Help! rebuilt engine, no spark......

[fireblade]

I just rebuilt my nq50 motor.
I used to ride it to work everyday untill it got slower and slower and slower. Untill one morning a guy on a push bike burned me off. So I parked it up, and started riding another scoot. I tried to run it some time later, and it wouldn't start. I found the crank seals were leaking, and the crank was out of true.

fast forward a few years.
I stripped down three engines, and embarked upon full rebuild using the best bits. I had a crank trued up by an engineer. And I've replaced the crank seals, crank bearings, final reduction bearings, and seals, and all the gaskets. not to mention new rings, and a head with .016 shaved off it and a ported intake too.
So I carefully assembled all the bits, reusing the alternator, and ignition inducer from the scooter, as well as the rest of assumed to be good parts from the original scooter.
In order to set up the throttle cable into the throttle control, I tried to fire it up for the 1st time today. And wouldn't you know it, It wouldn't fire. I had changed the old fuel out of the tank too.
So I tried another spark plug earthed on the body, and cranked it over, but saw no sparks. I also tried a different plug, and a different (but still unknown) coil. But to no avail.
So What do I try next? I supose there's a chance that the coil had crapped out before I retired the scooter. (rememebr it wouldn't start last time I tried) But I chalked that up to the poked crank seals.

I also found when assembling it, that all the flywheels were a little different. and I had to try figure out which flywheel belonged to the crank I used. ALL the alternators I have were identical. And the mounting points were all the same. So I'm thinking it's unlikely that it's a fault with the ignition trigger sensor.

Where do I begin?????

I have a friend who is hounding me to get it fixed so he can buy it off me. (He's just lost his license, and needs some non descript transport so he doesn't get hassled by the man) So It's kinda urgent.

[Fishman43]

I just went through this very same problem on my Aero rebuild. With help from some of the furry critter friends on this here board (Thanks Mouse, and Bear!) and the handy dandy manual I was able to diagnose the problem using a Volt/ohm meter as my pulse generator (the little black cube right next to the outside of the flywheel), but that doesn't mean that is your issue.

Pick up the Volt/ohm meter at your local hardware or electronics store and break open the manual to find out the test limits for your electronics (eg. on my Aero the black/red stripe wire went to the Alternator Excitor Coil and should have read between 600-1000 ohms, wher as the blue/yellow stripe wire went to the pulse gen. and should have read 50-200 ohms).

By the way, you say you tried to ground ("earthed") the spark plug to the body. I assume you grounded it to the frame, and not the "body" since the body is plastic and wont ground the plug.

[bradmeehan]

I had this issue as well. Mine came down to a broken wire hidden under that shrink wrap coming from the pulse gen behind the flywheel. The tests above was how I found it.

[fireblade]

Thanks guys!
yeah, I earthed it to the frame, not the plastics. And a multi meter is already something I carry in my toolbox. Shame I don't have a printer, as the spree, and my computer aren't at the same locality.
Come to think of it, I was a bit un-gentle taking the spark sensor out of the old motor.

[fireblade]

I did a continuity test on the wire on my pulse generator, and it's not broken. I have two spare units, but the one off this bike has only one wire, whereas the two spares have two wires.

I was forced to use a different flywheel, and I'm worried that it could be different to the one that works with my pulse generator....

[Fishman43]

If the flywheel is from the same motor type it shouldn't be a problem. Did you check that the CDI unit was within specs?

[PimpinSpree]

post your results to

stator
pulse generator
cdi
coil
voltage regulator



also make sure nothing is grounded out, your ignition switch or kill switch could be the culprit too

[Bear45-70]

post your results to

stator
pulse generator
cdi
coil
voltage regulator



also make sure nothing is grounded out, your ignition switch or kill switch could be the culprit too

Voltage regulator has nothing to do with the ignition. The other 4 do, well part of the stator does, but not all of it.

[Gungatim]

How many volts coming out of the stator?

What is your resistance reading of the pulser coil?

Is your ignition coil a CDI coil and what are the resistance readings?

Double check all grounds! Not uncommon for the coil to get rusty/dirty where it grounds.

[PimpinSpree]

post your results to

stator
pulse generator
cdi
coil
voltage regulator



also make sure nothing is grounded out, your ignition switch or kill switch could be the culprit too

Voltage regulator has nothing to do with the ignition. The other 4 do, well part of the stator does, but not all of it.

I coulda swore a bad regulator could cause no spark. I'm probably wrong on that one, its been a long time since i've had ignition troubles. So you can you start a spree with the regulator unplugged?

[Bear45-70]

Regulator controls battery charging. The ignition system is totally seperate from the charging system.

[PimpinSpree]

gotcha. Makes sense and i knew that, but never thought of it when not thinking about the stator

[fireblade]

Just to bump my old thread,
The piece of sh1t is still inoperative. I got a freind to print off section 14 for me. And I've had a few cracks at it. ALL the three coils I have have too high a resistance on the primary circuit. They all show 0.9 ohms, where as the book says 0.3 max.
I might try the coil out of my evePAX and see if that helps.
Do coils give trouble often? One of the spares I have has "nifty" written on it in white paint pen, (Spree's were badged as niftys here) so it must have been replaced at some time. Although I found the scooter that came off at the tip, so god only knows what it's history was. (It did have an overbore, and was still in spec though )

I'd be lucky if it's 5*C here today, so It's hard to get motorvated to had out to the workshop and have another crack.

Also, the manual doesn't have any tests for the CDI module. It just says to change it?

[fireblade]

I tried the coil off my evePAX (It's resistance wasn't to spec either?) and still no spark.
Everything else has the correct resistance, except the alternator. It's 50 ohms under. I tried the other two I have with the meter, and one was dead, and one was in spec. But now I can't get the god damned flywheel off again. I'm almost ready to throw the whole thing in the dumpster!

[Wheelman-111]

Greetings:

It sounds like the Alternator isn't giving enough Motor-vation to them electrons. A common issue is previous attempts at removal with steering wheel puller. If the bolts are threaded into the flywheel too far, the ends produce gouges in precious copper windings and short the device out.

A tool like this one is the easiest way to remove the wheel. Call them to be sure you get the right size - they come in L- and R-hand threads. Honda's is RH.

If you're in a big hurry, thread a couple of expendable nuts to the crank end, hold the engine up by the flywheel and whack on the nut to drop the flywheel off its tapered crank end. I don't recommend this as ideal, but have done it a time or two before I got my puller.