A 3AJ Rebuild getting ready for Sandraiders 2026

[Peen]

Oh no, that 5th gear is goosed, looks like mine did. You can still get them new from Yamaha, at least you could last year, I got mine through Fowlers Parts in Bristol.

Id check the oil pump for damage too as the finer bits of gear which will get past the strainer did some damage to my oil pump, luckily second hand 3aj oil pumps are plentiful as they were used on all the xt600's after this and even the 1990s xtz660 teneres.

[firestarter_phil]

Thanks - gears have already been ordered and will be with me early next week.

Should be getting the parts back from the powder coater Friday so will start on rebuilding some of those parts in the meantime.

[cadno]

I bet you're glad you took that advice!
5th gear pair goosed, strainer full of rubbish both items you didn't want to find.
Both Kedo and Motoritz make upgraded heavier duty 5th gear pairs. That's what I'd be fitting.

[cadno]

With the strainer you need to prise open the tangs on the side to open it up fully.
There will be more small items of concern in there

[firestarter_phil]

With the strainer you need to prise open the tangs on the side to open it up fully.
There will be more small items of concern in there

Thanks - yes I worked that out and that where the real rubbish came from. Got it all out, cleaned up and back together. Am waiting on the new gears to arrive and then will rebuild.

May need some guidance as to how to get the gear off the input shaft as I’ve never replaced a gear before.

[Peen]

I used a big hydraulic press at a mates house to swap the gear, make sure you measure the clearance between 5th gear and the one next to it before you press it off and press the new one on to the same clearance, it was like 0.5mm or something. Otherwise its pretty straight forward.

The new Yamaha ones are a slightly diferent part number to the originals, 2JT at the start, and I'm led to believe they improved them due to the wear issue at some point, although theyre not as good as the Kedo/Motoritz ones I dont think.

[firestarter_phil]

Thank you, that's very helpful - I will run that down to a mate's shop once I have the replacement parts.

I am aware that the ones from Kedo are better in all accounts, but the difference for me of £210 plus shipping for the Kedo ones or £90 delivered for original Yamaha ones gave me an immediate choice.
I want this bike to be great, but it isn't going to be a brand new bike and the most important thing is making is as good and as reliable as possible but without throwing unecessary money at it.
The original plan was to see if we could do all the work and some upgrades for £1500 - looking a bit more challenging now I'm deeper into the engine than I planned but we will be pretty close.

Appreciate the advice and guidance from the forum - and hope to be able to contribute soon rather than just tell a story

[firestarter_phil]

Well, it’s been an exciting day with the pick up from the sandblasting and powdercoating today.

All looking pretty good!

Have already got excited enough to build the calipers up with new seals and pistons and have pressed in new bushes into the top yoke.

Am going to start getting some parts built up this weekend

[firestarter_phil]

Fifth gear pair have arrived



......and pressed on




The engine rebuild can begin!

[Doubleyoupee]

Nice! Did you check the oil pump for damage? Might be worth while you're there