The Engine Starting Blues

[TheSereneOutsider]

Hi. Super newb here. I recently bought a 49CC engine kit from ebay seller boygofast and installed it on my 70's free spirit cruiser. After a good amount of tweaking (tightening the clutch cable, adjusting choke, securing wire connections, etc.), I was finally able to get it going. It seemed to be running OK, but I didn't really ride it around much—just around the block a few times. The next couple of days I had a harder time starting it and/or keeping it running. I read through a number of threads relating to starting problems and noticed there was a decent amount of smoke leaving the exhaust, and thought perhaps the mixture was too rich. So I decided to increase the fuel to 20:1, instead of 16:1. After that it seemed to be running much better. The engine sounded robust and it accelerated great. A lost idle screw and a few days later, I began experiencing similar symptoms as I did before, and now I can't get it to start at all. There were a couple of times after letting up on the clutch that the drive chain and rear wheel would lock up, so I suspected that the engine might be flooded. Accordingly, I pulled out the plug and rode it around with the engine engaged to try and dry things up. Still no go. I replaced the stock plug with an NGK B-4L, though both plugs get spark. Interestingly, there is no visible smoke leaving the exhaust. The kill switch is disconnected, though it doesn't seem to matter if it's connected or not. Any suggestions for an ignorant newcomer?

[Greg58]

Sounds like a fuel problem, some have had the main jet to fall into the bowl of the carb. I would pull the carb and check for debris.

[2door]

If you've done any reading then you have to have seen this:
The engine needs three things to run, fuel, air and ignition. Test for these and let us know what you find.

Fuel flow from tank to carburetor?
Choke plate open?
Spark?
Tom

[TheSereneOutsider]

Originally Posted by 2door

If you've done any reading then you have to have seen this:
The engine needs three things to run, fuel, air and ignition. Test for these and let us know what you find.

Fuel flow from tank to carburetor?
Choke plate open?
Spark?
Tom

Fuel Flow:I disassembled the carburetor. Fuel appears to be flowing to the carb, as the carb bowl was completely full of fuel, although it looks as though the fuel line is leaking where it fits onto the carb.

Choke: I've tried starting the motor with the choke lever at various positions—on, off, half-way, two-thirds of the way up, two-thirds of the way down, etc. From what I can tell, it doesn't appear to have much bearing on how close it sounds to starting. Previously I had consistent success starting the engine with the choke lever in the upward most position.

Spark: I can see spark coming from the spark plug when I remove it, engage the motor and push the bike. The spark plug isn't wet, but does smell of fuel. I've tested with two different spark plugs.

[maintenancenazi]

Almost sounds like you may have developed a vacuum leak somewhere. Did you check your carb to manifold sealing? And although it sounds like you still have compression, have you checked the torque on your head bolts after all that previous running?

[Greg58]

Have you pulled off the magneto cover to see if all is tight, you said it was firing but if the mag. has gotten loose or sheared the key you could be out of time. Also look for fuel in that area that would indicate a blown seal behind the magneto. It would be a good idea to pull the clutch cover off and look there for fuel also.

[TheSereneOutsider]

Thanks for all the replies. Working on this engine has been immoderately frustrating, and it's awesome to get some helpful feedback.

I turned the bike upside down and slowly turned the wheel and dark fuel sputtered/dripped out of the head. Not a whole lot, but a small puddle worth. I rode it around with the spark plug removed, and then tried starting it but still no go. I was getting visible smoke when starting before (back when it would start), now I don't get any at all.

maintenancenazi, I wrapped up the carb to engine manifold with teflon tape in hopes that would ensure a better seal. I've inspected the carburetor and nothing seems out of order. I will note that I am using a replacement idle adjustment screw, which I have not yet rounded. However, it was running OK with it missing. I would just kill the engine whenever I needed to come to a stop, and then start the engine back up again.

Greg58, Unfortunately the bike fell over and landed on a loose socket bit on the floor, leaving a hole in the magneto assembly cover. I was concerned this fall may have damaged the magneto. Nothing is loose and the magneto is dry. There is some fuel on the outside cover, but that appears to have come from a leak from the carburetor. How do I tell if the magneto key is sheared?

[Greg58]

Try the link below it may help.
https://docs.google.com/document/d/1...ilebasic?pli=1

[Greg58]

Here is another good thread that might help.
http://motorbicycling.com/f4/motoriz...stall-195.html

[TheSereneOutsider]

Update: I took the bike down to a shop (Lar-eez motor bike shop, for anyone in the Boise area—really terrific guy) and had it checked out. In about five minutes he narrowed down the issue to a blown crank seal, and soon discovered about five missing ball bearings in the crankshaft. I suppose she's done for. Thanks for all the help.