Topic: Rocker rebuilds: need some input, please.

[HondaMan]

I'm considering a "rocker rebuild" service (like my "swingarm rebuild" service). There are several routes to this, but here's the two I am considering, could use your opinions (like, if anyone else is interested, or even really cares?).

1. Make bigger rocker shafts, then bore the cam towers and rockers, and re-harden everything. This would restore stock performance to the top ends, while making matched sets of rocker shafts and towers. (I'd like to try to figure out new cam bearings in the process, don't know if it's possible yet).
2. Cut (grind?) the rocker shafts down about .010", bore the rockers and towers about the same, and install needle bearings in the rockers. If the reduced shaft diameter is strong enough, maybe just turning down the rocker shafts for the whole diameter of the needle bearings and install those inside the rockers (this was a "kit" in the mid 1970s, about $300 worth then, but I have no idea how they turned out in street use: they were racing parts). This method would cut top-end frictions at the rockers by 80%, but is kinda expensive. It leaves the cam towers alone.

I am guesstimating the first method at about $250-$350 per head (not sure yet) and the second at about $400-$450 per head, if I can figure out an easy reassembly process (the old ones used press-fit everything, don't want that again).

Personally, my intent is to quiet down the noise: my Vetter reflects all that loose rocker action into my face, which became annoying after about 75,000 miles. All of my rockers are at (or past) the Honda wear limits, and the extra K4 engine I have was run hard with light oil; most of those are gone, too, at 36,000 miles. I recently heard a very low-miles CB750K and was reminded of how quiet (mechanically) they originally were. I'd like to get that back (yeah, purist...)

[kghost]

I think thats an excellent idea.

I'm curious weather it wouldn't be easier to just spin out a new shaft ( a solid shaft ) if you were going to install roller bearings in the rockers.

A conversion if it were possible to some sort of roller rocker at the tips would be cool and mighty trick.

[ofreen]

I will be interested to see what you come up with on this.  My 750F is at just under 105,000 miles.  When I replaced the cam tower seals at 82,000 miles 4 years ago, I could see a tiny bit of visible wear on the rocker shafts, though they were still plenty serviceable.  It is still running fairly quietly and the tappet clearances are holding, but sooner or later the shafts and rockers will have to be replaced.  

Either method you use would seem to be workable, but I think your estimated costs to do it are going to be on the low side.  (Unless you are operating a charitable organization for us old SOHC owners.  If so, I applaud you.)  I am all for rebuilding old parts instead of buying new ones, if possible.  The trick is to be able to do the work for less than the price of new parts.  Of course, if new parts aren't available, it is a whole different ballgame.

[HondaMan]

I will be interested to see what you come up with on this.  My 750F is at just under 105,000 miles.  When I replaced the cam tower seals at 82,000 miles 4 years ago, I could see a tiny bit of visible wear on the rocker shafts, though they were still plenty serviceable.  It is still running fairly quietly and the tappet clearances are holding, but sooner or later the shafts and rockers will have to be replaced. 

Either method you use would seem to be workable, but I think your estimated costs to do it are going to be on the low side.  (Unless you are operating a charitable organization for us old SOHC owners.  If so, I applaud you.)  I am all for rebuilding old parts instead of buying new ones, if possible.  The trick is to be able to do the work for less than the price of new parts.  Of course, if new parts aren't available, it is a whole different ballgame.

That seems to sum it up: I haven't seen new cam towers or rocker shafts (and rockers) for at least 8 years. Every now and then one piece or another shows up in some random place, but not rebuildable sets. And, they are mighty expensive. In 1972, rockers were $3 each and the shafts were about $5. The towers were about $25 apiece. The last time I saw an NOS rocker, it was $27+ without the adjusting screw.

The price pretty much depends on the equipment I could round up to do it with. I have a lathe: the grinding might be do-able on that. I have a drill press, so an adjustable hone might let me open the cam towers' rocker shaft holes. The rockers might require a special fixture and a mill, though. Some of my friends have one; it just depends on either the "rent" or if I can hire their help for a decent rate.

