Yamaha WR400F

[dvgonzo]

I would imagine since it is two they may have contacted the piston.

I see where you said the piston looked good but can you see any faint marks or gouges on the piston or valves to verify that is what caused it?

Valves can get bent pretty easily when a piston contacts them so
hopefully was not to hard a hit so nothing else got wankered.

[marbee40]

I finally got the durn thing running with the help of AKMud and Friar. Long story short, one silly little dropped cam-clip required a new cam chain, two new titanium (UNOBTANIUM) valves, two shims, and a woodruff key on the crank to get her going again!

Thanks all!

Jim

[Kawidad]

Too late now, but Ti valves are not a good idea. Check them often.

[MingRidesBikes]

Hey guys had some questions for ya about the wr426f. I recently purchased an 01 wr426f. looking to get the most power out of this bike. I had a 05 wr450f deristricted that was an absolute blast to ride. With that said I like my new to me 426 a lot. Smooth shifting, linear power band, but would like some more umph. it currently has a yz426 pipe on it. what mods will really bring it alive? I was thinking over the winter to do a yz450 exhaust cam, was contemplating getting a yz426 aftermarket pipe (i.e. fmf or a t-4) not sure how much more power that would be than the current yz pipe on the bike. Anything else to help bring this bike to life? And honestly will it ever have the power the 450 had? Thanks for your input guys.

[Kawidad]

Originally Posted by MingRidesBikes

Hey guys had some questions for ya about the wr426f. I recently purchased an 01 wr426f. looking to get the most power out of this bike. I had a 05 wr450f deristricted that was an absolute blast to ride. With that said I like my new to me 426 a lot. Smooth shifting, linear power band, but would like some more umph. it currently has a yz426 pipe on it. what mods will really bring it alive? I was thinking over the winter to do a yz450 exhaust cam, was contemplating getting a yz426 aftermarket pipe (i.e. fmf or a t-4) not sure how much more power that would be than the current yz pipe on the bike. Anything else to help bring this bike to life? And honestly will it ever have the power the 450 had? Thanks for your input guys.

Not really a power expert, but the cams will help. However, the supposed gain is in ease of starting, not really a power mod. Another mod you can do is switch the carb to a 450 carb. Again, it is supposed, the internals of the carb are better engineered since it's newer so that allows the bike to run better. I did it on my WR400 and it worked pretty well, but more power, who knows.

Honestly, though, only by dumping big $$ into it will you get any reasonable performance gains out it. Otherwise, it's only going to be modest gains, if at all.

[LucasLeader]

Originally Posted by MingRidesBikes

Hey guys had some questions for ya about the wr426f. I recently purchased an 01 wr426f. looking to get the most power out of this bike. I had a 05 wr450f deristricted that was an absolute blast to ride. With that said I like my new to me 426 a lot. Smooth shifting, linear power band, but would like some more umph. it currently has a yz426 pipe on it. what mods will really bring it alive? I was thinking over the winter to do a yz450 exhaust cam, was contemplating getting a yz426 aftermarket pipe (i.e. fmf or a t-4) not sure how much more power that would be than the current yz pipe on the bike. Anything else to help bring this bike to life? And honestly will it ever have the power the 450 had? Thanks for your input guys.

Make sure this is done first: http://www.thumperfaq.com/throttle.htm The WRs can only open to 3/4 throttle from the factory. That site is for 250s but still applies to your bike. Check out the other free mods on there and do all of those. Also get your jetting squared away and if you have a bad bog look into messing with your accelerator pump. I've heard people say the 426s can be just as fast with the 450s with the basic mods.

[yamahaman]

Originally Posted by MingRidesBikes

Hey guys had some questions for ya about the wr426f. I recently purchased an 01 wr426f. looking to get the most power out of this bike. I had a 05 wr450f deristricted that was an absolute blast to ride. With that said I like my new to me 426 a lot. Smooth shifting, linear power band, but would like some more umph. it currently has a yz426 pipe on it. what mods will really bring it alive? I was thinking over the winter to do a yz450 exhaust cam, was contemplating getting a yz426 aftermarket pipe (i.e. fmf or a t-4) not sure how much more power that would be than the current yz pipe on the bike. Anything else to help bring this bike to life? And honestly will it ever have the power the 450 had? Thanks for your input guys.

I have got a Hybrid yz/wr motor and I have tried everything with some good sucess and some bad! From personal experience the 450 cam is Not Quite right. If you can afford it, the hotcams (no affiliation) cams specifically for the 426 in the yz is really good http://www.hotcamsinc.com/ProductInfo.aspx?item_id=566
more power, easy starting and no stalling when brake sliding due to the auto decomp

The bk mod
http://motoman393.thumpertalk.com/tech/carbpics.html
http://motoman393.thumpertalk.com/tech/carbinfo.html

Make sure you have this matching carb with the red hot start button

The last option is the Vortex ignition I am friends with the owner of vortex and he has given me one of these that is tuned for the wr lighting coil/stator and it has a max power tune and a max tourque setting awesome http://www.vortexcdi.com/model_produ...=33&mp_id=1336

These three mods will give you all you need to give the bike all you can without loosing reliability


I have had Standard yz pipe, Titanium DSP pipe, FMF and also currently running a CRD pipe the power is un-noticable between all of the aftermarket pipes, just keep the yz its neat, works ok and not overly loud.

