Topic: CB550 Top End Rebuild

[RAFster122s]

Thanks for your service Chris. Which branch of the military are you in, Army or Marines?

Like Calj said, you may be OK with stock jetting. Worth a try and it will only cost a few sets of plugs, to do plug chops, to find out. You will need several sets anyway to be certain it is properly jetted even if it does need the 105s. Or a spark plug cleaner to blast them clean.

Good luck wrapping things up on the bike so she is running.
David

[CJK]

Thanks for your service Chris. Which branch of the military are you in, Army or Marines?

Like Calj said, you may be OK with stock jetting. Worth a try and it will only cost a few sets of plugs, to do plug chops, to find out. You will need several sets anyway to be certain it is properly jetted even if it does need the 105s. Or a spark plug cleaner to blast them clean.

Good luck wrapping things up on the bike so she is running.
David

Hey David, I’m in the Marines on the Reserve side, happy to do this as a side hustle but grateful to not be on active duty. I did a deployment, it was bittersweet.

Anyway, I just returned back home late yesterday. Today, I put some gas in the carbs, kicked it over a few times then used the electric start to get it running. It started! It was a great feeling to hear it firing on all 4 cylinders. I let it idle for a couple min, then shut it down due to time.

However, I’m concerned with noise coming from the valve cover. It’s a clicking noise that corresponds with RPMs so I’m quite positive it’s either Camshaft, Rockets, Valves, or Tappets.

I checked the valve tappets, and confirmed they are set at 0.05mm Intake and 0.08mm Exhaust. I checked the tappet covers, which show no signs of contact with the tappets.

I didn’t use a stethoscope, but I felt the valve cover while the engine was running. To my touch, it felt like rockers are contacts the top of the valve cover.

I did have concerns when fitting the valve covers about how it was fitting at TDC.

I took a video so you can hear audibly how loud it is.

Video:
https://share.icloud.com/photos/0OjwvxCxb6XDdWzw-UutvGHHw#San_Jose,_CA

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[RAFster122s]

If you do not have a 77 or 78 cam cover it could be noisy due to eccentric wear of the rocker shafts in the cover. They cause cam and tappet wear and is a design flaw they fixed on the later covers by pinning the rocker shafts. I could not open the zip file on my tablet so I could not listen to your video at the moment.
The valves on the bike do tend to be noisier on these bikes or is it noisier than normal.

[CJK]

Apologies, I wasn’t sure if that’d work, but here’s the video hosted on YouTube

So the new head is from a 77-78, I believe as the rocker shafts are the newer style that are not pinned.



I found a post where TinTop talked about these valve covers wearing down, which causes similar noises I’m describing. However, I don’t see an elongated (oval-shaped) rocker channel  (No gap visible in picture) so I don’t think it’s that.


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[flatlander]

according to this picture that you posted, you'd have one of the newer style covers:



this has 8 bolts under the breather cover. the old style has only 4. the additional bolts keep the rocker shafts in position.

to be honest, i don't hear anything too unusual in your video. might be the video sound or might just be me. but with the 650 cam and right clearances, there would be no risk of rockers contacting the cover.
just checking: are you sure you set the tappet clearances at the right points? the description in the honda manual confuses many people.

[bryanj]

Check that the exhausts are tight in the head you would not be the first to chase a noisey tappet then find a slight exhaust gasket blow(got that tee shirt!)

[flatlander]

good call bryan!

[CJK]

Flatlander - Thanks for info about newer valve cover. I think I set tappet clearance correctly.

- Place correct feeler gauge between top of valve stem and bottom of tappet.
- screw tappet down just to point where feeler gauge can slide out, but next size gauge will not fit.
- tighten 10mm nut to secure

I will check exhaust flanges for any leaks. I put the copper crush gaskets in there and tighten down pretty good. I’ll check for any leak.

Any guidance on engine break-in following a top-end rebuild?
I would assume first 500 miles should be taken easy and oil changed.


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[flatlander]

there are different break-in philosophies. i'm in the fast and hard camp but other opinions are available

with that disclaimer out of the way... avoid idling and avoid keeping it at the same rpm for longer times. so start it up, get riding immediately and keep varying the rpms throughout the gears. like on your local twisties. accelerate and decelerate on the engine. warm the engine up doing this, 5-7 miles up to 5k rpm, another 5-7 miles up to 7k, then use the full rpm range. get back home when you have up to 50 miles on the clock, then change the oil and filter.
then keep riding the same way, meaning avoiding sustained rpms if you can but otherwise you can ride it like normal. don't baby it, give it the spurs once warmed up. change the oil and filter again after about 200 miles. after that you can stick to the normal oil change schedule.
the point is to get the rings to seat properly and you won't get that without load. that's why all the accelerating and decelerating. so have some fun, avoid city and highways and head for some small exciting roads. the oil changes are important to get the metal dust out early.

