Hello all, My 2001 WR426 bargain bike, just rebuilt top end, and now I have coolant pouring out the flywheel plug and TDC inspection plug? Also airbox is full of coolant.
Decided to rebuild WR426 after recent bargain bike began using too much oil every ride, was "fill up the oil, and check the petrol"
Removed head as per Clymer manual and discovered so much carbon around valves and ex port, it would take me forever to clean.off everything, had a look on flebay for second hand head to use, only one I could find was YZ426 head and barrel from same year YZ , with owner stating low hours after rebuild. I bought them hoping they would fit Said head and barrel arrived, and head looked same as mine, but shiney, barrel looked ok too.
Had also recently purchased a Hot Cam exhaust cam and shim kit to replace the current exh with auto decomp, so seemed like the perfect time to do that as well.
Took both barrels (WR+YZ) to machine shop with new genuine std piston and ring set, shop measure both barrels and they are both unservicable? that was a surprise? Low hours from o/h? Left both cylinders at shop to re-sleeve the best one and I will pick up in week.
On the bench the YZ head with valves already installed, appears to be OK, recent carbon removal visible upon closer inspection, but all functions ok, The studs and dowells are fitted and cant remove them to check flatness, but steel ruler across all directions, doesn't reveal any problems, and the previous owner told me they were great condition! The YZ head came with cams and cam holders. The YZ inlet cam appeared to be in good condition, so went with that one, the WR cam covers were better that the YZ ones, so used them. The hotcams exhaust cam, brand new out of box. Test fitted valve caps, shimmed to correct clearance with cams installed.removed cams and holders and put them aside.
had left bottom end undisturbed, fitted piston rings, barrel, and YZ head as per manual used genuine WR426 head gaskets and seals. Only real issue in this process was getting the head onto cylinder whilst in bike frame with limited clearance, but all good at the end. Fitted cams, holders and torqued no surprise that clearance measured perfect as per bench setup. Installed external oil lines etc. Installed radiators and hoses, all simple and no surprises here. The front long water pipe from head fitted ok with new o ring, but very loose, continued the install.
Bike all back together with no plastics, new oil and filter, began to fill the coolant system, didn't check the fluid quantity in the book, but after a short time, leak began out the from long water tube in head, damn o ring leaking, drained system and replaced o ring with the one that was previously installed here, slightly thicker. refitted hoses etc. refilled system no leak from front o ring continued to pour more coolant into the filler waiting for to come to top, bottle empty 4 ltr still not at top, decided to have a look in side cover on flywheel (elec side) opened and out poured green liquid??? Spewed out all over my floor?? What the hell???? Looking into airbox, it is also half full with coolant???
Bike hasnt fired a shot. But removed plug has coolant visible on it?
Removed sump plug, many ltrs of green fluid poured out., slowly began turning brown,
What have I done?
Is YZ head different to WR water/oil port?
Is WR head gasket different to YZ
Is problem with YZ head, cracked/damaged etc.
Any help appreciated, but haven't pulled down engine yet. So I dont know what is inside yet.