I also have mixed the yz and wr grearboxes to make a custom box 1st wr 2nd yz 3rd yz 4th yz & 5th wr (this was popular with the european enduro guys when the bike came out)

I have run the wr box and yz box, I have found the yz to last the longest and be the most useable in the woods where as the wr box is a bit better for the open stuff. Be aware these bikes are suseptable to fifth gear not holding due to loading up the gear and not reving it out dont labour the bike in fifth keep it on the boil and the gearbox will last

I have done heaps of work on these motors and have come accross all of the major problems that can be encountered with them, great bikes if you know there limitations and more help pm me

[MingRidesBikes]

Originally Posted by yamahaman

I have got a Hybrid yz/wr motor and I have tried everything with some good sucess and some bad! From personal experience the 450 cam is Not Quite right. If you can afford it, the hotcams (no affiliation) cams specifically for the 426 in the yz is really good http://www.hotcamsinc.com/ProductInfo.aspx?item_id=566
more power, easy starting and no stalling when brake sliding due to the auto decomp

The bk mod
http://motoman393.thumpertalk.com/tech/carbpics.html
http://motoman393.thumpertalk.com/tech/carbinfo.html

Make sure you have this matching carb with the red hot start button

The last option is the Vortex ignition I am friends with the owner of vortex and he has given me one of these that is tuned for the wr lighting coil/stator and it has a max power tune and a max tourque setting awesome http://www.vortexcdi.com/model_produ...=33&mp_id=1336

These three mods will give you all you need to give the bike all you can without loosing reliability


I have had Standard yz pipe, Titanium DSP pipe, FMF and also currently running a CRD pipe the power is un-noticable between all of the aftermarket pipes, just keep the yz its neat, works ok and not overly loud.

I also have mixed the yz and wr grearboxes to make a custom box 1st wr 2nd yz 3rd yz 4th yz & 5th wr (this was popular with the european enduro guys when the bike came out)

I have run the wr box and yz box, I have found the yz to last the longest and be the most useable in the woods where as the wr box is a bit better for the open stuff. Be aware these bikes are suseptable to fifth gear not holding due to loading up the gear and not reving it out dont labour the bike in fifth keep it on the boil and the gearbox will last

I have done heaps of work on these motors and have come accross all of the major problems that can be encountered with them, great bikes if you know there limitations and more help pm me

Thanks for all the info! I'm gonna be reading into the carb and ignition mods. Didn't think these would be substantial area's of opportunity. I do need to check the throttle stop screw for sure. I know it has the yz pipe I believe off an 2001? they are different between 01 and 02 if I'm not mistaken. And when doing the hotcams from the 426f, The exhaust is for auto decomp, the intake is where the power comes from correct? Jetting I'll have my shop dial down, is there an airbox mod that actually helps this bike breathe and get more power, or keep it stock?

[ADV-Wes]

Anyone direct me to where I can download a Workshop Manual for 1999 WR 400F??

(And in the meantime, does anyone now the oil volumes for this model? A mate who knows even less than me about bikes has left one a my place for me to clean up for him! Oil change, new clutch, Clutch cable, de-comp cable, clutch perch, brake pads.......the list goes on...........my latest project )

Cheers,
Wes.

[yamahaman]

The specs are the same for 426 400
1.5 litres of oil with out filter change
1.6 litres of oil with filter change
1.7 litres of oil total (there is always 100ml of oil left in the bike after and oil change)

inlet clearances of 0.10mm - 0.15mm cold
exhaust clearance of 0.20mm- 0.25mm cold

drive chain slack 40mm - 50mm (measured at last bolt on top of chain slider between slider and chain)

that should get you started message me for more info

[yamahaman]

Originally Posted by MingRidesBikes

Thanks for all the info! I'm gonna be reading into the carb and ignition mods. Didn't think these would be substantial area's of opportunity. I do need to check the throttle stop screw for sure. I know it has the yz pipe I believe off an 2001? they are different between 01 and 02 if I'm not mistaken. And when doing the hotcams from the 426f, The exhaust is for auto decomp, the intake is where the power comes from correct? Jetting I'll have my shop dial down, is there an airbox mod that actually helps this bike breathe and get more power, or keep it stock?

These have heaps of power stock most of the mods are for rideability.

