After only a couple of outings to RJs Motorsports track in Midhurst near Barrie on the old RM125, I was hooked again. On the second outing I had tuned the suspension and was doing much better but it felt very sensitive to throttle input, like the power band was very narrow. After riding my kid’s KX100 that had a much smoother power delivery, I started playing with the power-valve setting, however, since the kids now had a bike to ride and I was keen on riding more often, I decided it would be a good idea to get something a bit newer. Started looking on Kijiji for a newer 125 but people seemed to want a lot of money for them. I really didn’t want a 4 stroke but most of the bikes at the track were YZ250Fs and I found 3 for sale under $2500 on Kijiji. My research only turned up glowing reviews of the YZ250F and some people were suggesting they were better than 2 stroke 125s in virtually every way.
Decided to go for it and picked up this 2001, a couple of minor issues but pulls nice and strong and seems to be in good condition.
To Do List
- Can be hard to hot start – lowered the idle and then had a tough hot start, opened up pilot fuel screw about 1/16 turn. I read that these bikes are supposed to idle at around 1800 rpm because with a low idle the cam chain not consistently loaded making them run very rough – new plan, raise the idle back up. Had a bit of a wandering idle and backfire on shutdown, closed pilot screw 1/8 turn so now is 1/16 turn in from original setting
- Left side radiator guard is missing
- Repair bolt in upper fork yoke, winter?
- Replace main bearings
- Repair exhaust stud in cylinder head – investigate thread inserts to repair stud in cylinder head, I assumed there were supposed to be two exhaust studs but checking the parts list and exploded diagram there is only one – check threads in the exhaust bolt hole – got new 2003 head
- Install new head, valves, cams, cam chain, piston and rings
- Tiny bit of play in swing arm – replaced linkage bearings, still some play – traced to a clearance between lower rear shock bolt and ID of bearing inner race, shimmed with coke can. Similar issue with a clearance between the bolt that connects the linkage to the swing arm and the collars, put old collars back in. Are these linkage bearing kits not made to tight tolerances???New (used) rear brake lever – made new clevis to replace bolt
- Replaced bolt in upper fork yoke with longer bolt with nut on the end because threads are trashed (not by me!)
- Install new front wheel bearings
- Install new lower shock bearing
- Kick start lever (aluminum) worn – welded blob on steel hub
- New muffler bracket – made one from exhaust hanger band and tool drawer liner
- Repack muffler with FMF standard packing
- Repair huge dent in muffler
- New shouldered bolt for front brake lever
- New rear brake fluid reservoir
- Check valve clearances
- New handlebars (from RMX250) – a touch wide so cut 1/2″ off each end
- Add spacer to spring in kick start lock so it doesn’t vibrate out while riding
- Solder loose wires on pick-up coil
- Remove numbers from side panels