jaber
Registered user
Do I presume you can set both sides once TDC is in the window
Steve
Steve
tappets and TDC
- Thread starter jaber
- Start date
Nope 
remove plugs and put into top gear and use the back wheel (top forwards) to
rotate the engine and watch the inlet valve close on one side
bring the mark OT up in the window and set the side that has just closed
Rotate the motor 360 degrees and you should notice that the valve on the other side will have just closed and once you have OT in the window set that side
Remember depending on age of the bike ( if you can change shims for end float e.g. 85-> mono) check and adjust the rocker end float Before you set the clearances
remove plugs and put into top gear and use the back wheel (top forwards) to
rotate the engine and watch the inlet valve close on one side
bring the mark OT up in the window and set the side that has just closed
Rotate the motor 360 degrees and you should notice that the valve on the other side will have just closed and once you have OT in the window set that side
Remember depending on age of the bike ( if you can change shims for end float e.g. 85-> mono) check and adjust the rocker end float Before you set the clearances
I find it easiest to put my thumb over the plug hole. Rotate the engine, then when you feel the compression as the piston rises, stop it at TDC.
TBH I generally don't look at the markings, but when I feel compression, I take my thumb off and stick a screwdriver down the plug hole to gauge TDC.
repeat for the other side.
TBH I generally don't look at the markings, but when I feel compression, I take my thumb off and stick a screwdriver down the plug hole to gauge TDC.
repeat for the other side.
Rotate the engine until the exhaust is opening and the inlet is closing. Then adjust the inlet and exhaust valve clearances on the other cylinder. Simples.
Beemerboff
Registered user
Why anyone would want to do it any other way other than the correct procedure outlined by Dr Farkoff is beyond my comprehension, it is the simplest and most accurate method.
But , just add a bit more stupidity and complexity, I have developed another twist.
I whip the rocker boxes off a hot motor, and with a oil catch pan still below each head, I start the motor and let it tick over, until it is good and hot.
You will instantly tell if the rocker end float requires adjustment, and the clearances can be checked by feel - they should all feel the same on a hot motor, with a bit less clearance than you would feel on a cold motor.
If you feel the need to check / adjust them with feeler gauges you will have to let the motor cool , of course, but it is worth checking them again by feel on a hot motor after setting them cold - then you can be certain you have done it right.
And setting them cold does not always give the correct result on a hot motor, but don't ask me why.
FWIW this how the mechanic would have checked and adjusted the valves when you have your push rod or rocker equipped SOHC car done at a service, and most car motors will tick over slow enough that it will be done without even stopping the motor.
On DOHC bucket follower motors the clearance will be checked hot, audibly with a stethoscope, and only the errant valves touched - you dont want to be pulling 16 valves apart to reset one!
But , just add a bit more stupidity and complexity, I have developed another twist.
I whip the rocker boxes off a hot motor, and with a oil catch pan still below each head, I start the motor and let it tick over, until it is good and hot.
You will instantly tell if the rocker end float requires adjustment, and the clearances can be checked by feel - they should all feel the same on a hot motor, with a bit less clearance than you would feel on a cold motor.
If you feel the need to check / adjust them with feeler gauges you will have to let the motor cool , of course, but it is worth checking them again by feel on a hot motor after setting them cold - then you can be certain you have done it right.
And setting them cold does not always give the correct result on a hot motor, but don't ask me why.
FWIW this how the mechanic would have checked and adjusted the valves when you have your push rod or rocker equipped SOHC car done at a service, and most car motors will tick over slow enough that it will be done without even stopping the motor.
On DOHC bucket follower motors the clearance will be checked hot, audibly with a stethoscope, and only the errant valves touched - you dont want to be pulling 16 valves apart to reset one!
Beemerboff
Registered user
Why anyone would want to do it any other way other than the correct procedure outlined by Dr Farkoff is beyond my comprehension, it is the simplest and most accurate method.
But , just add a bit more stupidity and complexity, I have developed another twist.
I whip the rocker boxes off a hot motor, and with a oil catch pan still below each head, I start the motor and let it tick over, until it is good and hot.
You will instantly tell if the rocker end float requires adjustment, and the clearances can be checked by feel - they should all feel the same on a hot motor, with a bit less clearance than you would feel on a cold motor.
If you feel the need to check / adjust them with feeler gauges you will have to let the motor cool , of course, but it is worth checking them again by feel on a hot motor after setting them cold - then you can be certain you have done it right.
And setting them cold does not always give the correct result on a hot motor, but don't ask me why.
FWIW this how the mechanic would have checked and adjusted the valves when you have your push rod or rocker equipped SOHC car done at a service, and most car motors will tick over slow enough that it will be done without even stopping the motor.
On DOHC bucket follower motors the clearance will be checked hot, audibly with a stethoscope, and only the errant valves touched - you dont want to be pulling 16 valves apart to reset one!
But , just add a bit more stupidity and complexity, I have developed another twist.
I whip the rocker boxes off a hot motor, and with a oil catch pan still below each head, I start the motor and let it tick over, until it is good and hot.
