The faithful '75 CB750F rolled over 170,000 miles yesterday on the 47th anniversary of its hauling me all over the place.
Looking back at the 165,000 mile post, I see it took almost 3 years to get the last 5000 miles. Much of what is in that post still applies. The bike is running smoothly, not smoking or showing any other operating issues. I commented then that oil consumption may have been increasing. It probably is as I had to add 3/4 of a quart over the last 3400 miles since the last oil change to keep the level at the upper mark on the dipstick. Kind of hard to get excited about that. As I recall, in 2017 it used about a quart over the 2100 mile trip to Delores River and back in hot weather, extended running at 65+ pushing a Windjammer and carrying me and camping gear and climbing numerous passes. Understandable that it would use more under those conditions. The bike rolled over 160,000 miles on that trip. It used more on the run to Redding to meet Mooshie on one of the relays back in 2016 at 155,000 miles. That was a hot ride with strong headwinds and long climbs that time too, so there is a pattern. Still using Spectro 20W50 HD. I took it out this afternoon to warm it up for the oil change. Temperature was right at 100 degrees and even after some stop and go, shifting was smooth and neutral easy to find. Pretty good considering the oil had over 3400 miles on it.
Looking at the maintenance log for the last 5000 miles shows very little. I did a 3000 mile service at 166,586 miles, changing the oil and filter, checking tappet clearances (no change again), cam chain, and Metzeler tires installed. I used the Metzeler Lazertec front and ME77 rear. Looking back at the maintenance log, I see I put the first ME33 front tire on the bike in August 1988. They changed the ME33 name to Lazertec years ago. It is an excellent front tire. I run 38 PSI in it and get no cupping or scalloping like some report using lower pressure. I bought the ME77 reluctantly because my experience with them wasn't good decades ago. I settled for it because it was available during the scamdemic. They aren't bad for traction and handling, but they simply don't last. I would say it is already 2/3 of the way to the wear bars in only 3500 miles. I was spoiled by the great ME88 tire for so many years. Sadly discontinued in 2012. Damn you Metzeler.
I did another 3000 mile service this afternoon. The tappets still needed no adjustment. I use Honda's recommended clearances as I have since I bought the bike. Looking at my notes, it appears the last time I made an adjustment there was back at 149,000 miles where a couple were half a thou tight. The RK x-ring chain and Sunstar sprockets installed at 153,000 miles are still on there, the chain still needing no adjustment. I lube it with Maxima chain wax. Spark plugs were last changed at 158,000 miles. The Dyna S ignition installed in 1990 is still going strong.
The tach is still wonky and I've noticed for some time that the speedometer starts reading low when air temps approach 90.
Your dashboard is in excellent shape! I haven't seen one that nice in 15 years or more.
I remember your comment from years ago about how the Windjammers shielded the dash. No doubt true, and the Windjammer has been off the bike for 5 years, but the bike has always been stored inside, and covered when parked when I used to work for a living. It also helps if you don't keep your bike under a drainpipe like a neighbor used to do.
Greg, have you given the old girl a check-up, in the form of a compression test? I've read some things on a certain blog that challenge the fact that your bike can still perform so well with so many miles, as the compression will be too low. 
I'd like to have a look at that blog if you can point me to it. I wasn't aware the bike was a topic of conversation anywhere other than here. I generally don't do compression or leak-down tests except as a diagnostic tool. I don't drag race it or do top speed runs, so as long as it is running well, I don't even think about it. But since you asked, and I decided I was curious and I always enjoy a good science experiment, I pulled the plugs and did it. I'll attach photos of the results at the end of this. #1, #3 and #4 hovered around 120, while #2 for some reason lagged way behind. (I have a theory.) Threading the hose and fitting on 2 and 3 is a bit of a pain in the butt and I can't say for certain I got it sealed completely on #2. Also, these numbers were taken at ambient temperatures, not with the engine warmed up. It was already 95F in the shop as it was and I didn't want to try to do 2 and 3 with a hot engine with that pesky rubber hose. The numbers won't blow anybody's skirt up, but the fact that my house is little under 3000' MSL, the rubber hose adds volume, and it was hot as hell need to be taken into consideration. The Boise airport ASOS was reporting density altitude of 5900' this afternoon. Just figuring in the elevation correction without air density loss due to it being 95 degrees would take the numbers into the 130 range. (except for underachiever #2) And I don't believe the #2 reading is accurate. And the gauge I have has a reputation for reading low. So the skeptics can make of it what they will.
Excellent, Greg!
I’d say the poll needs several more notches.
I’m pretty sure you and your CB750F are at the top of this class.
You’re leaving boundaries behind.
Thanks Kevin!
Poll