Topic: The "Why am I building this?" bike - 1971 CB500 K0

[Restoration Fan]

Sorry, Nils.  Just saw your response a moment ago.  I went and grabbed one of the ball bearing packages and dropped it in the mail but I don't know if the mail will run on Monday so it may be Tuesday before it gets out of Atlanta.  Heading your way though.

Ron

[NobleHops]

Sorry, Nils.  Just saw your response a moment ago.  I went and grabbed one of the ball bearing packages and dropped it in the mail but I don't know if the mail will run on Monday so it may be Tuesday before it gets out of Atlanta.  Heading your way though.

Ron

Thank you VERY MUCH Ron!

[Camrector]

Love seeing that clean, blasted motor in the frame. The one you did for me is close to being there!

[NobleHops]

Love seeing that clean, blasted motor in the frame. The one you did for me is close to being there!

Pics or it ain't happening!!

:-)

[SOHC4 Cafe Racer Fan]

Love seeing that clean, blasted motor in the frame. The one you did for me is close to being there!

Pics or it ain't happening!!

:-)

+1 Let's see it!

[NobleHops]

Update time:

RestOratioN Fan (Ron) did me a massive solid, dug out a top bridge I need, and hustled down to the UPS store to get it on its way, on Friday afternoon while a significant snow event was bearing down on Atlanta. I appreciate that so much Ron. So this nugget can get retired as soon as that arrives next week.



We had plenty to entertain ourselves with including the manky fork and steering head bearings.







We skinned the stem of the lower bearing and knocked the races out of the steering head, blasted off the horrible rust and masked and painted it with some appliance epoxy, massive, fast improvement. My welder friend fixed the busted steering stop on the right, and I figured, well, AS LONG AS I WAS IN THAT AREA ANYWAY, you know, JUST AROUND THE CORNER FROM THE PLATER I'd re-plate all the fasteners I had removed. I suck at flipping bikes.



The fork got the usual spa treatment, disassemble and clean, although one damper rod bolt gave us Extra Fun, and so it got the good soak in PB Blaster and then I heated up the leg with the map gas torch till the brew was bubbling, and then the cordless impact made short work of that one too.



Muahahaha



Fork tubes were surprisingly good near the seal area, had some fine scratches that I polished with 1000-grit wet/dry and a few drops of 3-in-1 oil. The area under the clamp was ugly, so I thought I'd try something I haven't used for a long time, and give them a good soak with Naval Jelly, after knocking the loose rust off with red Scotchbrite.







I was unimpressed. I put it on nice and thick, and its a gel so it stays put pretty well. Tried two applications of it as thick as I could get it on there and it didn't do much. I bailed and soaked them overnight in Metal Rescue and that did a decent job of derusting. Hosed them down pretty well with WD and called it good.

We naturally vapor blasted the fork legs, and this is kind of a good illustration of the finish, and why some hand finishing is sometimes necessary to get parts to look just right. The further leg is vapor blasted only, the nearer is too but was then hand finished in the vice with WD40 and red Scotchbrite, shoeshine-style, then polished up with white Scotchbrite.



Both done, derusted tubes behind, about to get reassembled:



Heated up these copper crush washers to glowing red, let them cool slowly, buzzed off the scale with the wire wheel, good to go.



...

[NobleHops]

Here's my little trick for getting that layer of cruddy spooge out from the very bottom of the fork leg: Drop a bore brush into the leg upside down, and then fish out the handle through the damper rod bolt hole.



Chuck it up in the drill, and let 'er rip while you put a bit of tension on it.



Works perfectly to get that stubborn crud off the bottom.


This is my new favorite fork seal remover.



Derusted the rear of the ears (and the underside of the front fender) with the vapor blaster then hosed them with WD40 as well, tidied up the caliper bracket and reassembled the fork with new Honda seals plus dust seals and gaiters from 4-into-1. 

Pressed in new steering head races and reinstalled the steering stem, and the fork. Damn, it looks (and is) so much better.





More fun, but few photos. The steering head and several other spots around the frame had some ugly rust in spots, so we cleaned the areas and degreased them, and did some spot paint touch ups and that worked surprisingly well.

(before)



The disk center had been repainted and the hubs vapor blasted, so we reassembled the wheel with the replated fasteners and we just need to balance it and bend the lock washers and that is ready to reinstall too.



Odds and ends: sidestand is repainted, centerstand will be next, gauge bracket is repainted and the gauges cleaned up. The tank has been dusted off again and the epoxy setup smooth and hard, tank is ready for paint as are the sidecovers. Clutch pushrod is inbound, when it arrives we will replace that seal and install it and also the shift shaft seal, button up the left side cover and install the new clutch cable.

