Topic: 1972 CB750 Four K2 -- Rebuilt to NEW OLD STOCK -- PIX ON PAGE 50

[edwardmorris]

Before cutting new seats, I usually lap them first with fine compound. This highlights if they need it (or not) and helps to outline the areas that need to be watched closely. Cutting is a bit of an art when done by hand. 

Yep, will do.

Anyone on deshrouding? How bad do these look?

[Terry in Australia]

Yeah mate, those seats definitely need cutting or replacing. Cheers, Terry.

Thanks Terry, I think I will go ahead and cut them. Prokop has so very generously agreed to loan me his set of neway cutters, this should save me some time, money and grief hopefully. I will push back painting the head and cylinders till I'm done with the head.

How do the domes look? Should I grind off the high points a bit around the seats or leave them be? Looking at Mike's work, it seems that he almost hemi's the heads and polishes them smooth. I'm planning on gentrly grinding/sanding off the casting flashes in the ports, these are way too high and obvious so I can safely clean them with the tapered bits I have from Eastwood. Anything else I should do with the head before I prep it for paint?

No worries Rafi, those Neway cutters are great, and there are heaps of vids to watch on Youtube to show you how to safely cut new seats with them. Looking at your pics I think you're wasting your time trying to lap them in, but that's up to you.

I cleaned up the ports on the head I used on the K2 engine with my die grinder and some eBay abrasive paper cones and rolls, and the ports came out nice and smooth, but the combustion chambers looked pretty good so I just wire-wheeled them, as I was concerned about losing some CR if I removed too much material to reshape them. Cheers, Terry.  

[edwardmorris]

Head work on hold as I wait for things to arrive and people to respond.

What a punishing Sunday, but the rear hub is done and ready for lacing finally! You'll have to pardon the abysmal pictures, I will take better ones and post soon. Damned thing was too heavy so I hung it form the ceiling and had at it. The center, is soooo not worth the effort or time. I didn't sand it but buffing and cleaning it is just a pain in the butt. Oh well, its done this time so moving on. Sanded 500->1000->1200 then buffed Red->Green->White and a final buff and seal with white diamond metal polish.

[Terry in Australia]

Looks great Rafi, I'm always impressed with guys like you who have the ability to spend hours sanding and polishing, i have the attention span of a Goldfish, so my polishing efforts never look that good!

[edwardmorris]

Looks great Rafi, I'm always impressed with guys like you who have the ability to spend hours sanding and polishing, i have the attention span of a Goldfish, so my polishing efforts never look that good!

Thanks Terry. Just the buffing part took all of Sunday, the center buffing took most of Saturday night. The sanding however, I've lost track how many hours/days it took. I have the exact same issue, sanding is so horridly boring, I never finish a piece in one sitting. Right now, all covers have seen some sanding but none are ready for buffing except the front-hub. I'll have to fast track this stuff if I'm to fire it up this season, but can never get myself to missing work in favor of the project

On the head chambers, both the head and cylinders were milled few thous, so I'm hoping reshaping them a little and going with an MLS gasket will bring back the CR. Thoughts?

[edwardmorris]

Yeah, you've got a 17 inch rim Ed, as Ron mentioned, it might be off a K7 or K8, but you should have an 18 inch rear rim on your K2. That hub will work fine with an 18 inch rim though, so just buy a new rim and spokes. Cheers, Terry.

HALP!!

I REALLY hope you're right Terry. I can't get the damned wheel laced up correctly. Outer spokes just won't reach after the inner one have been correctly installed. What am I doing wrong?? NOS rims and spokes. Also, a better pic of the hub as promised.

[oldhatt45]

Edward,

I looked at your picture and it looks like your offset (from top to bottom) is off by 1 hole on the Hub Side.  See my Step 3 thread (unless the Moderator was able to put it back with the Step 1 thread.)  Unless the picture you posted is off, the hub is closer to the top (I think) than it is to the bottom.

I will try to take a couple of pictures of my Rear (untouched stock) Hub later today and post, but I'm betting the offset on the hub got you the same as it got me.

