New airhead owner here, so sorry if this is an annoying question...
I recently purchased a 1971 r75/5. The bike seems to be in good original shape overall, but it's been sitting for a while, so I'm taking care of lots of deferred maintenance to get it road worthy.
One of the first issues I've tackled is the pushrod tube seals, which were leaking tons of oil on both sides. After lots of homework, this weekend I pulled everything apart and replaced the tube seals, base gasket, head gasket and valve cover gasket. I have lots of experience working on BMW cars, but this is my first motorcycle.
Everything came apart and went back together fine. All the internal parts looked to be in good shape. But I did check the valve clearances before taking off the rockers, and they were very tight. A very small gap for the intake and almost no gap for the exhaust. When reassembling I set the valves to .06 intake and .08 exhaust.
Upon firing it up, everything appears to be fine. No leaks and I'm getting oil flow to the rockers. My only thought is it's just ... loud. The ticking overpowers the sound of the exhaust, and is really noticeable to me.
I've done lots of searching, and I don't know whether this is just now the bike sounds, or if something is off.
They noise is similar on both sides, which leads me to believe it may be normal. But I'd the opinion of those with more experience than I have (which again, is pretty much none).
Here's a video I took yesterday (cold start) https://youtube.com/shorts/pNCObI0kNTo
The intake spec is .004, so .006 will be a little noisy.
Gotcha. I was working off the owners manual and a quick internet search that confirmed .006 and .008. I suppose I can try tightening up the intake clearance and see if that helps.
> The automobiles have methods (such as hydraulic lifters) to quieten the valve noise. Cars need that because the engine noise gets into the drivers area and can be heard. The motorcycles use solid flat lifters, which is why it takes special engine oils with the "zinc package". In the shop you will hear these solid lifters, but because the valves are well BELOW your ear position, the noise will not be heard on the road. It is literally lost in the wind.
> I would definitely not set the valve clearance any tighter than what the specs on the cam call for. DO NOT experiment with tighter clearances, especially just for noise. Airhead valves tend to tighten as you ride. If you set them tighter than the spec, then the clearance can easily close to zero and damage the cam and/or lifters. The correct clearance insures proper oiling and longer valve seat life.
> You may not remember the pre-1990 leaded fuels. These fuel additives cushioned the valve landing. Now that we only have "unleaded" fuels, any valve wear is accelerated. Yes you can have new valve seats installed, but the price is hardly worth the trouble with so many spares available. A much better plan is to start adjusting your valves every 3000 miles and keep records. You may find that your bike can go 4000 or 5000 miles between valve adjustments.... but you need to keep records to know that. Your bike's previous owner (with the tight valve settings) was obviously not doing that.
> Since you are new to Airheads, you may wish to search for a series of tech articles that all start with the words "Home Mechanic".
Hope this helps.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Thanks for the information! I'll definitely check that tech article out.
Valve noise is ever present with these engines. I agree with Richard, don’t set the clearances tight to try to reduce noise. The clearance is too important. .006 and .008 is good. Some folks even use .006 and .010, as exhaust clearance tends to diminish quicker.
Now, what I don’t know is; on a /5 is there adjustment for the rocker end play? On my /7, the end play between the rockers and the mounting blocks can be squeezed down to a minimum as the head is torqued down. This is also important to minimize valve train noise. Later airheads used shims. I don’t know about your /5.
SO, someone with /5 knowledge chime in here!
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