Box of engine parts and boots and tyres the previous owner gave me with the bike



Came with a spare set of black plastics too.



So current plan is to

rebuild engine

check gearbox (for the 3/5th gear issues and selector fork)

braided brake lines

rebuild calipers

buy and fit supermoto wheels

buy and fit trailtech vapor dash (or similar)

either buy new plastics, or new stickers to freshen her up



Powdercoat frame


So, its now time to get saving for either full replacement engine, or get a piston/cylinder head and barrel (if anyone has any of those let me know).




Hi guys, Just a little update on what the plan is and what me and my friend steve have found today.


Put the bike on the stand and took all panels off etc.



Found the sprocket could do with erm.....replacing. (a few years ago haha)



Found the chain sliders completely worn through the plastic/rubber and has just started ruining the slider metal and the chain




So.... we started going through the rest of the bike and found the airbox has been drilled, Should there be a top on this too?



We then found this in the airbox:




Carb full of metal



Bottom end has bits of metal in



So... Im on the look out for a complete engine now (anyone have one for sale? PM Me) From what weve found we think the top end dropped an intake valve/melted the piston then bits came back through the intake path.

We checked the gear cogs and they are spot on so worst case ive got a spare gearbox.


Overall the bikes in a bit of a mess and also needs headbearings and fork seals but.... I bought this as a project and it looks like its going to be a fun one.


I've ordered the fork seals and head bearings etc... so ill update once ive got those bits (or an engine haha)

  • rossonza

Posted April 09, 2014 - 05:59 AM


Head bearings and fork seals arrived yesterday in the post. Hoping to get it all changed this weekend/maybe next, Still on the search for a replacement engine.



  • rossonza

Posted April 12, 2014 - 07:16 AM



Picked up a wr400 engine this morning from a running bike..looks like the intake has been ported.

Wheels next :-)

  • aspiring

Posted April 14, 2014 - 12:50 PM


ive got a set of supermoto wheels from a wr450 might part with them,im in yorkshire

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  • rossonza

Posted April 14, 2014 - 12:52 PM


Thanks dude, What colour? any sprockets/disks/tyres?

  • aspiring

Posted April 14, 2014 - 01:16 PM


alloy/silver rims excel rims....talon alloy/silver hubs....talon 38T sprocket....pirelli diablo rain tyres....also a braking wavy oversize disc and a braking caliper which bolts straight to the 450 forks,these are definetly not going cheap but they are for sale

  • rossonza

Posted April 17, 2014 - 01:11 AM


Hi guys, Just an update to say..SHE LIVES!!


My friends Ian and Steve came over to help with the swap (i say help, they pretty much did it all)


Here she sits before we took the bottom end out:



Got the old bottom end fully removed:



New Plug:



Feeler guage out:



New engine in:



Subframe off to clean air filter box and air filter (helped get carb in too):



Here she sits, all plumbed in (however there were a few ports on the carb that didnt have any hoses any ideas?)



Heres a video of her running (took about 40 kicks), my legs actually aching now. found out it didnt need the choke on to start and kicked after the 2nd full kick.

After that shed go on 1st or 2nd kick:


 - no air filter used during this run.



Turns out the water pump has a little hole in the bottom (as by design) but it was weaping a little coolant, so ill be replacing the water pump seals.

Also, Found the top of a valve which was obviously what caused the original motor death:




Will update with video's/more pictures shortly


Items remaining:

Clutch cable

Throttle cables

Pump seals

fit head bearings

fit fork seals

replace valves

push bike speedo

supermoto wheels

chain and sprockets


Oh and i need a decomp bracket if anyones got one? or can find one anywhere?



  • rossonza

Posted April 25, 2014 - 12:31 AM


Right so today i had 15 minutes free so i started by taking the forks out of the frame ready to do the fork oil seals and dust shields:



Got the brake caliper off and secured out of the way (looks like she needs a clean/new pads):





Wheel out:



Forks fully out, ready for seals to be done:



Bike's a bit wobbly in the garage now but i should hopefully get the fork seals done soon :-)





  • rossonza

Posted April 25, 2014 - 12:32 AM


Well i took my forks out and took the bits up to my friends in Bromsgrove.


Bench laid out ready to work:



Top of the forks out:



Springs and rebound rods out:



New seals on:



However, the new dust seals just would not fit, so we will be tackling them Saturday afternoon hopefully along with my head bearings.


On another note, my water pump seals came so i will be tackling that soon too:



FYI i used this guide to rebuild the forks with the new seals:



Ordering valves Friday (oem yamaha) so thats my next job. Hopefully i dont need to order new shims, guess well see.


Next update should hopefully have the bike together again :-)


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