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2004 XR250 resurrection

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Well, our last XR finally bit the dust. began to consume oil quite rapidly, and finally gave up the fight a few weeks ago. Been using this bike as a teaching bike, daughter's boyfriend is learning to ride, and this XR has seen its fair share of abuse. It's been through 3 other riders, thrown off a cliff in Baja, submerged in a small pond, and generally had the snot beat out of it. I had done a 270 kit in it about 4 years ago, stage 1 cam, and not much else. Kid was riding it basically DRY, very little oil actually came out of the case. Oil starvation from the top down consumed the cam, all 4 rocker assemblies, but only ONE cam bearing- sprocket side bearing is ok (Still needs replacing but at least it turns with little effort).


Surprisingly, the piston did not seize in the bore, and has little to no galling- sleeve looks ok, but we are still replacing that as well. Yes, there's the opportunity to just go to 77mm with the stock sleeve, I already ordered the 78mm sleeve and piston kit so we are going 284cc. Connecting rod small end was at the wear limit, as was the play on the bottom end so a new connecting rod and bearing are on the way.  New hotcams stage I cam is ordered, new timing chain, and a handful of new bearings in the case including crank bearings, counter balance bearings, etc.


I helped another member out here a few years back with his XR400, figured I might as well document my own crap being rebuilt.


I'll get some pictures up here soon, to show progress and improvements.

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Well, off to a slow start. Ebay seller on the connecting rod sent a rod for a CR250R, not the XR. Not going to work LOL. waiting for the right rod to show then I will start taking pictures and posting build progress. Lots of parts have arrived, bearings, clutch, piston and sleeve, rocker arms, cam, timing chain, etc.

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Regretfully, I have taken ZERO pictures of the rebuild. It's almost done, waiting for a wrist pin and cam chain guide to arrive this week. Shop that did the cylinder work and connecting rod replacement lost the wrist pin.

So far, here's what I've done:

Replaced piston and sleeve for 78mm bore, out to 284CC with Wiseco piston.

Replaced connecting rod, small end was at service limit and big end was out of limit on the thrust washers but not on the pin.

Replaced cam with Hotcams stage 1. Cam was toast from lack of lubrication.

Replaced all 4 rocker arms, originals were ground CONCAVE from no oil.

Replaced the majority of bearings in the entire engine, cam bearings, crank bearings, transmission, counterbalance shaft, etc. Anything that had signs of wear. Cam bearings were almost seized from oil starvation.

Replaced cam chain and guide (not tensioner). Guide had worn through the plastic to the metal backing plate on the leading edge.

Replaced clutch frictions and steels, new heavy duty springs. Clutch basket was inspected and minor notching on fingers filed smooth.

Skid plate purchased and installed to replace the stock tubing, much better protection.

30mm mar risers added to Applied triple clamp, the rider of this bike is 6'2" and had a hard time being comfortable for long rides standing. The bike is being given to my daughter's boyfriend. He's 17 and this is his first dirt bike.

Replaced valve seals, inspected valve seats and decided to leave them alone. Did mild head port polishing on intake and exhaust, no profiling just smoothed the casting marks.

Ground header welds smooth to match.

Replaced the packing in the Q4 exhaust, was LONG OVERDUE as there wasn't much packing material left.

Removed and lubricated all wheel bearings, pivot bearings, shock linkage and set compression and rebound for his weight, have to wait for the rest of the engine to go together to set sag for him.

Added fork bleeders to the front forks.

Lubed clutch cable

replaced front and rear brake pads

New Maxxis Desert IT rubber front and rear with ultra heavy duty tubes

Wheels trued by me

Hope to have the cam chain guide and wrist pin this week, and have this running by the weekend. Maybe I can get video of the initial start up and post it.

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cooked head, look at all the burnt oil




Cam was well worn. lobes had significant flat spots and wear.





Old piston and new 78mm wiseco with larger sleeve. Notice the step in the sleeve? allows up to 80mm bore with NO case machining. XR's only. Also a new OEM connecting rod




Rocker arm faces literally DESTROYED. Notice the rocker for the manual decompression on the right, more wear than the rest. cable was adjusted correctly, I have a feeling the previous rider was randomly pulling the lever for no good reason.





Clutch basket had some wear on the fingers, not as bad as my WR450 was- having a hard time finding neutral while the bike is running? This is usually the culprit. All of these got filed smooth. Clutch should be good as new with new plates/frictions.




Old connecting rod on the crank, thrust washers on the lower end were worn past service level.




SLight difference in steels for the clutch- the old ones were HOT at least once.




And an interesting development- the cam chain at one point had debris under it and managed to gouge the oil pump. Nice.








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