Fine tuning an 850

[Suzuki_Don]

Thanks Ian

[psyguy]

So one would think the 650 total advance figure should be further away from the T (tdc) mark, but in fact the totao advance for the 650 unit is closer to the T mark. Can anyone explain?

Looking at the pics it would seem that the distance between the two advance marks is smaller for the 550 than for the 650 mechanism. And that should be so as the 550 has an advance difference of 20deg total wheras 650 has 30deg difference. No?

[Suzuki_Don]

Thanks for the replies guys.

I am still puzzled by the timing marks on the 550 and 650 advance/retard units. Could someone explain or is it just that the Japanese mind sees things differently from us westerners.

I have transferred the timing marks from the 650 unit to the 550 unit by centre punching the new timing marks. In the picture below it will be seen that the new idle timing mark is closer to the T (tdc) mark than the original 550 timing mark and that is how it should be according to my understanding. Because the original 550 idle timing was at 17 deg and the 650 timing at 10 deg. So 10 is closer to tdc than 17. Right.

But when it comes to total advance the 550 was at 37 deg and the 650 at 40 deg. So looking at the picture below the 650 mark to my way of thinking should be on the RH side of the original 550 total advance mark not on the left and closer to tdc than the 550 mark is. it looks to me that the 650 centre punch mark for total advance is at around 34 deg.



Do you get what I mean? Am I understood? If so what do you think and can you explain it to me?

BTW I have transferred the timing marks from the 650 unit to the 550 unit extremely accurately so I know they are correct.

[49er]

I have transferred the timing marks from the 650 unit to the 550 unit by centre punching the new timing marks. In the picture below it will be seen that the new idle timing mark is closer to the T (tdc) mark than the original 550 timing mark and that is how it should be according to my understanding. Because the original 550 idle timing was at 17 deg and the 650 timing at 10 deg. So 10 is closer to tdc than 17. Right.

But when it comes to total advance the 550 was at 37 deg and the 650 at 40 deg. So looking at the picture below the 650 mark to my way of thinking should be on the RH side of the original 550 total advance mark not on the left and closer to tdc than the 550 mark is. it looks to me that the 650 centre punch mark for total advance is at around 34 deg.

Don there's an anomaly here. I have just checked my spare 850 advance unit. It is visually identical to the 650G unit in your pic, except there's no 49 stamped on it. Also my springs are lighter than yours. I know that the 850 unit is all in at 37 deg, just like your 550 is supposed to be.

You need to be accurate when transferring those marks. The 650 plate assy has a smaller arc. This can be seen when checking the gap and the alignment of the TDC lines.

After thinking about it further, you are trying to replicate the advance rate of the electronic unit by a weights and spring combo, which will be extremely difficult, if not impossible to achieve.

You shouldn't compare the 650G and 55OE advances, because they both advance faster initially than the 650E and then continue for a shorter duration up to 2500 rpm. You need a mechanical setup that advances only 10 deg by 1650 rpm and then another 30 deg by 3500 rpm.

You've got yourself a nice 650 engine, so I would save yourself some agro, bite the bullet and set up the stock electronic unit. Or, you could go with a Dyna S, if they make one suitable for the 650E. Decisions, decisions!

[Suzuki_Don]

Ian I measured the distance across both of the units from the arc on one side to the arc on the other side and there is only 1mm difference, so for all intents and purposes they are the same size with the same arc. I am having trouble finding a Dyna S for the 650 motor, I will keep searching and see what I can find. I have the signal generator on the backing plate with the two modules, and the rotor that fits on the end of the crankshaft so all I am missing is the igniter (black box) for the standard 650 setup. I will see if I can find one of them.

Thanks again.

[Suzuki_Don]

I have timed the ign statically and the idle is fairly rough to say the least. Don't know why that would be. It idles better at 17 deg btdc than the recommended 10 deg that it is at now. I will have a ride when it warms up a bit and see what it is like on the road. Then I will probably set the timing back midway between the original timing mark (17 deg) and the present mark (10 deg), just enough to get the ping out of the motor.

[49er]

I have timed the ign statically and the idle is fairly rough to say the least. Don't know why that would be. It idles better at 17 deg btdc than the recommended 10 deg that it is at now. I will have a ride when it warms up a bit and see what it is like on the road. Then I will probably set the timing back midway between the original timing mark (17 deg) and the present mark (10 deg), just enough to get the ping out of the motor.

Try that intermediate setting Don. But if it still runs better at 17 deg, you could try a stronger spring on one set of weights. Most advance units used to have a light and heavy spring combo. The heavier spring was delayed until the light one had partially advanced the weights. Advance would slow down until enough centrifugal force was generated to overcome the heavier spring and then advance would continue. You may have to experiment with this type of advance to achieve a good result.

[Suzuki_Don]

Try that intermediate setting Don. But if it still runs better at 17 deg, you could try a stronger spring on one set of weights. Most advance units used to have a light and heavy spring combo. The heavier spring was delayed until the light one had partially advanced the weights. Advance would slow down until enough centrifugal force was generated to overcome the heavier spring and then advance would continue. You may have to experiment with this type of advance to achieve a good result.

Thanks Ian, will do.

[Suzuki_Don]

Well last night I re-marked the timing marks and threw my old (30yrs) timing light on it. I was not able to see the timing mark at idle because I did not let the paint dry before I did the test (so you can guess what happened) sometimes it pays to be patient. But I was able to see the total advance mark move from it's position back to line up with the stationary timing mark on the backing plate and I was getting full advance with no problem when the engine was reved past 2000rpm.

I ordered a new timing light today as the one I have has an orange light emitting from it and it's not easy to see the timing marks unless it is almost completely dark (shed lights off). Also it's a headache trying to connect up the timing light in the old fashioned way of putting one lead on the spark plug and the the other one into the spark plug cap especially when they are designed for car plugs and leads with the screw on spark plug caps. The new one which clips onto the spark plug lead should be much easier to use.

I also bit the bullet and ordered the new Dyna "S" DS3-1 ecletronic ignition for my motor. Hope I can get away with using my standard coils -- cheaper that way.

[49er]

Well last night I re-marked the timing marks and threw my old (30yrs) timing light on it. I was not able to see the timing mark at idle because I did not let the paint dry before I did the test (so you can guess what happened) sometimes it pays to be patient. But I was able to see the total advance mark move from it's position back to line up with the stationary timing mark on the backing plate and I was getting full advance with no problem when the engine was reved past 2000rpm.

I ordered a new timing light today as the one I have has an orange light emitting from it and it's not easy to see the timing marks unless it is almost completely dark (shed lights off). Also it's a headache trying to connect up the timing light in the old fashioned way of putting one lead on the spark plug and the the other one into the spark plug cap especially when they are designed for car plugs and leads with the screw on spark plug caps. The new one which clips onto the spark plug lead should be much easier to use.

I also bit the bullet and ordered the new Dyna "S" DS3-1 ecletronic ignition for my motor. Hope I can get away with using my standard coils -- cheaper that way.

The Dyna S should make tuning easier. Good luck with the coils. The later model timing lights are easy to use too.