1e40qmb lost spark :(

[Deleted]

So my 40qmb big bore swapped spree was running great when I rode it yesterday morning. Parked it for 30 mins and it wouldn't fire. Weird..I was thinking it was flooded with a fouled plug cause it fired twice briefly then I pulled the plug and saw I had no spark? Well how could I lose spark when it fired briefly?? I pulled off the fan cover and saw the pickup sensor mount was broken so I thought for sure that's what it was. I swapped stators with a oem zuma one I have and nothing!! It's possible the zuma stator was bad but I was told it was from a running bike..I'm thinking maybe when the pickup broke it sent a signal to the cdi and fried it? I bough a 40qmb stator and a 86 spree cdi on eBay but this has been bugging me all night. Could the regulator be bad? My lights work and it turns over I seriously don't get it

[gy6fandan]

Hello,


Try the link below, hope it helps.

The Ultimate GY6 Starter & Ignition Troubleshooting Tutorial

[Deleted]

Regained spark after flicking the kill switch a few times? Now the bike is acting like it's not revving out. Can't even go past 15 now. The fuck. At first I thought fuel but after pulling off the bowl and making sure the jets were clean I have no idea. I swapped plugs and stators and now I can't go anywhere

[Elektrey]

Replace CDI sounds like its fried.

[Deleted]

replaced zuma stator with the Chinese one and I was able to get back into the powerband but it cuts out throughout the powerband like its really lean or not getting a good spark. so frustrating cause this thing ran like a dream yesterday

[niz76]

My scoot was "cutting out" and it ended up being a cylinder head leak. Just an idea...

[Deleted]

I've noticed a little oil from underneath the base gasket but I snugged up the bolts awhile ago and this problem is very recent. I had another mention bad ground possibly.

I'm thinking ground, coil, air leak, electrical issue

[maddog21]

Sounds like the gasket is leaking change that and see what happens

[90GTVert]

Fix that base gasket leak. Even if it's not the cause of this, air leaks are hard on 2Ts. They can cause lean conditions and soft seizes.

Since you said flicking the kill switch on and off changed your no-spark condition, I'd try to see if that is having some sort of intermittent short. You can run the scooter with the 1 wire for the kill signal to the CDI disconnected. If it's fine then, you know something is up with the kill circuit. Just be aware that the scooter will not shut off with the ign or kill switch so it's not the safest thing to do and do it at your own risk. Best way to shut it off would be to make sure that wire is somewhere it's easily reached, then touch the end to a ground or reconnect it so the kill/ign switches will work again. Pulling the plug wire off kills the engine if all else fails, but it will shock you so it's not a great idea.

Also check your spark plug gap and condition. Gapped too wide they'll break up at higher revs. Stock should be something like 0.024-0.028". You can gap it tighter by 0.010-0.012" or so for a test as well and if it stops breaking up that way you can be pretty sure something in the ign system is weak.

If you have access to a known good CDI, try it.

[niz76]

Or at least if you're pulling the plug cap to kill the scoot, grab someone else first so it passes the shock onto them instead of you haha.

[Deleted]

Oct 1, 2014 9:30:51 GMT -5 90GTVert said:

Fix that base gasket leak. Even if it's not the cause of this, air leaks are hard on 2Ts. They can cause lean conditions and soft seizes.

Since you said flicking the kill switch on and off changed your no-spark condition, I'd try to see if that is having some sort of intermittent short. You can run the scooter with the 1 wire for the kill signal to the CDI disconnected. If it's fine then, you know something is up with the kill circuit. Just be aware that the scooter will not shut off with the ign or kill switch so it's not the safest thing to do and do it at your own risk. Best way to shut it off would be to make sure that wire is somewhere it's easily reached, then touch the end to a ground or reconnect it so the kill/ign switches will work again. Pulling the plug wire off kills the engine if all else fails, but it will shock you so it's not a great idea.

Also check your spark plug gap and condition. Gapped too wide they'll break up at higher revs. Stock should be something like 0.024-0.028". You can gap it tighter by 0.010-0.012" or so for a test as well and if it stops breaking up that way you can be pretty sure something in the ign system is weak.

If you have access to a known good CDI, try it.

the studs are as tight as they get and i have good compression.. ill double check for leaks and retighten if i can.

i pulled the kill wire but i can still shut the bike off with the key just not the switch. and the problem still persists. ive tested for grounds with an ohm meter and im good there. im pointing my finger at the cdi, its the only thing i havent changed and since this problem has gotten gradually worse it makes me think the cdi lost some juice and my timing curve/rev limiter changed. 

i went from a few sputters and cutouts throughout the powerband to the bike feeling like its bouncing off rev limiter as soon as it hits the power. it still gains speed but its just bouncing off the limiter...i dont get that, like its gotta be an air leak leaning it out or the cdi. im sooooooooo frustrated with this

[90GTVert]

You can put all new parts together with new gaskets/sealant/etc... and still get leaks. Leaks below the piston crown don't generally change compression... well, not secondary compression which is what most people think of. Intake, case, and base leaks can allow additional air to be drawn in though. They can cause some crap that is hard to hunt down without a leak tester like random seizes when the engine appears to be in a good state of tune. IMO anyone serious about building and servicing their own 2T should have one of these...

49ccscoot.proboards.com/thread/506/make-2t-leakdown-tester

The CDI can do what you describe... or other ign components. Actually sounds more like an ignition issue to me from the symptoms, but I wanted to throw the info out there since leaks were mentioned. Sputters tend to be a rich condition... which is not just from large main jets and such but if the ignition system is not up to par it can do the same. A spare CDI is a good tool. Can't really test a CDI without some special tester that I know of, so when you run across one cheap on eBay or wherever, it's worth getting one even when the scoot is running just fine.

[Deleted]

Oct 1, 2014 16:02:57 GMT -5 90GTVert said:

You can put all new parts together with new gaskets/sealant/etc... and still get leaks. Leaks below the piston crown don't generally change compression... well, not secondary compression which is what most people think of. Intake, case, and base leaks can allow additional air to be drawn in though. They can cause some crap that is hard to hunt down without a leak tester like random seizes when the engine appears to be in a good state of tune. IMO anyone serious about building and servicing their own 2T should have one of these...

49ccscoot.proboards.com/thread/506/make-2t-leakdown-tester

The CDI can do what you describe... or other ign components. Actually sounds more like an ignition issue to me from the symptoms, but I wanted to throw the info out there since leaks were mentioned. Sputters tend to be a rich condition... which is not just from large main jets and such but if the ignition system is not up to par it can do the same. A spare CDI is a good tool. Can't really test a CDI without some special tester that I know of, so when you run across one cheap on eBay or wherever, it's worth getting one even when the scoot is running just fine.

i am going to ace hardware after i finish this reply to purchase the parts for a leak down tester. i originally wanted to do it but my more mechanically inclined friend said it wasnt necessary and just do a compression test..  

i have a cdi and stator on the way it should be here friday. i dont have an up to par igniton system.. i was told it wasnt necessary for this build even though this crank is rated for 16000 rpms and the pipe for 14000. the bike ran very consistant and solid at the drags friday night. saturday morning it lost spark so i tried all day to figure that out, one of the things i tried was swapping in my zuma stator and Sunday after playing with the kill switch i got spark back but with the zuma stator in, the bike would not go into the power band. the power would get cut right before and wouldnt budge. swapping back in the chinese stator i was able to get into the power band but its not at all what it used to be like. its got me scratching my head cause i dont know what went out. 

so the ignition sytem right now is: 
stock cdi
chinese stator
zuma flywheel
2 wire coil
champion plug
im doubled up on grounds too..