pred 212cc wont start

breath_easy13

Active Member
Aug 27, 2019
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North Caronlina
So, there i was, carried the beast down the stairs of my apartment - 7 months of building and dreaming in my office space, and finally the day has come. Threw oil in, some gas, went to start it up, BOOM gas i dripping from the carb filter. That issue was resolved quickly - realized i ran the fuel line in a vent hose rather then fuel nub. Dang, i felt stupid. Anyway, took the carb apart (brand new) but i did so to make sure the jet looked fine, and the floats were functioning propery. Put it all back togther, changing the angle of the carb so that it lays more leveled, using a radiator hose and clamps for good compression. Turned on the fuel, and nothing leaked. Made sure fuel was reaching the carb, turned the choke on, pulled the starter a few times and nothing at all. A few more pulls, still nothing. Super bummed out. Put ALOT of work and money unto the bike. These are the troubleshooting steps i took so far. Following a lot of what the manual says but basically.

Engine wont start -
-carb not primed -- pull on starter handle to prime
-carb needle stuck -- tap side of carb (take apart carb)

Testing electrical issues
--Unplug spark boot, pull starter, does spark
--unplug spark plug, inspect, visually clean, brand new plug
>>The spark is there so it cant be electrical

Compression related
-loose cycl head or damaged gaskets (hissing noice )-- no hissing noise
-engine valves or rappets mis-adjusted or stuck -- made sure alignment was there when putting case back on
-compression lost due to leak in intake manifold--re adjust carb set up, fastening with radiator hose and clamps tighting intake.

So as you can see, pretty much went through everything we can without out take the crankcase back off and checking the alignment and timing. Not to sure whats going on. We went ahead an tried to spray fluid into the carb, while pulling the starter, and still nothing. It turns with ease, sounds like it wants to start up, then doesnt.

the only step i havent attempted is
-too much fuel in chamber, caused by carb needle sticking --

Turn Choke to RUN position.
Remove spark plug and pull the start
handle several times to air out the
chamber. Reinstall spark plug and
set Choke to CHOKE position.


Any suggestions ?
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IMG_20200422_232751_5[4943].jpg
 

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Greg58

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May 1, 2011
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Try holding your finger in the sparkplug hole and pull the starter cord to see if it blows your finger out of the head, that will tell a lot.
 

breath_easy13

Active Member
Aug 27, 2019
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Try holding your finger in the sparkplug hole and pull the starter cord to see if it blows your finger out of the head, that will tell a lot.
I cleaned the bowl, it not leaking, made sure the floats werent stuck when taking it apart.

Are you saying, take the spark plug out, plug the hole with my finger there and pull the cord?

or unplug the spark plug, place my finger on the boot side and pull the starer?
 

Greg58

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May 1, 2011
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Press your finger on the spark plug threads in the head, as the engine reaches the compression stroke it will move your finger. You should have around 100 psi or better so you will not be able to hold it back.
 

Greg58

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May 1, 2011
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Find a compression gauge and do a more accurate test, I don’t know what the compression should be but 100 psi or so should be ok. Autozone has a tool rental program where you pay for the tool then get a refund when you return it.
 
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Greg58

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May 1, 2011
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If you can get someone to help you can try this, put the spark plug in the boot and hold it on the engine to ground it, now hold your finger in the plug hole while a helper pulls l the start cord. You should see fire at the electrode just before the compression blows your finger away from the threads. That will tell you if it’s firing right before TDC.
 
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breath_easy13

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Aug 27, 2019
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i
If you can get someone to help you can try this, put the spark plug in the boot and hold it on the engine to ground it, now hold your finger in the plug hole while a helper pulls l the start cord. You should see fire at the electrode just before the compression blows your finger away from the threads. That will tell you if it’s firing right before TDC.
ill give it a go. if there is weak compression, or none at all, what wuold that indicate?
 

Tom from Rubicon

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Apr 4, 2016
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Check your kill switch position. Visiting Lynn at MBrebel I was liking a 79cc Predi / Q-Matic setup on one of her builds. She was complaining that she couldn't understand why the engine wouldn't light. About the third or forth time I picked up parts at her business, She always lined up her bikes outside for viewing and I was looking that bike over as I was doing a similar build. Then I spotted it, kill switch in the off position. I didn't have the heart to tell her. So look at that little red knob on the fan housing.
Tom
 
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EZL

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May 13, 2016
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Chenoa, Illinois, USA
Check your kill switch position. Visiting Lynn at MBrebel I was liking a 79cc Predi / Q-Matic setup on one of her builds. She was complaining that she couldn't understand why the engine wouldn't light. About the third or forth time I picked up parts at her business, She always lined up her bikes outside for viewing and I was looking that bike over as I was doing a similar build. Then I spotted it, kill switch in the off position. I didn't have the heart to tell her. So look at that little red knob on the fan housing.
Tom
Operator Error! :rolleyes: A Mikuni carb has to have the throttle opened a little on the 212cc.
 
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EZL

Well-Known Member
May 13, 2016
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Chenoa, Illinois, USA
Check your kill switch position. Visiting Lynn at MBrebel I was liking a 79cc Predi / Q-Matic setup on one of her builds. She was complaining that she couldn't understand why the engine wouldn't light. About the third or forth time I picked up parts at her business, She always lined up her bikes outside for viewing and I was looking that bike over as I was doing a similar build. Then I spotted it, kill switch in the off position. I didn't have the heart to tell her. So look at that little red knob on the fan housing.
Tom
That looks like a good combination on a Preditor 79cc!
 
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EZL

Well-Known Member
May 13, 2016
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Chenoa, Illinois, USA
Those engines have a 'low oil shut off switch' inside the engine... When you mounted the engine up on it's side, did you cut the wires coming out of the engine case?
I never even fired up my new 212cc with a low-oil-kill switch plus a governor in it. I removed both when I got the new engine and the first
pull on the engine on the bike it started with the stock carb. A Mikuni carb will start on the first pull and I was doubtful until I put a
Japanese Mikuni VM22 on the engine and pulled it for the first time, it lit on the first pull. :)
 
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