wont start

[ccmnova]

just cant get it started - new carb, new tank petcocks, new kill switch, new fuel lines/filter - NOW IT WONT START !

[firstturn]

What bike?  little more details.  I think you just bought a new Bing?


Ron Carbaugh

[ccmnova]

74 125 6 days. New Bing carb. Plug is wet but no spark, it ran well before i did some work on it. Can't understand it

[242]

check the kill button again

[ccmnova]

Disconnected the kill button - still no spark.  Can someone help me with the wires coming from the motoplat - there is some kind of connector on the bike but its all corroded - please if you can tell me where the various colored wires should go....

[ccmnova]

here's the connector coming from the motoplat - all corroded anyway.  Should i just eliminate it ?

[Steve Minor]

Search Wiring Diagram on the site's search feature. There are several conversations that might help.

Steve Minor

[Richard]

The wires going to the terminal block that your picture shows are all used for lighting. They don't have anything to do with spark. You said the bike had spark before you worked on it and that you installed a new kill switch. I'm just guessing that your kill switch connects to a wire at the coil under the tank. There should be two blade type connectors at the coil, the top one larger than the other. The large one probably has a pig tail off of it that goes to your kill switch. Make sure that that pig tail is not grounded. It might help if you post a picture of the coil with the fuel tank off, you never know we might notice something wrong. If the blade connectors are clean and bright and fit tightly to the coil and you still don't have spark with a new spark plug (don't use a resistor type plug), you might try checking that the coil is grounded to the frame, the engine is grounded to the frame, and that the motoplat stator is grounded to the engine. Just to be clear, all of these grounds require good metal to metal contact, which means no paint or corrosion between the components. Best regards, and try to have some fun working on your bike. It's a good machine and deserves your best efforts.

[ccmnova]

Here's a couple picks of the coil area with the tank off.  I took off the coil and cleaned/sanded all contact points, then ran a separate lead from one of the mounting bolts to the engine.

Still no spark.......

[Richard]

A couple of things. That sure is a lot of electrical tape on the wire harness up next to the coil. If the coil wires see ground then no spark. If you have an ohm meter, disconnect the coil wires from the coil and read back to the a good engine ground. Both wires should be about 375 ohms. If it's less than 10 ohms or so, I'd be looking for bare wire in your harness. If you don't have a ohm meter, first go back down to your terminal block and pull the blue wire out of the block. It looks like that might be connected to the upper connector at the coil. It also looks like you have another wire spliced into the upper coil wire that is going to a kill switch. Make sure that wire isn't grounded. I think I'd open up all of that electrical tape and look how the wires are spliced. You may have an open wire in there. Also, it looks like you have at least a cut in the wire insulation right next to the upper coil connector. It looks like it may be the kill switch lead, but if it's a stator wire, make sure the wire is not broken there. And one more thing, what type of spark plug are you using? Have you tried another plug?

I'm going on the assumption that the engine had spark before you did some work on it and that you may have moved some wires around or a wire has pulled loose in your harness.

[ccmnova]

Took your advice and opened up all the tape - at least pretty far down to where that old terminal connector was (got rid of all that).  Ran a separate ground wire from the coil mount to an engine mount.  Disconnected and got rid of the kill switch wire for now.  Used heat shrink tubing at the joints and some good fresh tape - everything looks good and I HAVE SPARK !!  now am afraid to put everything back on and try it.....will do tomorrow.  The plug i'm using is an NGK B8HS. The manual says to use a .020 to .024 inch gap (seems very small)  - please let me know if that plug and gap are recommended.

[ccmnova]

also want to ask if there is a replacement for the old motoplat coil - it's just so old...

[Richard]

Glad to hear that you have spark, good job. If you want, you can replace the coil with a new PVL coil. There are lots of suppliers that sell PVL ignitions, one of them is Penton Racing Products. They know more about ignitions then I ever will and I'm guessing that they can answer your question about spark gap better than I can.

Here is a link to their website for some reading if you want, and it has a contact phone number. Give them a call.

http://www.pentonracingproducts.com/

[ccmnova]

No spark this morning - I give up !!!

[firstturn]

Just reverse anything you did last evening when you stopped working on it.  You are not the first to have these issues and as Richard so justly stated you are chasing ground and bad wiring problem.  Don't give up.  I have run these ignitions since 1972 and have had great luck with them.  Good luck.

Ron Carbaugh