gpzkat
12-20-2024, 08:43 PM
New member here, hello all.
https://youtube.com/shorts/MAsA74IzbVM?feature=sharedSo my son got this pretty nice '79 for a couple hundred bucks and I've been giving it the going over. I have restored many bikes so it's not my first rodeo, but I have only worked on one - a '74 ST90 that just needed brakes, electrics, and tires etc. This bike runs but I noticed a knocking sound when the idle is just loping over (after I fixed the carb). I adjusted the valves and changed the oil, and wow, it runs much better. There was zero valve lash clearance, I'm sure it was never checked. The pull cord was like a wet noodle. Now the compression is there, for sure. Interestingly I got 145 compression before I did the valve lash. Seems pretty good! Haven't checked after but by feel, it's way better.
OK, cut to the chase. When adjusting the valves I pulled off the pull cord housing and the inner ring thingie (not sure what it's called, 3 10mm bolts like the outer assembly) so I could set it at TDC. as I was doing the valve check I wiggled the crank by hand, and watched the valves for movement. Pretty sloppy. So I'm thinking the bottom end bearings. I did a video of it. The other concerns were cam chain and piston lap. But this just seems way loose. Any opinions welcome. I don't mind diving in and rebuilding, last bike I did is a '66 Norton N15CS (750 twin desert sled) from ground up). Hondas are a dream to work on, I've restored several.
The thing runs fine and once off the low idle it pulls hard, I don't want the thing to self-destruct tho. Video of the noise and pic of the bike below that.
https://youtube.com/shorts/MAsA74IzbVM?feature=shared
Here's the little beastie...
https://i.imgur.com/PXLpoWY.jpg
https://youtube.com/shorts/MAsA74IzbVM?feature=sharedSo my son got this pretty nice '79 for a couple hundred bucks and I've been giving it the going over. I have restored many bikes so it's not my first rodeo, but I have only worked on one - a '74 ST90 that just needed brakes, electrics, and tires etc. This bike runs but I noticed a knocking sound when the idle is just loping over (after I fixed the carb). I adjusted the valves and changed the oil, and wow, it runs much better. There was zero valve lash clearance, I'm sure it was never checked. The pull cord was like a wet noodle. Now the compression is there, for sure. Interestingly I got 145 compression before I did the valve lash. Seems pretty good! Haven't checked after but by feel, it's way better.
OK, cut to the chase. When adjusting the valves I pulled off the pull cord housing and the inner ring thingie (not sure what it's called, 3 10mm bolts like the outer assembly) so I could set it at TDC. as I was doing the valve check I wiggled the crank by hand, and watched the valves for movement. Pretty sloppy. So I'm thinking the bottom end bearings. I did a video of it. The other concerns were cam chain and piston lap. But this just seems way loose. Any opinions welcome. I don't mind diving in and rebuilding, last bike I did is a '66 Norton N15CS (750 twin desert sled) from ground up). Hondas are a dream to work on, I've restored several.
The thing runs fine and once off the low idle it pulls hard, I don't want the thing to self-destruct tho. Video of the noise and pic of the bike below that.
https://youtube.com/shorts/MAsA74IzbVM?feature=shared
Here's the little beastie...
https://i.imgur.com/PXLpoWY.jpg