Can cast rocker arms be "REBENT"

[JEEPRUSTY]

they seem to be not rare

http://www.ebay.com/sch/i.html?_odkw=yamaha+tx+750&_osacat=0&_trksid=p2045573.m570.l1313&_nkw=tx+750+rocker&_sacat=0&_from=R40

[chuck hahn]

I will have to sit down with Randy and Wayne and brain think this possibilty thru with the cam towers and valve inserted in the head so we can mock up a "shifting" of the rocker to the right just a tad. I am gonna bet this problem effectively resolved because it make absoultely no sense to get the new valves and adjusters so that they will be subjected to the same conditions that caused this failure. Its apart now, so it has to be resolved somehow.

[tkent02]

it make absoultely no sense to get the new valves and adjusters so that they will be subjected to the same conditions that caused this failure.

What exactly failed?

[chuck hahn]

Jeep..its not a matter of needing any parts..its a matter of getting things aligned properly. I can buy one of those cam blocks and it may or may not be right. If I can machine and shim ot over myself then I can be 100% sure and satisfied that it is gonne mesh things the way they are supposed to be. The left intake was the only real damaged thing in the top end because of this misaligned adjuster.

[JEEPRUSTY]

I just figured for 20 bucks yah cant go wrong
pics look pretty clear

http://www.ebay.com/itm/YAMAHA-TX750-TX-750-CAM-BLOCKS-WITH-ROCKER-ARMS-1973-/370688739582?pt=Motorcycles_Parts_Accessories&fits=Model%3ATX&hash=item564ec548fe&vxp=mtr

[chuck hahn]

Tom what exactly failed was the adjuster got hammered from the offset and the stem got beat to death and chipped on the edges of the stem as a result...I will post the pics of the side view of the intake stem...youll see what "broke" Other than this causing a pretty loud tick at high RPMs, the bike was running just fine. I took the head off to replace that leaking head gasket..remember? Then as i inspected things i came upon the hammered parts.

Side view of the stem...worn at a slant and also chipped around the edges.

[Agemax]

maybe worth buying those from ebay. if they fit properly then all good but if not you have a spare set in case the machining mod goes wrong

[chuck hahn]

IF it goes wrong I can always succomb to buying a set...but i think this is gonna work. Will mock it all back together and do some finagling and get some numbers and a game plan in place.

[chuck hahn]

Greg T...Now that seems to be a much easier approach than machining the cam block itself. Wayne has a lathe at the shop as well. We can use the lathe to make the required spacer as well!!

[john82q]

Just a thought, are you sure the valve guide is in square and is straight, and its not some malady with that thats causing the missaliginment?

[Agemax]

Just a thought, are you sure the valve guide is in square and is straight, and its not some malady with that thats causing the missaliginment?

the valve wouldn't seat properly in the head if that was the case

[Nessism]

Agemax...In the above post i answered that we swithed the left and right side rocker arms around and duplicated the same results..the "bad" left one now was perfect on the right side and vice versa.

Chuck,

This experiment indicates the rocker arm and/or base is bad. I'd be concern with machining the rocker since it may mess up the way the cam wiper pad contacts the cam. Since these parts are readily available and cheap, getting some new/used parts seems like the appropriate thing to do.

I'll defer to you guys when you say they are not cast iron, but how can they be forged with numbers like this on the side?

http://www.ebay.com/itm/Yamaha-NOS-Arm-valve-rocker-1973-74-TX750-/180504291610?pt=Motorcycles_Parts_Accessories&hash=item2a06e4e91a&vxp=mtr

[rustybronco]

Ed, by the looks of that arm, I'll have to go with it's a casting.

[Nessism]

Ed, by the looks of that arm, I'll have to go with it's a casting.

Dale,

Do you also agree that shimming the rocker to center the tip over the valve will also effect the way the wiper sits on the cam?

[chuck hahn]

Its only gonna shift 1 1/2 to 2 MM..but when i can get to the shop and take all the stuff up there to set it all back in to the head, I wll scope it all out very well. Thats a very good point to consider as well. If there was just a way to fill the adjuster hole and add some material to the right side of it and then redrill it, that too would be a viable solution and not disturb the wiper in any way.