'86 WR400 rebuild

[dukkman]

a mate who is a "newbie" to a degree to muddaboik offroading loves the "rebuild process" he got a PE and gave it the $$s to make it a good rider, (no cosmetics) but he found he was struggling to "enjoy" the bike and decided it "wasn't for him".... his brother did a "trials" course and suggested he did so as well which he did...gave him big confidence ....so he then decided to do the "enduro" course and duly rocked up on the PE not realising ......that it would be an "extreme enduro course" a la Graham Jarvis never occurred to him..just ideal for a pipey PE he sat out most of the days activities and decided off roading was not for him ...ENTER THE 400!! he has bought an 85 400 WR Twin shocker and in 1 ride has totally rediscovered what he thought off roading is about. having a scoot that doesn't hurl him into the scrub if the main jet is actioned has given him great confidence...

I've got a rebuilt 78PE250 in the shed. has done 200mtrs. I woke up a little earlier than your mate. It's the only bike I own that I absolutely hate. Thinking of burning the thing. Piece of sh#t.

 

[suprize]

his is the x model and I quite like riding it (I had one near new and did quite well on it) basically the 81 rm engine with a bigger flywheel, once sorted, they have good poke

 

[Eurofreak]

So after racing the 400 at Unadilla in the cross country event, my forks need work. They are punishingly harsh. I spoke with Drew Smith at WER. He said to check for bent fork tubes and my springs need replacing. I removed the springs and checked the fork action. Seals work well but there's a bit of stiction, no binding. The axle is slightly bent.
Some of the harshness may be due to poor alignment, springs are definitely too stiff, maybe coil bind.
Drew said the softest race tech spring is a .44 and I need a .4 or .42 He can get them custom wound. Anyone know of alternative springs available?

 

[suprize]

you made sure the forks were straight by measuring between them at the seals and just above the axle? pinching the forks in with the front axle can make them very harsh. too much air can also harshen them up. thirdly, make sure the springs are out and the tubes bottomed in the sliders before tightening the damper bolt up. apologies if all this was done, its just a bit of huskiness that is needed to get the plusho happening. I use 15wt oil but im going to mix up some12.5 as i found 10 was a little bit light and15 a tad too heavy.

 

[Eurofreak]

Thanks Suprize- I usually tighten the damper bolt under compression with the spring in. How do you hold the damper rod from turning w/o the spring installed?

pinching the forks in with the front axle can make them very harsh.

I take that to mean don't squeeze the fork legs in when tightening the axle clamps-understood.
No air in the forks.

 

[justintendo]

Thanks Suprize- I usually tighten the damper bolt under compression with the spring in. How do you hold the damper rod from turning w/o the spring installed?

I take that to mean don't squeeze the fork legs in when tightening the axle clamps-understood.
No air in the forks.

you have to tighten the rod spring out, fork compressed completely. i use the factory holding tool, similar to what the husqvarna-parts sells.
one could be made somewhat easily with a lil weld n grind action.

these forks just arent known to be overly stiff, unless you are really light. or too much oil...

 

[suprize]

ive never had an issue with the damper rod turning although I see on here it happens occasionally. the bolt only needs to be snugged to centre the damping cone then you can slip the spring in to give the tension if necessary.

its important to get the forks parallel when putting the front wheel in. I measure the front "fin" on the fork slider just through the wheel under the rim at the highest point and then just above the hub to make sure the forks are parallel as the floating axle arrangement can have you pinch the forks in by doing the axle nut up if the spacers etc aren't just right.

 

[suprize]

I've got a rebuilt 78PE250 in the shed. has done 200mtrs. I woke up a little earlier than your mate. It's the only bike I own that I absolutely hate. Thinking of burning the thing. Piece of sh#t.

Amazing, the 400 is out having the radiator repaired so he got the PE out for a ride...loves it! a couple of rides on the 400 has just lifted his confidence so that the PE is now a heap of fun!. we tackled a hill that pulled him up big time on the PE last time he tried and he just launched up in 2nd this time....

 

[Eurofreak]

I have the wrong springs in it-they may be CR springs. I had to cut them down about 3"-couldn't get them back together. They may be coil binding.
i will take the advice and re-tighten the damper rod.
Still not sure how much impact a slightly bent axle will have. I'll assemble w/o springs with axle and check the action.
Glad the PE dude got to smile

 

[suprize]

I had to cut them down about 3"-couldn't get them back together.

some issues there allright. should be able to slip the fork cap on with a mild pressure and turn.

some std WR springs should be fine

 

[Eurofreak]

Well, I'm looking for heavier springs-the rear has a firmer spring and I want to match it.
I ride too fast... errr I'm too fat for the stock springs.

 

[justintendo]

Well, I'm looking for heavier springs-the rear has a firmer spring and I want to match it.
I ride too fast... errr I'm too fat for the stock springs.

have you set sag at the rear? is it correct or close? how much do you weigh?

 

[suprize]

never ask and old bike rider how much he weighs didn't your mother teach you manners?? you should enquire generally "what load capacity does the machine deal with..."

 

[Eurofreak]

I set the sag at 100mm/4" I'm 250 lbs. I'm checking the straightness of the triple clamps/tubes and seeing if I can straighten the axle a little.

 

[justintendo]

I set the sag at 100mm/4" I'm 250 lbs. I'm checking the straightness of the triple clamps/tubes and seeing if I can straighten the axle a little.

im about 230 geared up, had to crank the stock spring real hard to get sag numbers anywhere near what i needed. a stiffer rear spring with hardly any preload got my sag almost perfect. major difference in handling.
i have quite a few fork springs out of forks, im using the yellow progressive springs. 480ml of atf and the forks are pretty good for woods, very plush. very controlled when pushed too..
you have a little earlier forks tho..im surprised you are able to get the 4 inch sag sitting at the front of the tank in an "attack" position..the stock springs are usually way soft.

 

[Eurofreak]

I have a stiffer rear spring installed. I get on the pegs and bounce up and down a few times after setting the initial sag.

i have quite a few fork springs out of forks, im using the yellow progressive springs.

Do you know what the spring rate is for them ? Drew Smith said I should install .42/k and Race tech only has .44's and up.

 

[justintendo]

sorry, ive never come across anything that says what the different codes or what weights were available.

 

[Eurofreak]

I disassembled the front forks on the 400. I found a bent axle sleeve and straightened it some.
The fork action was fine with the forks clamping a bar at the axle, found fork stiction.
Reclamped the front wheel-the forks moved up and down fine without springs. Hope to try it out soon.

 

[Eurofreak]

The front end is better but I need some rocks to pound in to see how much. Added new bars and a rubber mount system for more comfort-definitely nicer.Handles nice around the grass track, the woods were very slick-been raining a lot!

 

[Alistair Frisby]

Hi guys, can i get your guidance on this (trivial?) question. I am trying to work out which of the rubber/screw mounts (attaching the radiators to the frame) go where. I understand there are three slightly different lengths (probably just thicker rubber middle section). Does the longest one attach the bottom of the radiator, shorter ones on the middle and top connection points? I said it was trivial - welcome your guidance so i dont have to undo and relocate them later. Thanks all.