First XS650 Build, What to Look For

Could I use a carb cleaner? I would think that the two solvents would be quite similar, but I'm no chemist.

Simply looking to use what I've already got, as I just picked up that can of carb cleaner for servicing my also-dirty carbs.
 
Really, I would stick with the brake cleaner. It's special made for that purpose and won't harm the shoes or other parts, and won't leave any oily residue. Don't worry, it won't go to waste. It's a good general de-greaser too. But for general heavy cleaning, like under that left cover, I just use plain old kerosene. It's cheap, it works, it's not too flammable, and it's not too hard on the hands.

Most don't clean under that left cover as much as they should and what you found is typical. It's mostly years of build-up from chain lube fling-off, but there are several oil seals under that cover that are prone to leaking. They will add to the "mix", lol. In your pic, it appears wetter under the sprocket so there's a good chance that seal is leaking. Many times it's because the sprocket nut has loosened up, and the seal is fine. These sprocket nuts need to be run very tight (like 90 ft/lbs) or the seal leaks badly. Oh, and 36mm is the largest metric socket Sears sells, so you're in luck.
 
No need to buy that tool. Look up "floating tool" in the classified section. We have one we pass around to those in need. Just call dibs on it and you'll get it in the mail. You mail it to whoever calls next.
 
Honestly, I never measured the size. I just bought the tool from Mike's several years ago and never looked back. This is a tool you do want to use. While many "special" tools have work-arounds, this isn't one of them, at least not without running the risk of damaging the components.
 
Threw my name in the floating tool section, so when that arrives I'll pull that rotor off and be done with it. Never going to need it again anyways since I'm going w/ a PMA which has a different size rotor bolt. I'll buy that tool instead for future maintenance.

Anyways...onto tonight's progress.

Began teardown of the engine, goal was to get the rocker head off.

Started by watching Nightflyers video on youtube, huge props to that guy for making those disassembly videos. Really made me feel at ease about disassembling. Hopefully this build thread does the same for some other novice so that I can pay it forward in a way.

Starting in by taking off the left and right ignition and advance assembly covers, respectively. Didn't snap of pic of the points, but here's the backing plate. Sorry for potato quality.
F9g5oBQ.png


Here's a shot of what it looks like once you remove the housing unit as well.
eDBFVqj.png


Onto the right side. Advance unit removed, tapped the advance rod with a BFH from the left side and pulled it out the right side. Here's a shot with it pulled out just a bit
BUD5Xnu.png


This comes off by placing a flat punch in the grooves and tapping it counterclockwise. A few knocks with the punch and it should be finger twistable. A reminder that the one side has a raised groove on it, this side faces OUT or away from the engine. Or at least mine was installed that way.
djuzq5u.png


Here's the unit that holds the mechanical advance arms and springs. It's a PITA to get off, and I snapped a file while trying to get it out. But eventually it came loose.
IfTQ27E.png


Went to take the valve covers off and realize that 3 of them are 3-hole covers but this one has 4. Is that normal??
RlPBH5h.png


Removed the oil delivery tube. Always wrap it up guys, prevent the spread of disease into your engine lol
wvhhigY.png


Cam chain tensioner, looks decent.
FmzbMJo.png


And of course, the dozens of little baggies holding all the bolts and pieces I've removed so far. Labeled with sharpie to remind me what came from where. A good practice for any first time engine rebuilder.
aynuI4z.png


Currently I'm waiting 24 hours for the PB blaster to soak into the space between the head cover and the surface it mates to. There is some red sealant between them that is refusing to allow me to get the cover off. So I didn't quite hit my goal for the night, but I'm only one step from it. Better to let the solvent seep in and pull it off tomorrow than break something trying to pull it off tonight.

Back tomorrow with more progress pics.
 
You're going to need to remove that fitting that was at the bottom of the oil pipe, the one you covered with a baggie. It hangs in over a lip on the bottom of the cylinders and will stop them from lifting off.

If you're seeing red sealer between the top cover and head, someone's been in there before. Yamaha used Yamabond which is gray colored.
 
That's a bummer, was hoping this engine would be unmolested, and given how the PO left the rest of the bike this makes me very concerned. Guess I'll be learning quite a lot and won't necessarily be able to simply note how it was installed upon disassembly as PO could have put things in wrong, failed to get it running then sold it to me. Here's hoping there are pistons inside lol
 
Something else you'll want to keep track of and not lose are the 3 little locating pins for the advance rod and unit. There is one on each end of the advance rod to lock in the position of the points cam and the little advance disc. The third is stuck in the cam on the advance unit side and locks the unit in the proper position. The three pins lock all the components in so the timing is correct. They are just stuck in holes in the rod and cam, and can fall out and get lost easily if you're not aware of them.

Since you removed the points cam and the advance unit, you should see those two pins. Pull them and put them in a safe place. Even if you switch to a Pamco ignition, you'll still need the pins to lock those new components in the proper place.
 
I saw two of those pins. One keeping each side from sliding out of position. The third must be underneath one of the portions I didn't remove from the rod. Advance side maybe?
 
