Electrical whoas

[stevo3176]

I just bought a 86 yamaha moto 4 for the kids to ride on and I am having electric problems. I bought this machine as a non runner thinking that the top end needed to be rebuilt. The previous owner said that the quad was hard to start butwhen it ran it ran fine. If he stopped and let it sit for a long time it would be hard to start. This why I thought it was the top end. So I go to check to see if it had spark and of course it did not. After tinkering with it I could see that it did have some spark but not all the time. This is what happens when I run the started there is no spark at all but as soon as I let off the starter switch I get one shot of spark. What is strange is that the strenght of the spark depends on how long i run the starter before I let off. So If I run the starter for 20 seconds I get a nice fat spark but if it runs five secs I get a little one. This only happens once only when I let of the starter. Needless to say I am very confused. Anyone have any experience with this type of problem?????

[underpowered]

hmm. that is kinda odd. but i can explain why you are getting a stronger spark at the end of a longer crank time. it simpl is spinning longer and has more time to build up a charge. it could be your voltage regulator not letting the chage go through, could be yoru stator, could be teh CDI, could be many things. the best way to check is to get a service manual and a volt meter and start checking to see if the electronics are in spec. teh only problem is the CDI cannot be checked and can only be checked by replacing it with a known good unit.