Found this on the Australian XS Club Site: (also references Mazda part option)
Did you know that the Tappet adjusters for a VW, Porsche and Mazda 808 are the same as those used on the XS650 except they don't have that annoying little square on top for adjustment they have a screwdriver slot (much better) There are two types and these are commonly referred to as elephants foot and ball foot adjusters because of the way they look. It is necessary to modify the rocker arms to fit these to the XS650 and they must be fitted before the rocker box is fitted to the motor because you can't screw them in from the top like the standard adjusters. So if price is no object and you don't mind modifying the rocker arms and your motor is already apart then go for the elephants or ball foot adjusters they are the best! The picture below is the ball foot adjuster.
I recently found out that the ball foot adjuster pictured is from a Mazda 808 and you need to remove about 4mm from the bottom of the rocker arm to fit this type of adjuster. When I do mine I'll post a picture.
It has occurred to me that the socket type may not be desirable if they are too long and need to be shortened. If it's necessary to shorten the slotted type, then the existing screwdriver slot can be used as a guide for your hacksaw, Dremel cut-off disk or other weapon of choice to deepen the slot before cutting or grinding the adjuster shorter. I personally prefer the socket type however.
I would think that any of the suggested ball/swivel type valve adjusters put forward so far would be an improvement over the stock setup, for reasons previously stated.
Post by tomterrific on Apr 14, 2007 10:58:09 GMT -5
Consider that the elephant foot adjuster has a different contact point vs stock with regards to rocker arm geometry. The pivot point of the elephant foot is the center of the ball inside the foot where on the stock adjuster it is the tip of the valve. Think about this and discuss the ramifications please.
Edit: This sounds sort of like I'm giving an assignment for class. Boo! What I mean is there are some guys on this list that have good visual mind skills and I want their opinion.
If you'll observe the design of the elephants foot and visualize the opening of the valve,then it becomes obvious that the load on the valve is more evenly spread on the tip and stem, reducing side loads and wear of stem and the guide itself but with the foot fulcrum socket ,friction could be reduced also since oil is used for lubrication of the socket. But more importantly is the pitting issue of the valve tip with the stock arrangements valve adjustment will be minimal ,maybe every two years,depending on mileage with the elaphants.............Jack
Post by tomterrific on Apr 14, 2007 19:16:05 GMT -5
I've got that figured out and I know the good benefits. What really confused me was why the VW elephant foot kits came with a shim to raise the rockers. Then it hit me that the tip of the adjuster was really inside the foot with a space between the valve tip and the tip of the adjuster. It's like putting a spacer on top of the valve to change the geometry. The swivel foot would not be the same as it rolls on the tip of the valve. Ideally the valve should be shortened the distance of the added space to keep the geometry the same. At least that is the way I see it. It may be uncorrect but unnecessary to fix because the EF adjuster is so kind to the valve.
The elephant foot fills with oil and stays lubed with a bunch of oil pudling in the foot to cushion the "tick" of the valve train. I really like that.
Hey Tom....That's a good point,had to think about it for a minute ;D I guess one would need to figure rocker angle at closed position to align the center of the socket ball with center of valve tip but there's little tip exposed,so removal of material will have to minimal or the foot will most likely make contact with the valve retainer. This mod is very popular in Germany with great success but like you I see the oiling benefit,gonna have to order some............Jack
Just went and looked at my rockers and it seems to me there might be a structural rigidity issue with the required removal of material in order to fit these adjusters,I may have to give the elephants a second thought...........Jack
Your last post got me concerned so I went out to the shop and had a look at one of the rockers for my spare head and I see your concern.
The lateral web in the bottom part of the rocker measures just over 4mm in thickness and would no longer provide lateral support to the end of the rocker if removal of 4mm was necessary to fit the elephant foot adjusters. The adjuster screw (shown in the photo) which was not altered during engine disassembly (and I assume was adjusted correctly) protrudes just over 4mm from the bottom of the rocker.
I know this mod has been done successfully before but it will be important not to create any stress risers during the modification that could lead to failure of the rocker.
BTW, this rocker has the tip for use with the compression release, that has been discussed in other threads.
I guess one would need to figure rocker angle at closed position to align the center of the socket ball with center of valve tip but there's little tip exposed,so removal of material will have to minimal or the foot will most likely make contact with the valve retainer.
