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Update:

So the 1 tooth off of the camshaft did the trick of the vrraap. It's all gone and runs strong with the stock CDI. I should have never trusted factory or the previous owner with marking the chain and sprocket with a sharpie to align it back. I should have just trusted the 3 holes and T mark.

Sailracer,
From what I have researched, the DC ones can have 1 wire on the 2 pin plug. The AC ones could have 3 wires on the 4 pin plug. Mine has 4 wires on the 4 pin plug with a 2nd green one. Maybe this could be a restrictor.

Here is the pic of the A/C wiring diagram. However, mine has another green wire on the 4 pin plug. I will disconnect that one to see if it starts.



Thanks everyone for the feedback. Sometimes it is a simple over look and other times, it takes experience from others.

I will give an update again after disconnecting the extra green wire on the 4 pin plug.

I did that. Light is not on, but I noticed the gas gauge turns on (shows gas level). I did the homework, from the headlight, to seeing if there is power to the CDI, to the size of the box, to swapping with both AC and DC CDIs, and also looking at the wires. This has me completely baffled. I went here www.scrappydogscooters.com/Tech_Talk_with_Mo_.html and also looked at the wiring diagram. Mine follows the AC wiring diagram, but I have 2 green wires in the 4 plug.

Another thought is if the factory timing was off at the camshaft. So, when either AC or DC CDI tries to start, if they are advanced on start-up, it won't fire up the engine. The DC CDI is from Scrappydog and the AC CDI is an AC NCY unit from Enviromoto.

I am still baffled...

Hi,

So I installed the 2nd bbk in the last month on 139QMB. It is identical to what I did before. NCY 47mm, Uni filter, # main jet, new fuel filter, NGK spark plug. I also changed fuel lines, vacuum lines, and battery. I am running out of ideas to try to trouble shoot.

The 1st one I did was on a 2012 TPGS-811 and I have a used 2009 MC-17. Same body style. 1st install is running strong and fast.

History with this MC-17 is I bought it used non-running. I cleaned up the carb, used speaker wire, blew out all holes with air compressor, changed fuel filter, changed spark plug to a spare one I had, drained old gas, and added new gas. Started right up and I rode it around the block. I needed more power for the city streets here and ordered a bbk.

I installed it, I even marked the timing chain to the cam sprocket with a sharpie so I re-install it in exactly the same place.

Now here is my problem
The scooter starts and idles perfectly.
I rode it around and it does a vraap, burp or brrruup when I wot or almost wot.
1. Thought I might be lean so I raised the needle on the carb. It got worse where half throttle it would vraap or burp.
2. So I leaned it out with the needle, it got better, but still would do it in upper rpms.
3. Checked the plug and it looked kinda dark.
4. Switched # to # I had around. Did the same thing. Raised the needle and it vraap. Leaned out the needle, and it did it again.
5. Check all connections and grounds, where I even sanded the ground connections to the case and frame. Used Dialectric grease. I double checked/tightened the coil, wire, plug connections.
6. Checked I didn't over oil Uni filter, I didn't. I used the spray oil and I even blotched the filter with shop towels to make sure it wasn't too saturated.

So, I am guessing:
1. Fuel not atomizing well enough - clean carb again or get new carb
2. Spark not good. Maybe a bad CDI? Found out the hard way it was DC even though it has 2 wires etc. after installing and ruining an NCY CDI. I have an Orange DC CDI coming in the mail today.
3. Timing might be off from factory. I noticed the stator timing doesn't settle on the T, it settles on the F. When on F, the cam was aligned correctly. Again, I also marked the chain to the cam sprocket. I installed this exactly the same way I did the previous one and that one is running strong and fast.
4. Exhaust has clogged or rusted blocking flow

I don't want to start buying extra parts. Any ideas? I do have the proper tools as I was an auto tech years ago, but I don't have the same energy or muscle recovery as I did years ago. So, I am almost to a point where I am going to take the engine apart to inspect, but don't want to do that.

Thank you for the help.

I have this MC-17 scooter with 139qmb that I bought used and I just installed a bbk. Trying to fine tune it and when I removed the variator, the ramp plate is stuck or fused to the crank shaft. I am thinking of taking a torch to the plate and heat it up. I also don't want to bend it by trying to yank it out.

Thoughts on how to get it off?

I bought a replacement carb for my brother's 139qmb and it came with an # jet as well. Do you have the old carb? If so, you can try using the main jet from the old one.

Maybe pics would help to show your problem.

Thanks. That helped with the search.

I found this. It's a good start: