I think he's asking what I have been wondering.
What chain tensioner parts are need for the BBK? Type E?
-
Enjoy XS650.com? Consider making a donation to help support the site.
XS650.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
1974 TX650A Restoration Project
- Thread starter SomervilleXS650
- Start date
-
- Tags
- 1974 build thread tx650a
What chain tensioner parts are need for the BBK? Type E?
If these were mine, I'd put a fork in 'em.
'cording to yammies sorta reliable partz diagrams, the shaft is the same all year 74 up but 5 twins explorations sez different, or that a new number superceded and was a direct replacement for the old?
edit; I'm all for using a rubber washer.........
edit; I'm all for using a rubber washer.........
Last edited:
@jim
I think you need the type D or E tensioner (I would use the type E w/ lock nut). I seem to recall reading that somewhere, that this is what the big bore cylinder uses. Even if your type C adjuster screw threads in, I think it's going to stick out too much and not allow the small cap nut to screw on enough. If you watch eBay, you can usually score a type E assembly for about $20, sometimes even less.
I agree the E type seems to be the best with the D a close second. Will the lock nut fit the D type?
Somerville, If it turns out you need a descent "E type" tensioner and it becomes difficult to find, pm me. My extra E type isn't going to be installed for awhile. There are even descent left side rockers in that 82 head as well.
This Big Block project TX is way too cool to go too unexpectedly slowly for you. (us)
I'm at work but could provide parts pics this evening.
Edit, lft or rt rockers.. are those even interchangeable?
This Big Block project TX is way too cool to go too unexpectedly slowly for you. (us)
I'm at work but could provide parts pics this evening.
Edit, lft or rt rockers.. are those even interchangeable?
Yes... one
Ok, just got back from spending a couple hours with the bike. Firstly - thanks for all the help today fellas, I'm very glad I'm doing this real-time this time around (I'm guessing this cam/rocker wear issue would have been caught last year if I was posting the rebuild in real-time).
@5twins Thank you for that.....exactly what I thought might be the issue. I don't have a little acorn, so I couldn't mock it up today, but I did take some measurements that are maybe useful for the 'collective cam chain tensioner' archives, haha.
One idea I had - Is there any reason a second locknut couldn't be used to fill the gap?
Ok - some additional pics of the cam and followers. I'm very glad I asked this group...I can say with some certainty that I would not have pegged the visible discoloration as anything significant. (Sorry in advance for so many pictures....I was trying to change the angles and lighting slightly between pics to make it easier to see the surfaces).
Let me know what you think. And if the feedback is still replacement - suggestions for options are also welcome (even if answer is 650central, yamahaxs650 and/or Mike's)
@Machine Randy - you rule. Thanks for the offer, I might take you up on it. Wondering if you were changing rockers if you wouldn't change them all?
@5twins Thank you for that.....exactly what I thought might be the issue. I don't have a little acorn, so I couldn't mock it up today, but I did take some measurements that are maybe useful for the 'collective cam chain tensioner' archives, haha.
One idea I had - Is there any reason a second locknut couldn't be used to fill the gap?
Ok - some additional pics of the cam and followers. I'm very glad I asked this group...I can say with some certainty that I would not have pegged the visible discoloration as anything significant. (Sorry in advance for so many pictures....I was trying to change the angles and lighting slightly between pics to make it easier to see the surfaces).
Let me know what you think. And if the feedback is still replacement - suggestions for options are also welcome (even if answer is 650central, yamahaxs650 and/or Mike's)
@Machine Randy - you rule. Thanks for the offer, I might take you up on it. Wondering if you were changing rockers if you wouldn't change them all?
Yeah, that cam's just a good core for a regrind. All the followers are shot too. Hate to be the bearer of bad news, but that's a no brainer... replace 'em. Have a good look at the rocker shafts when you pull 'em. Pics maybe? There's a better'n even chance that was oil starvation..... and it galled the shafts too.
Oh man. Thanks for shooting me straight @Jim , haha. Can you help me understand what you're seeing here for my own understanding? Is it just the dulling of the polished surface or something beyond that? What would happen if one were to continue to run that cam and followers, out of curiosity?
Ooooh boy.....talk about a rabbit hole......I never even contemplated another cam when I was researching for my rebuild last year. I'd have no idea where to start. Regrind mine? Something more aggressive? What are the implications then on valves and springs and does that turn into a head-rework? (this is where I stop being excited and start getting sort of bummed out about it since it's all work I'd have to farm out).
What would my sage colleagues consider, if in my shoes??
Galling. It's where two surfaces exert force against each other without (adequate) lubrication. Think friction welding. The cam and follower (rocker) have deposits of each other on their surface. Yours would be considered pretty minor. Problem is, none is really acceptable for this application because it means the surface hardening (nitriding et al) is breaking down. It will only get worse.
The really sad part is it's just begun, otherwise there'd be more heat discoloration. I'd guess the cracked oil pump you found was only a hundred or so miles before you tore the bike down. In the words of Max Smart... Agent 99.... "Missed it by that much."
If you do a google search for "camshaft galling," here's what you'll find....
... and here's your cam...
... and here's your cam...
Got it. And that makes sense as to why it wouldn't be wise to button it all back up now that it's occurred. Most of my technical knowledge is in the organic side of things, I'm kind of a dolt when it comes to metallurgy or inorganic materials science.
Hahaha....I guess laughing about it is better than the alternative...
Been reading about cam options for the last hour or so. Seems like a regrind (or replacement) with a stock profile is a safe bet, but also seeing the other popular options are the Shell #1 from Hoos (which are maybe back in stock soon) or the "Web Cam" 59 or 59a grinds. The new Yamahaxs650.com site has these in stock for $199 after the core charge refund (here). And seeing advice to stay away from anything with a bolt-on sprocket, which intuitively makes sense to me.
