Please help with no-start issue

[frysause]

Hey all, I have a buddy 125 (161 kit w/ big valve head, etc) engined Honda Metro (bought from Crackerman, think he posted it here when he was building it).

Anyway, it ran like a top for at least 3k miles until it cut out on my way home from work. I was unable to get it to restart.

- the starter cranks
- there is fuel flowing through the carb
- there is spark
- there is compression
- ?
Starter fluid doesn't help.. I have had to use it after it sits for a few days in the past

I put in a new spark plug
I replaced carb and fuel pump (Met fuel tank is in floor board).
I drained the tank and put in fresh gas
I replaced the CDI and the coil with Bando units from the guy on eBay.

I am now at a loss. My next theory is the stator but at this point I have run out of ideas and would just be throwing parts at it.. I don't really want to do that, obviously.

The local Genuine dealer went out of business and I don't really want to truck it 50 miles to the next one, but at this point it might have been cheaper (if they would have even touched this frankenscoot).


Any ideas or anything would be greatly appreciated!

[jrsjr]

...My next theory is the stator but at this point I have run out of ideas and would just be throwing parts at it.. I don't really want to do that, obviously.

...

Any ideas or anything would be greatly appreciated!

The part on the stator that will cause the bike to instantly stop running if it fails is the ignition sensor. That must be working in order for you to have spark. And you say you have spark, sooooo...

In order to have internal combustion, you gotta have spark (at the right time), gas (in the right air/fuel mixture), and compression (high enough to sustain combustion). In your case, one of those must have failed suddenly. So, the Psychic Mechanic Service is putting bets on incorrect fuel air mixture caused by carb malfunction. The Premium Psychic Mechanic Service thinks you sucked a big ol' piece of trash into your jets (or your main jet backed out and fell into the float bowl). OTOH, the Frankenstein Institute Non-Local Mechanics are putting their money on a stuck valve in that trick big-valve cylinder head of yours. You don't need exotic equipment to check that, just a compression guage.

I hope this helps or at least keeps you busy (and entertained) until one of our real mechanics shows up. I hope you'll be rolling this weekend.

[mhardgrove]

Have the coil pack checked and see if it's getting spark to the plug.

[frysause]

Thanks for the ideas.

I will pick up /borrow a compression tester to see exactly where I'm at but my automotive service manager brother in law said compression was good. The top valve was fine, didn't check the exhaust side. Will try that next.

The carb is brand new (jets and all) as is the CDI and coil but I will be sure to test the coil when I get home tonight (the old ones tested fine too but I wanted to upgrade anyway).

Was hoping there was something obvious we missed but it's never that easy, is it?

[jrsjr]

Thanks for the ideas.

I will pick up /borrow a compression tester to see exactly where I'm at but my automotive service manager brother in law said compression was good. The top valve was fine, didn't check the exhaust side. Will try that next.

The carb is brand new (jets and all) as is the CDI and coil but I will be sure to test the coil when I get home tonight (the old ones tested fine too but I wanted to upgrade anyway).

Was hoping there was something obvious we missed but it's never that easy, is it?

Rats! I missed in your OP where you said compression was good. My bad. Sorry! The thing is, now that I see that, it sounds like you have the nominal basics of internal combustion. Normally, I'd say stop and first make absolutely certain that your battery is good, but, if the battery will pull the starter motor, that usually means the battery is not a worry.

You're really at the point of having to go back and double-check everything, just as it sits right now. Go through it step by step. Verify that the battery is good. Then verify that you really have a nice blue spark by holding the plug against electrical ground while you spin the motor. Then put the plug back in and try spraying starter fluid into the carb intake again to see if it will start. If you have a nice blue spark and you spray starter fluid directly into the carb intake, it should at least try to run for a second. If it won't do that, then I'd be suspicious of the valves and check that again. A sneaky hidden major mechanical failure may be at the root of this, but that's very unusual and you should have heard something when it stopped if that happened (plus something should sound wrong now when you turn it over).

One sneaky electrical problem that sometimes catches people out is a short in the kill switch wiring, but the way I read the schematic, you should not have spark if there's a short in that wiring. If you have spark, that rules that out. Hmm...

Seriously, the best thing I can suggest is to clear your mind of all assumptions and check everything again, starting with the battery, the fuses, spark, fuel (try starter fluid), compression and see if something shows up.

[agrogod]

And now for the simple question. Did you check the kill switch?

[jrsjr]

And now for the simple question. Did you check the kill switch?

The problem with that theory is that, if the kill switch is shorted out or shorted to ground, then he would not have spark, which he says he has. The reason for this is that the Buddy kill switch works by shorting the ignition trigger wire to ground (see schematic below). No trigger, no spark. That's the same reason why I've ruled out the ignition trigger coil on the stator...

[frysause]

Really wish it was as simple as the kill switch!

Battery is freshly off the tender (full charge) and will probably go ahead and replace fuses when I get a chance after work this evening.

I am starting to get the feeling it is something electrical just because I remember my GPS that was in the 12v outlet fried shortly before the engine cut off.
Does this help anyone? It is the second GPS I have had do this from exclusive use on the scoot. The first I chalked up to a faulty unit but the second, now I wonder...

[agrogod]

Now that is a useful bit of info. Possibly an electrical surge from the charging circuit? Multimeter time.