Author Topic: 1975 CB550 K Rebuild & Small Mods from AUS (Read 14019 times)

Bootsey · « **on:** May 07, 2014, 08:05:54 pm »

Hi

I'm in Australia, and I'm working on rebuilding a 1975 CB550K at the title suggests. The bike has done 16000 miles. Planning on doing a restoration, with a few small mods along the way. It was a fair mess when I got it, engine was seized, but hopefully nothing that some work and hours wont fix.

Started by stripping down everything, bagging and labelling it all. Cleaned and blasted the frame, and repainted with satin black epoxy enamel.

The motor was seized when it arrived. Pulled down the top end. The cam journals and followers seem to be OK.

The camshaft has some pitting on the leading faces of the lobes, I'd say 0.1mm - 0.2mm. Anyone able to suggest whether it will still be OK to run?

These are the cam chain guides, do they look re-usable? Doesn't seem to be much wear. I plan to replace the cam chain.

The pistons took some persuading to get out, but eventually I got there.

The cylinders look OK, some carbon build up, but I can also see some of the original cross hatch. The cylinders are at stock size of 58.5mm

I've ordered a set of CB500 +3mm Oversize pistons and am going to have the cylinders bored to match at 59mm.

I kept working through, and split the cases.

I've read that the primary shaft can be removed by threading a frame bolt into the shaft and using it as a slide hammer, but I've had no success yet. What am I missing?

All of the gears and dogs look OK. The selector forks seem OK.

My cases are stamped BBAAA

The rods are marked "2" on one side and "D" on the other.

Cant see any markings on the crank, apart from this which sort of looks like and "N" with an arrow.

All of the journals in the cases that I can see so far have some shinning, but are smooth.

So I was hoping someone might be able to help me understand what clearances I need to be looking for, when I plastigauge the crank journal bearings, and the rod big end bearings. I am a bit lost to honest.
These are the tables from the Clymer book I have.

Also, what do people suggest with the main seals, are they re-usable if they look OK?

So that's where I am at, any advice or info that would help me out, so I can get this build done right, would be greatly appreciated!
Cheers

MickB · « **Reply #1 on:** May 07, 2014, 09:22:50 pm »

Bootsy

I'd send the cam to Ivan Tighe Engineering (in Qld) and get them to retire the cam, they have the full specs for your 550.

Can't help with the primary drive, but suggest you replace all seals (eBay), and get a replacement cam drive.

Basically if you're rebooting and new pistons rebuild it and you'll have years of riding ahead

MickB · « **Reply #2 on:** May 07, 2014, 09:23:29 pm »

I meant restore cam - not retire. Stupid spell checker!

Bootsey · « **Reply #3 on:** May 09, 2014, 07:23:52 pm »

Thanks Mick, I'll have a look into the cam. Yeah from what I've heard these motors can last for years, so I'm keen to do what I can to help that happen. Cheers!

Bootsey · « **Reply #4 on:** May 13, 2014, 02:49:41 am »

Got the primary shaft out, just took a little more force, I used so larger sockets as the slide hammer.

Theres a little bit of marking from the primary chain. Thoughts? Does this warrant replacing the primary chain?

So when my plastigauge arrives I will check the camshaft main bearings, and the rod big end clearances. The Clymer manual states, if the clearance is above 0.08mm on both sets, then they must be replaced.

Some of the camshaft journal bearings have some scratches, and I assume they must be replaced. Is it possible to replace 1 half, or do both halves need replacing? Some appear to have what looks like pitting, but are smooth to touch. Any thoughts?

dave500 · « **Reply #5 on:** May 13, 2014, 03:04:50 am »

gday shaun,replace that primary chain!its just starting to rub the cases now,id just reuse the main and bigend bearings,they haven't run out of oil and its low kays,theyll be fine,just be clean as on your re assemble,too many guys throw out perfect mains and bigends as a matter of course?these are way over kill size parts for this calibre engine,if the bearings aren't worn etc they'll be fine and already broken in.

martin99 · « **Reply #6 on:** May 13, 2014, 02:51:38 pm »

Cross hatch visible after 16K miles? That's not a lot of miles for sure, but I'm still surprised. Makes me wonder if someone hasn't been in there before. Generally, that motor doesn't look like it's had too hard a life. I'd agree with Dave, no point spending money where it's not needed, although I would replace the cam chain guide regardless of condition - 40 year old plastic can get brittle. Nice find, enjoy!

Bootsey · « **Reply #7 on:** May 14, 2014, 12:07:24 am »

Thanks for the advice fellas, much appreciated! I'm all for saving money where I can, if it's feasible.

So Dave, you suggest I button it back up with the plastigauge, and see what clearances I have? And if they are within spec, use the mains and big ends as is?

A couple of the mains have scratches, that I can feel an edge with my fingernail. These candidates for replacement straight up?

dave500 · « **Reply #8 on:** May 14, 2014, 12:12:46 am »

I wouldn't even plastiguage them,theyll be fine.

Bootsey · « **Reply #9 on:** May 14, 2014, 12:26:39 am »

OK, no worries. I've got some plastigauge on the way, so I'll probably check 'em anyway, so I learn how its done.

I was cleaning up the cylinder gasket faces today, they've been quite painful get the baked on gasket off. I was soda blasting, and mustn't have been diligent enough & a bit of crap must have got in the line, and this happened.

There's a couple of small dings on the top surface, that one being the worst. Would now be an appropriate time for cursing, or do you think between the gasket and some sealant, that I might be lucky enough to get away with it?

dave500 · « **Reply #10 on:** May 14, 2014, 12:28:14 am »

don't use sealant itll be ok.

trueblue · « **Reply #11 on:** May 14, 2014, 02:52:02 am »

Scratches into the bearings are not a problem, they just hold a little more oil. What you don't want are lumps up from the surface of the bearing. These will catch on the shaft.

