1 Timing a K100 to find the "sweet spot" Sat Aug 29, 2009 10:18 pm
scottiesharpe
Silver member
I want to discuss timing the ignition of your K100.
I have had my bike for about a year now and I have been all through the ignition - getting a better sense of it and how it works.
I replaced my hall sensor troubleshooting a coils failure problem.
In the course of doing that, I had a chance to really "play" with my timing. I know how timing works from my experience with other engines. However I just didn't understand how the hall sensor worked until I removed it and figured out how it worked.
What I want to report on is the amazing difference in drivability you can acheive by making small changes to your timing.
Now - by adjusting your timing, I know I will hear from the hardcore technicians who say I should follow the BMW technique of measuring the #1 cyl movement from top of center. While my method may be more of a "tune it by ear" method, I think it is pretty easy to do. Don't blame me if you melt your engine into a pile of molten aluminum! :cherry:
I first advanced the timing until the engine started pinging (pre-detonation) on a hot day with my normal use Chevron 91 octane fuel. To do this, I advanced the hall sensor ring (turned it clockwise) a few degrees at a time until the engine started pinging on harder accelleration (once completely warmed up). In otherwords, I made a small adjustment in the hall sensor "ring", tightened it up, put the cover on and went for a drive. I did this repeadedly over and over making small adjustments in the hall sensor ring until I could no longer get it to ping, or just a very small amount of ping. (Warning: take it easy when doing this - don't forceably ping your engine, you could damage your engine quite severely.)
In this max-advanced-to-just-before-ping position I noticed that the idle increased, the power increased and the engine seemed noticibly "torquey". There was also a very noticable clicking or popping sound from the exhaust when idling or running. I enjoyed the engine response in this position quite a lot. (Note: when changing the timing, you may need to change your idle position screw to bring the idle back to normal.)
From that position, I began to experiment by retarding the ignition more and more (rotating the hall sensor counter-clockwise). By doing this a little at a time and by riding the bike extensively between adjustments - I was able to find a "sweet spot".
In this sweet spot position, the engine is incredibly smooth and quiet! It purrs at idle without making any popping or clicking exhaust sounds. Although the power output is diminished somewhat from the "advanced to the point just before ping" position, my bike now cruises as smooth as glass (amazingly smooth and quiet really!), and this is really the primary purpose of my motorcycle. Here is the best part: I used to have a buzzy vibration between 4400-4900 (and have been told that other K100's do this too) and this has mostly vanished. The engine now has a rubberband-like torque response quality to it - hard to explain.
I still can't believe the difference I've acheived simply by toying around with the timing.
If you have not done this to your K100 - I urge you to try it.
Start by marking your original starting position (I used a carbide scribe to scratch two marks into the aluminum). Now advance the timing a little bit at a time (rotate the sensor clockwise) until you experience ping (pre-detonation). Ping comes on at low rpm (2000-3000) when you accellerate on a hot engine and sounds like nails being rattled in an empty soup can. If you have a full faired model, or a full face helmet, put your head down low near the tank so you can hear your engine.
Once you know where it is pinging, retard the timing a little at a time until you find the sweet spot! Good luck and let me know what you find out.
I have had my bike for about a year now and I have been all through the ignition - getting a better sense of it and how it works.
I replaced my hall sensor troubleshooting a coils failure problem.
In the course of doing that, I had a chance to really "play" with my timing. I know how timing works from my experience with other engines. However I just didn't understand how the hall sensor worked until I removed it and figured out how it worked.
What I want to report on is the amazing difference in drivability you can acheive by making small changes to your timing.
Now - by adjusting your timing, I know I will hear from the hardcore technicians who say I should follow the BMW technique of measuring the #1 cyl movement from top of center. While my method may be more of a "tune it by ear" method, I think it is pretty easy to do. Don't blame me if you melt your engine into a pile of molten aluminum! :cherry:
I first advanced the timing until the engine started pinging (pre-detonation) on a hot day with my normal use Chevron 91 octane fuel. To do this, I advanced the hall sensor ring (turned it clockwise) a few degrees at a time until the engine started pinging on harder accelleration (once completely warmed up). In otherwords, I made a small adjustment in the hall sensor "ring", tightened it up, put the cover on and went for a drive. I did this repeadedly over and over making small adjustments in the hall sensor ring until I could no longer get it to ping, or just a very small amount of ping. (Warning: take it easy when doing this - don't forceably ping your engine, you could damage your engine quite severely.)
In this max-advanced-to-just-before-ping position I noticed that the idle increased, the power increased and the engine seemed noticibly "torquey". There was also a very noticable clicking or popping sound from the exhaust when idling or running. I enjoyed the engine response in this position quite a lot. (Note: when changing the timing, you may need to change your idle position screw to bring the idle back to normal.)
From that position, I began to experiment by retarding the ignition more and more (rotating the hall sensor counter-clockwise). By doing this a little at a time and by riding the bike extensively between adjustments - I was able to find a "sweet spot".
In this sweet spot position, the engine is incredibly smooth and quiet! It purrs at idle without making any popping or clicking exhaust sounds. Although the power output is diminished somewhat from the "advanced to the point just before ping" position, my bike now cruises as smooth as glass (amazingly smooth and quiet really!), and this is really the primary purpose of my motorcycle. Here is the best part: I used to have a buzzy vibration between 4400-4900 (and have been told that other K100's do this too) and this has mostly vanished. The engine now has a rubberband-like torque response quality to it - hard to explain.
I still can't believe the difference I've acheived simply by toying around with the timing.
If you have not done this to your K100 - I urge you to try it.
Start by marking your original starting position (I used a carbide scribe to scratch two marks into the aluminum). Now advance the timing a little bit at a time (rotate the sensor clockwise) until you experience ping (pre-detonation). Ping comes on at low rpm (2000-3000) when you accellerate on a hot engine and sounds like nails being rattled in an empty soup can. If you have a full faired model, or a full face helmet, put your head down low near the tank so you can hear your engine.
Once you know where it is pinging, retard the timing a little at a time until you find the sweet spot! Good luck and let me know what you find out.
__________________________________________________
Scottie Sharpe
1987 K100RT