Cam Chain Guide

I'm also going to install a new set of pistons and rings. YamahaXS650.com has new stock type pistons with rings (looks like Taiwanese made) on sale for $80 a set. I was also looking at the pistons/rings on XS650Direct, which are from Japan, but they run about $170 for a set. I'm inclined to go with the Japanese set, but anyone used the Taiwanese pistons?
 
Well, replacement of the cam chain guide, including a compete top end rebuild is just about done. I wound up boring it, adding new pistons and rings, and a valve job including new valves. It all went together nicely. Jim's "Top End Buildup" thread was an excellent guide. Had to deal with a few PO bubba jobs, but got those sorted/fixed. Also spent a bunch of time at my buddy's shop using his polishing wheel to clean up the side covers. Have to wait until my son comes by this week to get it back in the bike.
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Having one issue at this point. I was setting the point gap and timing, and I noticed that the mechanical advance on the right side is a bit sticky and doesn't always want to return to the fully "closed" position. I've taken the shaft out, cleaned it, re-lubed it, cleaned and re-lubed the weights, etc., but it's still sticky. Any recommendations (other than getting rid of the points)?
 
Well, replacement of the cam chain guide, including a compete top end rebuild is just about done. I wound up boring it, adding new pistons and rings, and a valve job including new valves. It all went together nicely. Jim's "Top End Buildup" thread was an excellent guide. Had to deal with a few PO bubba jobs, but got those sorted/fixed. Also spent a bunch of time at my buddy's shop using his polishing wheel to clean up the side covers. Have to wait until my son comes by this week to get it back in the bike.View attachment 242249
Looks great! Whose engine stand is that?
 
Having one issue at this point. I was setting the point gap and timing, and I noticed that the mechanical advance on the right side is a bit sticky and doesn't always want to return to the fully "closed" position. I've taken the shaft out, cleaned it, re-lubed it, cleaned and re-lubed the weights, etc., but it's still sticky. Any recommendations (other than getting rid of the points)?
Here's what I go by....
I'll loosen the points so they arent touching the points cam and see if the advance returns then. If it does, then I don't worry about the stickiness.
If it still won't return with the drag of the points taken away, then I have a problem.
Otherwise, reset the points and run it.
 
Looks great! Whose engine stand is that?
TC Bros/Mike's XS. It's kind of a POS. I had to enlarge the holes for the assembly rods just to get it together so it would sit flat, and then enlarge the holes for the mounting bolts to get it to fit the engine. In the end though it was cheap and it provided a stable base to build up the engine.
 
TC Bros/Mike's XS. It's kind of a POS. I had to enlarge the holes for the assembly rods just to get it together so it would sit flat, and then enlarge the holes for the mounting bolts to get it to fit the engine. In the end though it was cheap and it provided a stable base to build up the engine.
K thx for the intel. Don’t need one right now but think I’ll make one this summer according to @5twins drawings.
 
Yes, here's a couple I whipped up last summer from old (free) bed frames I picked up on trash day .....

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Then a coat of cheap spray paint and they're all good, lol .....

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Also, I've switched to using pins instead of bolts, mostly because I didn't have enough long bolts, lol .....

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Got the engine back in the bike over the weekend and got everything hooked up today. Spun it a few times without plugs to make sure I was getting oil to the upper end, which looked good. Added some gas to the tank and went for it. Took a bit to get some gas in the carbs, but once it got some, it fired right up. I'll fine tune the timing tomorrow and then take her for a ride. How much run time should I put on the engine before re-torquing the head?
 
Got the engine back in the bike over the weekend and got everything hooked up today. Spun it a few times without plugs to make sure I was getting oil to the upper end, which looked good. Added some gas to the tank and went for it. Took a bit to get some gas in the carbs, but once it got some, it fired right up. I'll fine tune the timing tomorrow and then take her for a ride. How much run time should I put on the engine before re-torquing the head?
I'll usually go by heat cycles on a fresh top end. About 10 - 15 cycles and retorque. Then about 500 to a thousand miles and do it again. Should be good after that.
 
Took it out for quick shakedown ride today. New top end and new bronze swing arm bushings. Runs sweet and handling is tight. Need to sort out an intermittent starter issue that I have more or less traced to the starter relay and possibly replace the clutch cable (it has a lot of free play and not much adjustment left). Well, I wanted a project...
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Took it out for quick shakedown ride today. New top end and new bronze swing arm bushings. Runs sweet and handling is tight. Need to sort out an intermittent starter issue that I have more or less traced to the starter relay and possibly replace the clutch cable (it has a lot of free play and not much adjustment left). Well, I wanted a project... View attachment 243040
Now go ride the wheels off it!! :laugh2:
You'll find that these XS' are like most mechanical things... the more you run 'em, the happier they are. Problems will get less and less frequent.
 
I'm trying to resolve the intermittent starter issue. This is a 1978 SE we're talking about. I pulled the starter relay and bench tested it; it works perfectly. I also checked that the starter switch on the handle bars was creating a good ground when pushed; it is a perfect ground. I then noticed that the red/white striped wire feeding both the starter relay and safety relay was intermittently losing 12 volts (12.8 actually). Based on the wiring diagram this red/white wire comes out of the light checker. I do notice that when I turn the key on, the red brake/tail light on the instrument panel comes on as well as the taillight (even if the headlight is turned off). Not sure if this is typical or not. However, when I lose 12v power to the red/white wire, the red brake/tail light also goes out. In this situation, the bike still runs and everything works (lights, brake light, turn signals, horn, etc.) except the starter and the red brake/tail light. I'm wondering if the light checker is the culprit? I can't find the thing on the bike, though I suspect it's buried back behind the battery. Any thoughts or suggestions on what to try or look at next?
 
Should be on the back of the battery box. You have to pull the inner plastic fender to get to it.
 
I hate just replacing parts hoping that is the problem. The more I look, the more confusing it gets. It's a 1978 SE, which according to the wiring diagram, it should not have a headlight switch, just a dimmer (high-low beam) switch. Yet, mine has both a headlight switch and dimmer switch. Looking at both the E and SE wiring diagrams in the factory manuals, mine seems to be some blend in between. I also seem to have about a 1.5 volt drop in the system when I turn the key on. I'm charging the battery out of the bike now to make sure it's not battery related and eliminate that.
 
The '78 models still had the headlight on-off switch. It was the last year for them. But, it only works with the engine not running. Once you start the motor, the auto-on headlight "safety" relay kicks in, bypassing the handlebar switch. Pretty silly set-up in my opinion, but easy to "fix" by just unplugging one wire .....


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This is the only year you can do this on. It was the last year of the handlebar on-off switch and the first year of the auto-on headlight relay.

The tail light is wired right into the ignition switch so it's normal for it to come on with the key. First year for this too. Not too much battery draw if you switch the bulb to a LED.
 
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