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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
Update! Resoldered everything and remounted, it will make a spark at certain speeds with the drill but kicking it yields no spark.
21 Jan 2023 16:45
#21
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- 19stuberd
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Replied by 19stuberd on topic [Help] with my '73 DT3 250, having ignition issues
Okay everyone, I have a vague plan of what I might try next that is totally subject to criticism and change. Read my other post about the coil rewinding concept for more info, but I am thinking that tomorrow I am going to remove and unwind the other source coil that I have here, 3D print two more sheaves for each side to wind on, and then rewind the coil with a good number of additional windings. I am thinking that I might try to measure the current voltage output on kick with my voltmeter and then set a simple proporiton of windings to voltage between the current and ideal circuits which would be 440 / [present voltage that I will measure] = x / 160, with x being the goal number of windings. I read somewhere that the voltage coming out of the source coil should be between 150 and 300 and on the lower end i.e. kicking it I would want to have the lowest voltage in that range so as not to mess up the points. I would then use that to deduce the number of turns I need and then I could rewind a new coil while I watch TV or something, pop it in, and give it a shot. If it's at all convenient for anyone, if you either know offhand or could measure and see how much voltage your source coil puts out on kick I'd love you forever. Anyway please let me know if anyone has any thoughts or input. Thanks again everyone!
21 Jan 2023 17:36
#22
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- MarkT
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Replied by MarkT on topic [Help] with my '73 DT3 250, having ignition issues
Cam is inside flywheel.
One of the windows in flywheel will be over points when they open so you can observe/measure gap.
Finally, you don't "adjust gap". You get points to just open with piston at correct position BTDC to set timing. Then gap is what it is. You can set the max gap at like 0.012" or so until you get to the point of timing correctly.
There are no voltage specs but what you said is about right. You really need a oscilloscope or high tech meter that can measure the very short AC voltage peak. Regular meter readings are "average" and will be much lower than the voltage spike that should be just peaking when points open.
You might just have dirty points... even new they often have an invisible non-conductive bit of corrosion.
One of the windows in flywheel will be over points when they open so you can observe/measure gap.
Finally, you don't "adjust gap". You get points to just open with piston at correct position BTDC to set timing. Then gap is what it is. You can set the max gap at like 0.012" or so until you get to the point of timing correctly.
There are no voltage specs but what you said is about right. You really need a oscilloscope or high tech meter that can measure the very short AC voltage peak. Regular meter readings are "average" and will be much lower than the voltage spike that should be just peaking when points open.
You might just have dirty points... even new they often have an invisible non-conductive bit of corrosion.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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21 Jan 2023 18:02
#23
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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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- AirborneSilva
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Replied by AirborneSilva on topic [Help] with my '73 DT3 250, having ignition issues
Good morning, I think you're getting too hung up on where the cam lobe is to open the points, not that it matters but unless I'm mistaken it's on the flywheel, someone correct me if I'm wrong. I have a DT2 so it's probably exactly the same as what you are looking at. So, having said that you will be able to see the points through one of the slots in the flywheel when your dial indicator is on the 3.2 BTDC and will be able to get a screw driver in to set the points. Attached is a video that may help you out, he cheated and took a flywheel apart so just the part that has the cam on it is there and makes it easy to get to the points but like I said you should be able to see the points through one of the slots and get a screwdriver in to adjust them. Make sure you get the points good and tight once set or they will slowly close, ask me how I know
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DT250 points adjust
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DT250 points adjust
2023 Tenere T7
1976 DT400C
1975 DT400
1981 DT175H
1972 DT2 250 Sold
1980 GT80
1972 JT2
1976 DT400C
1975 DT400
1981 DT175H
1972 DT2 250 Sold
1980 GT80
1972 JT2
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22 Jan 2023 03:18
#25
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- 19stuberd
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Replied by 19stuberd on topic [Help] with my '73 DT3 250, having ignition issues
Alright update for everyone! Anything I talk about here will be included in the updated photo album, linked below, new pics at the bottom. I have rewired the stator to make it all nice and pretty, feel free to take a look. Wired both black wires, the yellow wire, and the coil to a red jumper wire as everything is ALMOST the right length but not quite long enough, an issue I'm sure we've all encountered at one time or another. I also didn't like how the yellow wire was bridging the points and so I cut it, soldered it to another red jumper, and routed it under the stator and through one of the holes up to the points, as pictured. I decided I'd go the whole nine yards or 8.2296 meters for the metrically inclined of you on this one to make sure nothing's loose and that this stator won't be a problem again. Also not sure if the casing of the capacitor has to be grounded to the stator, please let me know if that's the case because if so I will need to find a way to affix it.
