General Category >> Technical Documents/Reference >> Refurbishing Worn Rocker Arms

Message started by Oldfeller on 03/17/10 at 14:48:05

Title: Refurbishing Worn Rocker Arms
Post by Oldfeller on 03/17/10 at 14:48:05

Here is a web page listing all the varieties and hardnesses of the various electrodes available to do this job.

Obviously we don't want the welded up tappets to be harder than the cam lobes as that would transfer the wear to the wrong piece.

Lancer has asked Webb Cam how hard cam lobes are and they said theirs are around RC 60-62.  Case hardened (stock) cam lobes would run around RC58-62 depending on quench and how hot the item got in use.

It is obvious that Suzuki has made the stock tappet softer as most the wear seems to go to the tappet face.   Yet the rocker material is harder than a pocket knife blade (RC 45-50).

So we are looking for RC 50-55 for a weld up material ???

Title: Re: Who has old rocker arms that need resurfacing?
Post by Oldfeller on 03/18/10 at 18:26:59

Here is another source for a very small amount of hardsurface rod

Title: Re: Who has old rocker arms that need resurfacing?
Post by Oldfeller on 03/20/10 at 02:13:42

Address is sent, now I need to go ahead and get the welding rod on the way ....

I would think our tappets are a case hardened job as it seems when you go through the case wear is pretty drastic past that point.

Some of these rods are relatively heat proof materials and the "case" will be pretty thick, so that shouldn't happen again.

Might eat the cam lobes off instead -- but Lancer can recover that with a hotter cam profile so that might not be a totally bad thing as your money gets you something better.

Title: Re: Who has old rocker arms that need resurfacing?
Post by Oldfeller on 03/20/10 at 07:23:09

Note for future readers .........  

There are 2 main likely reasons your tappets wore out on your bike.

1)  First is the lack of ZDDP in modern car oils -- you should use a bike rated (JASO rated) motor oil.   Car oils will not provide what your old style flat tappet engine needs.

2)  Next is low oil pressure, you can cause this by running your idle speed too low (should always be 1,000 rpm or slightly higher)

If you don't fix these two issues the $100 you just dropped at Bike Bandit to order a new set of rockers will likely go south inside 20-30,000 miles due to simple lube related wear out.   And yeah, your cam lobes likely took some wear damage too so you might want to measure your cam lobe heights as well.

Title: Re: Who has old rocker arms that need resurfacing?
Post by Oldfeller on 03/23/10 at 02:03:42

Our thanks to Alcam, manufacturer of welding rods for their excellent technical support.


"We will send you two products.

Alcam 93 will reach the hardness of approximately 57r after two passes depending on the base metal dilution.

Alcam 81 will hit approximately 58r on the first pass and 60r on the second pass.  This is an air hardening tool steel and should not require annealing. The second item we normally make as a 3/32 electrode but we can do 1/8

Thank you for your inquiry

Al Carlsten
Alcam Mgf.

Title: Re: Rocker arm tappet resurfacing
Post by Oldfeller on 03/24/10 at 18:50:26

Justin, there is a performance portion to this fix as well.   As you wick you put extra stress on the stock tappets, promoting even more rapid failure of the stock part.

The Web cam is a RC 62 hardsurface build up, so it isn't going anywhere.  The stock tappet material is too soft, so it does.

Alcam recommended a tool steel build up rod as it can be a few points softer than the hardsurfacing materials commonly used for cam build up but still be TOUGHER to wear -- it won't damage the cam but it will last much longer internal to itself.

This sounds like a good fix.

Title: Building the fixture
Post by Oldfeller on 03/31/10 at 10:53:43

Here are some perspective shots on a very simple crude aluminum heat sink fixture for padding up a set of very worn and torn up rocker arms.

Notice my "complex high tech"  ;D  mounting fixture that preserves the rocker face  nice and square to the rest of the rocker assembly.

The arc will be struck on a piece of waste steel off to the side of this aluminum block and the electrode brought up to full laydown temperature and a stable arc.  Then the arc will be drug a short distance across the aluminum block and focused down on the tip end of the rocker (electrode angled 15-20 degrees low to the main the rocker body).

Then pull back some for a wider puddle and weave back and forth while backing up the face of the tappet until the entire recess is full and the active puddle is back at the heel next to the main rocker body.


The rod is Alcam #91 tool steel AC/DC arc electrode, size 3/32" wire diameter.  The thought at this time is to simply jack the power up to around 100 amps and long arc a wide puddle starting from the tip end and weaving back until the entire aluminum recess is filled with tool steel with the slag all sitting proud to the face of the aluminum block.

(that's the plan anyway -- we all know how "the best laid plans of mice and men" last in arc welding reality, now don't we?)

According to the folks that make the rod, it will air harden into a stress and crack free solid tool steel pad at between 55 and 60 Rockwell C.  Red hardness of this material is about 55 RC, so it won't get overheated and get soft like the original cast rocker steel did when it got hot in use.  Current wear face on the rockers is less than RC 45 as it got very soft due to overheating.

By using the chiller block I intend to "soak back" the weld heat and try to keep it from transferring into and further annealing the rest of the rocker (which will be wrapped in a wet paper towel mass the at time of welding BTW).


Note please the large amount of damage you can do to a cam and rocker set when you have interrupted oil flow in your engine.

Normal use and abuse does the EXACT SAME THING over a lot more miles, it just takes a lot longer to take place.

