Topic: 550/650 engine build...going for??

[Raef]

I finally decide to start my 550/650 project engine.

I have had a 76 550f engine sitting on the bench disassembled for about a year and a 82 650 custom sitting in the back of the garage for several years.

today I disassembled the 650 top end and found  very clean valve train, I was very optimistic, that is till I got the head off and found 3 bent intake valves. Now I am completely stumped, the cam, sprocket, chain and rocker arms all looked brand new, then you get to the top of the valves, they show a little wear. I then pull the head off and three valves are not seeded so I pull the valves and 3 are bent. You can see where the valves hit the pistons but there is no real damage to the pistons, it more or less just knocked the carbon off of them.

I may have just answered my question, is it possible for there to be enough build up to bend the valves?

[Hasenkopf]

chuck them in a drill and see if they wobble....

[Raef]

no need, sittin on the table, they look like there gona fall over

[Raef]

I have not split the case yet But it seems there is a fair amount of play in a couple of the rod bearings.

 the bike is showing 21,000 miles and most of the motor looks really good But I still have not found the cause of the bent valves. The top of the pistons and the combustion chambers were pretty carboned up. At this point I am thinking;

1 excessive wear at the rod bearings
2 someone over tightened the valves
3 someone changed the cam and installed it wrong

I may be looking for another donor engine or backing down to 591. should be able to get the case split this weekend and check the crank out, time will tell

[Raef]

After taking inventory of parts on hand and checking there condition I have decided to tone it down a bit. the project motor and bike will be built, as much as possable, with parts on hand.

I will be using,
550 case and lower end up to the rods.
650 pistons, rings, wrist pins and jugs.
550 head with the 650 cam.

I know the pistons will have to be machined and a slot cut in the top half of the case to accept the 650 chain tensioner.

if I am missing something feel free to chime in now.