Bootsey · « **Reply #12 on:** June 06, 2014, 03:12:17 am »

Got around to pulling the rods off the crank. All the bearings and journals look good. One set of bearings has a slight bit of oxidation from where it sat on the oil hole.

Measured the clearance of the bearings with plastigauge. Cranked the nuts to 20.5 Nm, and all the bearings measured at 0.038mm. Specs dictates that they be below 0.080mm.

I've cleaned and painted the top case half. Next up I'll put the cases back together to check the clearances on the mains.
Do I need to put every case bolt in, or just the 10 that secure the crank?

dave500 · « **Reply #13 on:** June 06, 2014, 03:16:48 am »

put a couple at the other end to square it up.

Bootsey · « **Reply #14 on:** June 06, 2014, 03:32:10 am »

Too easy, will do.
Can I do both top and bottom mains in one go, or will plastigauge top and bottom give me inaccurate results?

dave500 · « **Reply #15 on:** June 10, 2014, 12:35:28 am »

do one or the other not both,thats the clearance then.

Bootsey · « **Reply #16 on:** June 19, 2014, 05:04:51 pm »

Worked through and checked the clearances on the mains, all of them checked out to be good. Ran them at 17 Ft/Lbs, and they all measured in around the 0.038mm mark, so that was good news.

Cleaned the top half of the case, and painted it, now just need to do the same with the bottom half, and clean up the threads.

Just got cylinders back from being bored and honed to suit the new pistons.

Not sure how this happened, not too happy about it though. It wasn't there when I left it with him. This likely to cause me any headaches?

Got some of this to use on reassembly. This motor is likely go to sit for +6 months before being run. I've read this stuff is good on mains and big ends, should I put this on the gears in the transmission, or are they better with a coating of oil? Or can the assembly lube go on anything?

All going well, should be able to seal it back up once a new primary chain, cam chain and seal kit arrives.
Cheers

dave500 · « **Reply #17 on:** June 20, 2014, 01:07:48 am »

that chip on the bottom of the cylinder is out of the swept area itll be ok,just oil the transmission gears.

Bootsey · « **Reply #18 on:** June 20, 2014, 01:51:13 am »

Thanks again Dave

Bootsey · « **Reply #19 on:** July 10, 2014, 11:36:56 pm »

Bit of an update.

The cases have been cleaned thoroughly and given a lick of paint. Cleaned up the threads and blew them all clean. All the transmission was thoroughly blown clean.

Got a M16 x 1.5 bolt and popped the rotor off. Then I tried your trick I read on another thread Dave, and scuffed the rod halves on some used 600 wet & dry. Also tried the shoelace trick to deglaze the crank journals.

My seal kit just arrived, so I think I'm ready to seal it up. Plan of attack is to:
- Put in a new primary chain. I marked the old one I took off. Can't see anything indicating direction of travel, so I assume these go in either way? Same with the new cam chain?
- Put a light smear of the assembly lube on the rods and main bearings.
- Put the rods back on the crank, and torque in the midrange of torque values. Drop the crank into the top case half with new seals. Transmission is already fitted into top half, with a good coating of oil.

-Fit the primary drive gear into the primary chain, sans primary shaft
- Wipe the case mating surfaces with acetone, then brush on 1-2mm layer of Threebond 1104
-Then seal it up, and torque the crankshaft bolts, and nip tight all the other case bolts.
-Then I should be able to fit the primary shaft into the case and primary gear.
- Then fit the remaining seals with a touch of 1104.

Anything I missed or should do differently? Sorry, I like to be thorough...

Bootsey · « **Reply #20 on:** July 12, 2014, 08:00:53 pm »

Cases are back together. Here's hoping they are sealed up OK. New cam chain, primary chain and seal kit installed.
Mains and big ends got a light coat of assembly lube, everything else got a light coat of oil.
Everything went pretty smoothly. Ended up leaving the primary shaft out until after the cases were sealed. Left it in the freezer for a few hours, took it out, lined up the needle bearings, and in it popped.

Bought this oil seal kit from eBay. Seals were good and supple, not bad for $25 delivered. Just doesn't include the main shaft blanking plug seal.
http://www.ebay.com.au/itm/Honda-cb550-Oil-Seal-Kit-/161346472393?pt=Motorcycles_Parts_Accessories&hash=item2590ffc9c9&_uhb=1

Next up hopefully I'll be fitting the new pistons and cylinders.

Bootsey · « **Reply #21 on:** July 15, 2014, 02:41:14 am »

Checked the new piston ring end gaps in cylinders, all came within spec at 0.200 - 0.230mm.
Installed new pistons, rings, piston pins, and clips.

Got the jugs painted, next up will be throwing on a new base gasket, o-rings and installing the cylinders.

Tews19 · « **Reply #22 on:** July 15, 2014, 04:14:47 am »

Very impressive and detailed! Subscribed! Do not forget the big one rings that go on the outside of the cylinders. Do this before putting the cylinders on the lower end.

Bootsey · « **Reply #23 on:** July 16, 2014, 02:38:22 am »

Thanks Tews. Trying to be as detailed as possible, so someone might be able to pull up any glaring mistakes I make...

Nice 550 build of yours, interested to see how it all turns out.

rogg · « **Reply #24 on:** July 17, 2014, 05:48:33 am »

Keeping an eye on this one. Good work. Also in AUS and might have to do a similar pull down on my 550.

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Author Topic: 1975 CB550 K Rebuild & Small Mods from AUS (Read 14019 times)