Aprillia Tx 320 ?

[martin 305]

Just got myself a twinshock aprillia with a a hiro motor think it may be a tx 320??? looks to be in prety good nick but needs a kickstart shaft as its been welded has anyone got any info on theese bikes ? Only got it for the wheels and forks but its way to good to break and it sort of feels right steering angle ect, just needs the pegs lowering and moving back so i feel another project coming on

Any info on parts availability or pics would be very welcome thanks in advance for your help . Will try and get some pics posted

[martin 305]

OK so to answer my own question spoke to steve goode today and he has some spares inc shaft and kickstart realy helpfull guy !!! This bike has a amal carb is that standard ?? anyway gave it a good clean out blew out the jets cleaned out the tank and gave it some fresh fuel bumped it down the road and bingo she lives, sounds sweet !! no rumbling mains or piston slap .Has anyone got a workshop manual for the Hiro motor as i think you have to split the cases to do the kickstart shaft ????

So its all good

[woody]

You can do the kickstart shaft without splitting the cases.

Remove clutch case. There is a shim on the end of the kickstart shaft which may stick on the inside of the case so look out for it. Once the case is off you have access to the shaft. Remove the circlip followed by the shim, gear, needle roller and another shim.

If I remember correctly, if you rotate the shaft in the direction of the kickstart, the spring that preloads the ratchet assembly will shoot everything across your garage as the ratchet slides out from behind the stop, so take care here. Hold it all in your hand when rotating. You need to rotate it far enough to disengage it from the stop and slide the shaft out. If you can, slide your finger inside to hold the spring in order to draw the return spring out with the shaft. I'd recommend lying the bike on its side to do this as there is another shim at the end of the shaft under the spring. If the bike is upright, it may drop into the gearbox. Not the end of the world as you can retrieve it, but better if you don't have to go fishing.

To refit is just a reversal of the above. The large bolt head you can see in the top of the crankcase above the shaft is the kickstart stop. It may be easier to refit the shaft if you undo it (can't remember if I did or not) Don't forget the shim on the inside end of the shaft - plenty of grease to make it stick as you insert the shaft. The return spring location is pretty basic, you should see the marks of where it locates both ends when everything is removed. Once the shaft is fully home, tension the return spring by rotating the shaft and then slide the ratchet fully home so that it engages with the stop. DON'T be tempted to then turn the shaft to test the tension otherwise the ratchet assembly will fly off with no case fitted to stop it. You should be able to feel if there is enough tension with just a small turn. Don't forget the outside shim and replace cover. Make sure the kickstart stop bolt is fully home if you removed it (not sure you have to but can't remember)

This is from memory but should be about right.

There are parts diagrams for the hiro engine here.

http://www.armstrong-trials.co.uk/

[martin 305]

You can do the kickstart shaft without splitting the cases.

Remove clutch case. There is a shim on the end of the kickstart shaft which may stick on the inside of the case so look out for it. Once the case is off you have access to the shaft. Remove the circlip followed by the shim, gear, needle roller and another shim.

If I remember correctly, if you rotate the shaft in the direction of the kickstart, the spring that preloads the ratchet assembly will shoot everything across your garage as the ratchet slides out from behind the stop, so take care here. Hold it all in your hand when rotating. You need to rotate it far enough to disengage it from the stop and slide the shaft out. If you can, slide your finger inside to hold the spring in order to draw the return spring out with the shaft. I'd recommend lying the bike on its side to do this as there is another shim at the end of the shaft under the spring. If the bike is upright, it may drop into the gearbox. Not the end of the world as you can retrieve it, but better if you don't have to go fishing.

To refit is just a reversal of the above. The large bolt head you can see in the top of the crankcase above the shaft is the kickstart stop. It may be easier to refit the shaft if you undo it (can't remember if I did or not) Don't forget the shim on the inside end of the shaft - plenty of grease to make it stick as you insert the shaft. The return spring location is pretty basic, you should see the marks of where it locates both ends when everything is removed. Once the shaft is fully home, tension the return spring by rotating the shaft and then slide the ratchet fully home so that it engages with the stop. DON'T be tempted to then turn the shaft to test the tension otherwise the ratchet assembly will fly off with no case fitted to stop it. You should be able to feel if there is enough tension with just a small turn. Don't forget the outside shim and replace cover. Make sure the kickstart stop bolt is fully home if you removed it (not sure you have to but can't remember)

This is from memory but should be about right.

There are parts diagrams for the hiro engine here.

http://www.armstrong-trials.co.uk/

Thats fantastic information thanks very much for that