And now on to everyone's lovely comments. It seems all three of the comments made were about the points and whatnot, so I will address that. Unfortunately today is a rainy day here in Pennsylvania so I think I'll have to wait until tomorrow to put any of this into action. From what I'm hearing from you guys, the gap itself isn't actually the important part. The point is to adjust the gap at a known position (say at TDC) so that since the flywheel cam has a fixed/known profile, we know that a certain amount of point-open-ness in one angle of rotation will equal another amount of point-open-ness at a different angle of rotation, such as, say the point of rotation where we want ignition to happen. This is to say that changing the gap at TDC will change the time at which the points close, I think. Please correct me if I'm understanding this wrong. Also the manual and Markt mentioned use of a dial indicator to gauge piston position, doesn't this require removal of the engine's valves and head? I would like to avoid that because that sounds like it would suck. Is there some other way that's used to measure piston position?
It seems that RT325 is saying that since we know that certain positions on the keyed flywheel are IDEALLY equal to certain positions of the piston, which is what I would imagine the timing tab is for, although I don't know what it's supposed to represent in terms of piston position (TDC? ignition point? something else?). So I guess RT325's approach is using flywheel positions to determine timing instead of piston, which sounds like an attractive option. One issue: I don't know where this mark is you are referring to, so I have included an image of the stator with every remotely screw-like object circled in a different color, just let me know where you are talking about and that will settle that. All that being said, I think I can give this a try tomorrow depending on what you guys say re: which method of timing you suggest. I will have to buy some feeler gauges or make something 12 or 15 thou thick (I do have a caliper) and/or borrow/buy a dial indicator (I found one in an abandoned factory but I'm not sure how accurate it is).
Now on to the couple of other things mentioned. RT325 mentions a flywheel puller, and I have actually made one myself! It's of the type that uses the slots to pull the flywheel, I made it out of some other kind of puller. I know people are wary of these because you can ding up the coils through insertion of the two bolts but I am being very careful and so it seems to work for me quite well. Images are attached in the same album as before. Also nobody seemed to react to the coil idea, still would love input on that. I take it that this is the better thing to do first because if I am putting an overpowered coil into a bike where the points just need adjustment, I might not even fix the problem, I might cause damage to the points through increased wear, and if it worked it would be fixing the problem in the wrong way anyway. I see what Markt is saying about the voltage measurement, so if I make this coil I might just guess & check it. Please let me know what you guys think. Also what's the thing circled in pink in the diagram?
Thanks again for everybody's help, these responses are really giving me hope that I might get to finally ride a motorcycle.
And now on to everyone's lovely comments. It seems all three of the comments made were about the points and whatnot, so I will address that. Unfortunately today is a rainy day here in Pennsylvania so I think I'll have to wait until tomorrow to put any of this into action. From what I'm hearing from you guys, the gap itself isn't actually the important part. The point is to adjust the gap at a known position (say at TDC) so that since the flywheel cam has a fixed/known profile, we know that a certain amount of point-open-ness in one angle of rotation will equal another amount of point-open-ness at a different angle of rotation, such as, say the point of rotation where we want ignition to happen. This is to say that changing the gap at TDC will change the time at which the points close, I think. Please correct me if I'm understanding this wrong. Also the manual and Markt mentioned use of a dial indicator to gauge piston position, doesn't this require removal of the engine's valves and head? I would like to avoid that because that sounds like it would suck. Is there some other way that's used to measure piston position?
