I received a 99 400f and partially revived it. it runs ok, but the carb is gunked up and it has a hanging idle. I plan on sending it to Zip-Ty over the winter... Anyway, here is the issue. Over the past 2 oil changes i have noticed a lot of metal on the oil filter. I also noticed a noise from the engine after the last one. It is not valves - had them checked at yamaha 5 hrs ago. Since there is a lot of metal, I am guessing big rod end bearing based on info found on this site. So, I guess it is time for a total rebuild. And since the crank is most likely the culprit, I prob should install a 426 crank and top end. Maybe i will go 444 with the $$ i save by doing most of the work myself. So here are some questions i couldn't find answers to in the search forum... 1. will a 400f clutch assembly work with the 426 crank, or should i get a 426 clutch assembly? i read the 426 was different (larger) and therfore stronger. 2. will the stock 426 cyl head bolt to a 400 cyl, or should i just get a 426 cyl off ebay? 3. how difficult is it to replace all the bearings in the cases/entire engine? do i need any special pullers for the bearings? 4. does the 426 cyl head allows the bike to rev faster? my 400f (and others according to my buddy) is very lazy compared to a 426. any other info, or tips for the rebuild would be appreciated.