I'm finally able to pursue this, having done a Lot of bike work in the meantime. The mechanic passed away a few years ago. I was thinking I "tuliped" the valves, me being just stupid enough back then to not recognize the problem and that a '74 needs lead additive for unleaded gas. I bought a set of '75 heads to swap and relegated myself for lead additive from now on.
The issue: I pull the heads and compare both sides with the bought set, I Can't See Any difference. The valve disc and keepers are visually at the Same distance on all 4 heads and the valve shapes & concaves are the Same too. But when I pulled the right head, it was so "bound" on the low side, I had to slowly pry it off. The stud in the low side middle had gasket sealer all over it, And No thick washer ! The left side had both washers, but right only had upper.
Question, could the missing washer cause the problem? If so, how? If not, what should I be chasing?
Thanks in advance... Kevin / SW Mich
But let me ask so that we can all go from there. Were the valve clearances set with the right side cylinder at top dead center on the compression stroke? It's a little different, but there are numerous situations were the mechanic rotates the engine so that the left cylinder shows the TDC mark in the window...and maybe gets lucky that it is on the compression stroke. Then, without rotating the engine 360 degrees, they go to the right side and set the valve clearances. In truth what this results in the left side with proper clearances and the right side with huge clearances. It's possible I suppose, if one can get past the loud clatter on the right side, the extra pounding could break off a rocker arm.
Beyond that, I suggest reading this website on rockers and heads over the years. See if there's something here that might help point to an issue:
The '76-on rockers are different than the '74/75. If you bought some '75s to replace your originals, they would essentially be the same.
'78 R100/7 '69 R69S '52 R25/2
I'm still caught up on the one washer on bad side and both washers on good side. The "bound" was all the gasket goo around the lower middle stud. I suspect the missing washer allowed the leak and the "mech" packed it with goo instead of fixing it right.
Thanks for the link too. I've got some checking to do, looks like all 4 shafts were upside down. Maybe just reassembling what I have Correctly will "fix" the problem.
92 R100RT/69 R69S
2004 Aprilia Atlantic 500cc single cylinder Scooter
83 Honda V65 Magna, fastest production bike in1983
2015 Can Am Spider SE6 1,688 miles
2018 Moto Guzzi V711 Special
Idiot mech put 3 of the right side head nuts on BACKWARDS !
The locking side of the nut is ~.060-.070" high and of a much smaller diameter.
Running the engine progressively "mushroomed" that smaller diameter, so the valves opened up.
Resetting just allowed it to happen again until the rockers broke.
I only found this recently when refitting rebuilt heads and finding 3 nuts that a socket won't fit over the "flange".
The "AH HA" moment was a flashbulb.
I post this just in case somebody else runs into this issue.
- 11 12 1 261 775 HEX NUT (to 09/75)
- Fit 1970-1975 models. In many 1974 models, they were not properly hardened.
So maybe you were the unlucky one to have nuts that just mushroomed because they were of poor quality.
'78 R100/7 '69 R69S '52 R25/2