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[Help] with my '73 DT3 250, having ignition issues
- 19stuberd
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Replied by 19stuberd on topic [Help] with my '73 DT3 250, having ignition issues
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- 19stuberd
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Replied by 19stuberd on topic [Help] with my '73 DT3 250, having ignition issues
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- RT325
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Replied by RT325 on topic [Help] with my '73 DT3 250, having ignition issues
Sorry if i'm talking over the top of people at times. I might be slowly typing away & someone gets there faster haha, so what i'm saying might look like i'm saying it against them, but not the case--just my ideas.
I must say you're not afraid to get stuck into things, which is great. Bit hard to be sure in one pic but make sure that the wire feeding the points is 'not' touching the steel & is sitting against fiber washers & the bolt also has a small piece in the middle to stop any chance of the bolt moving sideways & touching earth.
Look in one flywheel window & the notch should be visible. On the top side of the window, just a narrow shallow original mark or groove.
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Replied by RT325 on topic [Help] with my '73 DT3 250, having ignition issues
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- 19stuberd
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Replied by 19stuberd on topic [Help] with my '73 DT3 250, having ignition issues
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- shyted
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Replied by shyted on topic [Help] with my '73 DT3 250, having ignition issues
All of it. I know that because I have a DT3 and downloaded the manual from this site. Don't assume anything where bikes and other folk are concerned. Half the time they talk out of their arse !
You need to set the timing to set the points. It goes through the process in the manual. A tip for you as well . Wrap insulation tape around the blades of the feeler gauges so the magnetic parts don't grab them.
It's a frustrating task until you get the hang of it.
If you have feeler blades you can set plug gaps . I learned that when I was 8 years old.
A good you tube clip to watch if you haven't already is one by Jason Scot ,DT 250 timing. A later bike than yours but the principal is exactly the same.
I take it you're in the US so find a Clymer manual for your bike in hard copy form. Brilliant.
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- RT325
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Replied by RT325 on topic [Help] with my '73 DT3 250, having ignition issues
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- 19stuberd
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Replied by 19stuberd on topic [Help] with my '73 DT3 250, having ignition issues
I also checked the spark plug gap and that was off too! Set it to .22 from .28 or something like that, all of the numbers kind of blended together but I know it was pretty off and it's not off anymore. All of this work, however, and still no spark on kick.
Then it was on to the real reason I went to the school: The $15,000 oscilloscope. I took readings of various conditions of the bike, rotating at various RPM ranges with the drill as well as kicking the bike manually, taking readings with both the points covered and points uncovered. The main problem that occurred, however, is that the oscilloscope only recorded 10 seconds of the data. I didn't expect this and so I did long test runs where I would start in the low RPM range and increase with kicks (the important part) thrown in at the beginning or end. I figured that I would be able to contextualize the data later given the bigger picture, but now it's proving a bit difficult to determine what's what. I also took off the flywheel at the end to find that the thing wedging the points open may have fallen out during testing, which I think it did.
Let's take a look at the data! Images in the album, all labeled in the top left for your convenience. photos.app.goo.gl/6jgCeySzinjXLGHRA
I have included seven graphs of the seven saved files in the album. The first one looks like it shows me kicking it, but that's just me using the drill and it slipping off. The second one appears to be me kicking it WITH points, but there's a catch that I'll explain. 3 and 4 seem to be duplicates, and it looks like it's just the tail end of one session of me cranking it with the drill, not terribly useful. Five is also me cranking with the drill. Seven is when I realized that the points may have been uncovered (it looks like they were) and so I covered them more reliably and did the same test as before (drill then kicks) but it only caught two kicks in the test.
In images B and C (showing graph 5) we can see that the voltage is consistently at 18v or so at about 630 RPM with some spikes above 30 and 40 volts. Image D (also graph 5) shows voltage at around 22v at about 860 RPM. Image E (of graph 1) shows the readings from a standstill, starting at about 420 RPM where it generates about 12.5 v and then increasing thereafter as the RPM increases. Image F (of graph 6/7) which is kicking with no points shows an initial reading of 10, increasing to 20, and then diminishing afterwards.
This is where things get strange. Image G shows what I think is me kicking the bike over with points functioning, and it looks interesting but most significant is the fact that it is registering a maximum of 3 volts. I don't know if this is a bad reading or if this is my problem being illustrated before my very eyes. Not sure what to make of all of this! I may go back down and do it right this time. Let me know if this is an expected voltage range for a coil and what you guys think.
Thanks for the long read! I hope the data is useful, I have it all in case there's some maniac that wants to see it themself. I can't wait to hear what you guys think! As always, thanks a million times for the help.
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- RT325
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Replied by RT325 on topic [Help] with my '73 DT3 250, having ignition issues
Actually i think the high compression version available in DT1--gyt kit & MX in "71-ish was 2.9btdc without looking. Don't panic--does it run is the important bit.
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- 19stuberd
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Replied by 19stuberd on topic [Help] with my '73 DT3 250, having ignition issues
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