Just picked this up (Jan 2019), really wasn’t sure about getting another 4 stroke but couldn’t find a nice 2 stroke and got a great deal on this.

Notes

RM-Z 250 parts list and exploded diagrams
Jan 2019
Race sag = 95mm, static sag = 41mm, preload length 255mm
All damper settings set to stock
Valve clearances:
Exhaust 0.17 – 0.24mm (0.007 – 0.009″)
Actuals Jan 2019: L 0.178mm, R 0.178mm
Intake 0.09 – 0.16mm (0.0035 – 0.006″)
Actuals Jan 2019: L 0.152mm, R 0.127mm

To Do List

• Tire pressures
  
• Install new fork protector rings
• Front brake rotor and pads
• New fuel pump – wiring?

Completed Tasks

Mar 2019

• New rear brake rotor and pads
• New rear tire – Metzeler MC5 Intermediate
• New rear wheel bearings and tire clamp

Feb 2019

• New U linkage – picked up a used set from a 2009 RM-Z 250 but is different part number, looks very similar, will take measurements some time
• Straightened rear rotor and tried to re-seat rear tire. Rotor is badly worn, new one required. Even at 80 psi with washing up liquid, could not get the tire to seat properly, then noticed large cracks in some of the knobbies on the edges = new tire, ugh.
• Oil and filter change
• Oiled and installed new air filter
• Repaired tear in seat cover
• Soldered wires back on to fuel pump
• Replaced all linkage bearings

Jan 2019

• Check valve clearances
• Replace upper rear shock bearing
• Install new grips
• Set all damper settings to stock
• Set race sag = 95mm, static sag = 41mm
• Stitched rear mudguard with zip ties
• Repaired muffler mount
• Re-seated front wheel
• Replaced handlebars with slightly cut Renthals (stock?)

Saw this on Kijiji and thought it would be good for us all to play with and even for the wife to use as a pit bike at the MX track.  Sadly when I got it home I found that most of the stuff I was told about it was not accurate …

“Brand new rear rim and hub assembly” – really, with dirt all over the hub and sprocket, a bent spoke with broken nipple and a dent in the rim???
“Upgraded battery pack” – looks like 4 x 10Ah SLA batteries to me, same as stock, what’s upgraded about it?
“It’s only been ridden about half a dozen times” – it’s 5 years old!  And I suppose that in those 12 hours (charge lasts about 2 hours) the rear tire was worn down, and a lot of the stickers fell off???
Also, the rebound adjuster on both the forks AND shock was damaged so they wouldn’t turn, the rear end has been smashed so hard that the mount screw for the rear shock was bent and the bushing trashed, the steel bead in the rear tire was all bent, the front mudguard was snapped in half, there was no air pressure in the forks and the battery cover was under the battery.
Oh well, this all just shows that I should perhaps not be so trusting and do a better job of inspecting stuff before I buy.

Set to work on it.  No room in the garage, sat it in the trailer,

After the MaxTakeoff treatment,

The torque on this thing is insane, but being a trials bike, it’s not very fast.  You need to be super careful with the throttle response setting and it takes a bit of getting used to especially when riding slowly.  It’s really designed for kids 9-12 years old but it is well made with decent components and easily copes with my 5’9″ and 160lbs.  I was sold on it after watching this video,

We’re planning on frequent visits to the track this year and I wanted to be able to transport all 4 dirt bikes and keep all the riding gear out of the rain.  We rented an open trailer from U-Haul last summer when we went camping but it was only 5’x8′ so could only really fit 3 bikes.  I was looking at bigger open trailers but I soon found that I would have to increase my budget or buy brand new from Canadian Tire where I could get interest free equal payments on their credit card.  As usual, the budget crept up until I found this 6’x10′ enclosed trailer.

It has some issues but seems to be pretty solid and once I’ve cleared out the shelving, I think we should be able to get 4 bikes in.

