This repair has been a long time coming, its taken over a year to gather together all the parts required to complete the top end rebuild on this YPVS 2 stroke motor after it seized up....

TDR250 top end rebuild - we hit a PROBLEM!!

By Andy Mechanic on 19 September 2016

Following on from video #1149 covering the install of the cylinder head, I was running through a couple of basic checks on the newly assembled engine after I had finished filming.

This short video covers a very serious problem. As those of you who have been following the series will know, the barrels have been re-bored to 2mm oversize, new oversize pistonsand the head had been skimmed too

Parts Worked On:

Engine

TDR250 cylinder head fittment

By Andy Mechanic on 19 September 2016

Following on from video #1148 covering the install of the two cylinder, this short video covers the next step in the engine's assembly. Namely, installing the power valve connection plate, fitting the head gasket, cylinder head, the tightening sequence for the cylinder head retaining nuts & the fitting of the spark plugs too.

As usual, I have included all the relevant specifications and torque settings from the official Yamaha workshop manual so you'll have all the info to hand to perform this work to a high standard.

Parts Worked On:

Engine

Fitting the rebuild barrels to the crankcase

By Andy Mechanic on 30 August 2016

Following on from Ep 2 - video #1147 where I run through how to install the new power valves, bushes & seals into the newly re-bored cylinders this next video covers installing the two barrels over the new pistons & onto the crank case.

Parts Worked On:

Engine

YPVS power valve replacement - all new parts

By Andy Mechanic on 30 August 2016

The second video in the series covering the top end rebuild of Yamaha's infamous TDR250. This episode covers the inspection & diagnosis of failure of the old power-valves & the full, step by step installation of the new Genuine Yamaha power-valves, bushes and all related seals.

The video includes all specifications & torque settings required to complete the task in line with Yamaha's factory workshop manual.

Parts Worked On:

Engine

Big end bearing check, ring gap & install

By Andy Mechanic on 30 August 2016

Finally its time to make a start rebuilding the 'top end' of the Yamaha TDR250's engine. Due to a previous Power-valve to piston contact causing immediate engine seizure I performed a complete top end strip down to see what had gone wrong...

After a full inspection and many, many hours or research we (Ben an myself) decided the best course of action was to re-bore both barrels to 2.0mm oversize (larger than Yamaha's maximum of 1.5mm) and source aftermarket pistons, rings, little end bearings & new Yamaha power-valves, bushes, seals etc...