All of your high mileage rockers have damage of this type to a lesser degree and all will require replacement or refurbishment at a major rebuild.

Suzuki soaks you for a $100 to buy a set of replacement rockers, which won't last you any longer than the first set did.

Title: Re: Rocker arm tappet resurfacing
Post by Oldfeller on 04/09/10 at 13:48:35

OK, got me a changeover day (when you work nights and they want you to switch over to days they have to give you a day off to adjust your sleep pattern).  So I welded instead.

Arc welding isn't a precise laydown method, so expect some irregularities in the metal.   Plus I had to get my hand back in -- I only weld every year or so so I get rusty.

You can poke fault at stick welding as a system, but for an inexpensive buy in that allows you to do just about anything, you can't beat a buzz box and a stick electrode.

Heat proofing the part for welding involved rolling up a paper towel into a tube and sticking it through the hole and wrapping the excess around the legs and then tightly mummy wrapping everything but the part being welded in a 3" wide strip of cotton sheet material.  Soak the whole thing in the sink and let it drip dry in the drainer before carrying it out to the welder -- the water turning into steam blocks the body and the legs from getting any hotter than 212 degrees F during welding.

This is examples of the arc puddled pads and one rough dressed tappet pad.  This pad is harder than the pocket knife I tried to scratch it with -- look at the tip of the knife and you can also see the deposited knife metal on the surface finish of the pad.

Title: Re: Rocker arm tappet resurfacing
Post by Oldfeller on 04/14/10 at 14:46:01

And here are the finished ground and polished pieces.   Not perfect mind you, but certainly serviceable -- out of pocket cost was $5.00 for Serenity to ship the second set of rockers to me.  Tool steel welding electrode was donated by the vendor and the sanding belts and finishing wet/dry paper already was on hand.

Cost avoided was $195 (two sets at $100 each less the $5.00 shipping) -- not too shabby a savings for the 4 hours invested.

Next thing needed for the motor project is a worn first over piston (or a used piston and a jug if you have a spare set lying around gathering dust)


New list knowledge yielded by the motor project so far is:

1)   a easy to do durable method of recovering torn up cam bearing journals

2)   a method of repadding rocker arms with a much more durable material

3)   two new "assignable causes" for loss of oil pressure

4)   a documented method of cutting cheap clutch cover gaskets to a printed pattern

5)   a method to refit (not gouged up) piston skirts back to spec fit to a worn bore

6)   a method to tap into the "end of the line" oil passage and put that pressure reading out where you can see it
     (at a cost of less than $10)

So far the trip has been worth it -- who has an old first over piston or some sort of used piston/bore set so we can continue to see what comes out of the bushes?

Title: Re: Rocker arm tappet resurfacing
Post by TommyRocket on 06/16/10 at 20:11:43

Very nice work. Any updates on this?

Title: Re: Rocker arm tappet resurfacing
Post by Oldfeller on 06/16/10 at 21:11:21

It takes a long time to wear out a set of tappets, especially in your disaster/spare engine that isn't in service right now.

Both Serenity and I might well die of old age before installing either set of tappets ....

Title: Re: Refurbishing Worn Rocker Arms
Post by manny87 on 01/09/14 at 07:25:09

My rocker arm tappets look as damaged as yours did in those pics, I live in Guatemala City and it's a pain in the neck to get parts here, I could order them from the states but I don't wanna have to spend over a hundred US$ if they can be refurbished for a fraction of that.... So i have a couple of questions:

-overall, did they work fine?
-any side effects?
-how did you get the thickness right? I mean, did you have to compensate for any excess or shortage by simply adjusting the valve height or something?
-how do i know which electrode to get? I understand its a tool steel electrode but can i just say "tool steel electrode" to the hardware store guy and he'll know what i mean? or is there some generic code or something so i can say "give me a xxxxx type electrode for tool steel"?
Thanks for any info.

Title: Re: Refurbishing Worn Rocker Arms
Post by Oldfeller on 01/09/14 at 07:43:55

You are not going to buy these sorts of esoteric tool steel electrodes from a hardware store.   You can buy hard surfacing rod, but the experts kinda thought hard surfacing rod might just be too hard and too abrasive, so they sent both kinds and recommended using the tool steel rods.

One of these days we might have to put the engine into use to see how well the idea works, but as durable as my in-use fully built engine is acting I might die of old age first, so who knows?

Title: Re: Refurbishing Worn Rocker Arms
Post by manny87 on 01/20/14 at 15:59:04

Well, i ended up giving the rocker arms to a guy who rebuilds engines and works with more industrial type stuff ... he said he had done it before so i took a chance and let him refurbish them for about $30  ... he also did something to the camshaft ... "polished" ... would be translation from the word he used. I dunno, but apparently it was not too damaged. I cranked her, the insane clicking/tapping noise is gone, but i guess we have to put some miles behind her to really know if the guy did a good job... the bad news is, since i also replaced the cam chain, it looks like i didn't put the clutch assembly back on properly, the clutch handle is tight as hell, i can take off in first gear but when i shift higher and give it more gas, she revs but does not accelerate, like the clutch is slightly depressed. But that's a job for next weekend ... and does not worry me as much as the rocker arms did. I guess i'll post or look for tips on how to get the clutch right. So anyway,   Thanks again, at least this thread showed me what to do.. even if i had to get someone else do it for me. » Powered by YaBB 2.2!
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