Gearbox problem- 81 Jota

blab

blab

Hero member
Location
Adelaide South Australia
I have a gear change problem with my 81 Jota.
Under engine braking going into a corner, the bike wont change down from 3rd into 2nd.
I only get neutral, holding the lever down only results in a clatter, clatter of gear dogs hitting each other,
no amount of attempts will select 2nd.
The only option is to sail into the corner in neutral (dangerous to say the least ) and then change up to 3rd which ruins the corner.
Has anyone had this problem ? Is it an adjustment problem or an engine split rebuild ?
This renders the bike un-rideable on a tight winding road.
 
Right, one of potentially 3 problems:
- try adjusting the mechanism under the triangular plate on the sprocket cover
- broken gear selection drum spring (engine out job)
- bent gear selector (engine out job)

To be honest it sounds like option 2. I had that once. Had the engine out, spring replaced, and back in the frame in 4 hours.
 
Grant said:
Right, one of potentially 3 problems:
- try adjusting the mechanism under the triangular plate on the sprocket cover
- broken gear selection drum spring (engine out job)
- bent gear selector (engine out job)

To be honest it sounds like option 2. I had that once. Had the engine out, spring replaced, and back in the frame in 4 hours.
Click to expand...
Great ! Not a crankcase split job then ?
 
Yes, a crankcase split job!
But if you remove the inner alternator cover you can invert the engine and remove the lower crankcase half without having to remove head and barrels.
 
Grant said:
Yes, a crankcase split job!
But if you remove the inner alternator cover you can invert the engine and remove the lower crankcase half without having to remove head and barrels.
Click to expand...
Cant say I'm looking forward to that, not what I expected.
 
Try adjusting the mechanism first. But if not successful then it means getting into the cases to check that spring.
It's only a dollar part but it tensions the selector drum and your symptoms sound exactly like mine when I had to replace one back in the 80s.
I also had one with a bent selector fork but that showed up as not being able to select 5th gear. Someone had hammered on a gearbox sprocket and had pushed the shaft through enough to bend the selector fork.
 
blab said:
The only option is to sail into the corner in neutral (dangerous to say the least ) and then change up to 3rd which ruins the corner.
Has anyone had this problem ? Is it an adjustment problem or an engine split rebuild ?
This renders the bike un-rideable on a tight winding road.
Click to expand...
Use a higher corner speed then you wont need second  :o

Tell me is it OK when just riding normally ? I would suggest checking the adjustment on the linkages to make sure is going all the way in. Also when you the issue if you have a second bite at the cherry lift lever back up slightly and try again does it improve.
The spring may need a bit of tweaking to allow the pall to fully into the drum .. mine is a bit suss when cold from second to third but am too lazy to adjust so just put up with it... gives my right foot a good workout and saves on gym fees
 
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