...

[NobleHops]

Next up, reassemble the master cylinder and front caliper and install it with the new brake lines, install the front fender, then the wheel. Need to reinstall the headlight bucket and turnsignals. All that wiring has all been cleaned and serviced, and is ready for another 45 years with luck :-).





Then it's onto the battery box and try and assemble the airbox, find out what we're missing to do that and get it back together. Then install the rebuilt carbs, manifolds with new orings and insulators.






We've got a new-to-us set of bars and controls from Bill Benton to clean up and refurbish, along with Ron's top bridge. BLAC is digging up his take-off exhaust and so that will be enroute next week too. So that will keep us busy on this through next week and a bit beyond.

[Restoration Fan]

Dang, Nils, you boys have been busy but it all looks really good.  And that's a great idea to chuck up the bottle brush in the drill.  I think I'm going to have to try that one.

You're most welcome for the top bridge of the triple tree.  Just trying to repay some of the kindness that was shown to Logan and me when we were working on Stella.  The unselfish attitudes and willingness to help with parts and expertise, often times to complete strangers, is what sets this message board apart from any other and it is simply astounding.  I'm just glad to be a part of it.
 

[calj737]

The unselfish attitudes and willingness to help with parts and expertise, often times to complete strangers, is what sets this message board apart from any other and it is simply astounding.  I'm just glad to be a part of it.

You meet the nicest people on a Honda Forum 

[Stev-o]

Great update, Nils, this is going at a fast pace.

BTW - who is the "we" and "us"?  You have shop help?

[NobleHops]

Ron, I feel the same, my stuff gets built "with a little help from my friends", every time.

Cal, you are so right :-).

Steve, I do have help three days a week, plus a really great network of collaborators in town. I had a Honda trained tech for a few months too, but he didn't work out. Could use more help.

[RAFster122s]

Don't forget the peanut oil trick on your unpainted black plastic parts...

[NobleHops]

Don't forget the peanut oil trick on your unpainted black plastic parts...

A favorite! :-)

[SOHC4 Cafe Racer Fan]

Amazing! This build is moving impressively fast.

[Bankerdanny]

Well well, what have we here? Anybody got a solid top bridge in their stash? Cosmetics unimportant, I will refinish.

And so we get a photo tutorial of the purpose behind those little tiny washers with the flat spots that are often missing from these bikes.

[NobleHops]

Well well, what have we here? Anybody got a solid top bridge in their stash? Cosmetics unimportant, I will refinish.

And so we get a photo tutorial of the purpose behind those little tiny washers with the flat spots that are often missing from these bikes.

Haha, yes, Harisuluv said something similar, but in fact they were present!

[RAFster122s]

Wonder if they had a bent fork in the past from not stopping  for a curb?
Took a few hard hits for certain.

[NobleHops]

Amazing! This build is moving impressively fast.

Well it WAS moving impressively fast, and then it didn't! but we finished three other customer bikes in between and this one had to be the last priority, and that's just how that goes.

But we are back to it and so let's catch up :-)

[NobleHops]

We took a trip through the wiring harness and cleaned and tidied it all, including every connector, and some missing tape in a few spots. All in all it was in good shape, just dirty:



Going to try and use these original coils - tidied them all up and shortened the plug wires 1/4 inch, installed new NGK spark plug boots.



Ron (Restoration Fan) did send me a new clutch pushrod ball bearing and I did scare up a NOS pushrod, and we got a new Honda clutch cable in hand. Replaced the seal on the actuator mechanism. Ron also sent me a nice top triple clamp and wouldn't take any money for it, but it turned out to have a slightly different offset and so it got sent back, but I still think Ron kicks ass. Thanks Ron :-).





We are however going to pull that oil pump off and use one of member Elan's kits to renew all its seals. at $49 this includes all the hard-to-find orings and a new pickup screen and oil pressure switch. Also kicks ass.

http://www.ebay.com/itm/Honda-cb500-cb550-oil-pump-rebuild-kit-1971-1978-repair-o-rings-pressure-switch-/162179190728

Harisuluv (who kicks ass) rebuilt our carburetors a few months back, after we vapor blasted them and replated the steel, and as it happened he had a set of new Honda insulators on hand and who can say no to those? Yes we will replace those screws :-)



Bill Benton (the well-known kicker of ass) scared up a complete airbox setup for us, along with some other items, and so we vapor blasted them spotless and wet sanded them quickly to smooth, repainted them with the fantastic SEM trim paint and now we have a nice airbox and a new filter.



