Author Topic: Senior project for high school - 78 CB750K (Read 169533 times)

Bill/BentON Racing · « **Reply #775 on:** March 03, 2015, 07:33:05 pm »

What y'all doing after lunch? Haha, getting there, cmon you can do it, Bill

SOHC4 Cafe Racer Fan · « **Reply #776 on:** March 03, 2015, 10:55:38 pm »

It's coming together. The paint (especially) and wiring will be the bigger tasks.

Restoration Fan · « **Reply #777 on:** March 04, 2015, 05:14:11 pm »

Ever do something stupid to your bike and it just discourages the heck out of you? Yeah...been there did that tonight.

Putting everything back together on the front end with the rubber pieces on top & bottom of fork ears. Get all that back together and I tighten the fork nut that holds the top triple tree to the bottom rod that sticks up through it....and I overtighten it just a bit and strip it. Not sure if it's the threads on the rod or the nut that's stripped but I believe it's the threads on the rod because I have a spare nut and it's not wanting to go on there either.

So we took the top triple tree back off, removed the forks, ears, etc and punted on that section for a while. Still not sure what I'm going to do there.

We did get the black paint on the hand controls and have carb #1 soaking in the Berryman's. Got the front fender reassembled and ready to go back on but we have to wait on that until we get the front end straightened back out.

SOHC4 Cafe Racer Fan · « **Reply #778 on:** March 04, 2015, 05:34:46 pm »

A stupid question but how do the threads look on the stem? That's a tough thread to strip.

Restoration Fan · « **Reply #779 on:** March 04, 2015, 06:57:40 pm »

Don,
I can't see anywhere that it's messed up.

On a positive note, carb #1 is clean and getting shiny. I didn't take a before photo but here's a photo of #3 that will soon need the same TLC and #1 was in pretty much the same shape.

And #1 as it's shining up.

[/URL[URL=https://imageshack.com/i/p7XhXYJ5j]

madmtnmotors · « **Reply #780 on:** March 04, 2015, 08:02:14 pm »

Wire brush it clean followed by a thread file all around. You should see what I can do with a mutilated spindle on a trailer axle!

AintNoEasyWay · « **Reply #781 on:** March 05, 2015, 05:30:06 am »

That carb looks great, Ron. Is that from the wheel or did you do that by hand?

mark52 · « **Reply #782 on:** March 05, 2015, 05:31:12 am »

Hey Wilbur, from what I saw this weekend that may be a skill you can finally retire! Keep plugging Ron, you and Logan and doing a great job.

Restoration Fan · « **Reply #783 on:** March 05, 2015, 05:45:47 am »

Quote from: AintNoEasyWay on March 05, 2015, 05:30:06 am

That carb looks great, Ron. Is that from the wheel or did you do that by hand?

Thanks, Nate.
We used the polishing wheels on the carb and then followed that up with a small buffing wheel in the Dremel to get into the smaller spaces. It still needs a little bit more but it looks much better in person than in the photo. The lighting wasn't great so I used the flash on my phone when taking the photo and that sort of distorts the photo.

Restoration Fan · « **Reply #784 on:** March 05, 2015, 07:28:07 am »

SUCCESS!!!!!!
Thank you to everyone for the encouragement...sometimes just knowing there are others pulling for you is huge!

Also thank you, Wilbur, for the advice. I had tried to clean those threads before but I don't know why I had never thought to try a wire brush. Using a stiff wire brush, I was able to clean the threads. Then I matched up the threads to the 1.0 on my thread file I recently purchased from Amazon.

With cleaned threads, it became apparent to me that I had indeed rounded off the top thread. So a few minutes with the thread file and I had a new top thread up there to replace the one I had rounded off. Tested it with both of the cap nuts and both go on easily and will screw all the way on. *happy dance*

I do have a question about that top triple tree though. It doesn't appear to go all the the way down as far as I think it might should go. I only have about 3 or 4 threads sticking above it for the nut to grab onto. Is that normal?

madmtnmotors · « **Reply #785 on:** March 05, 2015, 08:24:21 am »

Quote from: Restoration Fan on March 05, 2015, 07:28:07 am

I do have a question about that top triple tree though. It doesn't appear to go all the the way down as far as I think it might should go. I only have about 3 or 4 threads sticking above it for the nut to grab onto. Is that normal?

That could be a result of the component stack at the bottom bearing, or the bottom bearing and/or outer race (inside the bottom of the neck) not fully seated. Did you use a spacer under the bottom bearing? Did you use a spacer on top of the upper bearing? Was the lower outer bearing race fully seated against the shoulder inside the lower neck?

3 or 4 threads doesn't sound like much.

