Topic: Just blew the top end of my CB550! Spare engine in LA?

[zeech]

Update:

Well I think I might have found the problem... Before I took it all apart I could manually cycle the pistons via the timing adjuster nut, they weren't seized, but they were very tight.

Valves and pistons look toast to me, maybe not though? Rings have spring in them but one broke easily. I think a small oil leak from the oil pump o-rings gone horribly bad is the culprit here, thus frying my guts. Also, the gaskets are in bad shape which is probably why I had lots of oil on the front of the engine. I knew this was coming, guess it's better to rebuild and fix it now.

What can I salvage and what do I need to buy new? Should I just buy new valves, pistons and rings?











Original post below:

Beast mode!

I knew she would break eventually, today was that day! The top end starting getting a little 'clicky' recently then today on the freeway I started to lose power, thought it was gas at first, but then it eventually just shut off. Engine smoking and oil leaking out of the head. Unknown miles but last title states around 30K. I've put 3K on it myself. It's been smoking out the exhaust for a while so I figured this day would be coming, which could also mean rings etc?

Not sure how hard a top end rebuild is, would rather do it myself if I could, but don't know how involved it is. Can you guys point me to some threads/resources? Would really appreciate it, thanks!

[goldarrow]

head over to the download section and start digging for the manual, download and study.  at the very least, you'll need gaskets set and rubber pucks, and hondabond.

[DustyRags]

Run a search for Glitter In The Oil. I did a top-end on a 550 about 15 months ago, and took photos of everything. And asked lots of questions. The good people here helped out. Loads of info there.

[Duanob]

Make sure the engine didn't seize up before spending the time and cash to rebuild the top end. You can remove the head without taking the engine out of the frame. Something tells me if you're going in that far you might want to do new rings and have your jugs freshened up. Depending on how much wear the cylinders have going on, you might be able to use standard size.

[KrautKoffin]

Saw your post on IG, sorry to hear that! I'm working on the same thing with my 750.

[goldarrow]

Get another bike to ride while this one is  going through a rehab.  Weather has been too nice not to ride!

[zeech]

Thanks, I'll do some reading up on removing the head while in the frame and take a look.

I did find something in the exhaust intake when I removed the carbs that wasn't reassuring... it looked like a small chunk of aluminum maybe, about the size of a pistachio. I'll have to get her opened up to investigate more.

Does anyone in Los Angeles happen to have a spare engine? Ideally I can just swap in a new engine while rebuilding this one. Haven't found any on Craigslist. There are a bunch on eBay but those are hit and miss, we'll see.

Duanob: It almost seems like it might be... I try and run the starter and it tries to turn over but nothing is moving, just bad noises from the electronics, starter and engine!

goldarrow: Haha! I've got a 750 I'm doing a complete rebuild on and a 350 that runs, just really badly. Need to get one of these going!

[DustyRags]

So- the starter spins, but the engine doesn't turn over? Tried kicking it?

Aluminum in the combustion chamber (?) sounds like a bad thing. Sure it isn't steel?

[zeech]

The starter does not even spin no. It seems seized up. My kick is stripped so I can't test it.

Doesn't look like steel, too porous. Looks like cast aluminum. Need to take the head off to see more.

[DustyRags]

Oy, doesn't sound good. Try putting it in gear and rolling it.

Honestly, though- rattle getting louder, shredded aluminum in the combustion chamber, engine seized... I suspect a tappet screw backed out and you've got a bent valve. Top end might be in sorry shape

[zeech]

Original post updated with photos and more info. Though I still have no clue what the metal chunk in the intake was yet....

[calj737]

If the motor is seized, drop the oil pan and check for more debris. Continuing to rotate a motor that is seized is not a good idea, especially if you've found metal chunks in your valve train. Part of a piston perhaps...

Pull the motor, pull the valve cover and drop the pan.  The damage will come clear quickly.

[lucky]

IF you took it apart, you can put it back together.

Rebuild the engine then you will know what you have.
If you get a used engine you will just have another engine with 40 YEAR OLD parts again.