To Do List

• Attach roof rack half to the A arms at the front
• Make container smaller ready for bigger bikes
• Install rack at rear to hold bikes instead of door frame
• Install skylight/vent
• Paint frame again
• Swap tires onto new wheels

Completed Tasks

• Find a way to secure the container to the floor – screwed blocks to the floor
• Replace side marker lights
• Remove sticker residue from back and sides – scraped off with Goo Gone and elbow grease!
• Paint new wheels
• Find a spare wheel, 205 75 R15 – Picked up 2 for $25 off Kijiji, cleaned up nice
• Paint frame underneath and welded door supports – 60% complete
• Bought new ratchet tie-downs for front bikes
• Make some ramps – made one that locates on bottom door lock
• Tidy up wheels – wire brushed and painted
• Install new PS tail marker light
• Tighten and grease wheel bearings, replace caps
• Offer up all 4 dirt bikes
• Repair side marker light and install new bulb in left tail light
• Install tie-down anchors at front
• Install shelf at front
• Repair rear door supports – both had come away from the frame at the bottom, found that the screws are 8 point Robertson, removed frame, peeled back the panel and welded some metal brackets on 2 sides to re-attach supports to the frame
• Purchase magnetic light
• Register trailer and install plate
• Obtain more tie-down anchors – 8 for $25 off Kijiji
• Fix interior panel at rear
• Remove all shelving
• Fix wiring for lights – bad joints at the connector
• Pick up 2 x padlocks for hitch and door

Sure enough there’s a good bit of room even with all the bikes loaded.

So I made a box to put the toolbox and gas cans in.

Now with the new seat,

Notes

YZ250Fw parts list and exploded diagrams
Valve clearances:
Exhaust 0.17 – 0.22mm (0.0067 – 0.0087″)
Actuals Dec2017: L 0.203mm, R 0.178mm
Actuals Jun2018: L 0.203mm, R 0.178+mm
Actuals Dec2018: L 0.178mm, R 0.178mm
Shims: L 1.72mm, R 1.75mm
New Shims: L 1.70mm, R 1.73mm
Actuals Jan2019: L 0.203mm, R 0.178+mm

Intake 0.10 – 0.15mm (0.0039 – 0.0059″)
Actuals Dec2017: L 0.102mm, M 0.102mm, R 0.127mm
Actuals Jun2018: L 0.127mm, M 0.127mm, R 0.127mm
Actuals Dec2018: L 0.102mm, M 0.127mm, R 0.127mm
Shims: L 1.76mm, M 1.73mm, R 1.72mm
New Shims: L 1.72mm, M 1.72mm, R 1.70mm
Actuals Jan2019: L 0.152mm, M 0.127mm, R 0.152

Aug 18: Backed off pilot air screw ~1/4 turn to address hanging idle and tough warm starts (although we weren’t following the procedure in the manual)

To Do List

• Replace upper rear shock bearing – got a set of bearings but there isn’t much play at all, probably install them next winter
• New front brake lever

Completed Tasks

Feb 2019

• Oil and filter change – AMSOIL synthetic

Jan 2019

• Re-fill with coolant
• Install new head gasket
• Check piston and con rod, visually inspect crank – looks good
• Repacked muffler

After losing confidence in the YZ250F reliability due to the valve failure, I listed it on Kijiji for trade for a 2 stroke.  I was offered a 2004 KTM 125sx that was ‘ready to ride’ and when I checked the reviews, this was the year that they sorted out the poor rear suspension.  So I met the guy and my heart sank when I saw the condition of the bike and the huge dent in the expansion chamber but it started ok and sounded alright and for some reason, I went through with the trade.  When I ran the VIN, I found out that it is actually a 2003, great but at least the VIN was not reported stolen.

When I got it home and started looking closer I found all sorts of little issues, front fender wobbling, play in front wheel bearings and rear shock lower bearing, bent rear sub frame, fork seals leaking, it looks like this poor thing has just been neglected – I would not class this as ready to ride.  It amazes me how people will sell something without even washing it???  Pretty disappointed with the accuracy of the description but I could have walked away and the issues really are relatively minor … so far.  So I got started on fixing it up, here’s a more recent pic,

Notes

125sx parts list and exploded diagrams
Jan 2010
Race sags: Josh/Jake = 95mm, Stu = 114mm, static sag = 44mm
Jet needle set to middle notch
24 Aug 2018
Compression damping on rear shock = stock + 2 clicks
Compression damping on forks = stock – 6 clicks
Jet needle lowered to 2nd notch from top to address mid throttle sputter – we’ll see??
Original
Race sag (Stu) = 105mm, static sag = 30mm

