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Can cast rocker arms be "REBENT"

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.



001-22.jpg
 
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
 
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.
 
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!!
 
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?
 
chuck hahn said:
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.
Click to expand...

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-...Parts_Accessories&hash=item2a06e4e91a&vxp=mtr
 
Ed, by the looks of that arm, I'll have to go with it's a casting.
 
rustybronco said:
Ed, by the looks of that arm, I'll have to go with it's a casting.
Click to expand...

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?
 
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.
 
If the cobbled up repair is going to cost more than $50.00 in time/effort/expense, why not just buy the new part and be done with it? :confused:
 
Chuck, give a little time this weekend , I think I have a whole head and valve train assy for that Yamaha. We tore one down about 15 years ago and I believe I have the remainder out in the trailer . I just have to spend some time going through totes. I'll look either tonight or Saturday.
 
Nessism said:
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?
Click to expand...
Yes I do.

What I think is, find out the reason why and if it's the arm correct it.
 
Scoobie...and what if I buy these off Ebay and that "just the way they made them" and I get shanked out of the cost and the shipping? Soon as i can get back to Randys shop I will put the cam blocks back on tnhe head and set in a valve and do some eagle eyeing of the situation. I will measure the valve seat placement for comparison from side to side etc etc etc.
 
Nessism said:
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-...Parts_Accessories&hash=item2a06e4e91a&vxp=mtr
Click to expand...


Didn't he see this post?
 
Dale..yes Randy has seen it for a bruef minute but he was up to his azz in alligators at the time I pulled the head. I am gonne go over there tomorrow afternoon and set everything in place and take lots of pics. The cam blocks show nothing worn or ground down on either side of the rocker either..stay tuned.
 
Took some pics...and I didnt recall that the right intake was off just a bit from center also..but it was the left cylinder that was trashed. They surely didnt have things laid out very closely on theses bikes. Not damage of any kind to the cam blocks as you can see. I just find it hard to believe aqnyone reviewing the data siad.."what the heck...close enough i guess" and signed off on this.



003-24.jpg

004-20.jpg

005-17.jpg

006-18.jpg
 
This is from an email exchange i had with the English Gent that is a respected authority on these. He has tried all the old AND new camblocks and it seems the misalignment issue prevails regardless of what blocks you aquired. I posed the idea of cutting slots on each side of the stiff back and rewelding..heres the exchange::



to argo1974

I am almost tempted to cut a small slot on each side of the stiffening ridge and give them a smack till the adjustersare over the stem correctly. The reweld the slots with my MIG welder and finsh grind the repair smooth. I was told the rockers are made of cast steel, so i can presumably weld it with a MIG.
 
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