Topic: Re: 77 CB550 Engine - Pulled My Head and I Don't Like It

[imgnr]

Hello SOHC Sages and Gurus,

The PO stripped the threads on the engine studs so I haven't been able to tighten the headers resulting in leaks and crappy performance overall.

I was able to retap the threads on the number 1 and number 4 cylinders.  They were originally M6 1.0 and I went up to an M8 1.25 which is the same size as a CB750 stud.  The 750 studs are way too long so I found some "reducers" with one end being M6 and the other end being M8.  I'm very happy with them as I have never had any luck with helicoils.  Pic attached.  I think the new studs are much stronger than OE.  Anyway, I digress.

For the number 3 and 4 cylinders, there's not enough space to drill out and retap the threads so the head's coming off.  I've looked at the service manual and I think I can do it without taking the engine off the frame.  In fact, it seems rather simple.

My questions are:

1) Anything in particular I should be careful of breaking that's not in the shop manual?
2) Any tricks/tips that's not in the shop manual?
3) While the head's off, anything I can/should check or service?
4) Can I reuse the seal?

Thank you!

[calj737]

Definitely some things to know:

Remove tappet covers, loosen valves completely, and use. Rubber band to restrain the rocket arm on both intake and exhaust side.

Remove all the bolts! Especially those hiding under the breather cover. Gently pry the head off. I would replace the valve cover seal, the head gasket, and the o-rings in the cam cover end caps. Also, new pucks are a good idea. 

[imgnr]

So, I pulled my head to fix stripped threads courtesy of the previous PO.  I think my cam chain tensioner is broken - can someone please confirm?  Would I need to pull the cylinder to replace it?  How hard would that be and can I do it with the motor still in the frame?  Arggh.  The more I dig, the more problems there are.

Also, looks like the end of one of the valves is missing a chunk.  I supposed I'll need to change that?  I'm thinking about just getting a used head and cover on E-Bay with all the valves in place.

p.s.  I am "handy" but not a mechanic.

Thank you!

[imgnr]

I checked my engine number (cb550E 20103xx) and it seems to be a 1977 engine.  What other year heads will fit?  I remember reading that 1978 will fit as well.  I checked the cmsml website and the part number for all the cb550 heads are the same.  Does that mean all the parts are interchangeable across the years?

[calj737]

All 550 heads fit, they later model valve covers had a slight difference in that the rocker shafts were pinned. That valve stem is badly damaged, look at the corresponding rocker. Is it damaged too?

[imgnr]

Calj - Thanks for the response.  I'm going to order a new head and take care of the valve problems.  This way I also wont have to mess with the stripped threads.I thought the cam chain tensioner was broken because it looked like it was in two pieces but I think the other is a "cam chain tensioner guide".

How do I check to see if the tensioner and guide are both okay? 

Darn.  I could've bought a parts bike for $300 but didn't think I'd have a need for it.

[calj737]

Best way is to wait until you pull the head so you can evaluate the blade. These are prone to cracking and wearing out, but they are no longer made. Finding a very good condition used one is your best route if it's worn.

[imgnr]

Calj737 - You mean pull the cylinder right?  I already pulled the head.  Can I damage the engine if the cam chain breaks?  The cam chain guide seems to just wiggle around and doesn't seem to be firmly attached or seated.

Thanks again!

[RAFster122s]

If you didn't back off the adjusters and rubber band them back you are likely to have bent a valve removing the cover. It is a gotcha that is common for people who have no familiarity with the motor and its quirks.
The cam chain can be split and as long as you don't lose an end into the bottom of the motor or pan. But, you will have to re-peen a replacement rivet to reconnect the chain.
Depending on mileage many replace the cam chain if this far into the motor for service.  Presumably you will be honing and re-ringing the pistons before reassembly if thd bore is within tolerance and not out of round. (A problem for the motors and drift seen in liners for 550 & 750 design, metallurgy issues.)
The valve that is buggered up likely took out the corresponding rocker arm.