Yes, there's one locating the little disc on the advance end of the advance rod. One more thing - when you re-assemble things, you have to align the locating pins on the advance rod so they point in the same direction. They can be installed 180° off from one another. That throws the timing 180° off .....

AdvanceRod.jpg
 
Alright guys, I can't get this top cover to budge.

All sides are coming up a little bit minus the side that has the 4 hole valve cover. I've tried PB Blaster in the seam, taps w/ BFH, white vinegar, rocking top cover, pulling straight up. Everything besides prying it apart from the open section. Don't want to risk marring the mating surface and causing a leak.

Any tips/ideas? Progress is pretty much halted until I can get it off.
 
There's two hollow alignment dowels in there that can cause havoc. If the camcover surface becomes cockeyed to the head surface, they can bind. They can also be corroded, and won't release. Check the manuals for their locations, and try to shoost some penetrant into whatever little sliver of gap you can get.

Heat (to soften the sealing goo), and shock (hammer taps in the region of those dowels) may be your next recourse.

Remember the trick to get tie-rod tapered fittings to release?
 
Got it. I could try to replace the bolts on the side that lifted up, so that they sit back down to where the top is level and see if I can get the stuck corner to budge a bit. Hopefully that helps the situation some.

Also, it seems that there are rubber spacers under each of the domed hex bolts that came off the top of the head. These spacers don't want to lift up. I managed to pry one off with a flathead screwdriver, but it seems like they're all on there for good and not meant to be removed. Can anyone confirm or deny?
 
I think you're talking about the rubber sealing washers used under the 4 outside acorn nuts. That's probably what's holding the cover from coming off. They get squished and the rubber sticks into the threads, effectively locking them in place. Yes, they need to come off. I carefully tap into the sides of them with a flat blade screwdriver and hammer. It's OK to destroy them (and you probably will) as they will get replaced with copper or brass washers. The rubber washers get so squished and tight that they usually don't lift off. They need to be pried or threaded off.
 
Ahh ok good to know. In nightflyers video he had no such washers present so I was wondering why these were even here in the first place. I will remove them and try again.

And those 4 phillips head screws on the sides of the cam cover (and directly outside of the point/advance covers) don't need to come off do they? Again in the video he did not remove these pieces and it seemed to lift off just fine.
 
Hey guys, sorry for the delay but I've made some additional progress and wanted to update!

5twins, I took your advice and removed the rubber washers. As usual, you were correct and the head came off right after. Thank you! Here's what lies beneath

2sUE0Mh.png

Another angle
smPd6rZ.png


Again, these pistons are seized. Or at least the right one is. Right as if you were sitting on the bike seat facing forward. When I initially took the cover off it was like a reeses peanut butter edition XS650. One peanut butter colored piston head and one dark chocolate lmao. I cleaned them up before I took the pic but you'll see what I mean shortly when I link the valves.

Before that though, here is the underside of the header
ZAYKI20.png


The camshaft
OhU2ciy.png


And a closer up shot of the cam chain sprocket teeth. I don't know what bad looks like but I hope this isn't bad
EWcY8dd.png


That's something I'm curious about as I go along. Being that I've never been inside one of these engines before, I'm not always certain what I should be looking for. If anyone has specific points of failure or common issue parts please feel free to chime in and I'll check tolerances etc.

Valve springs
WK0KB9S.png


Here's that shot of the valves. Can you tell which one was from the rusty piston? I'm assuming someone must have removed the right spark plug and left the bike out overnight in the rain then subsequently left it alone for another 20 years. Pretty nasty to see this but it did clean right up with no pitting so that's good.
16xiVPB.png


After the cleanup
VQLuS51.png


Stock stator, will be going straight to the trash unless one of you needs salvage parts for whatever reason. Just chime in and let me know.
XUkwuhj.png


Stator rotor unit w/ 17mm nut removed. Just awaiting the rotor puller from the floating tool section before I remove this.
mTbGRHb.png


Another shot of it
g9UB2mT.png


Lastly, at the front of the engine there are two small plateaus which almost look like something was there but is now broken off. What are these little things? I'm referring to the area below the oil stain which looks almost like a tobacco pipe. It's like two little mountains with flat tops. Like two little engine mesas lol. Hope nothing was supposed to be there!
gyEih4H.png


As for where the project stands now, still waiting on those pistons to free up. Every night I spray PB blaster in the seams, tap w/ 2x4 and BFH (on BOTH pistons), and wedge wooden shims between case block and bottom on cylinders per my research in other threads which recommend those procedures. If anyone knows of any other bright ideas, feel free to let me know. Until I can get these damn things loose, I can't get any deeper into the engine.
 

Similar threads

Hamon2
Building an XS.. that isn’t a 650
Replies
13
Views
763
Hamon2
Hamon2
S
xs650b down under build thread
Replies
16
Views
375
spresser
S
V
Any suggestions for new bike build?
3 4 5
Replies
80
Views
3K
Shelby
Shelby
Mike G
  • Poll
Bridgeport (clone) build thread on XS650, Yay or Nay?
Replies
14
Views
406
Mike G
Mike G
NerdyNerd
82 XS650 Cafe Racer Build
2 3 4
Replies
62
Views
6K
Adamc
Adamc
Back
Top