Ideally, the adjuster stem and the valve stem should line up straight at mid-travel. That way forces will be spread equally across the socket ball as the rocker arm moves through it's arc.... Dan
It's been awhile since I've tinkered with motors but Tom's opinion of valve geometry changes keep me up last night and the only difference the location the adjustments screws makes is how many turns it would take to set proper valve lash. On a shaft mounted rocker arm set-up,the only way for geometry to change would be to be either lower or raise the shaft itself changing it's pivot point, which would change the relationship how the rocker arm aligns with the valve tip and since this is a overhead cam motor changes in geometry would most likely occur if the cam base circle is cut or if the valve stem lengths are change,I don't know just guessing here,anybody else have a opinion?.........Jack
the only difference the location the adjustments screws makes is how many turns it would take to set proper valve lash. On a shaft mounted rocker arm set-up,the only way for geometry to change would be to be either lower or raise the shaft itself changing it's pivot point, which would change the relationship how the rocker arm aligns with the valve tip and since this is a overhead cam motor changes in geometry would most likely occur if the cam base circle is cut or if the valve stem lengths are change,I don't know just guessing here,anybody else have a opinion?.........Jack
I'm with you Jack. Changing the rocker arm shaft height is not possible and IMHO, changing the cam base circle or valve stem length to achieve altered geometry are both undesirable options due to potential loss of valve lift.... Dan
Post by tony101bikes on Apr 15, 2007 13:36:12 GMT -5
I agree - but anybody running a regrind cam has already changed the geometry by a fraction. The followers will ultimately be the same length as the stock adjusters. I'm waiting for a delivery and will try them out with the head off the bike. I suspect that the reason for the shims is to compensate for the increased length of the adjuster - nothing to do with the geometery.
r80rt: :)This is a splendid write up, THANK YOU!!!!
Dec 26, 2015 16:54:05 GMT -5
mashermoto: What the what is this shoutbox for? Or should I shout, WHAT THE WHAT IS THIS SHOUTBOX FOR!
May 12, 2016 22:22:21 GMT -5
motormike: Good Day ...just a FYI.. Wild Cat is this Labor Day weekend. Still go'n on. A few 650's still make the scene. Various rides at different skill levels each day.. awards dinner sunday eve. BS in the park'n lot after dinner.
Aug 23, 2016 7:57:01 GMT -5
lsettle: First post in over 6 years!
Aug 28, 2016 19:45:17 GMT -5
kardon: Wow quiet here, where did they all go.
Oct 7, 2016 2:18:13 GMT -5
gggGary: XS650.com LOL
Feb 16, 2017 20:49:02 GMT -5
buell88: Anybody have any idea who built the xs650 tracker used in the Draggin Jeans Ad on Pipeburn?
May 16, 2017 16:24:09 GMT -5
joshua: The regulator/rectifier unit I got from Mikes PMA has closer hole spacing than original. Are we supposed to mill the holes to fit?
Jun 7, 2017 19:25:58 GMT -5
joshua: My bad. I found the bracket they supplied to mount the rectifier/regulator... Uh oh. How is this meant to work? Which way is it meant to mount? Looks like I have to use some spacers or something. Good instructions would be nice.
Jun 7, 2017 22:09:52 GMT -5
craig8johnson: Not sure if this is the right spot or not but oh well...
Jul 11, 2017 18:04:15 GMT -5
craig8johnson: I'm checking the charging system. I'm afraid I might have fried the last battery. With the solid state regulator (after market) what should it be charging at. The book says, I think, 15 volts. I'm hitting 17 when revved. Is that too high?
Jul 11, 2017 18:06:19 GMT -5
gggGary: Yes 17 volts is too high, about 14 volts is max, sounds like you don't have the right regulator or it's wired wrong.
Jul 13, 2017 6:54:33 GMT -5
dean: Just saying Hello, new member who is going to fix up a 79 XS650 that has seen its better days. I will definitely have lots of questions coming up.
Jun 23, 2018 16:45:32 GMT -5
tt650: Trying to breathe life into a 1980 that's been stored (indoors) for 25 yrs. Air filters are dry rotted. Have cleaned carbs but she only runs briefly on choke then stops. Need jet setting info and other ideas that might help her idle and rev.
Jul 3, 2018 19:15:19 GMT -5
trix13: Hey everyone! New to the forum and am fighting those gremlins!! New charging system, ignition switch, coil and fuse box. Resistance is higher than normal on the ignition pick up so I'm trying to find one. No such luck yet.
Aug 16, 2018 8:50:48 GMT -5
trix13: Also, even though all of my connections are clean, I cannot seem to find out why , when at higher rpms, I hit the signals and the rpms pulse with the signals...hahah. same with the brake light. I appreciate all input!!
Aug 16, 2018 8:55:08 GMT -5
bob99: how do I post a question. I am new to the forum
Jun 6, 2019 10:52:10 GMT -5
adlpc: Hello all! Been enjoying your edifying posts and discussions - and as a fan of the XS650 since my early teenage years happy that I now own a 1980 Special which I plan to turn into a vintage half faired racer. Thank you all for being here!
Oct 1, 2019 0:58:56 GMT -5
jimothyj: Hello everyone, I just joined & wish would have known about this site in 2014 when I brought my 1974 TX650A back from the grave. I have spent a good deal of $$ and alot of time on it. Just painted it and working on electrical, I will post pics soon,
Apr 10, 2021 2:14:13 GMT -5
louisvan: trix13 - I had a problem with my 1975 SX650. When I got to highway speeds, the engine lost power. The problem was in the connectors. At a certain vibration and the wind pushing on the wiring loom, the connector lost continuity. A bad crimp to the wire.
May 20, 2021 1:19:09 GMT -5