1974 TX650A Restoration Project

Update: 2021 and 750 BBK install

Well - had an awesome first season on my bike and ended up putting it to sleep for the season in November, down at a friend's house. Put about 2200 miles on the rebuild over the summer and had some really awesome rides that kept me sane during covid. One thing I was never fully happy with was the exhaust; while the OEM headers/mufflers sounded great, they were in pretty rough shape mechanically (lots of rusting internally that would flake off like crazy and leaky internal pipes in the headers) not to mention a fair number of dents and scrapes on the mufflers and rust on the interiors of the headers. They were passable, but never quite what I wanted to complete the rebuild. I decided I would replace them for this year and pulled the trigger on a set of 1.5" chrome headers and the "good" Commando replicas, both from yamahaxs650.com.

Annnnnnnd while I was there...... because I apparently am a glutton for punishment...I picked up one of the very-affordable 750BBK kits. It would have been a lot smarter and easier if I put this kit in last year (when I had the motor out and rebuilt it!), but hey - here we are.

So this past weekend I came down to get to work, hoping I didn't open a can of worms that I would regret....

First, a few pics of the kit.... as has been reported....it looked pretty good (I guess?). The rings are supposed to be ready to drop in, but I measured the gaps and pre-determined which ring set/piston was destined for each cylinder.
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Then, on Saturday morning it was time to pull and dismantle the motor on a fully functioning bike because I think I might be an idiot...

Airboxes and carbs off...
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Exhausts off...(you know...they don't look too bad off the bike!). Chrome is actually in pretty good shape for the most part, but like I said they're slowly rotting away from the inside and have quite a few war wounds.
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Continued....

Now, the motor mounts and some frame protection. Now, unfortunately I am down at my stepdad's house and had to lug my tools down here....leaving me a little limited. So I had to get creative to get the motor out and used a block of wood and the spare-tire jack from my car to take the weight off and get the bottom motor bolt out.
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At that point, I contemplated the options and just went for the squat-clean to pull it out and onto the floor. Then another deep-squat hug and hoist up onto the bench.
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Ha.....and after just a few hours....there was no going back....:laugh:

Started stripping down the top end.
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Hmm....had a little leak there on the RH cam side....will need to check that oil seal...
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Tap tap tap
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Cam bearings out, sneak the cam out, endless cam chain intact.
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Whoooo. Some more carbon on the piston tops than expected. RH side much more so than LH side. I know I had an intake leak that I was battling last year,....I never replaced the original intake boots but have some new ones to swap on. Any other ideas as to what might be happening is welcome.
Other than that, things looked pretty good with the cams, rockers, valves, etc.

Trying to do this more in real-time this time around, will post again tomorrow about what I got done yesterday.
 
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Cam bearings out, sneak the cam out, endless cam chain intact.
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Whoooo. Some more carbon on the piston tops than expected. RH side much more so than LH side. I know I had an intake leak that I was battling last year,....I never replaced the original intake boots but have some new ones to swap on. Any other ideas as to what might be happening is welcome.
Other than that, things looked pretty good with the cams, rockers, valves, etc.

Trying to do this more in real-time this time around, will post again tomorrow about what I got done yesterday.
Hmm, I'm not seeing your pics just
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Even weirder.... his pic shows up in your comment Gary.

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Alright, think it's fixed up (let me know?)

Valve guide seals maybe?
Jim - I was thinking that....I just replaced 'em last year. That still the most likely thing? I wasn't planning on taking the valves off again but if they need replacing I can do it (I haven't buttoned it all up yet).

It's hard for my inexperienced eye to assess 'normal', but I felt pretty sure that ain't it. I also let the bike run the carbs dry 'til it died before I put it away and wasn't sure if that would confound any diagnosis.
 
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Cam bearings out, sneak the cam out, endless cam chain intact.View attachment 187105 View attachment 187106
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Whoooo. Some more carbon on the piston tops than expected. RH side much more so than LH side. I know I had an intake leak that I was battling last year,....I never replaced the original intake boots but have some new ones to swap on. Any other ideas as to what might be happening is welcome.
Other than that, things looked pretty good with the cams, rockers, valves, etc.

Trying to do this more in real-time this time around, will post again tomorrow about what I got done yesterday.
Yes, strange that one piston cleaner than the other. Recently had my TX750 in bits and this is what I found.
I see your pictures OK.
 
It would seem you have a ligneous avian infestation:D. But I'm certain that is unrelated to your carbon build up, thats most likely a leaky valve guide seal. Going from stock bore/exhaust to 750cc with Commando exhaust is going to be a night and day difference. Thats going to be whole different bike! You ought to throw a shell cam in while your at it.
 
It would seem you have a ligneous avian infestation:D

Hahahaha, I was waiting for that.... My stepdad is a retired biologist who spent his career studying birds. He also buys and sells wooden decoys. I had no idea this was even "a thing", but it's a whole world unto itself (probably a lot like pipes Rustie!). If you can believe it....the ones you see in the pic are probably just 20% of what he's got in his garage and basement. It was amazing to see what some of them sell for.
 
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