You will instantly tell if the rocker end float requires adjustment, and the clearances can be checked by feel - they should all feel the same on a hot motor, with a bit less clearance than you would feel on a cold motor.
If you feel the need to check / adjust them with feeler gauges you will have to let the motor cool , of course, but it is worth checking them again by feel on a hot motor after setting them cold - then you can be certain you have done it right.
And setting them cold does not always give the correct result on a hot motor, but don't ask me why.
FWIW this how the mechanic would have checked and adjusted the valves when you have your push rod or rocker equipped SOHC car done at a service, and most car motors will tick over slow enough that it will be done without even stopping the motor.
On DOHC bucket follower motors the clearance will be checked hot, audibly with a stethoscope, and only the errant valves touched - you dont want to be pulling 16 valves apart to reset one!
jaber
Registered user
Do I presume you can set both sides once TDC is in the window
Steve
I do know by the way it was just a rhetorical question, for those that don't!
steve
Archie Adv
Registered user
(RIP) Bin Ridin
Registered user
I whip the rocker boxes off a hot motor, and with a oil catch pan still below each head, I start the motor and let it tick over, until it is good and hot.
You will instantly tell if the rocker end float requires adjustment, and the clearances can be checked by feel - they should all feel the same on a hot motor, with a bit less clearance than you would feel on a cold motor.
Hi Beemerboff!
Please tell me more about how to see if endfloat is slack? My R100 top-end is clattery, less so since I added shims (plastic washers) to the rocker shafts, since as you will know the later ones have the "pillars" located by dowels and they cannot be squeezed together to reduce endfloat. I set it so the rocker arm movement is bordering stiff by hand. Is there a better way? Maybe you are observing the oil flow as a guide?
Here is a question for you:
On my bike, with the tappet clearance set correctly at TDC, I find there is a greater tappet clearance on the compression stroke before TDC. A lot greater, at least x2 the min setting. I thought that the TDC clearance would always be the tightest clearance of the cycle, but I found as above - wider gap elsewhere. Surely a cause of noise. Any comments?
Bin
You will instantly tell if the rocker end float requires adjustment, and the clearances can be checked by feel - they should all feel the same on a hot motor, with a bit less clearance than you would feel on a cold motor.
Hi Beemerboff!
Please tell me more about how to see if endfloat is slack? My R100 top-end is clattery, less so since I added shims (plastic washers) to the rocker shafts, since as you will know the later ones have the "pillars" located by dowels and they cannot be squeezed together to reduce endfloat. I set it so the rocker arm movement is bordering stiff by hand. Is there a better way? Maybe you are observing the oil flow as a guide?
Here is a question for you:
On my bike, with the tappet clearance set correctly at TDC, I find there is a greater tappet clearance on the compression stroke before TDC. A lot greater, at least x2 the min setting. I thought that the TDC clearance would always be the tightest clearance of the cycle, but I found as above - wider gap elsewhere. Surely a cause of noise. Any comments?
Bin
i've experimented on a low mileage, very quiet R100. i doubled the bmw max end float clearances and it was just as quiet as it was before. so i am unconvinced that it makes much difference.
as to your varying tappet clearance, if i understand your issue correctly, and i'm not sure i do, i would put that down to a poorly machined camshaft. something i suspect is not that uncommon, and the cause of a lot of rattly top ends.
as to your varying tappet clearance, if i understand your issue correctly, and i'm not sure i do, i would put that down to a poorly machined camshaft. something i suspect is not that uncommon, and the cause of a lot of rattly top ends.
(RIP) Bin Ridin
Registered user
Hi Cookie,
Interesting indeed.
I suppose what I am seeing is that there is a low spot on the cam after closing the valves and on the way to TDC on the compression stroke. I suppose I am setting the cleance on the cam base-circle but having a lower spot is odd indeed.
I found it very odd, and now i have the GREAT RED BIKE LIFTER, I will go into it a bit more when next home. I will check if inlet and exhaust are affected or just one pair. I think it is both pairs.
Bin
Interesting indeed.
I suppose what I am seeing is that there is a low spot on the cam after closing the valves and on the way to TDC on the compression stroke. I suppose I am setting the cleance on the cam base-circle but having a lower spot is odd indeed.
I found it very odd, and now i have the GREAT RED BIKE LIFTER, I will go into it a bit more when next home. I will check if inlet and exhaust are affected or just one pair. I think it is both pairs.
Bin
Beemerboff
Registered user
With the motor running you can see/feel if there is any end float. But like the previous poster I have found that a small medium amount of end float does not seem to make much more noise - not enough to make me want to order a few shims and go to the trouble of re shimming it.
But, for me, getting all the rockers feeling the same on a hot motor definitely made the motor smoother.
Almost as much as setting the carbs with a flowmeter instead of a vacuum gauge did.
But, for me, getting all the rockers feeling the same on a hot motor definitely made the motor smoother.
Almost as much as setting the carbs with a flowmeter instead of a vacuum gauge did.
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