sputters and backfires

[Twostroke]

Hi Norm!
I recently purchased and installed a china 80cc bike kit on my KHS bike frame. The install went surprisingly well and everything fit as it should. I'm running it at 16:1 fuel/oil (800ml oil to 5 lit of petro) during the break-in period. This is making for alot of blue smoke and might be causing the following issue. After about 20 minutes of riding the motor starts losing power, begins to sputter and if I give it to much gas, backfires all that unburnt fuel! Following some advice from this wonderful site, I noticed a small amount of gas around the carb.I took the carb apart looking for problems in float-bowl, or an air leak. Aside from some of the various parts needing a tightening, everything looked good. Next I took a look at the wiring, visually inspecting the whole thing from kill switch to coil and found nothing to indicate a short. If I manage to keep it running it seems to "fix itself" for a short time before happening again. Ive worked on alot of small engines in my life and never encounted something so vexing. If you need pics or more info I'm more than happy to include those in my reply. Thanks so much for your help

 

[geoffmaree]

Hi Twostroke
One litre of fuel (1000 divided by 16 equals 62.5ml.
Five litres of fuel (5000ml divided by 16 equals 312.5ml.
Hope this helps.

 

[Norman]

I don't work in liters very well. I can just get by using metrics.
I use 40 to1 polan syn oil can be gotten at Walmart.
your wiring can fool you its best to solder your crimps. what I mean by this is to crimp the wire then a dab of solder to make it a tight mechanical fit. you can still pull the crimp connector apart, but both ends of the connector is soldered to the ends of the wire. If you live where there is a lot of humidity its very important to solder along with the crimps. Corrosion will form inside of the crimp with out solder. I found this out long ago the hard way, I pushed my panhead chopper as much as I rode it due to being bullheaded and not soldering the connectors like my Dad told me to do. After rewiring and soldering my connectors I cut the pushing time in half.
I now live where the humidity is very low, I still make sure the joints are soldered on my wiring.