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  1. #1
    Super Moderator nigelrharris03's Avatar
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    Having new CB450/500T ignition advancer springs fabricated

    I sent this drawing to a spring manufacturer in the UK and he sent me 2 nice St St Samples which are working perfectly. To buy them, there is a minimum order of 500-1000 (from memory), and I was not prepared to put up that amount of money in advance.

    This spring came from a K0 advancer. My view was that if the wire was a very similar diameter and the turns were the same along with the other dimensions, then the resulting force it will apply will also be within a very good tollerance of the original spec.
    As I say they are still working well
    [attachment=0:125ui292]Advance spring for 450 Model (1).pdf[/attachment:125ui292]
    Attached Images Attached Images
    Nige
    CB450K0 Bomber 1967
    CB650Z 1978

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  3. #2
    Supporting Member pamcopete's Avatar
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    Re: Pamco ignitions

    nigel...,

    Are you using the springs with a PAMCO? What is the cost each in 500 lot?
    Ride. Enjoy. Life is simple.

  4. #3
    Super Moderator nigelrharris03's Avatar
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    Re: Pamco ignitions

    Quote Originally Posted by pamcopete
    nigel...,

    Are you using the springs with a PAMCO? What is the cost each in 500 lot?
    Hi Pete
    I didnt buy the Pamco ignition set yet simply because I was not able to afford it. However I did use my original advancer which was simply not wortking with the stretched springs.
    At the time I was not a forum member so I did some work seeing if I was able to blag some springs from a manufacturer.
    This I managed to do. Of course in all fairness I did not need 500-1000 springs, and I fully understand the costs of a single purchase from a company that is manufacturing in 100's of thousands of units.
    I will look for the information, as this was nearly 5 years ago. When I find it I will let you have it. It is a UK company of course.


    Found them after a lot of email searching here is the link
    http://www.leespring.com/uk_index.asp?
    Nige
    CB450K0 Bomber 1967
    CB650Z 1978

  5. #4
    Senior Member Dr.Jeff's Avatar
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    Re: Pamco ignitions

    Thanks to everyone for the great responses, I fully agree with them all.

    I guess my interest in this subject stems from prior discussions in this thread, where the removal of the points leaves the points-cam with reduced resistance and resultant instability of the timing. But it also goes a little beyond that.

    In my opinion, the proper length of the spring (i.e. not stretched) is one factor. However the tension of the spring is even more important, as that is mainly what governs the RPM and rate of timing change...both of which have a marked impact on performance/ride ability. Simply shortening a spring may not restore its proper tension. Therefore bending the ends of a worn and stretched old spring may not fully restore the engine's running characteristics. Similarly, using springs from another brand bike may not offer the proper characteristics either (I seem to recall someone saying earlier here that the Yamaha springs were notably different).

    Having looked at a selection of springs at a local industrial supply house revealed three things. There is a huge selection of them to choose from, their relative tension varies dramatically even between two seemingly identical springs, and they are very cheap to buy. It seems to me that if the correct replacement springs can be identified, then it might be smart insurance for another 30 years of top running performance and reliability...for just a couple of bucks.

    Nigel's reference to the UK source is great, thanks for that Nigel. If you click onto the "extension springs" link, you see a "find springs by specification" option. Note the second half of that page allows you to search by various tension factors, in addition to the dimensions above it. There are lots of such suppliers here in the US as well.

    While this spring issue may not be ultimately vital, it may be worth consideration. If a purchase was made directly for a quantity of say 500, they are likely to cost around 50 cents a piece. Perhaps even worth supplying a set with each ignition? Just a thought.

    It is unfortunate this discussion did not come up earlier. I recently attended a large industrial trade show where several spring manufacturers were present. I could have gathered the necessary information there....appologies for not thinking of it then. But a little internet searching can provide several sources to contact.

  6. #5
    motomax's Avatar
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    Re: Pamco ignitions

    Nigel, do you have a part number/stock number for the springs they sent you? Lee Spring Company has a number of locations worldwide, including five in the US, one of which is in Greensboro, NC; and that's not far out of the way for me in my work travels. So this might be a source for test springs. Since I'm still in setup/testing mode, I'd like to see if new springs make a difference. My current springs are working after I tightened them, but I have not checked/tuned the timing advance vs rpm yet. This discussion got me thinking, though...

    Considering the fact that my advancer springs are 41 years old and still playing a leading role in a rather important part of basic motor operation... making SPARK, I think it is worth trying a new set, what the heck. Especially if I can get a pair for relatively cheap--compared to the price of most replacement parts for these bikes.

    It occurred to me that my springs appeared to be stretched/fatigued differently when comparing one to the other, which might cause instablilty/oscillations or uneven wear on the Pamco rotor. Who knows, though? I tried to make them both the same length and tension, but maybe this is asking a lot of a 40 year old spring.