When I did my rebuild the valve springs were in spec, so I reused them. The Shell or Webcam would both need performance springs.
Will also need to track down some rocker arm options.
OHHH so it's literally in the dictionary next to galling. Glad I could provide such a textbook example
Here's the big bore rabbit hole as I see it.... More displacement means more potential horses. That means we can burn more gas... that means bigger carburetors . Bigger carburetors means more cam duration and lift to let them carbs breathe. More lift means better springs to coral the valves. Then there's the ports... and exhaust....
Guess it all depends on where you want to draw the line. I bought a big bore kit for my speed twin build. I'll prolly run across ya down that rabbit hole...
Guess it all depends on where you want to draw the line. I bought a big bore kit for my speed twin build. I'll prolly run across ya down that rabbit hole...
I am just loving this thread, and thankful for all of this shared knowledge! That said, you guys have now scared the shit out of me regarding galled camshaft lobes and rocker arm surfaces. I'm certain mine were not so pristine when I put my TX engine back together...
Looking forward to more great photos Somerville.
Looking forward to more great photos Somerville.
Well.....while I sort out my cam and rocker woes....I'll can get back to our feature presentation with a few more pics of what I got up to Sunday.
Pulled the head and jug off....turns out it doesn't take a real long time to get pretty filthy in there...gonna have to give those gasket surfaces a good clean.
At this point I realized the reason Jim's top-end thread is so great (and why I had a similar experience last year w/ my rebuild) is because he's starting with perfectly clean parts and leaving out the part that !*#$& sucks. Here's some very unglamorous pics of me stuffing the open motor w/ shop towels and scraping gasket remnants off the cases with a plastic scraper blade and Permatex gasket remover. It probably took 20 minutes or so and one of many grimy scraping jobs of the day.
Ok....new BBK gasket on my nice new clean mating surface.
Here are a couple that I thought were interesting showing the stock OEM jug next to the BBK.
Next one is pre-installing my Hoos cam-chain front guide (with some crappy HW). Centered within the tunnel to < 0.5mm tolerance which seemed plenty when I mocked up and eyed the width of the chain on the guide.
Forgot to take a pic, but I then pre-installed the pistons in the bores with the jug upside-down from the bottom. Lots of posts here and in the manual for ring gap orientation, so won't rehash that. Made sure to install the interior circlips on each piston as well.
Ok, so something I did find that was a little surprising....I don't know if it was just my kit, or play in my studs....but I actually had a bit of trouble getting the BBK jug onto the motor. It seemed to hang up on the threads. Whether it was the tolerances of the kit, or maybe my threads were splayed out from years of use, I don't know. It could move by hand but was just really snug and would bind every time I tried to push it down (almost felt like it was sort of cocking left, then right). I think the 8 individual points of movement amplified this 'cocking' effect. In any case, I ended up adding some assembly lube to the studs (although grease may have been better) and very lightly tapping left/right to get it on. I was concerned about this damaging something but I could feel it sort of 'wiggling' down the studs each time I tapped it, so I just stuck with it. It ended up taking longer than you might think, but it got on there eventually and I hand threaded a nut on each stud successfully, so I didn't damage any threads.
At this point I used whatever ridiculous combination of handy items (dead-blow handle and random block of wood) to position the jug so that I could get the wrist pins in. While I don't show it here, be sure to put those shop towels back into the motor when installing the other circlip...it's tempting fate otherwise...
And with that, BBK jug and pistons installed.
Pulled the head and jug off....turns out it doesn't take a real long time to get pretty filthy in there...gonna have to give those gasket surfaces a good clean.
At this point I realized the reason Jim's top-end thread is so great (and why I had a similar experience last year w/ my rebuild) is because he's starting with perfectly clean parts and leaving out the part that !*#$& sucks. Here's some very unglamorous pics of me stuffing the open motor w/ shop towels and scraping gasket remnants off the cases with a plastic scraper blade and Permatex gasket remover. It probably took 20 minutes or so and one of many grimy scraping jobs of the day.
Ok....new BBK gasket on my nice new clean mating surface.
Here are a couple that I thought were interesting showing the stock OEM jug next to the BBK.
Next one is pre-installing my Hoos cam-chain front guide (with some crappy HW
). Centered within the tunnel to < 0.5mm tolerance which seemed plenty when I mocked up and eyed the width of the chain on the guide. Forgot to take a pic, but I then pre-installed the pistons in the bores with the jug upside-down from the bottom. Lots of posts here and in the manual for ring gap orientation, so won't rehash that. Made sure to install the interior circlips on each piston as well.
Ok, so something I did find that was a little surprising....I don't know if it was just my kit, or play in my studs....but I actually had a bit of trouble getting the BBK jug onto the motor. It seemed to hang up on the threads. Whether it was the tolerances of the kit, or maybe my threads were splayed out from years of use, I don't know. It could move by hand but was just really snug and would bind every time I tried to push it down (almost felt like it was sort of cocking left, then right). I think the 8 individual points of movement amplified this 'cocking' effect. In any case, I ended up adding some assembly lube to the studs (although grease may have been better) and very lightly tapping left/right to get it on. I was concerned about this damaging something but I could feel it sort of 'wiggling' down the studs each time I tapped it, so I just stuck with it. It ended up taking longer than you might think, but it got on there eventually and I hand threaded a nut on each stud successfully, so I didn't damage any threads.
At this point I used whatever ridiculous combination of handy items (dead-blow handle and random block of wood) to position the jug so that I could get the wrist pins in. While I don't show it here, be sure to put those shop towels back into the motor when installing the other circlip...it's tempting fate otherwise...
And with that, BBK jug and pistons installed.
