Engine teardown advice needed

[Rabbid]

So Im in the process of rebuilding my motor. At the moment I have the top end machine work almost done (bore to 2nd, new pistons/rings, and guides so far). Where I'm stuck is whether or not I should split the case. On one hand its going to be a pain the ass on the other its fun to take shit apart and see if its fucked or not. Its a toss up for me right now. What are some common issues that require splitting the cases?

the engine its self was not in terrible shape but it was ran and maintained pretty poorly by the looks of the top end. its a 79' special with about 18,000 miles on it. I can only assume mileage because that's what it says on the smashed odometer.

 

[angus67]

I split my case because I had a piston pin let go, resulting in aluminum sand thruought entire. so I HAD to take it apart to get it all out. if my motor ran when I got it, I would have left it alone if it had good compression. whats your compression? does it run...errr ran until you got it?
just do the things that are on this list...
http://www.xs650.com/forum/showthread.php?t=390
if you do split the case, do it upside down. thats how they whent together. I didnot know that when I attempted to put mine bACK TOGETHER, NOW i HAVE CRESCENT SHAPED hammer marks on the top of my case. when I turned it over, it practically assembled itself!

 

[XSLeo]

How is the side clearance on the big end of the rods? And how much do they rock? Your repair manual tells how to check these things.
Check the crank runout and the end play.
replacing the clutch push rod seal, the seal behind the front sprocket, the shift shaft seal. These can be done without splitting the cases.
If it all checks ok I would leave it be. The lower ends and the trannys are almost bullet proof on these engines.
If it ain't broke don't fix it.

 

[gggGary]

XSLeo (as usual) sounds right on with his advice. Freshening the top at 18K miles sounds about right. Might want to remove the clutch side cover and check the electric start spring tension and maybe inspect and measure clutch disk thickness as long as it is on the bench anyways. Never hurts to look at the springs on the back of the clutch basket either.

 

[CDNTX650]

i agree. i havent done the bottom ends on any of the SOHC hondas or XS's i have owned. they seem very stout.

 

[Rabbid]

The bike was a basket case when I got it so it never ran. Plus it was missing the points on it so I just decided to take it apart. I have the clutch assembly off (used 2 vise grips and the clutch plates) so once my top end is back from the shop I'm going to pick up some new plates and springs. The seals are already on my todo list. Is there anything I should spend a little extra cash/attention on? now would be the time for me as I soon plan to change jobs and its going to be rough for a bit. Thanks for the replies guys.

 

[5twins]

I wouldn't bother replacing the clutch plates. They rarely wear out. Measure the thickness of the fiber ones, should be 3mm. Use that $50 or $60 you save for other stuff like the complete seal kit, long clutch pushrod, new carb manifolds, whatever.

While you have the clutch all opened up and off, I would also do the Allen bolt clutch screw mod and bend the drag clip tighter on the #4 starter gear.

 

[gggGary]

If you plan on using the electric start, now would be a good time to clean it and check the brushes.

 

[Rabbid]

Yeah that screw mod looked appealing after trying to remove those screws and realizing I was no match for them. I did plan to leave the electric start just in case. I don't think Los Angeles traffic would understand me trying to kick start my bike if it stalled during rush hour.