To Do List

• Test ride

Completed Tasks

• Give it a good wash
• Fix wobble in front mudguard – Front brake cable clamp is missing that provided a spacer, put large washers in for now; new brake cable clamp installed
• Fix huge cracks in rear mudguard – Used the old tie wrap stitching trick
• Fix dent in exhaust
• Remove seat cover – original cover still underneath with only minor tears
• Bend radiator mount tabs back, prevent them from fouling the forks
• Threads damaged on oil level check screw – replaced with radiator mount screw since replacement screw had larger (10mm) head
• Replace worn vent screw in fork cap – not needed, with good screwdriver not much effort is required to undo
• Check rear brake cylinder, push rod comes out? – looks like it could be normal on parts diagram but the rod is well corroded
• Replace front wheel bearings
• Replace rear shock lower mount bearing – replaced with MSR bearing, not teflon
• Fix seized rebound adjust screw on rear shock – got a 2007 XC-W shock PN 12178C04 mono compression control
• Fix spring on kick-start shaft – ratchet gear was mis-aligned on shaft – rectified
• Replace fork seals – refilled with AMSOIL SAE 5 synthetic
• Thread in left side fork protector mount hole damaged – one or two threads seem ok, new screw held in with thread lock
• Install new piston – plenty of blow-by on piston skirt, got Wossner piston and ring (awesome!) and new small end bearing
• Cylinder stud broken, the nut and top of stud were glued in place!!! WTF?!?! – got the old one out with stud remover, installed new
• Screw and bucket holding the rubber chain guard on the swing arm missing – threads in hole on swing arm trashed, aluminum is thin on swing arm not much there to hold heli-coil, tried tapping to M6 and thread locking, not overly happy with it though
• Ball bearing for kick start – thanks Dan and TSR
• New right side drain plug M10x1 – threads in clutch cover are trashed!  There is a bit of the old threads left but the drain bolt slips straight in, tried installing an M10x1.5 Fix-A-Thred insert in the remaining threads but the hole was too small.  Plugged with high heat JB Weld
• Threads in oil level check screw are trashed – repaired with Fix-A-Thred repair kit
• Fix broken arm on sub frame – Josh welded it up in auto class.  Update: the weld failed so a small steel bar was fashioned and inserted.  Thought about filling around the bar with JB Weld or drilling holes and holding in place with screws but the bar was a tight fit and there should not be any load trying to pull it out the back of the bike so I think it’s good now
• Spring for rear brake lever is missing – bought new one
• Clutch basket and inner hub are both damaged – replaced with used parts found on ebay
• Clutch holding tool required – used impact driver
• Replace spark plug – ordered from Fortnine
• Install new clutch actuator gasket, screw and banjo washer – screw was too long?? had to cut one down
• Get mineral oil for clutch, top up and bleed clutch actuator – also bled the front brake again
• Little play in rear wheel – replace bearings, ordered from Fortnine with grips
• Installed new grips
• Set race sag and suspension settings to stock – race sag = 105mm, static sag = 30mm, compression damping on rear shock = stock + 1 click
• Clean rear rim
• Install new Shinko rear that came with the bike
• Adjust chain tension
• Loctite the handlebar perch mount screws
• New front tire – picked up a very lightly used Dunlop Geomax
• Split engine and remove crank (big end bearing seized)
• Install new Hot Rods crank and new bearings
• Check power valve z dimension
• Teach the lad how to short shift
• Properly repaired the rear subframe using a strip of steel drillled and tapped to take 4 M6 machine screws and replaced all the broken zip ties

The little guy was way too big for the PW50 so started looking for an upgrade.  I found a couple of 4 stroke TTR90s but didn’t get any replies and once the little guy got wind of a potential bike change, he put the pressure on!  I found this PW80 fairly close by and it was listed as having ownership and manuals but was in pretty rough shape compared to some others that were a similar price.  We went to see it the day before we went on vacation and as it turned out the guy didn’t have ownership, only some registration paper from the previous owner and no manual???  I should have left it but the guy was firm on his price and my lad was very keen on it (what a surprise) so we paid the money and brought it home.

Here’s what it looked like after a bit of cleaning up.

Notes

PW80 parts and exploded diagrams

To Do List

• Sell – https://www.kijiji.ca/v-view-details.html?adId=1404354254

Completed Tasks

• Fix gas leak in carb – cleaned float needle valve, again and set float height to 22mm
• Replace broken gas tank – installed brand new
• Check rear suspension bearings – seem fine
• Clean up gas tank (oxidization?)
• Straighten handlebars in clamps
• Straighten gear pedal