YAMAHA TZR250 3MA

Jeff has more motors than he can deal with!

G’day! Things are progressing well with the TZR250 3MA. Last update I ran you through the initial inspection and strip-down of the engine.

Darren, the owner, had managed to source three spare motors, so we were all set to get the engine work underway. Wanting to keep the original cases, we sent those away to be repaired (a con-rod had got up for a late-night stretch and left the fridge door open) so while we waited for those, we sorted the rolling chassis so Darren could take it away and make it pretty again…

This bike has been well maintained and on inspection no chassis bearings needed replacing, so that was good news. Tim, my offsider, got to work servicing the main pivot points while I sorted the forks.

The bike was stripped both ends and I quickly disassembled the forks so Darren could get the bottoms powder-coated grey. While that was happening, we cleaned and re-packed the steering-head, swingarm pivot point and all of the suspension linkage bearings and bushes. We then greased the wheels bearings and wirewheeled, then lubricated the axles. The rear shock also got stripped, cleaned, re-assembled and greased rose joints, plus all pivot points and linkages on the chassis were given the same treatment.

The fork lowers arrived looking mint, so I put those back together with new seals and slotted those back in the bike. The YZR250 look-a-like was looking forking mint by now (ahem) and with the wheels back in, it was time to hand the bike back to Darren, who is detailing it and taking care of the cosmetic side of things.

We are waiting on custom-made black Hel brake lines at the moment and have ordered a new chain and sprockets. Darren sourced new grips that look close to the

originals and he also has a set of brand new aftermarket fairings. He sent the fuel tank away to get it matched to those as well. The fairings themselves were painted to Darren’s specifications, to match the original exactly. They are Chinese cheap jobbies, but the quality is outstanding for the price. The original bodywork is all wrapped up and stored away safely for when I buy the bike off him when he is too old to ride it any longer! Ha!

Continuing with making it look good, the rusty expansion chambers were sent off for sand-blasting, then re-painted in heatproof black enamel. Darren then stripped and rebuilt the billet aluminium/carbonfibre mufflers and set the pair aside for when we get the motor back in. He also cleaned the bike from top to bottom and tidied up the wiring loom as well.

As Darren continues to look after the cosmetics, I have turned my focus back to the engine. With four in total, it has been some job to work out the best options. Many a beer was required (sorry Malc Paul) so I decided the only way to go was to have one beer for each cylinder as I worked out the best way to tackle the four motors!

Originally Darren wanted to retain the original engine and chassis numbers, which is why the cases went for repair. However, none of us were smart enough to actually check the number and when the cases came back, I realised there are no numbers at all on the TZR 3MA, only the model code – and that is on all four motors! As a result it really doesn’t matter which engine cases we use so, although it is going to create more work, I will strip the best engine and rebuild that one. It has only done 7000km, but as it is now 20 years young, I want to replace all seals (particularly crank) and bearings. I can then build two spare complete running engines for Darren out of the other three motors. The plan is to have three large fold-out tables set up as benches with the three stripped engines laid out one on each table, then use my main engine building bench to assemble the actual engine we will use.

As I type this I have just ordered the seals, bearings, piston rings and other parts I need, and should have the engine built in a few weeks’ time! Next time, I build the one good motor out of three and get it back in the bike…

I use a chainhi blblockk ffor any projectsjt ththat t need both ends removed as that way I can winch the rest up the roof to create space while I work on or wait for parts.

8/ Such a cool-looking swingarm. Tim stripped it and gave it a full service, including all linkages.

6/ The shock was cleaned up and the rose joint cleaned and lubricated. It was bone dry.

4/ Tim did thousands of these when he was a car mechanic, during his apprenticeship. It is important to get all of the grease through top to bottom.

7/ The swingarm pivot came out smoothly and was greased, which was a great sign… We were expecting to have to get the copper hammer and punch out.

2/ The fork lowers before and after powder-coating.

5/ Once the bearings were done the triple-clamps were put back in and adjusted correctly.

9/ I know most people do this with a rattle gun, but I never do. I always torque fork bolts up correctly. If they come loose you are in big trouble and if they are overtight it just makes life hard for the next mechanic.

1/ With the wheel and forks removed we took the steering-head out and found the bearings to be serviceable.

3/ The lower bearing was cleaned of all old grease, then re-packed using Moly grease.

10/ Look familiar? Remind you of your late teens? t Get your mind out of the gutter… 11/ Fresh fork oil. I decreased the air gap from standard by 10mm and used a 7.5w fork oil blend. 12/ The finished forks. We could have re-chromed the inner-tubes but the rust spots are out of the travel zone and cleaned up with some wet-and-dry and WD-40…

16/ No numbers on aside from the model code were ever used on the 3MA. Unreal… All four engines are the same. 17/18/ The spare motors being cleaned ready for strip and inspection.

13/ 14/ 15/ The repaired original cases with the top case bead blasted. We could not do the lower case as we still had the balance shaft in. After a bit of extra work with the grinding wheel I got the repair to the right shape. These will now be the cases for one of the spare motors.