    Out of curiosity I have been doing a little bit of research on springs; there are several US spring manufacturing companies online with good information about extension springs--characteristics, materials, etc. It does look like they would be very cheap when bought in volume, but more expensive when buying only a handful. Key factors in selection seem to be material, wire diameter, overall length, end type (hook), number of "active loops".

    Another possible source is Diamond Wire Spring Company, which has an extension spring manufacturing plant in Taylors, SC... also kind of in my neck of the woods. If others are interested, I'd be willing to do some legwork and see about getting examples from a couple of different companies to test.

    Thoughts?

    I'm busy working this week, which is keeping me on the road and away from the bike; it will likely be Sat or Sun before I'll get back into the garage.

  7. #6
    Super Moderator nigelrharris03's Avatar
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    Re: Pamco ignitions

    Quote Originally Posted by motomax
    Nigel, do you have a part number/stock number for the springs they sent you? Lee Spring Company has a number of locations worldwide, including five in the US, one of which is in Greensboro, NC; and that's not far out of the way for me in my work travels. So this might be a source for test springs. Since I'm still in setup/testing mode, I'd like to see if new springs make a difference. My current springs are working after I tightened them, but I have not checked/tuned the timing advance vs rpm yet. This discussion got me thinking, though...

    Considering the fact that my advancer springs are 41 years old and still playing a leading role in a rather important part of basic motor operation... making SPARK, I think it is worth trying a new set, what the heck. Especially if I can get a pair for relatively cheap--compared to the price of most replacement parts for these bikes.

    It occurred to me that my springs appeared to be stretched/fatigued differently when comparing one to the other, which might cause instablilty/oscillations or uneven wear on the Pamco rotor. Who knows, though? I tried to make them both the same length and tension, but maybe this is asking a lot of a 40 year old spring.

    Out of curiosity I have been doing a little bit of research on springs; there are several US spring manufacturing companies online with good information about extension springs--characteristics, materials, etc. It does look like they would be very cheap when bought in volume, but more expensive when buying only a handful. Key factors in selection seem to be material, wire diameter, overall length, end type (hook), number of "active loops".

    Another possible source is Diamond Wire Spring Company, which has an extension spring manufacturing plant in Taylors, SC... also kind of in my neck of the woods. If others are interested, I'd be willing to do some legwork and see about getting examples from a couple of different companies to test.

    Thoughts?

    I'm busy working this week, which is keeping me on the road and away from the bike; it will likely be Sat or Sun before I'll get back into the garage.
    Unfortunately not. I was just sent the 2 samples that very closely matched the drawing I made. The material was St St the turns were the same and the total length was the same. This proved to be a good match for the existing springs. The major thing was that the hooks were rotated 90 degrees to each other. I have checked the advance on my strobe which has a advance setting and it does exactly what is required of it.
    I think the company would be interested in this if we were to order in a batch.

    However I have to say I do not know if the 450 advancer springs change with type, there were more than one manufacturer of advancer available. And further confusion whether later models and the 500T also have differing springs. The best way to measure the spring dimensions IMHO is to compress it fully and make the measurements from the compressed spring. Perhaps if we had several people do this with the advancer type and the year and model we could have a clear consensus of what springs are required. This would also apply to the 350 and 360, plus all others with mechanical advancers. My thoughts are as of now if we could come up with a plan to eg Lee springs that we could get some manufactured or use their stock units if they are near enough.

    Looking at the 450 advance curve it allows at least 10% variation. My Original spring was 0.95mm dia wire with coils compressed at 9mm into a 6mm dia spring coil with a total length of 22 mm.
    I believe that this is probably a pretty stock spring. I will measure the springs I got from Lee Springs when I get a little time to remove them from the advancer.
    Nige
    CB450K0 Bomber 1967
    CB650Z 1978

  8. #7
    Senior Member Dr.Jeff's Avatar
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    Re: Pamco ignitions

    Nigel makes a good point about the different models of Honda's possibly having different spring specifications.
    If we can get people with springs from low mileage bikes (hopefully not too worn) to take measurements as Nigel suggests, that would be a start (including the year, model, advancer number, etc). However we should also measure the tension ratings, in addition to the lengths, diameters, etc. This would require stretching the spring to a given length (or to a couple of lengths) while measuring them on a pull gauge or scale. The gauge/scale is a common item used to weigh small objects (search for a 'fish scale' or 'luggage scale' to get the idea). Tension measurements are part of the equation for selecting springs on the manufacturers web sites (as discussed earlier).

    Why determine the correct tension as well as length? As the weights on the advancer are spun and fly outward, the springs pull against this force to regulate their movement. The idea is to allow the weights to travel out in a gradual, progressive motion...not a sudden 'off-on' action. This will give a timing advance "curve" that begins at idle and progressively increases up to red-line. See this example (scroll down to the bottom):
    http://www.nichecycle.com/ProductDesc.a ... oad&key=it
    I believe the Honda factory service manuals also show timing advance curves? By recording the timing while running the engine at selective RPM's, starting from idle and increasing every few hundred RPM, we can plot this curve on a graph.

