yz426 total rebuild

hello people i thought id up load the rebuild process of my yz426 i picked up recently for a bargain youll understand why soon what im starting with is a 2001 yz426 i bought off a forum sight unseen i was told the engine was blown to what extent i wasnt told but for the price i cant complain

here it is just after i picked it up


and the engine after dissambly


after assesing the situation i descovered the gearbox had destroyed 3rd nd 4th gear with in turn destroyed the entire box,crank,barrel, crank cases and clutch basket so i decided a total rebuild is in order so i decidld to strip everything and start from sctratch every nut and bolt i usedto work as a bike mechanic in my previous job so all labour will be preformed by myself

here is the bike now totally stripped i plan on respraying the frame the factory colour


i also stripped down the wheels and decided to replace the outer rims

ive gone over all engine covers and small alloy bits with the beard blaster to remove the dirt staining and i also resprayed the engine covers black using a heavy duty coating came out nice i recon also all bits i left bare metal where buffed and polished to clean them up


also ordered all the nesscessary bits i needed from varous wreckers and my local dealer

i started going through all the bits i got with the bike and found that the l/h radiator was beyond repair so ebay to the rescue braind new pair of duel core radiators $100 bargain

heres the new fresh radiators i also stripped my rear shock because the spring had a fair bit of surface rust once again a fresh coat of black will get put on that


next stage will be preparing the frame for paint and once parts arrive i will begin engine rebuild i allready have cases box and crank just waiting on yamaha for bearings as i will be replacing all bottom end bearings

Lookin good :)

nice! id love to find a deal like this on a newer wr450, build it completely the way you want it, i love my street legal yz 426, but with the 16 tooth front and 48 rear the trails get to be a pain, and with the clutch thats in it 1st can be a pain in town as well

I also have an '01 426. I'm gonna follow ya on this rebuild.

I'm picking up a 01 yz426F later today. I can't wait I'm so fricking excited woot woot! I'll be following your rebuild pretty closely please post a ton of pics man

UPDATE 17/9/11

so over the last few days ive done a bit on the bike i finished rebuilding the rear shock fresh seals shaft rechrome and spring painted i was going to write a guide on this but rebuilding a rear shock can be quite a mission and high pressure gasses are involved so ill just posta pic of the finished product.



i decided after much looking at the wheels and coming to conclusion i wasnt happy i pulled them down blasted the hubs with glass bead and ordered new outers found these g force rims on fleabay look good happy with finish will do nicely bike isnt being built to a budget butim trying to save whati can

heres a pic of the hubs and rims


now ill walk through the steps of reassembling the wheels till i get to truing stage as without a video camera it gets hard to explainbut if you can build your own wheels to the last point in this guide and pay a shop to true youll save a fortune in wheel building fees now these steps apply to front and rear wheels just read the note ive left for variation of steps

step 1

this will take the averge person a few hours so i recomend geting some "oil" for the process makes things move much more smothly :smashpc:



my brand of choice is corona but any brand will do :lol:

step 2

step 2 - 3 are optional in that i will be reusing my old spokes nothing wrong with doing this if your old spokes are in good condition if not skip these steps and buy new spokes

now ill be showing a method i devised for polishing up old spokes over the last couple of years first you will need some green scothcbrite pads now with each spoke just go over each one as if your sanding it



just clean it to the point it has a dull shine to it

step 3

polishing the spoke for this step i woul recomend you buy some auto sol polish as shown




you will also need 2 rags one for applying polish to each spoke and one for removing its as simple as rubbing it on and rubbingit off and your spokes will shine :thumbsup:

before pic


after pic


bit hard to see but they come up close to new camera does no justice so im very happy

step 4

now i recomend to any one build a wheel check your spoke lenghs as NOTE on the rear wheel of a yz426 there are 2 differnt size spokes the outers are about 5mm or approx 3/8 shorter than inners so i recomed seperating them so when you lace up your not measuring each spoke you put in



step 5

lacing now ill quickly walk you through lacing up these wheels general rule of thumb start wth the inners on every wheel

you can split it into 4 steps

1) lace inners on left side



2) lace inners on right side



3) lace outers on left hand side


4) lace outers on right hand side



Step 6

installing wheel bearings i recomend for this step to use a water proff gress or marine grease i like the bellray one as i fine it to be a bit thicker than other brands



now start frome one side iof the hub and grease bearing cavity throughly and hit bearing in id recomend using a socket as a driver but mate sure its just smaller than the outer race of the bearing as shown



now its as simple as hit that in flip over install spindle i recomend greasing up your spindle throughly as more grease is better than no grease now just repeat what i did for the oposite side to install bearing pop seals on (you can reause seals as most bearings nare sealed anyway )and your done



SIDE NOTE: on the rear hub of a yz426 there is a circlip holging one bearing in you will need circlip plyersto remove/install it donnot leave this circlip ot as its there for a reason



now at this point youcan either take theme to your local bike store for truing if youve ever trued a bmx wheel its almost the same process but youll nned to borrow or make yourself a wheelbalancing jig im sure m.c.s sell them here in aus

Step 7

crack some more "oil" and relax :busted:

Edited by caps 999

Looking good. Enjoy watching the rebuild in process.

One complaint.....can you use a different term than "throat lube"? That's just disturbing hearing another man say that....hehehe

problem solved will have updates soon

nice write up on the wheels, did my rebuild, but didnt bother with the wheels because i was on a budget. i am going to get some super moto rims and lace them to the stock spoke, so ill be using this as a guide, good luck!!!

are you planning on street legalizing this bike?

Unfortunately in aus dirt bikes cannot be road regoed unless they had factory compliance plates fitted so unless I pick up a wr frame I can't but I will Rec reg so I can ride bush

UPDATE 28/9/11

soryy about the delay but have been busy

i finally got arround to pulling apart the linkage to my shock horror all the bearings were perfect well greased no rust so ipulled all the spacers out and gave them a quick buff with my wire wheel if anyone is considering a bike rebuild id sugest getting one simlear to this



so heres a quick before and after of the linkage while appart i cleaned wirewheels and repainted tem silver took me mabye an hour but the results speak for themselves i always try to look at the smaller details of a bike when im restoring one as doing all the little stuff can make a big differnce to the final product





repeat this process for the swing arm bushes and bearing and when reasembling use plenty of grease id sudgest belray marine grease keeps th mositure out

now so far to date i ahve also resprayed the frame and rebuilt the forks with fresh seals and racetech gold valves and began reseambly of the rolling chasis its also hard to tell in the photo but i fitted up a front gaurd from a 2006 yzf makes the bike look a little bit more modern


will have more updates soon have to rebuild my brothers race bike for next season so there may be a short delay in my next update

bike looks good. im currently rebuilding a yz 125 from ground up.

bike looks good. im currently rebuilding a yz 125 from ground up.

thanks yea total rebuilds are a pain but with how cheap i got this thing i couldnt say no

update pic


lot of work to go but getting there will start engine write up soonv :smashpc:


started motor assembly

starting from scratch with the engine got bearings and box in as the previos box was stuffed as were the cases i picked up a new set of cass from an 01 but the only box i could get was 00 no big proble as there interchangeable the 00 box just dosent have the revised 2nd and 4th gear




now whenever putting any sort of bearing into a crank case id recomend getting your hands on a cheap heat gun and heating the case up to allow the bearing a nice easy slot in

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