I had a vertical pull Quantam motor that the pull start was broken so I figured I would just swap it over to a horizontal top pull, can't be that hard. I ended up spending hours messing around, modifying this, then that only to reach the conclusion that the flywheel being thinner on the top pull has the coil sitting a bit higher on the flywheel means the spark is not right. I got it to run a couple of times for a few seconds but that was about it. I will try lowering the coil but if that doesn't work I guess that is the end of it. All part of seeing just what you can achieve and keeps you on your toes and the grey matter turning over
Just to update this I got back to it, ground down the coil mounting points by 10mm , got spark and it runs well . Big effort but a good learning experience