    Various spring tensions will yield different timing advance curves. Get the ignition's advance curve right and the ride ability is greatly improved (especially under normal road conditions). Take a look in any good text on the design/engineering of the internal combustion engine for information on the importance of proper ignition advance curves. It is the reason the advancer mechanism exists in the first place. And the reason it is necessary to find the correct specification springs for a specific engine design.

  9. #8
    XTOP20A's Avatar
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    Re: Pamco ignitions

    Quote Originally Posted by Dr.Jeff
    Nigel makes a good point about the different models of Honda's possibly having different spring specifications.
    If we can get people with springs from low mileage bikes (hopefully not too worn) to take measurements as Nigel suggests, that would be a start (including the year, model, advancer number, etc). However we should also measure the tension ratings, in addition to the lengths, diameters, etc. This would require stretching the spring to a given length (or to a couple of lengths) while measuring them on a pull gauge or scale. The gauge/scale is a common item used to weigh small objects (search for a 'fish scale' or 'luggage scale' to get the idea). Tension measurements are part of the equation for selecting springs on the manufacturers web sites (as discussed earlier).

    Why determine the correct tension as well as length? As the weights on the advancer are spun and fly outward, the springs pull against this force to regulate their movement. The idea is to allow the weights to travel out in a gradual, progressive motion...not a sudden 'off-on' action. This will give a timing advance "curve" that begins at idle and progressively increases up to red-line. See this example (scroll down to the bottom):
    http://www.nichecycle.com/ProductDesc.a ... oad&key=it
    I believe the Honda factory service manuals also show timing advance curves? By recording the timing while running the engine at selective RPM's, starting from idle and increasing every few hundred RPM, we can plot this curve on a graph.

    Various spring tensions will yield different timing advance curves. Get the ignition's advance curve right and the ride ability is greatly improved (especially under normal road conditions). Take a look in any good text on the design/engineering of the internal combustion engine for information on the importance of proper ignition advance curves. It is the reason the advancer mechanism exists in the first place. And the reason it is necessary to find the correct specification springs for a specific engine design.
    yeah i use a $6 electronic suitcase scale for my ebay and they are quite accurate
    any body that has a lathe could lash-up a rig using the cross-slide as a pull
    done thusly an accurate inch/lbs rate can be calculated
    we are talking small numbers so if it is done this way(a horizontal pull) then the scale needs to be grabbed a hold of by its body(or its body carefully supported) so its own weight doesnt fowl the accuracy

  10. #9
    Supporting Member pamcopete's Avatar
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    Re: Pamco ignitions

    Well, the advancer doesn't start advancing the spark until 2,000 RPM and has reached maximum advance of 35Deg at 3,400 RPM so the advance curve is very limited in its influence over engine performance. The engine spends most of its time above 3,000 RPM so I see the advance mechanism as more of a spark retard mechanism that reduces the spark advance for easier starting and smoother idle and hence its curve characteristics are of little consequence. What is important is that the timing is at 15 degrees at idle up to 2,000 RPM and that the timing does then advance in an orderly fashion to reach 35 degrees at 3,400 RPM. But as to how many degrees it reaches for each of the points along the way to full advance doesn't matter.

    From the factory manual:

    Here is the curve from the factory manual:



    Note that the "curve" is depicted as a linear straight line, which could just be for the convenience of the author, but if the curve were important, I'm sure that Honda would have shown it.

    So, this should make finding a suitable set of springs easier.
    Ride. Enjoy. Life is simple.

  11. #10
    XTOP20A's Avatar
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    Re: Pamco ignitions

    Quote Originally Posted by pamcopete
    Well, the advancer doesn't start advancing the spark until 2,000 RPM and has reached maximum advance of 40Deg at 3,400 RPM so the advance curve is very limited in its influence over engine performance. The engine spends most of its time above 3,000 RPM so I see the advance mechanism as more of a spark retard mechanism that reduces the spark advance for easier starting and smoother idle and hence its curve characteristics are of little consequence. What is important is that the timing is at 15 degrees at idle up to 2,000 RPM and that the timing does then advance in an orderly fashion to reach 40 degrees at 3,400 RPM. But as to how many degrees it reaches for each of the points along the way to full advance doesn't matter.

    From the factory manual:



    Here is the curve from the factory manual:



    It should also read "advancing the spark to 40 deg"
    excatly well said
    for all practical purposes it is on or off
    in lower gears my sl will pull from below 3000 but i am sure it has to do with the mild cam the sl uses compared to cl's or cb's
    from what i have read here a cb or cl is not happy below 3k pulling any load

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