Author Topic: 1972 CB750 Four K2 -- Rebuilt to NEW OLD STOCK -- PIX ON PAGE 50 (Read 245336 times)

edwardmorris · « **Reply #250 on:** January 10, 2014, 08:57:59 PM »

Here are some pics, at this point I'd rather get a new rim instead of trying to find a hub. If this hub will work with a proper 18" rim I'd rather go that way, but if the hub itself is the wrong size, then yet another PO fail.

Probably the worst way to measure but I gotta run, hope to get some good news when I check back

edwardmorris · « **Reply #251 on:** January 10, 2014, 08:58:45 PM »

Spoke and tire

Trevdawg · « **Reply #252 on:** January 10, 2014, 10:35:42 PM »

Definitely have to take some time and look over all these pages. Looks interesting

Terry in Australia · « **Reply #253 on:** January 10, 2014, 11:39:36 PM »

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.

MCRider · « **Reply #254 on:** January 11, 2014, 06:19:30 AM »

Yeah, 17". I don't know all the ins and outs of the conversion. Many here have done it. You have to swap drive plates and bits.

The rim measurement is from the bottom of the bead on each side, not the top, furthest most edges. You have to guess a little bit but essentially, don't include the outermost flat area of the rim ini your measurements. See thru the rim to where the bead of the tire is, with XRay vision, and measure from there.

edwardmorris · « **Reply #255 on:** January 11, 2014, 10:33:28 AM »

Thanks Terry and Ron, I'm so glad the hub will work! So for my upcoming birthday, should I get me two sets of stainless spokes? Or would you recommend something else?

Telescoping gauges from Gordon came in today, too worked up to go to bed so I took the measurements parallel and perpendicular to the pins as requested

I really hope I did this right, here are the numbers (upper and lower ends)

Cylider	#1	#2	#3	#4
Perpendicular	U60.94 L60.93	U60.95 L60.95	U60.94 L60.95	U60.95 L60.95
Parallel	U60.93 L60.94	U60.93 L60.93	U60.93 L60.92	U60.92 L60.92

Hone or rebore? Or redo measurements? I'll go read the manual while I try to catch some zzzs

MCRider · « **Reply #256 on:** January 11, 2014, 11:36:48 AM »

I'll just comment on the wheel/rim issue. Bores are above my pay grade.

The standard upgrade is oversize stainless from Buchanan's. But stock spokes (for an 18) Or stock size stainless.

Depends a bit on the rim you want to use. A stock 18" rim will not (may not) allow for the bigger nipples and OEM is your choice. A aftermarket aluminum rim can be drilled to fit the oversize spoke nipples if desired.

Terry in Australia · « **Reply #257 on:** January 11, 2014, 01:57:02 PM »

Your measurements look about right Ed, except the second last one, did you mean 60.92? 60.02 isn't right. they're all pretty uniform though, so as long as there's no obvious gouging evident, a hone will do the job fine.

I like fatter spokes on a hotrod CB750, I've got Ron's old Borrani rim and Buchanans (?) fat stainless spokes on the front of my bike and love the look, but I can't see any reason to go with fatter spokes on an otherwise stock bike, the OEM sizes are adequate for normal riding. Cheers, terry.

edwardmorris · « **Reply #258 on:** January 11, 2014, 02:12:50 PM »

Oops, that was a typo, fixed now

Looked at the manual and looks like I'm just under, hopefully honing won't push it right on the edge.

As for the rim and spokes, I was thinking about this rim with these spokes. Are these overkill?

Terry in Australia · « **Reply #259 on:** January 11, 2014, 02:20:56 PM »

I like the rim and have dealt with that seller before, they're good. I don't like the spoke nipples though, with the phillips screwdriver slots? The OEM nipples have straight slots, which I think would be easier to lace. Does the rim seller do spokes too? Cheers, Terry.

edwardmorris · « **Reply #260 on:** January 11, 2014, 06:09:24 PM »

The seller only has the front set NOS listed for more than the rim itself

I'll do some digging for a good replacement set with the DID rim.

Woke up and the mail was here! Head came in so I got right to work, springs are painfully strong and valves all passed the drill motor test, but have all kinds of crap on them, maybe even RUST?? The guides on the exhaust side are seal-less, but cruddy, not sure what that brown stuff is. How would this rust if the bike was running?

BPellerine · « **Reply #261 on:** January 11, 2014, 06:23:01 PM »

that may be just some deposit from age it should clean up great.sometimes things can rust a little if the bike was only run for short periods and then left to sit ie condensation.bill

edwardmorris · « **Reply #262 on:** January 12, 2014, 10:16:58 PM »

Looongass day today, made some time to start cleaning the head, there is severe carbon built up in the exhaust ports, hit metal after almost an hour of scrubbing, and its as if there are bubbles in it, so rough no wonder everything is sticking to it. Any tips on speeding up cleaning?

