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.

Hi Scottie and an interesting method. I knew a bloke who used to time his Morris Minor sidevalve in a similar fashion so that it would provide the maximum speed up a hill near his house. On a bike like ours that may be a bit of an issue but I have seen mention before the best way to reduce the vibration is to get the timing right.

Definitely food for thought and not terribly difficult in the scheme of things and also if you can get some 95 or 98 octane in your area you may be able to "sweeten it up" a bit more.

Regards,

Phil

The original timing is factory set at 6 degrees. After, the electronic ignition is adjusting it according to the rpm.

It would be interesting to know what is your setting now.
If you know a mechanic with professional tools, he should be able to quickly tell you what is your new timing setting.

Thanks for sharing your 'experimentation'

Bert

This may be considered old news at this stage in time but 91 octane 'gasoline' in the US is about like our 95 octane 'petrol' in OZ; something close to premium but not quite. 98 octane OZ petrol makes a big difference in the overall power and smoothness of my K100RS as compared to using 95 octane. The buzziness of my motor is right at 3200 to 3600 rpm (about 75 to 85 kph in top gear) but alas no ignition timing change makes any significant difference.

Later on...This got my brain thinking and I realised that I've never really put it to a more definitive step-by-step test. The bike is generally more buzzy than I like from a well-tuned motorbike. So I decided to have a really good squiz at it once again. I checked the timing with my ancient but trusty Snap-On stroboscopic light. It was set at the factory spec, as I'd intended. I retarded the timing a few degrees and rode the bike to and from work for about 60 kilometres return. Today was a 28c degree day, so it was seasonably warm for Summertime. The buzziness was lessened to quite a large degree and dropped from the previous 3200 - 3600 rpm down to 3000 rpm and under a bit. The bike felt slightly less torquey and sluggish, and the idle dropped a hundred or so rpm, as I'd expected. This arvo I've advanced the timing those same few degrees from the stock timing setting. I'll ride it tomorrow and see what she feels like.

Yeah, let us know. This has always interested me.

I wish there were a way to adjust timing dynamically while driving.

I suppose it could be done with an SMT box or the like, but it would still not be practical as they use a computer to make the adjustments and that would not be possible when driving.

After three days of country road and motorway riding to and fro from work (with more than a few faster-paced side trips) I can say that I prefer the slightly advanced timing setting over the 'mildy retarded' setting. The high-frequency vibes are still present, though not terribly intrusive, and only slightly above 3000 rpm. They dissipate gradually with the engine feeling like it revs more quickly, has better throttle response and seems to fire off instantly as well. I've dialled the idle back to about 900 rpm since it was pushing 1100 rpm when it was thoroughly warm at the end of a ride; it ticks over smoothly at that rpm too. I've noticed no pre-ignition pinging at all. I poured a fresh tank of 98 octane petrol (at AU$1.479 per litre!) into it and it's managed a typical commuting distance from the tank. It's really no worse, no better than the other timing setting. I'm gunnoo advance it a tad more tomorrow and give it a good run. I'll have a chance to give it some stick on the open road this weekend. Report to follow.

I think I've done it! At the end of the day the 'sweet spot' for ignition timing on my K100RS is a screwdriver blade width of advance from the stock setting; the bike fires right up, idles smoothly, has very good mid-range and higher rpm 'urge' and far less vibration where it was quite buzzy before. Also, the mileage has slightly improved. I used at or just under 5L per 100Km over a three day, 1800 km sporting ride, which was about a 50/50 combination of swift, two-lane country roads and steady motorway riding (and a few hard high-speed blasts mixed in). I'd advanced it until it just began to ping under load on hot days and up hills, then backed it off a tad to eliminate the pinging, but it was too buzzy still. In the end I tried five different positions until this most recent and I think most desirable setting. The variation in buzziness of vibes throughout the riding range have all been narrowed down to about 3200 rpm and have lessened.
By way of interest, a well-tuned, 22 year old K100RS, fully packed for camping with panniers and with no pillion will just kiss 220 kmh at redline in top gear on a level road with nary a puff of wind behind her. Deduct a bit for the usual speedo error and that's a fair number for a heavy old girl.

To revitalise this older post, is there anything you guys can tell us about where your timing sits now? (They sell many screwdrivers with varying sizes of widths ); mm or thou clockwise or anti from original?? Cheers.

Equiring minds want to know as they say. If you can get access to one of the dial adjustable strobes, winding the dial till it is on the TDC mark will give an exact degree figure.
Regards,
K-BIKE

Lets try again. Anyone what to share his 'advanced' settings and method? Cheers, Rene

ReneZ wrote:Lets try again. Anyone what to share his 'advanced' settings and method? Cheers, Rene

The circumference of the hall sensor plate devided by 90 and that is the distance you need to move the plate advanced to give 4 deg advance.
I cant remember what it is now but I did the K100 about 5 years ago and it had heaps of extra torque down low but only ever run ot on 98 RON fuel or detonation occurs and that is disasterous to a nicasil bore.