No start condition

[somaaaa]

Hi.I have Aprilia SR50 DiTech,but it has been converted to a carb 2 years ago and it ran perfectly.Now i got a wierd problem-when i crank it it looks like it doenst have spark but when i remove the cap from the plug and put it cca 5-6 mm from the spark plug it starts spluttering and almost wants to start,but saddly doesnt . Any idea what can cause this? Also new 50cc kit was instaled 10 months ago and still has great compression.Thanks in advance

[scooter7878]

Have you tried a new plug and coil boot I'm thinking maybe somehow the sparks shorting to ground either from the boot or maybe a cracked porcelain on the plug I'd start there