[Fezzler]

Apologies for lurking, but what a thread!  (And this top end was completed in frame?)

[CJK]

Thanks flatlander, that all makes sense.

After I get the carbs vacuum synch’d and then get carbs tuned, I’ll be sure to work it through the full range of RPMs with a huge grin on my face

Fezzler - I’m grateful to have so many experienced minds (Bryan, Cal, David, and Flatlander) helping me through this. This forum was one of the reasons I purchased a Honda SOHC motorcycle, it’s been a journey and learned so much through it. It’s been awesome.

I’m not sure I understand your question, can you re-phrase?




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[Fezzler]

Apologies.  I'll try again. 

Is it correct that you completed the rebuild of the top of the engine without removing the engine block from the motorcycle's frame?

I attempted my first project after seeing Dino's Hack-A-Week series, asking a bunch of questions here, and getting a lot of terrific help from some unbelievably nice, helpful and knowledgeable folks on SOHC4.  I still have a lot to learn, and my first bike isn't perfect, but it is a very fun Sunday rider and occasional commuter bike.

They instilled in me enough confidence to attempt a second restoration with the training wheels off some.

   

[CJK]

Oh, I understand what you're asking...

Yes, I left the bottom end mounted in the frame, while the top end was off. I stuffed shop towels around the rods to prevent anything from falling down in there, then I put a plastic trash bag over the top to make sure dust did not get down in there.

For a first rebuild, I've been pleasantly surprised with it. I'm sure the next one will be much easier

[bryanj]

 Fezzler, dont forget the 500/550 you can strip the top end in the frame but the 750 you can not(without a frame mod kit!)

[CJK]

Bad news:
the engine seized on me during its first test ride since the rebuild about a mile from home.

Good news:
no injury other than my ego, morale, and wallet.


I must have made a mistake somewhere along the way and forgot to check something or tighten down to spec.

Not sure what the extent of the damage is, but I won’t be able to open it up for a couple weeks as I’ll be traveling.

I was decelerating at the time, engine was at maybe 3-4K RPM from about 6K max. Engine felt odd so I pulled in the clutch to remove load, felt a clunk and the engine died. Tried the kick starter to see if it would even turn over, but it was seized.

Not much other details to share as I pushed it back (uphill the entire way, of course), parked it, and walked away. 




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[DaveBarbier]

Bummer! When will you be able to open it up? Check the oil filter for metal.

[wolf550]

reminded me of my last top end rebuild
after putting back together went for a ride
heard what sounded like my cam chain loosened and then chunk!
when i opened it up the gear was off the cam and bolts were gone
forgot to tighten the cam gear bolts i guess

[Stev-o]

Sorry to hear...

[CJK]

Thanks all, it’s a bummer and I was pretty upset for a while. However, I didn’t get injured and I’m sure there’s lessons learned so I’ll chalk it up to another learning experience.

I should be able to open up the engine next weekend. I’ll be happy if the work I had Mike do wasn’t for nothing.


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[CJK]

It took a bit as I’ve been busy with work and I haven’t wanted to know...but I finally opened it up.

This wasn’t the first run. It was the first time on the street.

Below is cylinder 1...looks like it’s now a Stage 2.5 paper weight and the piston is ruined too.







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[dave500]

dropped a valve,keepers let go?thats a big bad bummer I feel for you.

[CJK]

dropped a valve,keepers let go?thats a big bad bummer I feel for you.

Honestly, I have no idea.

@MRieck did all the head work for me and I have no reason to doubt his workmanship.

 

[CJK]

How do the other 3 cylinders look top and bottom?

Exhaust Valves definitely made contact with pistons heads on 2/3/4.

I had an adjustable cam sprocket. Maybe I didn’t tighten it down enough and I lost timing which led to this?













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[dave500]

yeah if all made contact it wasn't a keeper let go,either as you said cam bolts slipped or way to close clearance?if the clearance was too close id imagine both inlet and exhaust valves would collide with the pistons,being only the exhausts id guess the timing went off,or was set wrongly?was the valve clearance to pistons checked?if only those eye brows were bigger?

[CJK]

yeah if all made contact it wasn't a keeper let go,either as you said cam bolts slipped or way to close clearance?if the clearance was too close id imagine both inlet and exhaust valves would collide with the pistons,being only the exhausts id guess the timing went off,or was set wrongly?was the valve clearance to pistons checked?if only those eye brows were bigger?

I checked valve clearances with the clay method on top of pistons and they did not touch.

To set timing, I followed the manual exactly (Cylinder 1 @ TDC, cam notch parallel to head) and it ran very well in neutral when I was tuning it. This was the first time under load and it drove for about a mile before I suspect the cam sprocket slipped back several degrees, retarding the timing and sending the #1 exhaust valve into the piston.

When disassembling, this is where the timing advancer and cam notch were at. Timing advancer is a 3-5 degrees before F, the notch is probably 10-15 degrees behind where it needs to be.





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