[Big Jay]

Back in the days, there was a company that made needle bearing rocker arm kits for the 750s Their name was Amol Precision. I googled them and there are references to them, but they don't have a website/ May not still be in business.

Their kit was for use with new rockers as they were available back then.

Jay

[oldfart]

Back in the days, there was a company that made needle bearing rocker arm kits for the 750s Their name was Amol Precision. I googled them and there are references to them, but they don't have a website/ May not still be in business.

Their kit was for use with new rockers as they were available back then.

Jay

Yep.  They happened to be a Honda dealer also, as well as a BMW dealler, and the parts mgr way back when was one of the originators of the VJMC.  Udo Geitl came out of there, Todd Schuster too I think.  And they raced BMWs for Butler and Smith, the importer back then.  They later earned fame for coming up with a kit for the Honda V4 oil lines, apparently in concert with the Honda race team.  Like you I used the needle bearing rocker kit.  Neat.  Don't think there was ever an advantage.   Just neat hardware.   

[puppytrax]

I'm considering a "rocker rebuild" service (like my "swingarm rebuild" service). There are several routes to this, but here's the two I am considering, could use your opinions (like, if anyone else is interested, or even really cares?).

I'm interested, and I care...Like others here, I also just like neat stuff...   

I'm a 500/550 man; not too interested in the inclined SOHC4's...Will you branch out to the little SOHC4??   

I was interested and cared about the swingarm re-bush, too...The last I read about that, you said to hold off, you were moving or buying something new...anyway, you were backed up...Is that on again?? 

[kettlesd]

Needle bearings huh??? Hmmmm. I for one would pop the extra bucks to install bearings.

[HondaMan]

[I'm a 500/550 man; not too interested in the inclined SOHC4's...Will you branch out to the little SOHC4??   

I was interested and cared about the swingarm re-bush, too...The last I read about that, you said to hold off, you were moving or buying something new...anyway, you were backed up...Is that on again?? 

We''ll be back on the swingarm thing in about 2nd week of January, weather permitting (shipping is a real problem here right now because of the blizzard: I haven't even had mail for a week!). My machinist, Jeffro, was seriously tied up with the Cub Scouts stuff from about mid-November, probably thru New Year's, because several other parents bailed on their responsibilities in the Den. He thinks he'll get caught up on Cub Scouts about a week into January, then hit a slow spot with them until Spring events. So, we'll be back at it, soon. I'm going to order new (bushing) material this week, because about 4 guys here want theirs redone: it will be easier to do them all at once rather than piecemeal. We'll (I'll) precut the material to fit the swingarm types (750K, 750F, 500/550) and get them ready for when the arms get here. I have a 750 arm also that I'm going to build as an "exchange" unit for someone who might want that method later on.

Plan on letting us have the arm for about 3-4 weeks, because we have to catch a warm enough day or preheat the garage shop overnight to get close to 60 degrees (minimum) for the precision we want.

[HondaMan]

Back in the days, there was a company that made needle bearing rocker arm kits for the 750s Their name was Amol Precision. I googled them and there are references to them, but they don't have a website/ May not still be in business.

Their kit was for use with new rockers as they were available back then.

Jay

Yep.  They happened to be a Honda dealer also, as well as a BMW dealler, and the parts mgr way back when was one of the originators of the VJMC.  Udo Geitl came out of there, Todd Schuster too I think.  And they raced BMWs for Butler and Smith, the importer back then.  They later earned fame for coming up with a kit for the Honda V4 oil lines, apparently in concert with the Honda race team.  Like you I used the needle bearing rocker kit.  Neat.  Don't think there was ever an advantage.   Just neat hardware.   

That's them! Now I remember that name, since you guys said it. 
The advantage that I saw was at very high RPM, 10,000+ racing regions. They were also very quiet, which I personally like.
Does anyone happen to have specs on the shaft OD under the needles, or remember the diameter of those needles? I remember greasing them up to try to hold them onto the shaft while sliding the shafts into the rockers. Tricky, but it was do-able.

[andy750]

Try Axls site - he lists a number of modifications.....

http://www.satanicmechanic.de/

cheers
Andy