If you replace your cover, care to sell me the old one? I have a 74 with wornout rocker shafts & I am looking for a 77-78 cover assembly.

Thanks!
David

[imgnr]

RAF1226 - Oh, that's what they were talking about to rubber band the adjusters back.  I didn't do that.  I'll have to check and see if the valves are now bent.  If I end up with a new cover, I'll sell it to you for $15 plus shipping.  Figure that'll cover my time for boxing it up and taking to the post office.  I'll message you if you still want them.  Probably be a few weeks.

The PO said he changed the rings.  I don't know how to check whether the cylinders are out of round.  I'll have to figure that out.  Would prefer not to pull the cylinders if I don't have to.

[Trad]

RAF1226 - Oh, that's what they were talking about to rubber band the adjusters back.  I didn't do that.  I'll have to check and see if the valves are now bent.  If I end up with a new cover, I'll sell it to you for $15 plus shipping.  Figure that'll cover my time for boxing it up and taking to the post office.  I'll message you if you still want them.  Probably be a few weeks.

The PO said he changed the rings.  I don't know how to check whether the cylinders are out of round.  I'll have to figure that out.  Would prefer not to pull the cylinders if I don't have to.

To measure the cylinders, borrow or buy a decent bore gauge and measure at different depth's in the cylinder sleeve. Compare measurements with the tolerances listed in the shop manual. You'll need a mic to measure the pistons properly.

Too bad you've opened up a can of worms with this bike. haha

[goldarrow]

You don't have to use rubber band trick to remove the cover, but do use it when put cover back on

[imgnr]

Thanks everyone.  I just ordered a new head and cover from E-Bay.  Hopefully it'll get here soon.  Hoping to go on the Distinguished Gentlemen's Ride September 27th.  Should be able to - it only took a couple of hours to tear the top end off.

Bought the bike as a project from a kid who attempted to café the bike out.  I ended up ordering pieces that he stripped off and putting them back on such as the rear fender, turn signals (all four), mirrors.

Changed all the seals as the bike was leaking like a sieve.  Changed the fork bearings to tapered, changed the front wheels and triple trees (due to crack), rebuilt the carbs, changed all the cables, rebuilt and rejetted the carbs, changed the fuel lines, stripped the gas tank and clear painted it, rebuilt the brake calipers, rebuilt master cylinder, fixed wiring, changed both controls from a cx500, changed grips, changed bars to a superbike (more comfy), new headlights and reflectors, relocated idiot lights to the headlight, new old headers/exhaust, etc. etc. etc.

Learning a lot about old bikes from working on this one.  Just picked up a 1980 SR250 that's a basket case.  Have two 1962 BSA basket cases as well.

I'll post some pics when she's back together.  I think she's pretty - all oily and rusty.

[calj737]

was the bike running at all? Before you pulled the head, you could have run a compression test and a leak down test to give you heaps of insight into the motors health.

Used heads are often as much a can of worms as a used motor. Inspecting the valve seats and guides and seals is difficult to do assembled. You might as well disassemble yours and have it ready to go. I probably have some used valves that you can lap in and go. I'd replace the seals on either yours/eBay head. Guides (exhaust side) tend to wear and should be looked after.

When you can, get a clean/clear shot of the cylinders from a slight off angle. If there is visible "hatching" on the cylinder walls, you should be good. If not, rings may have been replaced but cylinder not honed (not good). If you find that condition, pull the cylinders, have them rigid honed (if they and the pistons are in spec) and re-install carefully with the rings (if the "end gap" is in spec)/ This sounds like a lot of involved stuff, buts its not really. And it will allow you really determine/correct the top end health of your bike.

[imgnr]

Bike was not running when I got it but I got it to run but very poorly.  It would die during idle and would have a hanging idle.  I haven't been able to go anywhere far - just a few miles to the grocery store, etc. while I dial in the bike.

The cylinders are super smooth (guess that's better than having marks on it).  Would I be able to feel the marks by running my fingernail over the cylinder?  I tried and couldn't feel anything.

