Ok so my bike won't spark. Ive tried everything I could think of. I checked for spark, and I'm not getting any. I checked the magneto, sanded and checked all the grounds, checked my wiring, re did the wiring In between the CDI and the spark plug. I'm stumped. I don't have an ohms meter so I can't check those. What happened was I was biking along and it just quit. Then I had intermittent popping, and now it won't even pop once. Got lots of gas and there oil and what not coming out the exhaust from me biking up and down the street trying to start it. I've searched alot of forums tryung to figure it out and I just can't. Short of replacing the CDI and magneto(i don't want to wait for parts to be shipped) or buying a complete new motor and having my current ones for spare parts, I don't no what to do. Help please?
help please?
- Thread starter bran8301
- Start date
dougsr.874
Active Member
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- Sep 15, 2008
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There is no Magic answer to your problem...either go buy an ohm meter or order a mag & cdi....I've had more problems with the mag than the cdi's. Replace the plug first
Sidewinder Jerry
Well-Known Member
Yes sometimes its the simplest of things. If you have a lawn mower you can test the plug before you buy another one. Inspect for any damage to your electrical system such as missing insulation or burn marks. These bikes are going to break down. If you wish to continue riding them then invest in to the tools it'll take to repair them.
KCvale
In memory of KCvale 1959 - 2019
You really need a meter.
You don't need a fancy $80 multimeter either, you can buy $10 analog multimeter's all over the place.
My troubleshooting procedure is simple these days.
Disconnect everything.
Ohm the black magneto wire to a head bolt, it should read a dead short (0 ohms).
If not, check the ground tab on the magneto.
Note:
The new skyhawk CDI's have no white wire, ground is the lower connector but it has a wire from it to ground.
Old style mags with a white wire have a tab out of the mag that solders directly to the mag base and they can come loose, just hold it down and re-solder.
Ohm the magneto from the black and blue wire, 320-380 ohms is ideal, an open or dead short means a bad magneto if the wires are connected.
Ohm the CDI in the 10K-20K scale.
Red+ meter probe to CDI black wire.
Black- meter probe to the spark plug cap.
You should get about 6.9K ohms.
If not it could be a bad wire or cap.
Unscrew the plug wire at the cdi, use pliers or even cut it off and dig the junk out if need be and do the same test above again to the cable screw on the CDI.
If that works get a new wire and plug cap, if not you have a bad CDI.
If all of that is good there is only one thing left, the magnet.
That was indeed the problem with a recent repair on a new build with a 2014 gasbike.net front page engine kit.
When you pull the 4 bolts out of the magneto mount it should slam itself against the magnet, I mean to the point where it is hard to even get your first bolt in.
A weak magnet that lets you move the mag around pretty easily is not strong enough to create a spark which is what this repair had.
Magnet replaced, problem solved and my repair is done.
V 35
Member
K C Vale did a great job explaining the troubleshoot, My thanks to him, I recommend printing his reply for future problem solving.
My own spin ... Buy a spare Mag Coil, and a spare CDI box. Put them on a running bike . Now you have * Known Good * spares, which beat new, but untested, any day.
My own spin ... Buy a spare Mag Coil, and a spare CDI box. Put them on a running bike . Now you have * Known Good * spares, which beat new, but untested, any day.
AssembleThis
Member
Backup Parts
Hi bran8301!
Do yourself a favor. Buy backups for everything that can down the bike for an extended period. I love my bike and couldn't handle being without it so I ordered and received 2 Magneto, 2 CDI, 20 feet of 41 chain and 4 master links etc. etc., you get the idea right? If you want to keep it running order that which may fail so there's no wait time to get it rolling again. Oh and yes I also ordered a backup engine. Go to Harbor Freight Tools and register, sign up for their email. Occasionally they will send an email that has a special deal, free items just for coming over. I've gotten 3, 7 function multimeter that way. Hope this helps.
Dave
AssembleThis
Hi bran8301!
Do yourself a favor. Buy backups for everything that can down the bike for an extended period. I love my bike and couldn't handle being without it so I ordered and received 2 Magneto, 2 CDI, 20 feet of 41 chain and 4 master links etc. etc., you get the idea right? If you want to keep it running order that which may fail so there's no wait time to get it rolling again. Oh and yes I also ordered a backup engine. Go to Harbor Freight Tools and register, sign up for their email. Occasionally they will send an email that has a special deal, free items just for coming over. I've gotten 3, 7 function multimeter that way. Hope this helps.
Dave
AssembleThis
KCvale
In memory of KCvale 1959 - 2019
Thanks V 35, I don't mind sharing when I have time and have this and some other things printed and tacked on my shop wall for reference, but then again we build and service a lot of bikes week after week here.
You might like this as well, it has pics ;-}
http://kcsbikes.com/topic.asp?TOPIC_ID=623
As you will see I don't use stock ignition parts down to wiring on my 2-stroke builds and it makes a big difference.
Just a secret tip if you want spare parts...
The gasbike.net front page $173 66cc engine kit by parts has 55% off all parts and the order form lists them by part.
When you get to the final 'place order' page you can bump the count on individual parts and get them at 55% off.
Throttles, clutches, CDI's, Mags, and Chain are things I usually add a couple of extra's but then again if you just have one bike don't go crazy like I do, but get what makes sense when you get them at 1/2 price.
