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Post by supercub on Mar 12, 2017 15:34:08 GMT -5
I removed my valve adjust caps and found that both intake adjusters are off center from the valve stem by quite a bit. It just hits the outer circle of the stem. The rocker doesnt have excessive side play to put them so off center. The stem tops look like they are sintered metal, not smooth ground as most are. The bike has 12k on it and It doesnt look like anyone has touched the engine. It is a factory replacenent, non serialized 1973. I havent ran it yet as Im going through it still, it sat for the last 20 years. Has anyone ever seen this condition?
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Post by farmrjohn on Mar 13, 2017 10:06:22 GMT -5
Mine aren't centered. The ends of the stems are hardened. There is a modification using "elephant foot" adjusters from VWs/Porsches available that is supposed to keep the adjustment for a longer time, and not be as rough on the ends of the stems.
Does you replacement engine have the deep sump?
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Post by supercub on Mar 13, 2017 17:21:45 GMT -5
Seems odd that they would make them off center. Are all four of yours off? My exhausts are dead on. All four rockers are the same part number in the book. My engine has the the deep sump and balance adjuster. Is there a porsche model engine that has a swap for the screws? Changing out would mean pulling the engine to remove the valve cover I imagine.
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Post by farmrjohn on Mar 14, 2017 10:21:58 GMT -5
Yes, the engine needs to come out for that project (which is why mine aren't installed yet). The Porsche part number is 901 105 370 02 and a good discussion here: link That forum also has other threads on the modification. The Porsche elephant foot is too long, so the threaded part needs to be shortened to length and either new slots of wrench fitting fabricated. The rocker arms also need to be hollowed out slightly for the foot to fit in and clear without hitting. |
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Post by retromech on Mar 16, 2017 4:14:00 GMT -5
Regarding the offset position of the adjuster on the valve stem, this was a method used by a number of manufacturers to spin the valve when the engine was running, some made it more obvious than others, have not taken much notice on newer engines but this is not used so much today as far as I am aware.
Regards Paul.
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Post by supercub on Mar 20, 2017 16:59:27 GMT -5
To keep carbon deposits from building up on the seated surfaces I bet.
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Post by scrambler on Oct 2, 2017 0:41:29 GMT -5
Hey folks,
I`m finishing up the head now and bolting down the head cover and just came across this thread now which makes me wonder if I should take a break and invest into these elephant foot adjusters. All my valve adjusters are off centered just like it`s reported earlier, so it seems this would be the trend in the seventies. What worries me is that all the valves that I took out from three engines are really worn on the stems where they are being hit by the rockers. I found new valves for cheap and I was thinking they should last long with frequent valve clearance adjustment. What is a typical valve adjustment interval for a TX? How much longer does it last before the valves start ticking with these elephant adjusters? Any experience on this?
Thanks,Greg
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Post by farmrjohn on Oct 2, 2017 10:44:22 GMT -5
The owner's manual calls for valve adjustment every 2000 miles. I have the elephant foot adjusters ready to go in the next time the head comes off. Folks on the XS650 boards seem pleased with them and indicate they stay in adjustmen. If Porsche used them they must be good.
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Post by scrambler on Oct 2, 2017 12:03:15 GMT -5
How about the lower turning force on the stems? Won`t that cause sealing issues eventually that you decrease the spinning of the valves? Or perhaps this was required for the gas available in the seventies and now it has less significance? Just wondering..
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