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1989 Yamaha moto4 project


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It's a 350 1989 2wd has 14k mileage and it Needs work.

 I bought this for a couple hundred. It turns on but the foot gear shifter broke off and the person said its stuck in 3rd gear. When you turn it on it moves forward.

How do I get it out of gear? 


Also the u joint is broken, how do I repair that? and seems like needs some kind of suspension work because I can move the front rims by hand.

Lights dont work


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  • Admin changed the title to 1989 Yamaha moto4 project

If there's a stub of shaft poking out of the engine then try gripping it with slipjoint pliers and changing gears.

The suspension might have worn ball joints, or bushes, or, the bolts that go through the bushes might be worn in their holes in the chassis.. 

The lights might just need a new bulb.. or wiring repaired..

The Universal joints.. It's all pretty simple to get them apart. You take the circlips out/off and then rest one yoke across the open jaws of a vice, then hit the other yoke downwards to drive one cap half out, then flip it and repeat the process with the other cap. Then use pliers to pull those two caps right out. One yoke will come off then. Then you rest the bare crosses shafts on the vice and do it again with the other two caps.
To get them back together you clean up inside the yokes with emery tape and give them a grease. You take all four caps off the new cross and make sure they are full of thick grease and use a finger to spin around inside there checking all the little needles are sitting nicely. Inspect the cross. If it has a grease nipple in it's center, then there will be one yoke with longer arms to give clearance for the grease nipple. You have to fit the cross the right way over if that's the case. Leave the grease nipple out for now,
Then work the cross into one yoke and poke one end out of the hole in the yoke as far as possible, fit a cap carefully on there making sure you don't dislodge a roller. Now keeping the cross into the cap so no roller can get dislodged, tap that cap right in, and use a socket to tap it through more than needed so the other end of the cross is poking out far enough that you can fit another cap, again fitting it carefully so no needles get dislodged. While you are tapping that first cap and cross through you need to hold the cross backwards so it stays in the cap. That requires holding the yoke and the cross in one hand while keeping a bit of pressure on but it's pretty simple. Then tap that second cap into it's hole pushing the cross and both caps into the center. Fit the circlips to those two and then repeat the process with the other yoke and two caps.
The danger is dislodging a roller, but that can't happen as long as you keep the cross fully into the caps as you work. You push the cross in and through too far so you can get the second cap on fully without needing to pull the cross out at all. The whole secret to doing it successfully is in pushing the first cap way through the yoke before fitting the second cap on. Sometimes they need pushing through until they are almost coming out inside the yoke, but most bike uj have a bit of recess that means that's not necessary. Take care no to push the first cap right through or it is hard to get back into the yoke. There's a bit of leeway.. You'll see.
It's simpler to fit the cross to the long shaft first, they you only have to hold and manage a short yoke for the second set of caps.
It's not essential, but after it's all together with the circlips in/on, hold the long shaft and tap on the sides of both yokes and wriggle the cross around a bit to settle things into place and centralise them. The cross should feel free and smooth to move, if it isn't, tap it some more..

You should download a service manual, it will be helpful for the wiring issues if nothing else.

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I thought that had an auto/centrifugal clutch, so no clutch lever or cable...

To get it out of gear you might have to rock the bike back and forwards while you are trying to move the gear change stub.. Really though to fix that gear change properly you really need a new change shaft and lever. To get the change shaft in will require taking the side cover off so you'll see if there is a problem with the change mechanism once you are in there.

Always best though to try and get them rideable before making the final list and committing to repairing them, so you don't spend money of it before finding the motor or the transmission's buggered..

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Does it feel like it's changing gears ? Do the grips move a suitable distance when you rock the bike ?

You say the bike tries to move when you turn it on, is that at an idle or only when you rev it up ?

Do you know whether this thing has an auto clutch ?

It may be as the old owner says and stuck in third..  If you pull the side cover to replace that shift shaft then you will be able to operate the linkages inside and tell whether it's stuck in third, or whether it's just the linkages and shift mechanism not working.  I'd do that before spending much money on the small stuff.

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On 1/9/2023 at 6:33 PM, Mech said:

It sounds like it is stuck in gear then. It might be in the shift mechanism which is in the side case on the motor. Some bikes the side case comes off with the engine in place..


I got it out of gear 

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To start it needs the neutral light on, and the key, and the kill on. They also start(for future reference) in gear, if you apply either brake hard enough to get the brake light on.

Since it's not starting you need to check whether the power is getting down to the starter solenoid on the small wire when you push the starter button. If it's getting there, check the solenoids other small wire is making a good earth and take not whether the solenoid clicks or shows any signs of life, such as buzzing or vibrating. You could also  use a jumper from one big solenoid terminal to the other and check the starter does spin the engine over. That checks the starter motor.

If there is no power getting down to the solenoid you need to check why. Check the starter button is getting power to it when the key and kill switches are on. Get a service manual and follow the wire diagram back from the starter solenoid's small wire to the start button and then on to where it gets it's power from. The starter button may have dirty contacts if it's sat out in the weather unused for a long time.

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