No Firing ? By lacrosseguy (Read 511 times)

[lacrosseguy]

Scooter Broke Down last fall at a stop light, never started again.
had low compression so i installed a bbk. still no start, also installed a new trigger pickup coil along with spark plug.

Any suggestions on why my scooter wont fire? i was going to clean my carb again, even though it was fairly new when the scooter broke down.

[Deleted]

Check for power on the low voltage side of the coil with a test light.

[Alleyoop]

Have you got a ground wire from the frame to the motor?

To get fire here are the parts:
MAKE SURE THE KILLSWITH IS ON THE RUN POSITION:
1. PLUG
2. BOOT CAP
3. COIL WIRE
4. COIL
5. CDI
6. PICKUP COIL
7. STATOR

And of course COMPRESSION, FUEL AND AIR and VALVE

The 2 PLUG on the CDI should have two wires.
a. The TOP ONE BLACK and WHITE is the KILLWIRE, you could get a small screwdriver and open the tab inside and pull the wire off to eleiminate the CDI being grounded which will give you NO SPARK.
Alleyoop

[lacrosseguy]

okay, i know for a fact im getting great spark. so thats eliminated ?
how would i go about testing Air & Fuel, and Compression. I did the finger test and it blew my finger off.

[Medman1952]

To test the compression accurately you need a compression tester, a gauge that screws into the spark plug hole to measure the PSI the motor generates when it is turned over. With a new big bore kit you should have no problem in that area unless the piston rings were not lined up correctly and unless you had to use the same head. The head could have a bad valve/valve seat and compression could be lost through there. I assume it looked good but it would have been nice to pull the valves out and done a hand lap on the valves to make sure they had a good chance of working well.


All that said you should be having over 120 pounds of pressure in there when the rings are worn in, new rings on a new cylinder may be a little less than that.

The fact the "finger test" blew your finger off sounds good, I use that test all the time.

If you think you have a fuel problem.

check the vacuum line going to the petcock at the bottom of the gas tank. You can actually pull the other end off and suck on it and that should let fuel go through the line to the carb.

Take off your fuel filter and see if you can blow through it, if no it need replacing

if you have fuel getting to the carb take the bowel off and see if it has gas in it, if not take it all apart and clean it out.

You can also try just squirting some starter fluid into the intake and see if it fires up, then you would be pretty sure there is a fuel problem.

[Alleyoop]

Well if you have compression and spark, I suspect 2 possible problems:
1. TIMING since you put in a BBK
2. Fuel being sucked into the intake.
Now if the timing is off it will not suck in fuel at the correct time.

So if you can line up the CAM at TDC two little holes even with the top of the head and the big hole straight up THEN TAKE A PICTURE of the TIMING CASE POINTER and the FLYWHEEL to see what the timing is.
Alleyoop

[lacrosseguy]

bleh. my timing was off and when i was turning my flywheel it wouldn't line up perfectly but i got it as close as it would stay. it sounds so close to turning over but wont ):

[lacrosseguy]

tomorrow ill go get a compression gauge from autozone also,will this one work www.autozone.com/autozone/accessories/OEM-Compression-Tester-Gauge-Set/_/N-263y?itemIdentifier=424906_0_0_

if i do not have the needed compression ill order another set of rings and gaskets.