Difference between revisions of "Yamaha TZ250"

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Unlike the [[Yamaha TZ350|TZ350]], and earlier Yamaha TZ250, which shared many components including ignition, Yamaha chose to have built-in automatically variable ignition advance in it's Hitachi TIA02-16 CDI unit. It was programmed to advance linearly from the initial mark alignment static to a maximum advance of typically 14 degrees at 3000rpm. It then returned slowly and linearly as the revs increased, reaching the original alignment set point again at 10,000 rpm. Beyond 10,000 rpm it continued to retard at the same rate at which it approached 10,000 rpm. (i.e. 2 degrees per 1000 rpm).
Unlike the [[Yamaha TZ350|TZ350]], and earlier Yamaha TZ250, which shared many components including ignition, Yamaha chose to have built-in automatically variable ignition advance in it's Hitachi TIA02-16 CDI unit. It was programmed to advance linearly from the initial mark alignment static to a maximum advance of typically 14 degrees at 3000rpm. It then returned slowly and linearly as the revs increased, reaching the original alignment set point again at 10,000 rpm. Beyond 10,000 rpm it continued to retard at the same rate at which it approached 10,000 rpm. (i.e. 2 degrees per 1000 rpm).


The motor spun in reverse direction as the factory tried to further reduce the stress on the rear of the pistons. The crank was no longer a single unit, it was now a pair of cranks with a gear on the end to deliver the power to the gearbox. Despite the frame shedding 3kg, the overall weight was reduced by just 1kg. The steering rake was  altered and the swingarm  also lengthened to compensate for the shorter frame length of this model. The engine was now mounted slightly further towards the front of the bike. The new rear shock became fully adjustable for both compression and rebound damping as well as pre-load and the shock picked up a rear rubber mounting. The fork diameter went up by 1mm and brake wise the factory reverted back to the old cast iron [[caliper]]s which didn't bend under pressure and also didn't fade when hot. The new ignition dropped an igniter and pulser coil, there was now just one of each and the  inner clutch hub now became a single piece unit to eliminate one reliability problem from previous years. The un-necessary neutral switch mounting disappeared
The motor spun in reverse direction as the factory tried to further reduce the stress on the rear of the pistons. The crank was no longer a single unit, it was now a pair of cranks with a gear on the end to deliver the power to the gearbox. Despite the frame shedding 3kg, the overall weight was reduced by just 1kg. The steering rake was  altered and the swingarm  also lengthened to compensate for the shorter frame length of this model. The engine was now mounted slightly further towards the front of the bike. The new rear shock became fully adjustable for both compression and rebound damping as well as pre-load and the shock picked up a rear rubber mounting. The fork diameter went up by 1mm and brake wise the factory reverted back to the old cast iron [[caliper]]s which didn't bend under pressure and also didn't [[brake fade|fade]] when hot. The new ignition dropped an igniter and pulser coil, there was now just one of each and the  inner clutch hub now became a single piece unit to eliminate one reliability problem from previous years. The un-necessary neutral switch mounting disappeared


==TZ250J==
==TZ250J==
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