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Top dead center seems off
- Srk97001@gmail.com
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Top dead center seems off was created by Srk97001@gmail.com
I’ve got a dial indicator to tell me where top dead center is on the piston. Unfortunately, it looks like the mark on my stater does not align at all with the mark on my rotor. I took a picture below and marked with a marker where the two would be aligned is this normal?I still can’t get this thing to start. I thought it was the timing.
23 May 2023 21:06
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- MarkT
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Replied by MarkT on topic Top dead center seems off
That's not a top dead center mark.
Those marks should align when piston is 1.8mm before top dead center.... IF tab isn't bent or something.
Spark should happen at 1.8mm before top dead center. Which means points should just open at 1.8mm before top dead center. (approximately 20 degrees before top dead center)
At the risk of stating the obvious.... If tab is correct, and the tabs aren't always correct!, points should just open when mark aligns with tab.
Note that "eyeballing" when the points open will always be off a few degrees. In other words, points will open before you can see them open. So if "eyeballing" the points will just start to open when mark on flywheel is just slightly to left of tab.
It seems you're stuck on "timing"... if spark is happening anywhere near 1.8mm before top dead center it will run. Not saying you shouldn't get timing set perfectly... just saying a slight variation in timing is not going to keep it from running.
Those marks should align when piston is 1.8mm before top dead center.... IF tab isn't bent or something.
Spark should happen at 1.8mm before top dead center. Which means points should just open at 1.8mm before top dead center. (approximately 20 degrees before top dead center)
At the risk of stating the obvious.... If tab is correct, and the tabs aren't always correct!, points should just open when mark aligns with tab.
Note that "eyeballing" when the points open will always be off a few degrees. In other words, points will open before you can see them open. So if "eyeballing" the points will just start to open when mark on flywheel is just slightly to left of tab.
It seems you're stuck on "timing"... if spark is happening anywhere near 1.8mm before top dead center it will run. Not saying you shouldn't get timing set perfectly... just saying a slight variation in timing is not going to keep it from running.
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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23 May 2023 21:57
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- RT325
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Replied by RT325 on topic Top dead center seems off
Is there two post going on this. Am i on the right planet. Am i really here haha.
The following user(s) Liked this Post: MarkT, Sneezles61
24 May 2023 02:51
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- darinm
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Replied by darinm on topic Top dead center seems off
I'll echo MarkT on this. The timing on my '72 CT2 was way, way off when I got it and it still ran pretty damn well. Could only tell at elevation.
And yes it looks like two posts going
And yes it looks like two posts going

1972 Yamaha CT2 175
1972 Suzuki TS185 Sierra
1986 Yamaha IT200
2013 Yamaha XT250
1972 Suzuki TS185 Sierra
1986 Yamaha IT200
2013 Yamaha XT250
The following user(s) Liked this Post: RT325
24 May 2023 18:41
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