What else to do while in the engine..?

[Snikare]

In the next month or so, I plan on tearing my build down for paint and reassembling with a handful of new goodies. While it's apart, a mechanic friend said he would Crack my cases for me and install the 5th gear over drive. While I've got it open though, what parts should I be replacing? I'm assuming I'll want to replace the main seals and gaskets. Should I replace any bearings or races while in there? Any suggestions of things I should have ready for when I get the motor opened up?

Any input is greatly appreciated.

The motor runs well with an original 10k on it.

 

[Marlin72xs]

There are thousands of threads for you and I don't know where to start. You will get mucho replies in a few days and the others in our clan will direct you in an orderly fashion.

I will say this, do not buy the over drive gear until you measure the shaft and original gear. See the thread on the OD gear.

FYI, I put one in my 72, and I like the change. A very small change, but it works. One tooth less on the rear sprocket also made a pleasant, but not too abrupt difference. Ok while I'm at it, carefully inspect your shifting forks and gears cogs. I bought an 81 trans and 78 shifting forks and drum.

Twomany, (remember that name), wrote his doctorate thesis on the xs transmission. He has 99.9% of the answers. Good luck! Your XS will become a wonderfully excessive hobby.

 

[TwoManyXS1Bs]

...Twomany, (remember that name), wrote his doctorate thesis on the xs transmission. He has 99.9% of the answers...

Haha, boy, do I have some of you fellas buffaloed. Thanx, Marlin.

Back in my shop days, an overhaul always called for the usual replacement items (gaskets, seals, oil and filter). But, we replaced hard parts on an as-needed basis. After teardown and careful inspection and measuring, the customer would be contacted and advised, then get his 'okey-dokey', unless it was a 'fix it all regardless' type overhaul, then all those things would be replaced.

The FAA has a better ranking system for classifying engine work, with different critera for each. Basically, they are:

Return to service. (Fix what's broke)
Return to service specs. (Get parts to fit within at least the bottom end of the limits)
Return to 'new' specs. (Get parts to fit at the 'new' end of the limits)
Rebuild with new parts. (Replace parts that are still good, Expensive)
Factory certified renew with all new parts. (Really expensive)

But, with bikes, you can run the full range of 'crippled-but-kinda-runs' to 'As-new-restoration'.
Lotta leeway in there, lotta judgement calls, juggling risk factors. And the money factor.

Basically, it's best to budget for the usual 'must replace' items.
Then decide the rest after teardown/inspect/measure...

 

[ryamatt]

My 2 cents...if the engine is already a runner and you are just wanting to freshen it up and reset the clock on its life a little, don't split the cases unless you deliberately wanted the OD gear or are having an issue with something requiring you to go into the bottom end. The wear and tear items that are going to have the most impact on your life are on the top end - Pistons, rings, sleeve condition, timing chain and guides, gaskets, seals. There is a case to be made for the "while I'm in there..." philosophy, but if you are budget conscious and want the most impact on your ride, spend the time and money on doing the top end right.