1993 Pro V problems

[weims]

My Yamaha has started skipping under a load on Number 4 and 6. I have tried a new power pack, new triggers, stator, fuel pumps and a carb job but nothing has worked. Ii comes outta the hole great but then starts skipping at around 4200 rpms and wont build more than 4400. Compression is good on all cylinders. Help!!

 

[Timberghost]

have you changed your spark plugs, i had this same problem once and my dad said it was the plugs and i thought no way they are less than a year old. ordered me 6 new plugs,put them in and it fix my problem, so it could be as simple as that for you, its worth a try if you hadnt already