SA50 Elite won’t start after BBK.

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Pinkfloydperson
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SA50 Elite won’t start after BBK.

Post by Pinkfloydperson »

Having a * of a time with my SA50 Elite. I can only get it to start if I put my hand over the carb intake to choke it, then I can keep it going with the throttle, but it eventually dies.

Some specs, and things I’ve checked out so far:

It’s a 97 Elite 50. Just put a Malossi 70cc BBK on it, along with a Malossi crank. Replaced the crank bearings and seals. Replaced the stock reeds with Malossi’s (came with the kit). Replaced the main jet with an 85 (came with the kit). Prior to this it would start, idle and rev just fine, it was just gravely sounding because the crank bearings were shot, which led to this rebuild. Got it all together and installed last night, and haven’t been able to get it to start and run.

I’ve checked:

Compression: just a hair under 120lbs.
Cleaned the carb multiple times. Idle circuit passed the flashlight test.
Swapped the reeds back to stock.
Checked out the bypass valve, which seemed to operate as it should. Plunger retracted when cold, extended when warm.
New plug.
I’ve tried no airbox, stock airbox. No difference.
The fuel petcock works when vacuum is pulled.

I’m stumped for the night, and worried all this starter cranking and choking it to get it to run to check things out is going to mess up my cylinder walls and rings. Does anyone have any ideas on what to check out? About to light this thing on fire.
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bonesv
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Re: SA50 Elite won’t start after BBK.

Post by bonesv »

So everything is stock except the crank and bbk? Is it the 88-93 af05 motor? You may have a bad air leak.
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Re: SA50 Elite won’t start after BBK.

Post by Pinkfloydperson »

It’s an AF16, and yes, everything is stock but the BBK and crank. I haven’t pressurized the case or anything, but I hondabonded it quite well while reassembling, have all the gaskets in place.
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bonesv
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Re: SA50 Elite won’t start after BBK.

Post by bonesv »

Check the exhaust pipe for leaks where it connects to the cylinder. You should have the air box installed with a new air filter, oil soaked and wrung out, in order for the carburetor to work properly. Is it an original carburetor you have? or is it aftermarket? That jet does not fit the original carburetor. It's for the dio or asian market scooters. How did you get it to fit? Was the bbk "brand new" in un-opened box? Are the rings installed the correct way, and the end-gaps facing away from the exhaust port? Have you over-oiled the motor for a first time start-up? Are you running premix gas or the stock oil injection? There's lots of things to cover from the small amount of info to work with. Anything else you can provide us to help you with?
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Re: SA50 Elite won’t start after BBK.

Post by Meatball »

Arrow on top of piston pointing toward exhaust?
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Re: SA50 Elite won’t start after BBK.

Post by vintagegarage »

First of all, if you are choking it by putting your hand over the intake, the airbox and filter are not in place. Put them back in place, and prime the carb by unscrewing the slide cap (the part pf the carb that the throttle cable runs through) and squirting a gas/oil mix into the slide. Then screw the cap back on and start the engine. Not saying this will solve your problem, as it most likely won't, but it will give you a better baseline moving forward. If you put in four squirts of gas/oil mix, the engine should run for about 3 seconds on half throttle. If it does, and then dies, fuel is not being drawn from the float bowl. If it doesn't run at all, then your problem is most likely not the carb.
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Re: SA50 Elite won’t start after BBK.

Post by Pinkfloydperson »

To answer some questions:

I should have mentioned that the jet that came with the kit did not fit my carb, but I had a Honda 85 sitting around that did, so I used that one. It’s the original carb.

I’m still using the oil injection system. The pump is a brand new SR unit. I also added maybe two capfuls of GN2 to the tank.

The rings are in the correct spots, as there really is only the one way they can be on the piston and allow it into the cylinder. There are little nubs the gaps have to sit between. The arrow is definitely pointing towards the exhaust port.
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Re: SA50 Elite won’t start after BBK.

Post by Rip_City_Spree »

if your running stock carb its in your best interest to run it with the stock airbox like noted above. take out your plug squirt some gas mix down in the cylinder. with the stock airbox secured properly. try to start it. it should run briefly. next id check to see if your actually getting fuel into the carb then into the cylinder. the petcock is vacuum run pull off the gas line and there should be a vacuum line suck on the vacuum. gas should come out of the fuel line. before any of this though clean your carb again. then before you put it back on clean it again. these motors are bullet proof and will run albeit poorly if you get fuel spark and air. if its not running and you are sure you put the kit together properly then it should run. if it ran before it doubt your pipe is clogged. even with a massive air leak it should still run. it would have to be pretty massive (aside from the airbox not properly setup) for it not to run.
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Re: SA50 Elite won’t start after BBK.

Post by Pinkfloydperson »

I think I found my problem after pressure testing the case. Air is coming out of the flywheel side crank seal. Looks like the flywheel woodruff key slid back into the seal while I was putting the flywheel on. Boner move on my part. Have a new seal and key coming. Any helpful tricks when it comes to pressing the flywheel on with the woodruff key?
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Re: SA50 Elite won’t start after BBK.

Post by bonesv »

Be sure to clean, not file or sand, the groove in the flywheel and seat the key in place all the way. Use a black fine tip felt pen to place alignment marks on both the end of the crank and on the flywheel to give you a visual aid.
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