Without a doubt I am so tired for running around in circles trying to set the timing on this bike. Long story short, bought bike , not running, tore it apart 5 years ago and due to real bad health just putting it back together now. This is what I have, bike is all together, motor was not torn down as it was low mileage. New points and condenser, coils tested 100 %, new battery, all new wiring. I downloaded the way too set the points and then adjust to the timing mark, BUT, no matter what I do the bike is a bitch to start and for a 61 year old body it doesn't take long to takes its toll. When it does run, I check timing on both cylinders to find the rotor mark way over retarded. If I adjust the point plate clockwise to its max movement it starts to bring my timing to Top dead Center, but still falls way too retarded. Am I doing the points wrong ? I have tried from .010 to .016 and got the same issue as far as I can tell, but my frustration is getting the better of me. I am living on a very small disability pension, so taking it to a dealer is out of the question and they probably wouldn't know anything about the bike anyways. I worked at a bike dealer and if the bike wasn't brand new, they had no idea on what to do ! HELP PLEASE, I need guidance before I bugger something up. Any help would be greatly appreciated by this lifetime Yammy rider.
Retard position timing should be approximately 15* before TDC (plus or minus a couple), and the factory advance mark falls at 40* BTDC (although many of us find that setting the advance timing to 37 or 38 is preferable). But I think you're saying (correct me if I'm wrong) that when you set the advance timing correctly, you find that the retard timing mark is too far retarded.
If that's the case, the culprit is the advance timing unit under the right side chrome cover. The tips of the bob weights wear where they contact the slots in the disc that controls the ignition rod, and the result is that the advance interval stretches due to the slop; if you dial in the idle marks correctly, the spark will advance into the piston holing range when rpm's pick up, and if you dial in the advance timing correctly you'll be far enough retarded at idle to result in hard starting and startup backfires that will blow the carbies out of the boots now and then.
Don't try to fix the condition by bending or beating the tabs on the ATU rotor to limit bob weight travel, no matter what the shade tree experts suggest; the material is very brittle, and no matter how careful you are, you'll start small fractures and vibration will do the rest. If you want to keep points ignition, one cure is to braze a thin layer of material on the bob weights where they contact the tabs to limit travel, and work it down with a fine file until you get the curve where it needs to be. A better solution is to replace the timing unit (the weights are not and have never been sold separately). Avoid cheap Chinese repops from Mike's XS, etc. Shop around for the Yamaha part; a batch of them was produced a few years ago. The best solution, in my opinion, is to install an aftermarket ignition with electronic advance and get rid of the ATU. Check Probe Engineering (my favorite), Pamco, and Boyer-Bransden.
Last Edit: Mar 31, 2016 21:18:49 GMT -5 by grizld1
Are you trying to time at static position (13-17 BTDC) or at full advance (40 BTDC)? For setting at full advance I wedge little slips of cardboard into the advance mech to hold the fingers in the fully open position.
First thing to remember, only ever rotate the engine anti-clockwise when viewed from the rotor side, rotating clockwise can introduce error due to camchain slack takeup being in the wrong place.
One thought, has anyone been into the engine before you purchased? If you can't get anywhere close even at static position then consider that a previous monkey has been in there and somehow got the valve timing out by a tooth? IIRC the XS1 has a 34 tooth cam sprocket(?), this equates to 10.58(ish) degrees of rotation per camshaft tooth and you say the closest you can get is more or less straight up at TDC? Allow a few degrees for the range of adjustment on the points plate and you see where I'm coming from?
You can easily check valve timing by setting the rotor at the "T" mark and then removing the advance/retard mech, the drive pin in the camshaft should be pointing either exactly vertically upwards or downwards depending on which cylinder is on compression.
Thank you for the responses, greatly appreciated. I was attempting to set timing at idle and found the mark was always over retarded. I looked into the cam chain timing, and it looks ok. Changed the points again just to rule out crap parts, issue stayed the same. Went to the timing advance unit and it looks like hell ( something I totally missed in checking). So I will attack that unit and see what happens. I wish this was happening on my 72, it would be a hell of a lot nicer that kicking the hell out of body ! Will report when something happens, either good or bad. Again, thank you for the help !
When you say the ATU "looks like hell," it makes me think of the slot that aligns with a pin in the camshaft to hold the ATU in place while the cogged nut is tightened. If the cogged nut loosens the slot will slam against the pin and deform or even break. And yeah, if that nut was loose and the ATU was wallowing around, it would be impossible to get the ignition timing to hold.
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