Yamaha TT 500G gearbox

[Flatty]

Hi All
I can only get 1st and neutral it just happened while pottering around. There were no crunches whining or other strange noises at the time. I have checked the gear selector return spring that is OK and there is no reduction of gear lever travel but no more gears! Do I have to split the cases? Is there another spring or selector mechanism that should be checked on this model? What do you reckon?
Thanks
Pete
 

[brent j]

You may have broken a selector pin in the selector drum or as mine did broken a piece off the drum which allows a pin to drop out.
Is there anyting in the sump?

You can check the drum and pins by removing the clutch cover but if it's a drum the cases need to come apart.

Brent

[matcho mick]

check the shift drum detent ,plunger might be jammed with debri?,(or wrong sump plug with recent oil change  ),hth,

[Flatty]

Thanks for your quick replies I have not found anything in the sump yet. I already have the engine out so I'll remove the clutch cover again and have another look. I have just reboard it and got a really low milage head from the us, so it is dissapointing this happend.
I'll let you know what I find?

Regards
Pete

[TT5 Matt]

what about the fine hair spring on the arm that contacts the shifter drum or has the c clip under the countershaft spocket on the gear lever shaft become stretched causing the shaft to go in slightly putting the gear selector out of time?

[Flatty]

Hi All

I have checked the gear shaft c clip & that appears OK but what I did notice is the shift drum has a star shaped tab washer on it held by a Phillips screw (clutch cover off). The points look like they should sit over the dowel pins on the shift drum. They appear deformed and do not sit over each pin. The pin/dowels look like they are in place though. I could not remove the clutch as I recently fell of the Bultaco & broke my collar bone and cracked a rib after finding a tree.  The shift arm spring seems to work but I can not see it with the clutch on. I'll have to wait until I can get the clutch off to have a better look.
Thanks for your ongoing assistance.
Pete

[Flatty]

Thanks for all your helpful replies.

It was the C clip under the counter shaft sproket. I took it off it and fiddled around with the positioning of the gear lever and pulled the shaft back out and guess what I now have all gears!

I probably will tear down the cases as there was a chewed up thrust washer in the gauze strainer at the bottom front down tube oil fitting assy. Addditionally the sump cover where the sump plug screws in had some in it as well aparantly my brother cleaned it out it did not know about this at the time.

I recall splitting the cases 20 odd years ago and found the inner thrust washer that lies on the clutch shaft was rather thin (yamaha did not have a replacement even on back order) I needed the bike to get to work so it went back together the way it was. I believe it was the same washer found in the strainer.

Can the additional end float of the clutch shaft cause any problems? The thrust washer was rasor sharp wen it went back in, in 1982!

Everything appears to work well at the moment.

Thanks for your help Pete

[brent j]

I think it was Carl Batey's article in VMX mag on rebulding XT/TT/SR engines where he suggestes replacing that particular washer at every rebuild.
I know mine was thin last time. I think they are supposed to be 0.5mm. I plan to buy a few as spares.

Brent

[TT5 Matt]

what about the fine hair spring on the arm that contacts the shifter drum or has the c clip under the countershaft spocket on the gear lever shaft become stretched causing the shaft to go in slightly putting the gear selector out of time?

hmmm so i was right about the gear lever shaft c clip glad i havent lost it

[Flatty]

I thought I had lost it when the c clip appeared OK?? Then I remembered someone else was riding the TT when it happened!
Thanks Matt & Brent for your valuable input & Keep up the good work. I'll be starting another thread soon on suspension mods so I'll be picking your brains again soon.
Regards Pete