2007 Kymco Grandvista 250 no spark By garyv (Read 2,926 times)

[garyv]

This really has me stumped.   The scooter sat for about 3 years and ran perfect when parked.  I started out by removing the fuel tank and dumping the fuel.  Added a gallon of fresh fuel.   I had fogged the engine so it turned over easily.  I installed a new spark plug and it fired right up.  Had it on the center stand and ran it for several minutes.
I then decided to perform routine maintenance.  I mounted two new tires, replaced the air and fuel filters, changed front and rear brake fluid, engine oil, drive axle lube, and coolant.  In doing so, I had it running to bring up to temp and bleed air out of cooling system and it was still running well.
I had almost all of the plastic off so with the maintenance complete and it running well I installed all plastic and put in a new battery.  
The next night I was going to take it for a test drive.  It wouldn't start.  No spark at the spark plug.  I bypassed the safety switches for the rear brake and side stand.  I started to pull off all the plastic while checking for disconnected/pinched wires.  Nothing out of line found so now I am thinking something decided to fail coincidentally to my reassembly.  All plastic has been removed as I checked all connections.
I checked the primary and secondary resistance at the ignition coil and they were within specs per the service manual.  I checked the resistance at the two wires from the pickup coil from the stator - ok.   The service manual tells me to check the black/white exciter coil wire from the AC generator.  I don't have a black/ white wire in that area.  In fact they say it is on the right side of the bike and I don't have a wire like that there at all. 
I then traced battery voltage from the fuse block to the ignition coil.  I followed that power circuit all the way to the cdi and to the coil and I have battery voltage throughout.  This made me think I have a bad cdi so tonight I installed a new one.  Still no spark.  
I've got to be missing something but this thing has me stumped.  Any ideas?

[cyborg]

Check all grounds,, particularly the engine to frame

[ellpee]

Very impressive list of things you checked, but the first thing I'd have checked would have been the plug wire. Maybe you did that and didn't mention it?

[garyv]

I checked the resistance from the coil primary through the plug wire and it was within the ohm spec in service manual.  Is there another way to check it?

All engine grounds are good.   I followed as many of them as I could by using the wiring diagram in the service manual

[ellpee]

Your checking skills are way above mine. What I've done is first see if I see a strong blue spark across the plug gap, and if no, remove the plug and put a nail or screw in the plug boot and see if I get a strong blue spark from that. If no, conceivably there's just something wrong with the plug wire itself, rather than the more complicated electrical stuff upstream. Simplest-to-hardest theory. But it's certainly possible what you did covers the same territory; I'm not enough of an electrician to know.

[garyv]

ellpee,
There is no spark from spark plug (tried two different ones) when help against and grounded to the engine. To confirm proper ground I also clamped a heavy wire from the threaded portion of the spark plug to the negative terminal of the battery.
My "checking skills" come from many years as an auto tech.

[cyborg]

Cdi is bad

[garyv]

As with all parts, I guess I ordered and received a defective one (CDI). To confirm and because I decided I have had enough with it, I took it to the local dealership last week. They checked it and agree, the CDI is bad. I decided to let them replace it to keep the burden of correct diagnosis with them. They had to order it and it is supposed to be in this week.

[ellpee]

What a saga. The good news is, you at least had a local dealer who would work on your scoot and -- presumably -- stand by their work. Would that I'd have been so lucky with my MAINLAND Chinese scoots, Roketa and Ice Bear. Who'da thunk it, in a metro area of close to a million (Tucson) nobody wants to touch anything Chinese. Lesson learned should I ever buy another scoot, though that's very unlikely: price ain't everything.

[garyv]

Well, it might be good they will work on it but when I checked yesterday they had put the new CDI on and it still has no
spark. Now they need to dig into diagnosis again

[cyborg]

Hall effect sensor

[ellpee]

Sept 30, 2017 7:23:50 GMT -6 cyborg said:

Hall effect sensor

Ah, another learning opportunity for Ellpee. I read up on WHAT that is, but WHERE is it on a scooter? From the Wikipedia description I'm guessing it's somewhere down near the rotor/stator stuff. Is it a wee gizmo that can be replaced individually, or is it built into some larger, more expensive assembly?

[cyborg]

It's just the trigger coil that tells everyone else in the chain of ignition to fire,,,, and should be a small coil held on by a 10mm bolt right next to the flywheel/stator

[garyv]

Cyborg,
Would the Hall Effect sensor be what my service manual is calling a "pick up sensor"? There are two wires for it - the pick up sensor - (plus the 3 wires for the three phase charging) coming from the the stator area. There is a spec for ohm's of resistance between those two wires in the manual and my readings were right in the middle of the stated range.

[cyborg]

Yep