When I got this free '79, I gave it a thorough going over before getting it running. I found the cam chain adjuster plunger quite deep in the adjusting nut. I remember thinking that if it had been run like that for very long, the front chain guide is probably toast. Adjusted it according to spec. and got the bike running pretty good.
I noticed that while riding it, as I go through the gears and approach the shift point where the engine is not loaded as heavily, there's a rattle (quite loud) that seems to be coming from down low. I can instantly eliminate the rattle by modifying the throttle either open or closed. Just changing the throttle a little makes the rattle disappear. Otherwise the engine runs just fine. At first, I thought that it must be the plastic all worn off the chain guide making the noise, but it seems to be coming from down lower than the guide. So I'm wondering if I have a sacked out crank bearing.
Anyone have any experience with worn out crank bearings and the sounds they make?
'72 XS2 (Lucille) '79 SF (popsycle) 'nuther '79 SF (freebie)
Usually you'll hear a loud whirring sound from bad mains. What you're describing sounds more like a rod knock, maybe from big end bearings (not a real common problem in these engines, but with a bit of abuse anything's possible). Couldn't hurt to pull the top end and check for vertical slop in the rods, check side play, inspect small ends and wristpins, etc.
Last Edit: Jul 25, 2009 14:50:02 GMT -5 by grizld1
Thanks, Griz. I'll be tearing into it soon as I get my mother over the hump from her two surgeries (carotid endarterectomy and triple coronary bypass.) An XS650 overhaul should be a breeze compared to these last four weeks of hospital camping.
'72 XS2 (Lucille) '79 SF (popsycle) 'nuther '79 SF (freebie)
Post by Phantom Phyxer on Jan 25, 2016 19:56:57 GMT -5
Hi, did Pops, ever find out what this noise was? I have the same noise with the same indications, change throttle position and noise goes away. Its only when I ride it though. I can run this thing up to 6 grand while sitting in my garage and no noise. If I get on it and go through the gears and really give it the gas, no issue, Its just riding along at about 3200 to 3500 RPM that it starts knocking. And its a low down sound. I can fill the vibration through the foot pegs when it happens and its pretty loud.
We haven't heard from pops since 2012. The worst thing you can do to yourself is to overthink the problem from the outside--pull that motor and open it up, the grief should be obvious when you start looking.
r80rt: :)This is a splendid write up, THANK YOU!!!!
Dec 26, 2015 16:54:05 GMT -5
mashermoto: What the what is this shoutbox for? Or should I shout, WHAT THE WHAT IS THIS SHOUTBOX FOR!
May 12, 2016 22:22:21 GMT -5
motormike: Good Day ...just a FYI.. Wild Cat is this Labor Day weekend. Still go'n on. A few 650's still make the scene. Various rides at different skill levels each day.. awards dinner sunday eve. BS in the park'n lot after dinner.
Aug 23, 2016 7:57:01 GMT -5
lsettle: First post in over 6 years!
Aug 28, 2016 19:45:17 GMT -5
kardon: Wow quiet here, where did they all go.
Oct 7, 2016 2:18:13 GMT -5
gggGary: XS650.com LOL
Feb 16, 2017 20:49:02 GMT -5
buell88: Anybody have any idea who built the xs650 tracker used in the Draggin Jeans Ad on Pipeburn?
May 16, 2017 16:24:09 GMT -5
joshua: The regulator/rectifier unit I got from Mikes PMA has closer hole spacing than original. Are we supposed to mill the holes to fit?
Jun 7, 2017 19:25:58 GMT -5
joshua: My bad. I found the bracket they supplied to mount the rectifier/regulator... Uh oh. How is this meant to work? Which way is it meant to mount? Looks like I have to use some spacers or something. Good instructions would be nice.
Jun 7, 2017 22:09:52 GMT -5
craig8johnson: Not sure if this is the right spot or not but oh well...
Jul 11, 2017 18:04:15 GMT -5
craig8johnson: I'm checking the charging system. I'm afraid I might have fried the last battery. With the solid state regulator (after market) what should it be charging at. The book says, I think, 15 volts. I'm hitting 17 when revved. Is that too high?
Jul 11, 2017 18:06:19 GMT -5
gggGary: Yes 17 volts is too high, about 14 volts is max, sounds like you don't have the right regulator or it's wired wrong.
Jul 13, 2017 6:54:33 GMT -5
dean: Just saying Hello, new member who is going to fix up a 79 XS650 that has seen its better days. I will definitely have lots of questions coming up.
Jun 23, 2018 16:45:32 GMT -5
tt650: Trying to breathe life into a 1980 that's been stored (indoors) for 25 yrs. Air filters are dry rotted. Have cleaned carbs but she only runs briefly on choke then stops. Need jet setting info and other ideas that might help her idle and rev.
Jul 3, 2018 19:15:19 GMT -5
trix13: Hey everyone! New to the forum and am fighting those gremlins!! New charging system, ignition switch, coil and fuse box. Resistance is higher than normal on the ignition pick up so I'm trying to find one. No such luck yet.
Aug 16, 2018 8:50:48 GMT -5
trix13: Also, even though all of my connections are clean, I cannot seem to find out why , when at higher rpms, I hit the signals and the rpms pulse with the signals...hahah. same with the brake light. I appreciate all input!!
Aug 16, 2018 8:55:08 GMT -5
bob99: how do I post a question. I am new to the forum
Jun 6, 2019 10:52:10 GMT -5
adlpc: Hello all! Been enjoying your edifying posts and discussions - and as a fan of the XS650 since my early teenage years happy that I now own a 1980 Special which I plan to turn into a vintage half faired racer. Thank you all for being here!
Oct 1, 2019 0:58:56 GMT -5
jimothyj: Hello everyone, I just joined & wish would have known about this site in 2014 when I brought my 1974 TX650A back from the grave. I have spent a good deal of $$ and alot of time on it. Just painted it and working on electrical, I will post pics soon,
Apr 10, 2021 2:14:13 GMT -5
louisvan: trix13 - I had a problem with my 1975 SX650. When I got to highway speeds, the engine lost power. The problem was in the connectors. At a certain vibration and the wind pushing on the wiring loom, the connector lost continuity. A bad crimp to the wire.
May 20, 2021 1:19:09 GMT -5