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Is this the dreaded "4 stroking"?

  • AirborneSilva
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Replied by AirborneSilva on topic Is this the dreaded "4 stroking"?

Snglsmkr wrote: The other source of oil is the transmission/clutch reservoir. A leaking crankshaft seal or missing/defective o-ring where the primary drive gear meets the crankshaft bearing inner race are potential problem areas.

Performing a leakdown pressure/vacuum test is a good way to find leaks.

You may want to go ahead and remove the primary drive/clutch cover and inspect the crankshaft seal. These can be popped out of place from high pressure in the crankcase.


That is my suspicion from the way it's been running and now all the oil in my exhaust. Guess I need to order some seals.
25 Jan 2021 13:13 #11

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Replied by Bigdog302 on topic Is this the dreaded "4 stroking"?

sounds like a corked up pipe. a true four stroking is when your 2 cycle is firing every other revolution like a 4 stroke engine does. a bad cdi box, stator problem or overly rich mixture is the usual cause. here is a example of cdi induced 4 stroking. when you give it throttle the engine does not increase in speed with the throttle. cause of this was bad primary and secondary source coils on the stator. a really really plugged up pipe can cause this too.


this is after repairs were made, note the way it idles now with a proper 2 stroke idle and how it revs.
2 1968 DT1s,1970 RT1M,1970 DT1C,1971 RT1B,1971 Honda Z50K2,1974 DT100A 1974DT250A,1974 Honda MT250,2 1975 DT400Bs,1975 Honda CR250M1,1978 DT175E,1979 Honda CR250R.
Dave
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Last edit: 26 Jan 2021 09:20 by Bigdog302.
26 Jan 2021 09:11 #12

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  • AirborneSilva
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Replied by AirborneSilva on topic Is this the dreaded "4 stroking"?

Roger that and thank you Bigdog for the videos! Mine idles rock solid at 1500 and revs great but when you try to hold it at a steady RPM is what I was doing in the video. I ordered the crank seals and will at least change out the right side since I believe it's ingesting oil from there since my exhaust is getting full of oil, my plug has oil on it too as you can see from the picture I posted.
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26 Jan 2021 09:45 #13

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