Bike won't start. Help getting in right direction.

[mrhammer2u]

I've researched and checked how to's but I'm not very mechanical. If I could at least narrow my issue I may be able to figure it out.

She ran perfectly couple weeks ago. This weekend she would not start. Turns over,..but not much combustion sound. It tried once for about 3 seconds,..then nothing.

The fuel should be fine since I fill up every couple weeks. Nothing sitting around.
I put a timing light on the plug wire close to the boot and current is flowing. I did not use a multi-meter so I don't know the strength of the spark. The plugs were dead (only a year old) so I replaced with new, gapped to .030.

She tried to start but only combusting for about 3 seconds,..maybe 5 this time. Then just lots of starter and motor spinning sounds again.

Thought maybe it was flooded but I left the plugs out for a while so any gas could escape. I visually inspected, best I could, inside the cylinder and no gas was visible.

Gas is flowing. I know this because carb #1 has a leak But this may not mean much?

I tried choke, half choke and no choke....nothing.

Fuses under side panel seem ok.

Thoughts?

[IanDMacDonald]

Combustion, fuel/air, and spark. Rule it out. Manually check each plug against the block. Give each float bowl a tap. Check your coils to make sure primary/secondary are within spec. Check for unplugged connectors. Check each fuse. And, make sure your advance did not fall-off your crank-locator pin.

[dbeardslee]

Might check your battery too. Should show about 12.6 volts. You can load test it by attaching dmm leads to the battery, then turn the ignition on. Voltage should drop a bit, but should still be over 12v. Then hit the starter and watch the dmm. It should drop to around 11v while cranking, but should bounce right back up over 12v when you stop cranking.

You might also check your voltages at the TCI. Stick a probe in from behind the big connector while it's plugged in with the ignition turned on, and check the grey to ground (12v) white/red to ground (12v) black/white to ground (6v) orange to ground (12v) and red/white to ground (12v).

[mrhammer2u]

Combustion, fuel/air, and spark. Rule it out. Manually check each plug against the block. Give each float bowl a tap. Check your coils to make sure primary/secondary are within spec. Check for unplugged connectors. Check each fuse. And, make sure your advance did not fall-off your crank-locator pin.

I've identified where the crank locator pin is (Google images) but how would I know if the advance fell off? Trying to find out what an advance looks like and where it would be....

I have to remove the gas tank to get to the coils you're referring to,..correct?

This is NOT my bike,....just the image I was referring to.

[aquamantx]

Might want to pull the plugs and put you finger over the plug holes. Make sure you are getting compression.

[mrhammer2u]

Might want to pull the plugs and put you finger over the plug holes. Make sure you are getting compression.

So remove all 4 plugs and put my thumb over one of the holes then hit the starter,...right? I know I should feel some air but what's the indicator? My thumbs compression meter hasn't been working

[mack]

Trouble shoot

As Ian said: air, fuel and spark must be confirmed. Remove one and you can't have fire. Fuel shouldn't be an issue, as it is unlikely fuel would stop flowing to all the carbs at the same time and these bikes will start with just two cylinders. However open your gas cap and see if you have a vacumm lock there preventing the the tank from fill the carbs. The air hole in the gas cap may be plugged. Thats the easiest thing to check.
You say the fuses look good, do you still have the old glass tube fuses? These are notorious for looking ok but really they aren't. Pull them out and check them for continuty with a voltmeter or replace them. Upgrade to TC blade fuse panel soonest!
If the battery isn't providing enough voltage the bike will not run! They run off the battery, the motor charges the battery. You need at least 12.4 I believe for it to run.Follow dbeardlee's suggestion for the check on the battery. Report back after you check this stuff out. Timing is not an issue if it was running before you parked it!

[dbeardslee]

You need at least 12.4 I believe for it to run.

3Phase spanked me over that one not too long ago. He said you need 10.5 volts at the TCI for it to run, but that it wouldn't be happy.

Connectors can rob quite a bit of voltage between the battery and the TCI, so you need to check both the battery as well as the voltage the TCI is receiving.