Charlie

[edwardmorris]

@Charlie, you're right about the offset being wrong, but that pic is my second attempt. I had it right the first time, but the outers didn't reach, so I redid it the wrong way (above pic) and it still didn't reach. I got too concerned with centering the hub and rim together horizontally, but completely ignored the vertical centering. I started over today, laced it correctly and took care of the vertical centering by stacking some magazines under the rim, and a tape measure under the hub (one side only) and they all reached fine. Now the challenge is to get it trued up.

@Terry, of course you're right!! I hope you'll forgive a panicky noob like me and continue watching over

[edwardmorris]

Forgot the pix...

[edwardmorris]

Ugh, I thought lacing was bad, truing is worse. More on that when I get somewhere with it.

Quick update on the head, I've decided that after investing in this bike so heavily, it only makes sense that I go with new valves, guides, springs and accurately cut seats. So, its on its way to JMR, best let the pro do his magic.

Speaking of magicians, look what Cal spun out for me  Also in the pic is a near perfect dash plate with the correct early K2 markings from SeanBarney, this will look great!

[Kickstart]

Take your time with truing... and you may need to step away for a day if you get frustrated.
I recently got a truing stand myself....  it was very frustrating at first.  I even took my wheels into the shop to have them re-do it.  However, when I got them back and put the front wheel on the bike I realized the offset was way off.  I put it back on the truing stand and realized I did a better than the shop!

I spent a lot more time playing around with adjusting the offset... going back and forth double checking the hop and runnout... and I started to get a good feel for it.

Keep at it, you'll get the hang of it.

Couple of things to pay attention of, which helped me:

• Have something to mark the wheel - don't assume you'll remember that low/high spot as you'll just frustrate yourself. Get something that will make clear marks (soft grease pencil) and that you can clean-up (you'll will be doing this multiple times) - I had a wax pencil that was too hard so I just ended up using a sharpie marker and cleaning up with alcohol rag.
• Pay close attention to the truing stand shaft and tapered collars - It looks like you have a similar "consumer" grade truing stand that I have.  It's hard to get them to hold the wheel on axis - I found it was better to gently hold the shaft in place and have the wheel spin on it's bearings (don't let the shaft spin on truing stand).  I noticed the tapered collars (with the set screw in one side) will/can hold the wheel slightly crooked... and there's a half decent chance the shaft that came with the stand isn't true either.  - It wasn't until I noticed this, and started holding the shaft in place, that I was able to get the wheel trued
• If you bump the stand/wheel/dial indicator - don't just continue your truing - give the wheel a couple of slow turns to see if you upset things

Good luck!
[/list]

[edwardmorris]

Thanks @Chris, it took me a few sessions to get to about 1/8" of play radially and axially, but that's still a bit much. Its hard to get them both under that at the same time, fixing one is messing the other. You're right about the cheap stand, the shaft that came with it was bent out of the box so I made my own with 1/2" rod. I'll have to think of a way to keep the shaft fixed and roll on just the bearings. I do have a dial indicator with a magnetic base that I finally figured a way to keep out of my way and still be useful. Got a few other pointers from others too, so hopefully it'll straighten out soon. The offset, I'm assuming you're talking about centering with the hub, I got it to the point where visually it seems that its in line with the (approximate) center of the hub, with equal parts of the hub on either sides of the rim.

[MCRider]

Thanks @Chris, it took me a few sessions to get to about 1/8" of play radially and axially, but that's still a bit much. Its hard to get them both under that at the same time, fixing one is messing the other. You're right about the cheap stand, the shaft that came with it was bent out of the box so I made my own with 1/2" rod. I'll have to think of a way to keep the shaft fixed and roll on just the bearings. I do have a dial indicator with a magnetic base that I finally figured a way to keep out of my way and still be useful. Got a few other pointers from others too, so hopefully it'll straighten out soon. The offset, I'm assuming you're talking about centering with the hub, I got it to the point where visually it seems that its in line with the (approximate) center of the hub, with equal parts of the hub on either sides of the rim.

I haven't seen an inexoensive (or expensive) stand that handles offset adequately. Luckily ours are centered. I sight thru the air valve hole, past the center of the hub ribs to the rim on the other side. You can do this on both sides of the hub, along with other visuals, and get it prettty close to center.