Member GMan had the airbox spring we needed, and also would not take any money for it, many thanks to you Greg. So that air filter is in there snug as it belongs. Greg, you also kick ass.

While we were in paint-it mode, we did the headlight bucket and the rear inner fender with the SEM too, and they were topcoated with clearcoat. It's not super original looking but I dig it. We did the chain guard the same way (no photo). These look fantastic.





Bill had also scared up a battery box and grommets for us, and so after a blast and paint that got installed along with the refurbished airbox:

[NobleHops]

We were not so lucky with an exhaust we bought off of Craigslist, which is a bummer because it was expensive to ship. So for the moment we are forging ahead with that period aftermarket 4 into 2.



We put the caliper back together, and the master cylinder, just have to install the repro brake lines once we have the bars drilled and installed so we can mount the master cylinder.



Points look good!



Had to chase the number 4 sparkplug threads, using a greased tap. always a little nervy, very hopeful that we captured all the swarf with the grease. This was strange - we'd chase it, install the plug, and it would still feel funny, so we switched from the thread repair tap to a thread cutting tap and chased it again, same result. I cannot see a helicoil in there but I won't be surprised to find one at the bottom if the head comes off.

What else: We've got a new Motobatt AGM battery installed and our initial check of the electrics seems good. Valves are all adjusted. Dropped the sump to inspect it and the oil pickup and found them amazingly clean. Just a thin layer of tarry stuff at the bottom of the sump and nothing sparkly and no gasket chunks or silicone boogers. This makes me think the engine has never been apart. The primary chain however felt VERY sloppy, but I don't have a sense of how it ought to feel. It'd be nice not to rebuild this, but que sera, sera.

Bodywork is all repainted and the original emblems on the tank and sidecovers are repainted by hand by a local pinstriper. It's gold. It glows in the dark. I dig it.

Got annoyed looking at the old crappy shocks and then noticed that I have a buttload of new Ikon shock absorbers sitting nearby on the shelf, and so a pair ended up on the bike. Funny how that happens.

OK that pretty much catches us up. Hope to have it substantially together next week, and then we will spark it up and see what we have for an engine. Fingers crossed!

[Stev-o]

A lot of ass kickin goin on in this thread, Nils!  Glad you found some shocks, but I have a good contact if you hadn't...

[NobleHops]

A lot of ass kickin goin on in this thread, Nils!  Glad you found some shocks, but I have a good contact if you hadn't...

LOL! Many thanks for referring folks to that dude Steve :-).

[NobleHops]

Alright, we have been pecking away at this bike in between other stuff. Most recently we replaced the coils and caps, installed the rebuilt carbs and an air filter, put some oil into it and fired the beast up. It ran after a fashion, sooted up the plugs pretty instantly, and we did not get very far into diagnosing this because after a minute or two of running we shut it down and turned out attention to a leakdown and compression test The numbers are interesting to me and I'd appreciate your thoughts on what they mean before we pop the top, because that is what seems to be indicated.

Leakdown: The engine was barely warm when we did leakdown. Pulled all the plugs, opened the crankcase, installed the OTC leakdown tester, used 100 PSI as our input pressure.

Compression: We did this a half hour after leakdown, and so the engine was just warm to the touch (which I think should have BOOSTED our numbers, if anything). Plugs out, air filter out, crankcase open, throttle wide open. OTC compression tester. We ran it three times each on compression and in one instance the reading climbed 3 PSI on the last running. The other readings were stable on all three runs.


#1 Leakdown 100/97

#1 Compression 115 PSI


#2 Leakdown 100/97

#2 Compression 98 PSI



#3 Leakdown 100/98

#3 Compression 115


#4 Leakdown 100/97

#4 Compression 102


We are thinking that this indicates a need for new rings, assuming the piston to cylinder clearance is still good, or pistons AND rings if it isn't.

We are thinking that the head is probably fine given the 3% or lower leakdown figures.

In either event, we're going to have to do some or all of the top end. Would you care to fill in on our diagnostics here? Are we reading this right? There is always so much to learn.

TIA for your thoughts as always,

Nils

[calj737]

Your compression readings are right on the margin. I'm personally not persuaded that a low mileage bike should need rings. More likely, it needs a good Italian tune Hp after having sat for a while (which a 40+ year old low miler must have endured). Compression readings are a glimpse and not terribly specific to exact conditions unless 1 cylinder is dreadfully out of spec.

My suspicion, and it's only a suspicion, is the rings may well be gummed up due to poor state of tune when last run and sitting time. I'd tune it, run it for 300-500 miles. Change the oil and re-test it. A vacuum gauge would be another diagnosis to determine cylinder health at that point.

Food for thought.