It seems that RT325 is saying that since we know that certain positions on the keyed flywheel are IDEALLY equal to certain positions of the piston, which is what I would imagine the timing tab is for, although I don't know what it's supposed to represent in terms of piston position (TDC? ignition point? something else?). So I guess RT325's approach is using flywheel positions to determine timing instead of piston, which sounds like an attractive option. One issue: I don't know where this mark is you are referring to, so I have included an image of the stator with every remotely screw-like object circled in a different color, just let me know where you are talking about and that will settle that. All that being said, I think I can give this a try tomorrow depending on what you guys say re: which method of timing you suggest. I will have to buy some feeler gauges or make something 12 or 15 thou thick (I do have a caliper) and/or borrow/buy a dial indicator (I found one in an abandoned factory but I'm not sure how accurate it is).
Now on to the couple of other things mentioned. RT325 mentions a flywheel puller, and I have actually made one myself! It's of the type that uses the slots to pull the flywheel, I made it out of some other kind of puller. I know people are wary of these because you can ding up the coils through insertion of the two bolts but I am being very careful and so it seems to work for me quite well. Images are attached in the same album as before. Also nobody seemed to react to the coil idea, still would love input on that. I take it that this is the better thing to do first because if I am putting an overpowered coil into a bike where the points just need adjustment, I might not even fix the problem, I might cause damage to the points through increased wear, and if it worked it would be fixing the problem in the wrong way anyway. I see what Markt is saying about the voltage measurement, so if I make this coil I might just guess & check it. Please let me know what you guys think. Also what's the thing circled in pink in the diagram?
Thanks again for everybody's help, these responses are really giving me hope that I might get to finally ride a motorcycle.
22 Jan 2023 15:16
#26
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- AirborneSilva
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Replied by AirborneSilva on topic [Help] with my '73 DT3 250, having ignition issues
No links...
2023 Tenere T7
1976 DT400C
1975 DT400
1981 DT175H
1972 DT2 250 Sold
1980 GT80
1972 JT2
1976 DT400C
1975 DT400
1981 DT175H
1972 DT2 250 Sold
1980 GT80
1972 JT2
22 Jan 2023 15:42
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- Sneezles61
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Replied by Sneezles61 on topic [Help] with my '73 DT3 250, having ignition issues
And no valves when you pull the head.. it’s a 2 stroke.
Sneezles61
Sneezles61
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22 Jan 2023 15:54
#28
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- AirborneSilva
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Replied by AirborneSilva on topic [Help] with my '73 DT3 250, having ignition issues
Like sneezles says, no valves. The head is not all that difficult to pull off, which you need to do to use a dial indicator and as far as I know that's the only way you can find 3.2 BTDC. As for setting the points you want to lock them down just as they open, that will give you the correct max gap but it doesn't hurt to check with a feeler gauge that it's 15 max. I got lucky that no one before me messed with the pointer on the stator so it matched up perfectly with the mark on the flywheel when I was at 3.2 BTDC so with the help of a multi meter I was able to see that the points were just opening then and locked them down.
2023 Tenere T7
1976 DT400C
1975 DT400
1981 DT175H
1972 DT2 250 Sold
1980 GT80
1972 JT2
1976 DT400C
1975 DT400
1981 DT175H
1972 DT2 250 Sold
1980 GT80
1972 JT2
22 Jan 2023 16:28
#29
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- RT325
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Replied by RT325 on topic [Help] with my '73 DT3 250, having ignition issues
Timing tab represents 3.2mm unles somehas bent it all over the place. Me thinking i can see yourse broken off & can see the remains i'd find the knotch in the flywheel window--call it a groove then--& line it up with the broken tab edge & set points to "just Touching" then tighten up screw. It'll be close enough for 'today'. Object is to get it going at this point. Talking dial gauge i'd not worry 'yet' as head has to come off as you have an anglerd plug hole which doesn't work for acuracy. Talking Cam--if you want to view it it's on the flywheel center obviously to lift the points & really is barely vissible as only raises the points a little. So look closely for the difference around it, slight raise.
22 Jan 2023 16:33
#30
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