1975 Commando 850 restoration

Larry S said:
Here's a picture of me, my bike and the woman I got it from.
Click to expand...
Looks like an interesting lady.

Congrats on a HUGE milestone (first test ride). I'm quite certain you'll debug it successfully very soon.

I wouldn't hesitate to lower the idle to 1200 RPM...
 
grandpaul said:
I wouldn't hesitate to lower the idle to 1200 RPM...
Click to expand...
It has been my understanding- perhaps erroneous- that the higher rpm during break in was for the benefit of new cam/ followers in order that the valves float a bit over the cam noses . Forgive me for not remembering or digging back through this thread - did you install new cam/ followers ?
 
It's not my rebuild, but I've never set the idle to 2000 RPM. I also never set classic Britbike idle below 1,000 RPM...
 
grandpaul said:
Looks like an interesting lady.

Congrats on a HUGE milestone (first test ride). I'm quite certain you'll debug it successfully very soon.

I wouldn't hesitate to lower the idle to 1200 RPM...
Click to expand...
I wasn’t sure what RPM to set the idle at so I’ll take your suggestion and drop it down. Thanks.
 
Richard Tool said:
It has been my understanding- perhaps erroneous- that the higher rpm during break in was for the benefit of new cam/ followers in order that the valves float a bit over the cam noses . Forgive me for not remembering or digging back through this thread - did you install new cam/ followers ?
Click to expand...
Nope, no new cam.
 
L.A.B. said:
With the gearchange pedal set so high in your previous picture possibly isn't helping?

It could perhaps suit you (with what look like steel toe cap boots?) but with the pedal set that high I'd have to lift my foot off the footrest to change up instead of 'levering' the pedal using the footrest, and similarly, I would have to lift my foot off the footrest to change down, both of which could make neutral selection more difficult.
Click to expand...
Reset my gear pedal to a straighter position. Shifting is still erratic with no 4th gear. The bike is running great otherwise. Please help me get this gearbox issue resolved as I’m getting real hungry for a proper ride.
 
Larry S said:
Reset my gear pedal to a straighter position. Shifting is still erratic with no 4th gear. The bike is running great otherwise. Please help me get this gearbox issue resolved as I’m getting real hungry for a proper ride.
Click to expand...
Timing of the camplate perhaps ?
 
Can you click through the gears with the bike off? Try using your hand.
Maybe your gear selector quadrant is bottoming/topping(?) out?
MH mentions quadrant hitting the bottom or top of it's window and popping the bike out of gear if camplate is off. Maybe yours is bottoming out before it can select 4th.
 
NPeteN said:
Can you click through the gears with the bike off? Try using your hand.
Maybe your gear selector quadrant is bottoming/topping(?) out?
MH mentions quadrant hitting the bottom or top of it's window and popping the bike out of gear if camplate is off. Maybe yours is bottoming out before it can select 4th.
Click to expand...
I can't click through the gears when the bike is off. It seems like it's in gear and then not but not in neutral. If that makes any sense. With the bike running and starting in first gear I can usually upshift to second then third gears. Trying to shift into fourth takes me to no gear and then the downshifting issues start.
 
Last edited:
Take your GB cover off and make sure you can select each gear using the quadrant. Notice the position of the quadrant in it's window. If you cannot select all gears your cam plate timing is probably off. Recheck your ratchet plate assembly as well.
Hope all is well.
 
Larry S said:
I can't click through the gears when the bike is off.
Click to expand...

Are you turning the rear wheel as you do so? If not then the gears won't always engage.


Larry S said:
It seems like it's in gear and then not but not in neutral. If that makes any sense. With the bike running and starting in first gear I can usually upshift to second then third gears. Trying to shift into fourth takes me to no gear and then the downshifting issues start.
Click to expand...

The quadrant could be mistimed to the camplate as suggested.
 
L.A.B. said:
Are you turning the rear wheel as you do so? If not then the gears won't always engage.




The quadrant could be mistimed to the camplate as suggested.
Click to expand...
I am turning the rear wheel as I try to engage the gears. I will check the camplate and quadrant tomorrow.
 
I put the gearbox in neutral and removed the outer gearbox cover and this is the position of the shift quadrant. It appears to me that it's not in the correct position. Agreed? Off to mow my grass, will remove inner cover to check the camplate position after. Suggestions?
 

Attachments

  • 1975 Commando 850 restoration
    20210829_125859.jpg
    420.9 KB · Views: 230
Larry S said:
I put the gearbox in neutral and removed the outer gearbox cover and this is the position of the shift quadrant. It appears to me that it's not in the correct position. Agreed? Off to mow my grass, will remove inner cover to check the camplate position after. Suggestions?
Click to expand...
Do you have the Mick Hemmings gearbox video ? He explains setting up the quadrant / camplate . I am a little rusty on it myself .
If you do not have it I can review mine and try to explain. LMK
 
Trouble is you don't time it from the 'neutral' position, but at it's furthest point upwards, and like Richard my memory fails as to whether that's first or fourth gear...
Either way, there's manual illustrations out there to check if all is aligned at that point...
 
Larry S said:
I put the gearbox in neutral and removed the outer gearbox cover and this is the position of the shift quadrant. It appears to me that it's not in the correct position. Agreed? Off to mow my grass, will remove inner cover to check the camplate position after. Suggestions?
Click to expand...

The outer end of the quadrant could possibly be one tooth too high but due to the camera angle with the quadrant at the neutral position, it's difficult to say as the quadrant should be checked with the camplate at the 4th gear position so a pic in 4th gear with the camera level with the stud would be more useful.
1975 Commando 850 restoration


Edit: Pic shows the oil filter housing locking plate tabs not bent up against the bolt flats.
 
Last edited:
4th gear is top of travel.
From neutral, use a flat screw driver to lever the quadrant DOWN into first. There should be a gap between the bottom of the window and the quadrant, this is the lowest point of travel.
From there, one click UP back into neutral. Next click UP into 2nd, next click UP into 3rd and final click up to 4th. There should be a gap at the top of the window in 4th as there was in 1st.
One hand on the rear wheel to check the bike is in gear at each position.

If this does not work, off with the inner cover.
 
NPeteN said:
4th gear is top of travel.
From neutral, use a flat screw driver to lever the quadrant DOWN into first. There should be a gap between the bottom of the window and the quadrant, this is the lowest point of travel.
From there, one click UP back into neutral. Next click UP into 2nd, next click UP into 3rd and final click up to 4th. There should be a gap at the top of the window in 4th as there was in 1st.
One hand on the rear wheel to check the bike is in gear at each position.

If this does not work, off with the inner cover.
Click to expand...
As you suggested I leverd the quadrant into first gear, second, third and fourth. Great to confirm the camplate timing. It appears to me that my ratchet spring is not bent correctly. Does everyone agree? Hard to see but the spring is actually touching the shift pawl on both sides.
 

Attachments

  • 1975 Commando 850 restoration
    20210829_195954.jpg
    670.5 KB · Views: 214
You must log in or register to reply here.
Back
Top