G5 Gearbox

[colinlinden]

Thankyou everyone for all the help & advice.
I think I will look for a replacement gearbox.
I have also read somewhere that the difference between the 250 & 350 box was the length of the shaft?
I also noticed the output sprockets are different, does this mean that the internal gearing could be the same? ie. could I repare my gearbox with good parts from a 250 box?
Just a thought.

[Ozmadman]

quote:
Thankyou everyone for all the help & advice.
I think I will look for a replacement gearbox.
I have also read somewhere that the difference between the 250 & 350 box was the length of the shaft?
I also noticed the output sprockets are different, does this mean that the internal gearing could be the same? ie. could I repare my gearbox with good parts from a 250 box?
Just a thought.


The internal parts for both boxes are the same (subject to mods that affected both boxes )The main difference IS the main shaft length and profile. 4 options... old main shaft 250 (mod mains haft 250) then old main shaft 350 ( mod main shaft 350) when I get a mo I will sort out the part numbers and g/box numbers. The 350 sprocket is 18 teeth as standard (some fit a 19 or even 20 as the 350 is quite low geared) the 250 is a 19 tooth.. Paul

[Ozmadman]

The internal parts for both boxes are the same (subject to mods that affected both boxes )The main difference IS the main shaft length and profile. 4 options... old main shaft 250 (mod mainshaft 250) then old main shaft 350 ( mod main shaft 350) when I get a mo I will sort out the part numbers and g/box numbers. The 350 sprocket is 18 teeth as standard (some fit a 19 or even 20 as the 350 is quite low geared) the 250 is a 19 tooth.. Paul

Sorry for the delay, had a few problems with the new forum. So, 350cc main shaft part number 041701 fitted to boxes number from 0 to 3757 and part number 041703 was an improved main shaft fitted from box number 3758 onwards.... 250cc main shaft part number 041263 was fitted to boxes number from 0 to 9974 also on boxes numbers 10064 to 10128 as a temporary measure then a modified shaft 043058 was fitted to box numbers 9975 to 10063 inclusive and all current boxes after 10128. The exact dimensional changes are shown in the workshop manual so you can check the scale drawings/measurements against your shaft as there are no guarantees which shaft you have as all the gearbox casings are the same and internals could have been substituted over the years. Also the clutch vaned centre needs to be matched against the shaft so shafts 041701 and 041263 use centre part number 043186 and shafts 043058 and 041703 use centre 043509..

Hope this helps

Paul

[colinlinden]

Thanks very much for the help Paul.
I think I will have to do a little more research before I remove the box for dismantling.
Colin.

[briansutlieff]

Hello Colin - A late reply to this post but I have only just logged onto the forum for the first time despite being an owner and club member for a few years. My G5 gearbox has had problems on and off during my ownership of it and I have found the best resolve is to buy as many used gearboxes at autojumbles and select the least worn parts. Not sure about the mod to later gearboxes as mine is quite late anyway I think. The gearboxes are reasonably easy to dismantle and put back together with some patience.
Check for worn selector forks and bushes. Good luck. Brian.

[colinlinden]

Thanks Brian, I think I will take your advice.
My bike is otherwise running great, so I will continue to enjoy ridding it and keep an eye out for a spare box. (would prefer experimenting on that before dissecting my own:-P
Thanks again for all the help.
Colin.

[briansutlieff]

Hi Colin

I do have a few spares if you are interested but cannot guarantee which will work. When I have had problems with mine I usually end up putting it in and taking it out a couple of times to get it right so you would need to have patience. It is not always easy to test the gearbox out of the bike as you need to be able to turn it to help it go into gear.

Feel free to give me a call if you want some help. I will help if I can.

Regards

Brian - 07768 635748