Carb mods make the bike pull throughout the whole throttle action, this model was renowned for an awful bog when the throttle was cracked open hard.

yz pipe increases responsivness Not much difference just an end cap and length I belive

Exhaust cam is 100% for the auto decomp this helps the bike because with out the cam they used to stall all the time in the woods when you would rear brake slide into corners the auto decomp cam totally eliminated this problem, However i did notice a small power increase down lower but could be mistaken

Keep the airbox stock.

You can get lots of power out of these,at one stage, I had a head that was fully ported with Kibblewhite diamond coated ti valves with a prox high comp piston and had a lightened yz flywheel vortex ignition with a raised rev limiter and the bike was an absolute weapon to ride, too much to handle then I dropped the high comp piston and put the wiseco 450 kit in it and then it was worse. All this pursuit for horsepower just ended up costing a bomb because I destroyed two complete heads. I have put nearly everything back to stock, kept the vortex ignition because it has two settings max tourqe (slippery conditions) and max power and it never comes off the max tourqe setting.

I was at an enduro and an old racer said dont spend money on motors spend it on brakes, tyres and suspension then go learn to ride. So I heeded this guys wisdom went to some riding schools and now brake much later and carry more corner speed and still round up most on the track and trail. Guys with the new bikes (especially the 16yo's) hate it when they get passed by a fat guy on a ten year old bike bike with a bad rep for being too hard to ride.

Try this carb setting (may not work real well in US)
standard yz needle (3rd from top clip)
38 pilot jet
165 main
1 3/4 - 2 turns out on the air screw

Bear in mind I have my bike running quite lean and I have tried the jd jetting kits and there recomended settings are way too rich for our fuel quality (quite a lot of setting on american forums dont work real well in Australia dont know why)

[ADV-Wes]

Originally Posted by yamahaman

The specs are the same for 426 400
1.5 litres of oil with out filter change
1.6 litres of oil with filter change
1.7 litres of oil total (there is always 100ml of oil left in the bike after and oil change)

inlet clearances of 0.10mm - 0.15mm cold
exhaust clearance of 0.20mm- 0.25mm cold

drive chain slack 40mm - 50mm (measured at last bolt on top of chain slider between slider and chain)

that should get you started message me for more info

Awesome mate, thanks a heap, EXACTLY what I was after - no need for a manual

Cheers.

[yamahaman]

Originally Posted by ADV-Wes

Awesome mate, thanks a heap, EXACTLY what I was after - no need for a manual

Cheers.

Forgot to mention chain slack must be measured with rear wheel off ground

Oil filter is a kn142 by memory but check listing at shop

[MingRidesBikes]

hey guys I just switched out the stock fender and tail light for a yz fender and DRC edge 2 tail light. Love the looks, but cannot figure out why the brake light will not work. I 1st just tried matching up the colors on the 3 wires. (btw, I have the brake pressure switch to activate the brake light) So the WR400's have a blue wire (constant i believe) and black wire (ground) that run from the bike to the stock tail light. The wire harness from the tail light has a yellow wire (brake light) that is not connected stock. The brake pressure switch is hooked up as so: The red wire from the banjo splices into the blue wire. and the yellow wire from the banjo hooks up directly to the yellow wire out of the stock tail light. This set up works perfect. no issues. here is the issue. When I switched to the DRC edge 2 tail light (again a red wire, a black wire, and a yellow wire) I hooked up black to black (ground), red to blue, and yellow to yellow. This is what happened: The running light works fine. but the 3 white licence plate LED's do not light up. when I press on the brake, the 3 white licence plate LED's light up. No change to the tail lights that are on. Okay so I look at the package, and what do you know it says the red is the brake light and the yellow is the running tail light. Okay, so I switch it around. Now I have black to black, red (drc wire) to yellow (bike), and yellow (drc wire) to blue (bike) and here is the result. Now the tail light AND the 3 white licence plate LED's are on, but the brake does nothing... The LED's don't get brighter, they don't dim. It's like the brake light (or pressure switch) doesn't exist! Can anyone help me??? Is there any other way to wire up 3 different wires knowing that the black on both the bike and the tail light is ground...

[LucasLeader]

Originally Posted by MingRidesBikes

Wiring stuff...

Did you ever figure this out? Sounds like the LEDs for the brake light might be messed up? I read through your post quite a few times and it sounds like you have it hooked up correctly. What I did with my Acerbis tail light to figure it out was just touch the leads to a spare battery to see which one controlled the brake and running light.

I had to deal with a wiring issue yesterday. I had no power to my tail light and eventually found a broken wire behind the headlight where the previous owner had used one of those cheap splicers that cut into the wire. I also got around to changing my steering bearings. They had grooves in the races and the bottom race was all pitted. The new bearings are nice and smooth! I felt like an idiot after mashing the fork tube caps when hammering out the fork legs (even through the piece of rubber I put on top). Don't know why I didn't think to just spread the clamps a bit with a screwdriver like a did when putting them back in.... Learn from my mistake!