03-15-2016, 12:33 PM | #1 |
Join Date: Feb 2015
Location: TENNESSEE
Posts: 392
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H E L P! Calling all 2-stroke mechanics!
OK guys, I am at a loss as to why I am having engine failure!!!
If you have the knowledge and the time, please check out my blown 50cc engine video and leave any thoughts / suggestions either here or over on my channel. Thanks!!!! .
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" If it ain't broke, I can probably still fix it!" ---- Tim Allen |
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03-15-2016, 12:37 PM | #2 |
Join Date: Sep 2014
Posts: 1,915
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Can't watch your video with my current internet connection but I'll be glad to help if you feel like writing about your problem. I was a professional 2 stroke mechanic for many years.
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03-15-2016, 02:09 PM | #3 |
Join Date: Jan 2016
Location: central illinois
Posts: 362
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ok, i know you asked for a pro builder, and i am not ... but i have built a few 2 stroke engines, and got all my tech info from a yamaha dealer and former racer. he told me the first thing you need to do if you make any change that requires a larger jet (and you have done at least 3) do not use the factory oil injector ... the pump is set to mix to the factory jet only and when you go up in jets, you go up in fuel:oil ... going up in fuel:oil will make a 2stroke scream, but it will also shorten the life of all the moving parts, so you may want to check the end play of the rod to be sure the rod bearing is not past its lifespan as well ... if it were my 2stroke, i would remove the gear from the oil pump, and mix it to factory specs ... as a side note, he told me to never trust the factory injector even on a stock bike, unless it is a polaris, they are the only ones that got it right
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03-15-2016, 06:12 PM | #4 | |
Join Date: Feb 2015
Location: TENNESSEE
Posts: 392
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Quote:
It makes since , , , really. 100 miles on hopped up engine after going up 2 times on main jet, then BOOM! ( well, more like, screeeeeeeeechhhhhh!!!!! ) motor seized. New motor, 1 mile , same seizure! It haaaassssss to be starving for oil Me'sa 'Tinks!!!! . Piss on that pump!!! I will mix my OWN for this next go around and see what happens! :-D . Thanks!
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" If it ain't broke, I can probably still fix it!" ---- Tim Allen |
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03-29-2016, 12:05 AM | #5 |
Join Date: Jul 2015
Location: Milpitas, CA. USA
Posts: 775
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I watched your video. You mention jetting changes but unless I missed it, nothing about spark plug readings.
Good observation on the piston scoring in relation to the head/cylinder studs, but that's only coincidence. Because of the geometry of the piston casting, that is the way it expands. It's indicative of overheating, not lack of oil. It's quite possible that air is being drawn in somewhere, i.e. crack in the carb mounting system, failing crankshaft seal on the magneto side. If you have gone up in jet size and the plug still reads as lean as it did before, that confirms the air leak. Good luck. |
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03-29-2016, 09:10 AM | #6 | |
Join Date: Jan 2016
Location: central illinois
Posts: 362
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Quote:
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03-29-2016, 09:41 AM | #7 |
Join Date: Sep 2014
Posts: 1,915
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Too much oil in the fuel will make the engine run leaner (hotter), not cooler. The more oil in the fuel, the slower it will flow through the jets.
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03-30-2016, 03:12 PM | #8 | |
Join Date: Feb 2015
Location: TENNESSEE
Posts: 392
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Quote:
Factory was 74 ( IIRC ) "stage 2 kit" from scooterworks came with an 85, After air pod filter I installed a 92 ( or maybe a 96???? I forgot. A 90-something ) but I still have a 102 and a 118 on hand that can go in.
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" If it ain't broke, I can probably still fix it!" ---- Tim Allen |
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