And depending on your riding style, you may be discharging your battery more than you might think. It takes about twenty minutes of riding above 2500 rpms for your battery to recharge from an electric start. So if you make a lot of short trips it can take it's toll on the battery. I recently started using a Battery Tender Jr. on mine because I make a lot of short, low rpm trips around the neighborhood, and I was amazed at how long it was taking for the battery to charge back up. One sure way to booger up a lead acid battery is to let the voltage drop too low for too long. A battery can get sulfated that way. JAT

[IanDMacDonald]

So remove all 4 plugs and put my thumb over one of the holes then hit the starter,...right? I know I should feel some air but what's the indicator? My thumbs compression meter hasn't been working

When you're doing this, remember to ground your spark plug to the block, otherwise you risk harming the coil.

Don't go overboard with everything, and everyone's suggestions. Make a chart and be methodical. Start with the easy, common-sense things first: battery voltage. 12+v? Check. Source voltage at the coils? (12+v). Check. Let's see if you have spark: remove one plug at a time, ground it to a fin, and hit the starter. Spark? Do all four. You have spark.

In-between checking for spark, put your thumb over the spark plug hole and see if you have pressure against your thumb. (sure check is with a compression gauge).

Third check is fuel delivery. Place your petcocks on prime, and attempt to start your engine with full choke. If no-go, put them back to "on", so u don't get gas in your oil just in-case u have faulty needles.

[aquamantx]

Thanks Ian. Job has had me out and about. It is just a quick check to see if you have any compression.
I have had motors where valves have stuck or cam chains have quit and this has helped track it down without gauges available.

[motoman]

I've identified where the crank locator pin is (Google images) but how would I know if the advance fell off? Trying to find out what an advance looks like and where it would be....

I have to remove the gas tank to get to the coils you're referring to,..correct?

This is NOT my bike,....just the image I was referring to.

Correct to your second statement. BTW, if your gonna either own or work on these older scoots(and ALL other older csoots), you BETTER learn their eletrical and fueling systems!

[ViperRon]

One more thing to look for is if you have no or poor spark then the gas will make the plug wet and when you crank the bike over with all plugs out open the throttle wide open you will more than likely smell gas vapor pumping out the cylinders. When looking for spark from plugs you need a blue spark so if it looks like a yellow that may be a weak spark that may not ignite under compression. No gas smell then pour just a little gas less than half a tea spoon full in each cylinder screw pugs in by hand fast, caps on, and crank it if it fires its probably a fuel issue if no cylinder fires at all continue with electrical some area common to all cylinders. Fuse voltage ground emergency cut off switch safety tip over switch. The emergency switch if not used for a while can corrode or have moisture inside and you bump it and then have problem. Bike falls over and the emergency tip switch sticks or you wash it or leave it in rain and it gets wet. Oil leaks into pick up switch connector near shift leaver on some. I am giving these simple checks tips assuming you have few tools meter or knowledge of electrical testing. If you have a meter there is a current thread where dbeardslee and a few others went through all checks on the electrical ignition system with catonicbug.

[mrhammer2u]

I haven't bailed on my thread. Should be able to update with progress by end of the week. Thank you all for the tips and I will report back.

[tomcos67]

Won't start

Did any body mention pull timing cover off jigle wires??When she cranks but doesn't fire!!!.??That's what happened to me couple times.(moisture).good luck....

[mrhammer2u]

Combustion, fuel/air, and spark. Rule it out. Manually check each plug against the block. Give each float bowl a tap. Check your coils to make sure primary/secondary are within spec. Check for unplugged connectors. Check each fuse. And, make sure your advance did not fall-off your crank-locator pin.

Reporting back. The Mechanic got bike started. Said float needle on carb 1 was sticking. Everything else seemed ok Really? 1 needle can make a 4cyl bike not start?

Told me if it happens again to give the float bowls a tap (also credit sue to Ian in my quote)

Battery was dead but that's after I spent half hour trying to start her up.