I bought a new head because about 50% of the threads were stripped by the PO.  Just too many things wrong with them.  Hopefully the new head (and cover) will be fine.

I'm sure there are lots of posts already on how to check the valve, guides, tappets etc. so I won't ask you to repeat what's been said.

[imgnr]

Since the bike probably has 200 miles on the new rings already, is there any reason to hone it now?  I'm guessing it's either already seated or it isn't.  I think it is since the engines not smoking.

[RAFster122s]

You don't have to use rubber band trick to remove the cover, but do use it when put cover back on

Thanks goldarrow, I wasn't aware it was only on reassembly.  I guess it was not clear when I had seen that explained previously.  I still have a lot to learn about the 550.
David

[RAFster122s]

http://www.enginehones.com/lisle16000.htm
lf you feel anything with the fingernail you have issues.  A hone job should have cross hatching visible as Cal has indicated.  Often it is visible after breaking in the rings, but, that depends on the rings. The rings should reseat in the newly honed cylinder, but not a flexible hone like the one tgat has lots of abrasive balls. I am not sure what a rigid hone is. Cal, can you elaborate?  I am going to do I need do a web search for that...
David

P.S. did a search and found what I was looking for.  Lisle rigid hone is adjustable to a setting that it won't exceed.
http://www.enginehones.com/lisle16000.htm
The model 16000 will go from 1.75" (44.5mm) to 2.75" (69.9mm)

[calj737]

More than likely the PO didn't re-hone the cylinders. If it wasn't smoking, then let it be. Just do a complete cleaning of the head gasket and get the mating surfaces as clean as possible. I'd still encourage you to have the new head milled to get a very flat surface. This will help promote a leak free seal.

Also, when you install the new head, torque it down in stages, don't set the wrench to full spec and cinch it down all at once. This too helps promote a proper seal. And, once you torque it down, let it stand overnight. Then, release all the bolts in reverse sequence, and re-torque. This insures the new gasket is fully compressed and the nuts remain at their proper torque. This is vital with new studs, but also a great idea for a new head gasket.

Afterwards, install the valve cover using het rubber band trick (mentioned above) and use some antisieze on the threads. Torque only to hand tight (6mm bolts only use 8# of torque, no more).

[Duanob]

You don't have to use rubber band trick to remove the cover, but do use it when put cover back on

Which is probably something the PO did not do.

Check for bent valves, broken or cracked valve guides, damages adjusters, etc. The head itself might be in good restorable shape but you may have to replace some of the things mentioned above.

[imgnr]

I'm expecting the E-Bay head and cover to come in today.  I did research on this site and the way to test the valves (without pulling them all out) is apparently to put gasoline into the intake ports, exhaust ports while having the head laying on its side as well as turning it upside down and putting gas directly on the valves.  If there're no leaks after a few minutes, the valves are probably good.

Thoughts?

Thank you!

[calj737]

That is a reasonable means of testing the valve seats, but not the guides.

[Duanob]

I think it would be a great idea at this point to take the head and valves into a machine shop and let them refurbish it. Between your old head and the newer one you should be able to come up with 8 decent valves and guides. Then use an OEM honda head gasket for installation. You can buy any decent quality top end gasket kits for the rest of the gaskets and o-rings like pucks, cover gasket, intake and tappet covers, valve stem seals, etc. I use copper spray on my head gasket. Pay extra attention to the rubber o-rings at the oil ports on each end of the head. Nothing worse than having those start to leak shortly after all this head work. You can pull the cam chain tensioner with the jugs on. Its not a bad idea to clean it and make sure it works good before putting the head back on. The screw adjuster only turns about a 1/4 turn. See below for rubber band trick. Also see below inside the cover breather area there are four bolts, that designates the newer better style cam cover.

[RAFster122s]

Four of the bolts in the breather cover are pinning the rocker shafts so they do not spin.

[imgnr]

Got the new head and cover in and it is definitely not "plug and play".  I ordered a valve compression tool and top end kit so will give the "hand lapping" a try.  I heard it's all in the wrist action.  Can't be that hard.