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Post by benji on May 3, 2018 9:47:03 GMT -5
I figured I'd do a thread on the bikes I buy just to resell since I do a few of em. First up is the current one, a Baja sc50 4-stroke with a 139qmb  Pretty little thing with only 17 miles on it. I may need some help with this one. I cleaned the carb but it still won't run right. Seems like a clogged muffler but does the same when I remove the silencer from the end. Checked air filter and put in new gas. It only has 17 miles, and it supposedly ran great until it got parked for 2 years. Would the valves need adjustment? Interesting note, I found a 125mj in the carb. I swapped it with whatever came in my oem 4t vino (should be close) and the motor runs the same, almost like it's clogged. Maybe a cdi? Seems to start up and idle ok but gets flooded out quick. |
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Post by 90GTVert on May 3, 2018 11:48:42 GMT -5
Start with the basics. Check the spark, but make it jump a large gap (HEI tester, adjustable gap tester, old plug with the ground strap cut off or bent back). Check compression. Did you make sure you got the diaphragm back in the carb right? There's a nub on it that you have to align, which is easy to overlook if you're not used to those carbs. Stock main jets are usually around 75-80.
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Post by Lucass2T on May 3, 2018 14:25:16 GMT -5
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Post by benji on May 4, 2018 15:13:17 GMT -5
I guess I'm buying some parts :/
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Post by kagetenshi on May 4, 2018 20:55:00 GMT -5
If the fuel lines sat with old gas in them for 2 years they might be crumbling from the inside out. I let mine sit for that long once upon a Time and the fuel lines were toast.
That could have clogged the carb after it was cleaned.
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Post by benji on May 4, 2018 22:00:46 GMT -5
The carb was the interesting part, it wasn't even really dirty. It looks brand new, and had a 125 main jet in it. I think he may have bought a new carb for it.
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Post by 190mech on May 5, 2018 3:36:30 GMT -5
Might look at the pilot jet again,4 strokes are picky about that jet flowing...
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Post by benji on May 5, 2018 8:42:06 GMT -5
I'll check it, since I didn't see a number on it. Maybe I should try swapping the whole carb to my 4t vino carb. It's the same type a ruckus/metro has, with coolant lines running to it. The Baja doesn't have those coolant lines.
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Post by benji on May 5, 2018 8:42:32 GMT -5
Or maybe it would be cheaper n easier to get a gy6 for it. Things a bottom mount so it should bolt on, right?
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Post by benji on May 19, 2018 12:55:34 GMT -5
So took another look at it, and the main is not actually a 125. It seems to be between 75-80 I think. I'm gonna try to adjust the valves and see if that works.
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Post by benji on May 19, 2018 21:53:17 GMT -5
Adjusted the valves and... Nothin. I hate 4t's. I'm gonna save up for a new friggin motor and flip it haha. Can't be more than $250? I saw gy6 150s going for that. Anybody gotta bottom mount 150 they wanna sell? Or 1e39qmb that runs?
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Post by benji on May 19, 2018 21:53:39 GMT -5
I shoulda known not to buy a friggin 4t.
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Post by Happypancake! on May 19, 2018 22:29:41 GMT -5
Don't flip the Met
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Post by benji on May 20, 2018 3:17:08 GMT -5
No no , this one's a Chinese 4t bike. I have two non-running 4t's right now haha.
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Post by fly on May 20, 2018 4:35:06 GMT -5
Check it's getting adequate fuel. Filter, petcock (esp vacuum), etc.
Take off the pipe and run it through, make sure nothing is in the way pre-silencer. I suppose two years of seeping might've produced some amount of guck.
You don't want to drop for another engine just to find out it was the petcock or there were the remnants of a dead mouse or some sh!+ in there. It's been sitting for two years so if something is binding, plugged up, or gummed up other than the carb it wouldn't be surprising. It probably wasn't put together great to begin with.
Also, I'd suggest working with the idea it actually was running fine before being parked. And subsequent to that I'd troubleshoot with the original MJ back in place. You've got the junction of fuel and air pretty well covered with cleaning and checking the carb. Just make sure its inputs are good. Because you have spark and a clean carb. Look upstream of that junction.
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