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Post by stillgar on Feb 10, 2013 12:50:47 GMT -5
Hi again. I did get my Baja SC50 to start, kinda. I swapped out the coil with a different coil and got a longer spark. (This after troubleshooting to the kill switch issue.) The bike ran just a bit, then died. I bought a new carb, thinking it was a fuel issue. Same deal- runs for a few seconds. Spark plug wire shocks the "poo-koo" out of me. It has gas, i cleaned the fuel filter. It runs for just a bit on starting fluid. I rechecked the cam sprocket holes with the stator timing mark, and they are all 3 visible and the top one centered. I actually had the bike running for a few yards under its own power, then it just died.
Edit: I also rechecked the valve clearances (I had replaced the cam) and both were good.
Late edit: Looking over similar posts, I checked the ground (engine to frame), and it is good. Has anyone had experience moving the timing by a tooth or so in either direction, or how to tell if this is necessary?
Any suggestions? Please? Thank you.
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Greg
Scoot Enthusiast
Posts: 218
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Post by Greg on Feb 10, 2013 21:39:45 GMT -5
I accidentally put a scoot back together that was one tooth off. It ran, but it ran like a pig. It had very little power, as if it had a blown head gasket, or bad compression. It bogged, with a little pop and sputter when given throttle but I do not remember it dying. I think I was one tooth advanced iirc. Your results may vary if you might be one tooth off in the other direction.
With some of these motors it is hard to tell if you are lined up properly. Luckily, it is not hard to pop off the valve cover and take another look.
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Post by stillgar on Feb 11, 2013 12:04:52 GMT -5
Thanks, Greg. I checked visually, and the cam sprocket looked like those in the pictures. I don't have a way to get my automotive compression tester in that tiny spark plug hole to properly check psi, or funds to buy a smaller tester. I will try to check the head gasket seal. To do so, do you remove all shroud covers from the cylinder and feel for any "puffs" while engaging the starter? Sounds like another engine/wheel assemble is in order.
I may take it to a shop before re-removing the engine, as I never knew it would take the dozens of hours to get a $150 scooter to run.
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Greg
Scoot Enthusiast
Posts: 218
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Post by Greg on Feb 11, 2013 17:51:19 GMT -5
If it ran for a short time, I doubt you have a head gasket problem.
Have you tried emptying the carb bowl to make sure there is gas in the carb?
You may have a bad fuel switch. To test this, I put the fuel line in a bottle, then I suck on the vacuum line to make sure gas flows, then stops when I stop sucking on the vacuum line.
You may also have an air leak in the intake.
You can also try taking the air filter off and try starting the scoot with your hand over the back of the carb. If it starts, you may have too much air coming in from the air box. While the starter is engaged you should feel the vacuum (and get some gas on your hand), if not the intake boot may be letting in air.
For the head gasket.. Yes, shrouds off. You should be able to hear the air squeeze out by kicking it over with your hand. This would be quieter than the starter.
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Greg
Scoot Enthusiast
Posts: 218
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Post by Greg on Feb 11, 2013 18:00:12 GMT -5
The more I think of your situation, the more I think you still have a fuel problem.
It really seems like it is either the vacuum operated fuel switch or the float valve in the carb. To a lesser extent beyond this would be a vacuum/intake leak.
I had a brand new carb that had a float valve problem. Gas did not flow into the carb fast enough so it would run, then die and throttle would really bog.
Also, the ethanol in gas has been destroying these fuel switches, especially on scoots that are stored for the winter, longer with gas in them.
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Post by Fox on Feb 11, 2013 20:08:10 GMT -5
Cracked intake maybe.
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Post by ryan on Feb 12, 2013 16:43:54 GMT -5
the sc50 is DC i believe and i worked on one that had all the problems you had...the fix was a new petcock..that fixed it for a bit but the second problem is\was the stator it had a wire that kept shorting out and turned it off. also if you dont have a battery do not let the positive lead touch the frame it will stop it from starting if your ground is to the frame
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Post by stillgar on Feb 12, 2013 19:59:15 GMT -5
Thanks for the good suggestions. I will check the intake boot for leaks. Seems a leak or fuel problem would be overcome with starter fluid. It runs a little on starter fluid, and the carb bowl as well. I can see the fuel filter fill when the vacuum hose from the manifold sucks the petcock open, and saw the fuel come out of the hose when I pulled it off the carb inlet.
The stater problem is looking interesting. The original problem when I got the scoot was that the cam bearing failed and the timing chain had fallen off. I assume the carb and stator were working at the time. Is there a way to check for an intermittent stater? it seems as if it gives out, but I can't afford to throw parts at it.
I do not have a good battery, so I am using a yellow "jump box" clipped to the engine case neg. and positive battery cable and smaller red battery wire connected to positive. The clock comes on, as well as the brake light when squeezing the handle (needed to engage the start button, I learned).
Thank you again for the replies. I will get back to it! I really want to ride!
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Blowin Smoke
Scoot Enthusiast
Posts: 289
Location: Port Orange, Fl
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Post by Blowin Smoke on Feb 25, 2013 10:31:52 GMT -5
To check if the engine is in time you can bump the engine starter until you see the piston at top dead center. Then inspect the timing gear position. Keep in mindthat it is a 4 stroke so you can see the valves move up and down. Intake, compression, power, and exhaust with relation to the piston position.
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