[grepper]

Been watching this thread, nice work.
I just did my wheels a few months ago.



I found Oakys Garage Motorcycle Wheel Trueing vid very useful
https://www.youtube.com/watch?v=F1_AdHG7fGY

[edwardmorris]

Thanks fellas!

Its looking a bit too good to be true, so wanna make sure I'm not getting ahead of myself here. My dial gauge says it has increments of 0.001" and the worst untrue point is now at 50 on the dial, meaning 0.05" which is well under 2mm. I don't think I want to be pushing further, so did I do this right? Spokes are all nice and tight now, few fighting hard and threatening to strip the nipple outer. This round of runout measurements were of course with the wheel spinning freely off the bearings, I don't trust the truing stand shaft.

[grepper]

I'm no expert, I've only done two wheels.  Front and back of my cb750 K5.

If those are the same D.I.D. rims I used, your probably seeing the same issue I did.  A little bump/dip at the weld for about an inch.  I just ignored that part and got mine well within the 2mm tolerances otherwise.  You will find that once you ride the spokes will seat themselves more and you may have to go back and re-tighten/true them again.  When I did the ping with a wench and listen to the tone test, I do get some variety, but no flat (loose) sounds.  I have only about 60 miles on the bike since the restore.  I plan on taking the wheels off this winter and truing them again.  BTW, I have gotten the bike up to about 80 mph and no shakes or wobbles.  It rides smooth and true.

[edwardmorris]

Thanks grepper, I'll probably do another check after the tire is on to see if it gets any worse.

Any objections/concerns using vulcanizing rubber tape under the rim liner?  I've seen people use electrical tape around here, but the thick rubber tape seems better to me, thoughts?

[Bill/BentON Racing]

Rafi, if needed, just use a second rim band, my .02. Tape tends to go away with time.

[edwardmorris]

Rafi, if needed, just use a second rim band, my .02. Tape tends to go away with time.

Bill, that's precisely why I wanted to see if I could use the rubber tape. Its basically a long strip of rubber that melds into itself if you go two rounds, forming one thick band. Tow rim bands would be a cleaner way to go I guess, I do have the ones from the old wheels, but the rear wheel was a 17", can't reuse that.Thanks for the tip!

[Terry in Australia]

+1 on what Bill said Rafi, use new rim bands. Cheers, Terry.

[edwardmorris]

Thanks Terry, was planning on new ones on top of the tape. None of the spokes are poking through so no big need to go with two, and the rubber tape *I think* would seal out water better. Since I have the old one for the front, I might just get an extra one for the rear and go with two if need be.


Little more progress today, might not be much more depending on work this weekend. For now, calling this done Last pic is without flash, terrible lighting isn't really doing it justice in any of the pix.

[Terry in Australia]

Looks great Rafi, did you replace your wheel bearings? Cheers, Terry.

[edwardmorris]

Looks great Rafi, did you replace your wheel bearings? Cheers, Terry.

Yep all new SKFs throughout the bike (even those stubborn needle rollers by the clutch basket) except the steering neck. Those weren't standard size so sticking with All Balls for that.

So the front wheel laced and trued up almost 10 times faster and a lot more precise  One of my buds saw the pix of the hubs and asked me why I did I get them chromed  so I take it the polishing worked out well  Credit goes to Ryan/73Nancy who let me in on his trade secrets, great guy!

Now the next decision, period correct look Conti Twins for a straight line rider or Avons for a psychotic rider?

[Bill/BentON Racing]

Well, if you spell it Pscyle then the Avon's!!! Haha, good work you doing....lacing easy, truing can suck!  Bill

[edwardmorris]

Well, if you spell it Pscyle then the Avon's!!! Haha, good work you doing....lacing easy, truing can suck!  Bill

Ha! I'll think it over if I get some sleep tonight

Not much progress today because of work, made just enough time to clean the garage a bit and put together my new hydraulic motorcycle lift. All the while in the background, got some of the final bits of the carbs zinced up. Good set of jets, floats and other misc items will be on their way from Harisuluv soon, time to get this thing back together!