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1974 TX650A Restoration Project
- Thread starter SomervilleXS650
- Start date
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- Tags
- 1974 build thread tx650a
Question for you guys.
Up to 850 miles on the rebuild, and the bike is generally running well. I thought I'd give the valve clearances a review now that the rebuild has broken in a bit. First thing to do was check the cam chain tensioner.
When I rebuild the motor I replaced the copper washer on the tensioner with one of the rubberized replacement units from Mikes. Found a ton of good posts, notably from @5twins on how these units evolved over time (Believe I have the type 'C" in my bike, if memory serves). Problem is, with the thicker washer, the adjustment instruction of "Set the end of the plunger flush with the housing" doesn't work, as the thicker washer pulls the plunger in, leaving the end of the plunger recessed slightly. So, I've seen advice here to adjust while the engine is running, and set the tension so that the plunger movement is ~1-2mm. Actually measuring this wasn't the easiest thing to do, so I took a slow-motion video:
Any feedback on this? Seem normal?
Up to 850 miles on the rebuild, and the bike is generally running well. I thought I'd give the valve clearances a review now that the rebuild has broken in a bit. First thing to do was check the cam chain tensioner.
When I rebuild the motor I replaced the copper washer on the tensioner with one of the rubberized replacement units from Mikes. Found a ton of good posts, notably from @5twins on how these units evolved over time (Believe I have the type 'C" in my bike, if memory serves). Problem is, with the thicker washer, the adjustment instruction of "Set the end of the plunger flush with the housing" doesn't work, as the thicker washer pulls the plunger in, leaving the end of the plunger recessed slightly. So, I've seen advice here to adjust while the engine is running, and set the tension so that the plunger movement is ~1-2mm. Actually measuring this wasn't the easiest thing to do, so I took a slow-motion video:
Any feedback on this? Seem normal?
Cool slo-mo vid.
The motion in there looks OK to me...
The motion in there looks OK to me...
Awesome, thanks 2M, appreciate the feedback.
I never really measure the plunger movement, just eye it up. My usual routine is to tighten the adjuster until the plunger movement stops, then back it off until I get the small amount of movement I desire.
I recently checked the adjustment on my '83. I did so just before changing the oil with the motor hot. I found it too tight, there was no plunger movement. I attribute this to the fact that I most likely set it before with the engine cold. I know it's been mentioned here that it should be done hot but I always thought if it was, all the parts would be hot and expanded, so it wouldn't be much different than on a cold engine. But apparently, this is another of those cases where different metals expand with heat at different rates and amounts. The alloy cylinders expand more than the steel chain so if set cold, it can be too tight when hot.
So, lesson learned, I will only be setting and checking the cam chain tension when the motor is hot from now on. I've made this part of my oil change routine so the chain gets checked at about 1000 mile intervals.
I recently checked the adjustment on my '83. I did so just before changing the oil with the motor hot. I found it too tight, there was no plunger movement. I attribute this to the fact that I most likely set it before with the engine cold. I know it's been mentioned here that it should be done hot but I always thought if it was, all the parts would be hot and expanded, so it wouldn't be much different than on a cold engine. But apparently, this is another of those cases where different metals expand with heat at different rates and amounts. The alloy cylinders expand more than the steel chain so if set cold, it can be too tight when hot.
So, lesson learned, I will only be setting and checking the cam chain tension when the motor is hot from now on. I've made this part of my oil change routine so the chain gets checked at about 1000 mile intervals.
Yes, your movement looks good. As I mentioned above, I feel the best adjustment is had by tightening the adjuster up first then backing it off. You won't hurt anything by running the chain tight like that for a few seconds. With this method, you get the chain just loose enough, just a bit looser than too tight. In my opinion, you get the perfect adjustment this way.
I had that thicker rubber/metal washer in my '78 for a while but went back to the copper one. I found no difference with that rubber/metal one. The bike didn't run or perform any better and there was no less noise. As you've noted, the only difference was it made adjustments more difficult. I think the way MikesXS advertises it as an improvement is just a sales pitch.
I had that thicker rubber/metal washer in my '78 for a while but went back to the copper one. I found no difference with that rubber/metal one. The bike didn't run or perform any better and there was no less noise. As you've noted, the only difference was it made adjustments more difficult. I think the way MikesXS advertises it as an improvement is just a sales pitch.
PS spark plugs out, use the electric starter is a good way to set the cam chain. Beats trying to get into that spot on a hot running motor....
Just added these to the 2021 Calendar thread but thought I’d post here “at home” as well. Few new ones from a nice ride around Martha’s Vineyard with my wife yesterday. Have about 1800 miles on my rebuild so far. One new addition is the snazzy luggage rack I snagged from phil240 that has been a huge game changer for the utility of this bike (and thanks to Randy/ @Machine for fitment guidance).
Great photos - your 650 just looks so at home in that environment.
Damn that's a nice looking 74
looks better than the one I had and it was only a year old at the time
Thanks Raymond! My wife and I spend a couple weeks out here every September so it’s been awesome to explore for the first time via motorcycle. I agree, she seems to be well suited to the locale
(applies equally to both bike and wife, I suppose)Damn that's a nice looking 74
Thanks!! It’s definitely a work in progress but I was/am really happy with how it’s coming along
Not sure how well known this is outside our neck of the woods, but for those who don’t know, Martha’s Vineyard was used as the fictional “Amity Island” from the movie Jaws.
Man! There is nothing about that post I don’t like! Beautiful scenery, beautiful bike! A real calendar girl!
I voted for ya...Heh heh, remains to be seen
Wow! Congrats on such a beautiful rebuild. I've really enjoyed reading this thread, and have learned a few more things abut my '74. You have a stunning looking bike, and I agree, it does look so "at home" on those two lane road pictures.
I like the rack. It suits your bike well. Looks right at home in there.