BPellerine · « **Reply #263 on:** January 13, 2014, 12:33:14 PM »

dremel and wire wheel.bill

edwardmorris · « **Reply #264 on:** January 13, 2014, 09:27:58 PM »

Here is how the ports are now. Tips, suggestions, advice on how to proceed? I'm nowhere near done cleaning the head, but it looks nice enough to share

#
4-3
2-1
4

on the exhaust side

edwardmorris · « **Reply #265 on:** January 13, 2014, 09:31:46 PM »

3, 2, 1

why do I always take these wrong side up?

edwardmorris · « **Reply #266 on:** January 13, 2014, 09:34:12 PM »

intake side
#
4-3
2-1
4

edwardmorris · « **Reply #267 on:** January 13, 2014, 09:35:41 PM »

3,2,1 inlet

MCRider · « **Reply #268 on:** January 13, 2014, 09:36:02 PM »

ordinarily this would be done with a media blaster, like plastic beads or soda. Glass beads but that means heavy duty cleaning protocol.

You're too far along now. Continue.

edwardmorris · « **Reply #269 on:** January 13, 2014, 09:48:10 PM »

Quote from: MCRider on January 13, 2014, 09:36:02 PM

ordinarily this would be done with a media blaster, like plastic beads or soda. Glass beads but that means heavy duty cleaning protocol.

You're too far along now. Continue.

Drats! I thought soda blasting was baaaaad because crap gets stuck in places? I have a poor mans blaster at home, think I can finish of the rest with it?

Besides, the carbon was so badly caked, I had to quite literally chisel it out first then wire brush it later, so maybe its for the best...

MCRider · « **Reply #270 on:** January 13, 2014, 09:57:46 PM »

Soda's not strong enough for the cake on stuff/ Plastic bead blasting would make short work of it. If you had one nearby. Still got cleanup/out issues, but residual shouldn't hurt anything.

Soda is water cleanup so the sink being big enough is the prob. Or good enough weather for a garden hose.

edwardmorris · « **Reply #271 on:** January 13, 2014, 11:27:31 PM »

I will ask the local machine shop to reconsider the motorcycle engine for at last bead blasting. Cleaning those pesky fins will take up too much time. I don't know why they're so fussy about motorcycle engines, this thing is as big as a small car.

If they do agree to blasting things clean, do I finish the valve lapping etc. before or after?

MCRider · « **Reply #272 on:** January 14, 2014, 06:23:31 AM »

Quote from: calj737 on January 13, 2014, 11:30:53 PM

Machine work AFTER blasting, whatever method you choose.

YEah, they're going to balst the seats, so machine/lap etc afterwards.

They probably had a bad experience with someone's part and did a knee jerk reaction, "no motorcycles". Should be no problem, done all the time.

Quote from: calj737 on January 13, 2014, 10:44:40 PM

Edward - you could also have the head Hot Tanked at a local shop pretty inexpensively. Soda is not on the phone corrosive not a problem for entering the engine, only the carbs. It can and will clean out pretty easily.

Glass beading, with your head at this stage of disassembly, is also pretty safe. Just need to rinse the head well to insure flushing is complete (same would be true with plastic media, sand, etc). You could soak the head in SeaFoam Deep Creep. It does soften hardened carbon, but will take some time and continued effort. Hot Tank it for best, complete and quickest results.

Do you have first hand experience with a "hot tank"? I took my parts to a hot tank shop and they turned me down. Said their tank would melt aluminum. I confirmed this at other shops and the internet.

A solvent tank of a lessor sort may work, but probably not an actual "hot tank".

My pref is plastic bead blasting. 2nd choice is soda. I actually soda blasted my VM29s (carbs) (in my build thread and services rendered thread) inside and out. Did a great job and cleaned up in water in my utility sink.

edwardmorris · « **Reply #273 on:** January 14, 2014, 02:15:31 PM »

Thanks for the info guys! No luck with the shop though, they still adamantly refuse to touch anything motorcycle related. I will see if I can find a shop in the Chicago area (comes with Chicago prices and Crook County taxes as they say out there) that will do the blasting. Last resort would be start heading towards Indy

Next few days are brutal work wise, hopefully I'll be able to sneak in an hour or two to get something/anything done.

edwardmorris · « **Reply #274 on:** January 15, 2014, 09:51:05 PM »

In between shifts, used the quick hour to clean up the valves. Mostly cleaned up nice (pic 1 and 2 before and after sample), slightly concerned with all the gunk on the seat/sealing area of the valves. Didn't want to go razor crazy on it, will lapping with coarse compound clean this up (pic 3)?

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Author Topic: 1972 CB750 Four K2 -- Rebuilt to NEW OLD STOCK -- PIX ON PAGE 50 (Read 245336 times)