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Post by aero on Jul 25, 2008 2:52:26 GMT -5
I've been messing about with CDi boxes for the SR500 recently and have got a working set up. My next project is a CDI conversion for POINTS model XT500s. It might just be possible to use the standard generator. To find out if this is possible I need some info. What I need is for someone to run the engine from idle up to near enough the red line and measure the voltage coming from the ignition winding of the generator. You will need a good multimeter set to AC and connect one led to the connector out of the generator and the other to the frame with the engine running. There is no need to pull the connector apart, the meter should have a high enough resistance that it won't effect the engine running. The coil that runs the ignition is on the right as you look at the generator and has a black wire. If the voltage being generated is high enough, and I suspect it is, it will be possible to use the standard generator to power a CDi box, with just a minor modifaction. I would be grateful to any one who can provide this info  |
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Post by colinjay on Jul 25, 2008 3:02:02 GMT -5
No problems Aero, I have to do a service and few repairs to my XT500 over the weekend, so I will take some voltage readings while I am at it.
CJ
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Post by colinjay on Jul 27, 2008 5:16:46 GMT -5
DOH!
When I started work servicing the XT550, I remembered that I fitted it with a SR500 electrical system to power the lighting system for the RT series, DOH!
So, I pulled out the TT500C and did some vlotage check on the magneto on it. From what I can find in my manuals, the ignition system is the same for both the XT and TT.
Results;
RPM VOLTAGE
1000 1.3 - 1.7 VAC
2000 2.5 VAC
3000 2.9 - 3.1 VAC
4000 3.5 VAC
5000 3.8 - 3.9 VAC
6000 8.0 - 8.7 VAC
I had a bit if difficulty with holding the revs steady, partly due to using a laser tacho which is a bit too sensitive and showed every fluctuation in RPM. I did't rev the old girl beyond 6000prm, due to a touch of mechanical sympathy, she has a few rattles that go un-noticed when you are riding and have a helmet on, but sound as if the engine is going too let go when you rev her that high in the shed.
I am a bit suprised by the low voltage readings at the lower RPM, I would have expected them to be higher, but even repeating the tests a couple of time gave very similar results. It would be good if there is someone else out there that could take some readings just to comfirm mine.
CJ
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Post by aero on Jul 31, 2008 5:36:55 GMT -5
Many thanks for that. They are extremely low! Even if the coil was 100:1 , a 200 volt spark is unlikely to fire the spark plug! I wonder if the points were causing a ripple that was confusing the meter? Laser tacho...look at you!  |
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Post by joneill4 on Aug 1, 2008 10:03:33 GMT -5
I hate to ask a stupid question, but are those values from a 1x scale? That doesn't sound right.
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Post by colinjay on Aug 1, 2008 15:36:09 GMT -5
The voltages were measured with a auto-ranging DMM.
The laser tacho is nothing special, it is just a $100 hand held unit that I use for checking electric motor speeds as a method of diagnosing faults (it will come in handy in my new job at the winery, as they use an awfull lot variable speed motors driving wine transfer pumps).
Although the voltages seem low, they are still workable voltages for a points/coil ingintion system. Most 1960 - 70's cars with points ignition only have a primary voltage to the ignition coil of 8 - 9VDC, as a ballast resistor is used to drop the 12 volts from battery down to this level, and there were (are) a lot of old Honda's with 6 volt battery coil ignition systems that produce a very good spark from similar low primary voltages.
It is a pitty that I left my old job, as I don't have access to a CRO any more, and it would have been handy to monitor the voltage with one to see exactly what was happening.
I am still looking into other means of checking/validating the voltage readings that I got and will let you all know how I get on.
CJ
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Post by aero on Aug 2, 2008 4:09:09 GMT -5
That's all good stuff, but I think the idea of using this for running a cdi box has gone out the window. You need 100-200 volts for that.
I wonder what the AC from the lighting coil is? I did a couple of 12 coversions to the charging/lighting coil and seem to rememeber the AC value comming off that was high.
Once again I'm really grateful for your effort on this.
Job in a winery! Bet you never rush home!
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Post by colinjay on Aug 2, 2008 4:57:40 GMT -5
From memory you can get about 7 to 8 volts from the lighting on the XT500 and a bit less from the TT lighting coil.
A job in a winery rate a close second to marrying a girl who's father owns a brewery, every mature Aussie's dream.
And, we did partake in a bit of product testing after work on Friday afternoon.
CJ
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