1974 TX650A Engine Rebuild

OhTimothy

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I have an abused (by previous owners) '74 TX650A and the engine has begun making bad noises, emanating from the crank case. I would like to do a home rebuild on the engine, installing a new crank and rod assy, new timing chain and new standard size cylinder assy and pistons. I am a reasonably mechanically competent DIY guy, but I'm not sure about the level of difficulty this job would present. A couple of questions:
1) Is it a job a fairly competent home mechanic could do, or is the level of difficulty too high?
2) I see many stock engine parts available at "Mike's XS" but I don't see a comprehensive overhaul kit that includes a crank set, cylinder block and pistons, gasket set, cam chain etc...is there a comprehensive rebuild kit available anywhere?
3) Would I really be better off waiting for a used engine in good shape to come along and just buy it outright?

Any encouragement, recommendations, honest discouragement or advice would be greatly appreciated. I attached a picture of my baby - I'm very sentimental about this old hack and want to fix it if possible. Again...thanks.
 

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Buy used..?.. ya got used now... The top end of these isn't that difficult.... pretty much straight forward... plenty of help on the forum ... I had to spilt my cases on my 70's Xs1.... wrist pin on early Xs1 used needle bearings that fail.... Before I did it.. I got the bottom end off another motor.. took it apart and back together about half dozen times... then did mine. Wasn't that difficult.... follow the book.. note the location and sequence.... The left side crank seal.. the big one.. I installed on the crank ...got it located then installed the case half...Yama-bond. I used a 73' Tx crank... still run'n.. no problems..... There's no " complete kit "... seal kits.... gasket kits.. the four upper copper washer seals.... can all be ordered....
 
On a 1 to 10 scale of difficulty of engine rebuilds, the XS is about a 3 or 4.
Just a suggestion... put a video up here of the noise. Not all "bad" noises require a full on teardown to fix. Get some more ears on it first.
 
Guys and girls have come on here with no experience and rebuilt the top ends no trouble. Bottom end isn't much harder. Secret is to take thousands of pics as you go and bag and tag everything as well.

The con-rods can be checked for play when the top end is off. If withing spec, (unless there is a bearing noise), then the bottom should be ok. Usually the top can be done 3 or 4 times before the bottom need to be done, (again as long as it hasn't been thrashed).

Pays to source components from different suppliers as some are quality and cheep and others are the only suppliers

Look up https://www.cruzinimage.net/ These guys have quality pistons and some other parts at a budget price.
 
Buy used..?.. ya got used now... The top end of these isn't that difficult.... pretty much straight forward... plenty of help on the forum ... I had to spilt my cases on my 70's Xs1.... wrist pin on early Xs1 used needle bearings that fail.... Before I did it.. I got the bottom end off another motor.. took it apart and back together about half dozen times... then did mine. Wasn't that difficult.... follow the book.. note the location and sequence.... The left side crank seal.. the big one.. I installed on the crank ...got it located then installed the case half...Yama-bond. I used a 73' Tx crank... still run'n.. no problems..... There's no " complete kit "... seal kits.... gasket kits.. the four upper copper washer seals.... can all be ordered....
 
Buy used..?.. ya got used now... The top end of these isn't that difficult.... pretty much straight forward... plenty of help on the forum ... I had to spilt my cases on my 70's Xs1.... wrist pin on early Xs1 used needle bearings that fail.... Before I did it.. I got the bottom end off another motor.. took it apart and back together about half dozen times... then did mine. Wasn't that difficult.... follow the book.. note the location and sequence.... The left side crank seal.. the big one.. I installed on the crank ...got it located then installed the case half...Yama-bond. I used a 73' Tx crank... still run'n.. no problems..... There's no " complete kit "... seal kits.... gasket kits.. the four upper copper washer seals.... can all be ordered....
Mike - you mentioned "follow the book" -- Is there a Yamaha shop manual that thoroughly covers disassembly steps, re-assembly and tolerances/specs?
 
Mike, I have a Clymers manual but it doesn't fully cover disassembly, re-assembly and specs for rod side play and so on. Is there a comprehensive shop manual available?
 
Collect up several different manuals if you can so you can cross-reference between them. Some will contain info others won't. In particular, the factory shop manual will have the most comprehensive spec listing, but since it was made for the mechanics in the Yamaha shop to use, it won't explain some of the more basic steps. I guess they figured a mechanic should know that stuff already, lol.
 
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