Tried it all, but it won't start again!

[mrkgp]

Hi all,

Firstly I'm new here so please spare the beheading

I recently installed one of the 80CC motor kits you find on ebay. The thing ran great for a while. I initially had the engine just die on the way to work but I put it down to loose wiring as I managed to get it started again after I re-attached the cables.

Later down the line, still running great. That is until recently. While riding, the master link flew off (yes I had it in the correct orientation). The reason it flew off is because my engine became un-centered on the bike and the chain was being warped to one side. My mistake that the bolts were not tight enough.

Anyway, the chain had jammed so I had to unjam that before anything else. Once I sorted that out, I checked everything again, resecured the engine and it was up and running with no issue for about 20 minutes. Then while riding, it just stopped. No noise, it just sounded as if it ran out of fuel.

So I took it back home, and for two weeks I've been trying to get it started again but am unable. I mixed with fuel and oil as per the break in instructions of 16:1 and hadn't had any issues. However I noticed that the tank was empty and mostly oil was left.

I assumed that oil had sat at the bottom and not fully mixed, therefore clogging up the lines and the engine with just oil.

I took everything off the bike. I took apart the carby and dried it out. I turned the engine upside down to expel oil from inside. Then after a few days of that, put it all back on the bike, added some fresh fuel and tried again. STILL nothing.

Today, I bought another spark plug. The old one still sparked, but I thought I would try it anyway. Still no start. It sparks fine.

So now I looked at the carby and compression. With the plug out and the carby off, when I rotate the wheel I can feel suction on the intake and it's forceful to pedel with the clutch dropped. The engine sounds as it should, seems to have nice compression.

The bowl in the carby definitely fills up, but it seems as if the engine is not pulling the fuel into the chamber. When I stop after trying to start a few times, I take the carby off and the bowl still seems full. The end of the carby with the plastic piece and the foam for air, seems to not fit snug anymore with the end of the carby metal (if that makes sense). Not sure if this would cause an issue when the engine is trying to suck the fuel from the bowl?

I've also tried starting with choke ON etc. the way I should.

When I go to start, it doesn't start. It's just me peddling with the clutch out and the engine moving as if it were running, but nothing is being ignited. It acts as if there was no spark plug installed, except it has compression so it's hard to pedal.

In summary:
*Compression seems good and carby bowl fills, but may not be sucking fuel into engine.
*Spark seems fine, tried a different spark plug anyway.
*Tested magneto, range seems fine

Carby and all manifolds/holes are 100% clean. It's a very new kit and I've verified and cleaned everything.

The only thing is the carby gap at the end where the air comes in. Is that plastic circular piece not aligning with the carby metal enough to cause a no start issue?

I've ordered a replacement carby but if that doesn't work I'll be at a dead end. Maybe the CDI?

Any advise would be great.

 

[Henshooter]

Hmm sounds like you have run through most issues ,have you checked if the jet in the carby is blocked or loose ,or is the muffler clogged somehow ( unlikely due to new kit )
You could check your CDI but if your getting good spark then that shouldn't be the issue.

The Small moon shaped brass tang in the carbys have a issue with the pin occasionally slipping out ,this overfeeds the motor and it will either run like a pig or not run at all

Have you checked the fuel cap breaths as if the seal is airtight it won't allow the fuel to siphon ,simply remove the fuel line from the carby and turn the tap on ,it should flow fairly easily .

Check the slide in the carby is moving well and not jammed ,simply remove the air filter and look into the carby whilst twisting the throttle ,you may have not reinstalled the pin correctly

Try all these and get back to us on how you go

Regards Henshooten

 

[Powertool]

Try checking all wire conections

 

[biknut]

Check you magneto coil. You should have about 350 ohms between the black and blue wires.

CDIs rarely fail, but magneto coils are easily damaged.

Change your break in oil mix to 24:1

Buy a good spark plug wire and cap.

 

[crassius]

first, check that filling the carb with oil didn't block the main jet

next, take off the air filter to see why it doesn't fit (note that there is an open part of the plastic screen that makes room for the choke arm to move) - while it is off, check that the choke is moving correctly

after this, you should see that the plug is wet after trying to start it

let us know

 

[allen standley]

The reason it flew off is because my engine became un-centered on the bike and the chain was being warped to one side. My mistake that the bolts were not tight enough.

Check under left side cover look at the woodruff key under magneto. If this has sheared your timing will be off and can cause a no start situation.

Use fresh gas - I'ld go 32:1 with the mix .

 

[mrkgp]

Hi all,

Thanks heaps for your replies! Great to see such a supportive community

Happy to say, it's running again! I noticed a link in the magneto soldering was broken, which I've heard is common. I re-soldered it and got perfect multimeter readings but still it wouldn't start. Then I realised, In all my troubleshooting, it seems I accidentally put the magneto in the wrong way after I fixed up the solder job. DOH!

After correcting that, it fired up again.

I'm having other issues, but I'll make a different topic for those since they aren't relevant to my no start issue.

Thanks everyone for your help!