SOHC4 Cafe Racer Fan · « **Reply #786 on:** March 05, 2015, 09:12:32 am »

It seems like you might have an issue with your bearings being fully seated or a spacer thickness.

martin_uk · « **Reply #787 on:** March 05, 2015, 09:43:50 am »

Without reading through all your posts, not sure if you converted to taper roller?

If you did, the upper race sits higher than with standard ball race and moves top yoke higher.

On mine I did not use thick spacer under lower race and only the thin one.

You do need to check that steering stops work OK with sufficient clearance with thinner spacer.

Also need to check that lower race is fully seated

madmtnmotors · « **Reply #788 on:** March 05, 2015, 09:51:42 am »

Thinking back through my post the issue could be a result of either the upper or lower races in the steering neck not fully seated, as well as the possibility of overly thick spacers.

martin_uk · « **Reply #789 on:** March 05, 2015, 10:08:44 am »

Close up of lower yoke showing position of steering stops on my K8 with taper bearings

2015_0116frame0015 by nitram2010, on Flickr

madmtnmotors · « **Reply #790 on:** March 05, 2015, 11:59:26 am »

The bottom looks pretty good. The only other item would be at the top: either the outer race (upper) is not seated all the way into the upper neck, or a spacer was used on top of the upper bearing (typically there would be no spacer on top of the upper bearing), or the top tree is not fully seated, or you tightened the pinch bolts before the top tree was seated. If the outer race for the upper bearing is fully seated, and no spacer is present on top of the upper bearing, then I would say you've got all you're gonna get. Did you tighten the three pinch bolts before making sure the top tree was fully seated? (the one at the top of each fork tube and the one on the neck)

I have had to gently persuade the top clamp into it's fully seated position occasionally, depending upon how everything lines up, since it is sliding down over both fork tubes and the steering neck all at the same time. It's a snug fit (as it should be).

Restoration Fan · « **Reply #791 on:** March 05, 2015, 12:33:25 pm »

I figured out the issue. The bottom of mine is good. The top race is fine as well. However, the top part wasn't being pushed far enough down. So the big nut shown in the photo wasn't screwing far enough down as well. That was allowing the gap.

The threads weren't stripped but there were some that weren't perfect. So I pulled that bad boy out a while ago and went to work on it with my handy/dandy thread tool. I decided what I really need is the 48mm pin spanner to tighten it up. So I'm hoping to get with Bill and see if we can use his to tighten it down now that the threads should be ready to accept it.

madmtnmotors · « **Reply #792 on:** March 05, 2015, 02:02:58 pm »

That spanner nut is used to set the "preload" on the steering bearings. Too loose would not be good...

Restoration Fan · « **Reply #793 on:** March 05, 2015, 02:12:48 pm »

I know. I have a tool that I was using for it but it's not the proper one. Combine that with the threads not being perfect and I wasn't getting it tightened down far enough.

I just texted Bill Benton earlier and he graciously agreed to let me borrow the proper tool. I'm heading over tomorrow night to get it. In the meantime, Logan and I will work on the carbs some more tonight and finish the controls up by painting the red writing on.

calj737 · « **Reply #794 on:** March 05, 2015, 02:24:33 pm »

Ron - there's a bit of a knack to tightening that spanner nut as the forks are involved.

I find it best to loosen the lower fork pinch bolts and the stem clamp. Then, I tighten the spanner drawing the stem/bearings up (the lower forks are able to slide thru the tree since the pinch bolts are loose). So it's a matter of either supporting things as you tighten, or allowing them to move so you can tighten.

Don't over-tighten that nut as it needs to allow the stem to rotate. There's porbably a lash setting somewhere in a manual somewhere...

ekpent · « **Reply #795 on:** March 05, 2015, 03:00:18 pm »

I ground off the round ridge inside the large bearing cap cover on my K4 for a better/lower fit with thin spacer at the bottom tree. Not sure if the later 77-78 K models have that round ridge inside the cap ?

Restoration Fan · « **Reply #796 on:** March 05, 2015, 03:14:59 pm »

Quote from: ekpent on March 05, 2015, 03:00:18 pm

I ground off the round ridge inside the large bearing cap cover on my K4 for a better/lower fit with thin spacer at the bottom tree. Not sure if the later 77-78 K models have that round ridge inside the cap ?

They do have it but I already removed that little ridge before we assembled it the first time. This was purely a function of me not tightening the cap down enough.

Restoration Fan · « **Reply #797 on:** March 05, 2015, 06:34:29 pm »

I'm pleased with the way the controllers turned out.

danyo · « **Reply #798 on:** March 05, 2015, 06:45:32 pm »

Looks great. What kind of paint did you use for red lettering??

Restoration Fan · « **Reply #799 on:** March 05, 2015, 06:47:28 pm »

We used red enamel model paint.

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Author Topic: Senior project for high school - 78 CB750K (Read 169533 times)