1989 Yamaha TZR125 from United Kingdom
Summary:
Good bike in all areas that you can keep for years
Faults:
I bought the TZR125 as a winter project. In all fairness, there wasn't a great deal wrong with the bike, probably due to the previous owner having a great deal of mechanical knowledge.
Certain areas of the bike I improved on, in order to improve its appearance.
I resprayed the Delta Box frame and swing arm in original silver. The rims were resprayed original white. The fairing, panels and tank were in good condition not to require a respray.
Fork seals and bush guides were renewed, as were headset bearings and wheel bearings. Renewed front disc pads.
Rebuilt the engine and renewed all bearings, seals and piston rings. I then foolishly adjusted the powervalve to the unrestricted position, resulting in having to thrash the engine to get it to move, and blew a piston ring.
Engine needed rebore and 2.0 mm oversize piston. Luckily, the broken piston ring never damaged the crankcase.
Reassembled the engine and set powervalve to restricted position.
General Comments:
The TZR125 is a good looking machine. If kept standard, the engines last a long time and give years of fuss free ownership. The UK model also has the powervalve (YPVS) engine, but powervalve is pegged in restricted position and thus can't operate.
In restricted form, the engine pulls well low down in all gears and has excellent spread of torque. However, turning the powervalve 180 degrees to derestrict the engine, I would not recommend. Reason being, you will have no low-end or mid-range power and a pathetic power band at between 8000 RPM and 10000 RPM.
Fitting the appropriate powervalve servo will alow the best of both worlds. The engine will pull well, just as in restricted form, and then still give mental power at 8000 RPM.
The TZR engine share a lot of its roots with the RD125LC. These engines are reliable and have plenty of tuning potential.
The TZR handles and brakes well and is comfortable even on a long ride. In restricted form it is able to cruise at 60 MPH on the motorway easily. Fuel economy wise you should see figures well into the fifties.
Top speed in restricted form will be about 75mph, and unrestricted models should see 90 mph when standard. Tuned ones will hit the magical ton and beyond, but will last a lot less.
Parts are not as expensive as one might assume, and are easily available as it was a popular bike. There are also many pattern parts available. A lot of two-strokes tend to have nickel coating on the bore, which makes a rebore impossible. The TZR doesn't have this arrangement allowing for rebores if necessary, thus being less expensive should you need to rectify a worn engine.
Would you buy another motorcycle from this manufacturer? Yes
Review Date: 10th October, 2007
3rd Apr 2022, 03:10
Hi, I had a new TZR in 1989. Gutless as standard, just a hint of power to come in the upper midrange, then they die off to the top end. Just de-restricted by opening the power valve wasn't enough and did as you describe i.e. 10500 max. In the day Ledar sold a kit; it was Ramair filter and air correction kit with a main jet. The kit supplied a new emulsion tube, different to stock - this fitted to full power motors developed at Ledar - let the bikes run best; mine hit 108 mph - way past the end of clock(100) regularly and did 100 quickly on many roads with a run up. Like you say, useless at the low end, a bit of a bad ride, but brilliant on the fast bits. Heavy on fuel, bad in town, obviously better restricted there. The servo motor and control unit gave you power everywhere - I tried for 6 months to get one, but was let down and could not afford one new. I had a full license - the bike had to go for a car in that winter as it was bad - my only regrets are having to let it go and failing to get a full servo kit on it - money issues sadly ha.
27th Nov 2016, 21:25
I have a 1989 TZR 125 that is derestricted and it hits 95+ with the powerband kicking in at 7000RPM, but f*** all below that. I also find there is a restrictor at 10500 RPM which stops the engine from revving any higher. Before it was derestricted it hit 80mph with power band at 5000 RPM. I'm currently getting 52 MPG out of it :)