[Duanob]

I'd buy another used motor and do a top end on it. The bottom ends don't go out too often. Maybe the OP had a bad oil pump and idiot light at the same time?

[goldarrow]

Buying and finding a used donor motor could be a challenge down here in SoCal.

[Vinhead1957]

Any pix of the debris?   Definitely drop the oil pan to see the oil filter screen debris.  That head doesn't look bad.  Yes due for a valve job

[zeech]

I'll drop the pan and see what it looks like from underneath. Do I need new pistons or do they just need a good cleaning?

Will get new rings and do a valve job. Also new oil pump o-rings and anything for the left hand side.

[goldarrow]

Get pistons a good cleaning and do measurements, check against the manual to make sure they are within specs.  Then decide if you need new pistons, that time decide if you needed new rings.  Also measure the cylinder bores.  You never know if you will need 1 size over of many parts until you do measurements and investigate everything to the root cause of your issues.  So, I say hold off and do not buy any parts just yet. 

[lucky]

Remember that after 40 years the crank oil passages could be full of trash.
The lower end bearings could be out of spec or gone.
All of these engines need complete rebuilds at this point. NOT just top end rebuilds now.
It has been 40 years!!! Think about that. Hard.

[DustyRags]

Pics aren't loading for me.

[Duanob]

All of these engines need complete rebuilds at this point. NOT just top end rebuilds now.
It has been 40 years!!! Think about that. Hard.

Dude you might want to find another hobby. This one stresses you out waaaaay too much.

[KrautKoffin]

All of these engines need complete rebuilds at this point. NOT just top end rebuilds now.
It has been 40 years!!! Think about that. Hard.

Dude you might want to find another hobby. This one stresses you out waaaaay too much.

I think we stress him out, not the hardware.

[zeech]

Just an update. Everything inside looks pretty good to me, don't see any chunks of metal or know where that one thing came from...

The biggest question I have is do I can I just clean the piston heads off lightly or do they need to be replaced? I haven't measured them yet and guess I should if I can figure out how to get the head off by itself...

I think I need to get the valves all cleaned and lapped, get all new o-rings and gaskets then might be good to put it back together.

Another good thing is that I was able to replace the entire kickstart gear which had been stripped since I got the bike. Will be doing a write up on how to do it with photos.

[mrbreeze]

All of these engines need complete rebuilds at this point. NOT just top end rebuilds now.
It has been 40 years!!! Think about that. Hard.

Dude you might want to find another hobby. This one stresses you out waaaaay too much.

From what I have been reading since Lucky joined up..............I do have to agree!!!!!!! WAAAAY too much stress

[Duanob]

Just an update. Everything inside looks pretty good to me, don't see any chunks of metal or know where that one thing came from...

The biggest question I have is do I can I just clean the piston heads off lightly or do they need to be replaced? I haven't measured them yet and guess I should if I can figure out how to get the head off by itself...

I think I need to get the valves all cleaned and lapped, get all new o-rings and gaskets then might be good to put it back together.

Another good thing is that I was able to replace the entire kickstart gear which had been stripped since I got the bike. Will be doing a write up on how to do it with photos.

I will reiterate, does you bottom end rotate freely? If it's stiff or doesn't want to spin easily then you might have bigger problems. Top ends are easy, bottom ends are another thing.

As far as the head goes use a bit of berryman's cleaner to get the jist of the carbon sludge. Disassemble and check: Valves for cracks and straightness of shaft, guides for cracks and fit of valve shaft, cam shaft for scoring or burn marks or weaird wear patterns. Then do a good media or soda blast. You should have the head decked for flatness. Jugs make sure there is no scoring in the cylinder walls. Check for wear, maybe just a good honing will save them. Replace all gaskets, seals, o-rings with new. A decent top end kit should have everything you need and then some. Although: personally I would use an OEM Honda head gasket. I learned a lesson but that's just me. I would suggest spraying the headgasket with copper coat and make sure it fits perfect around the little o-rings on each end. Otherwise it will start leaking very soon.