Author Topic: Engine rebuild thoughts. 77 cb550k. While I'm in there I may as well...... (Read 1941 times)

Lostboy Steve · « **on:** October 03, 2011, 07:16:57 AM »

So as per my previous threads I have to pull my head off due to a leaking intake valve on cylinder 4. I didnt get the head off yet as I didn't have my impact driver at home for these stubborn phillips bolts. My compression was all around 120 except for cylinder 4 which was 90 and the leak-down test uncovered my leaking intake valve. This engine had previously sat for 20 years in a climate controlled warehouse. It has an original 9k on it. I wasn't going to do anything with the piston's / cylinders but now I'm thinking I want to coat the cylinder due to its faded appearance, which obviously will require removal. If I pull off the bores I may as well hone and install new rings. I'd like to pull off my pistons and have them coated in an anti-friction skirt coating and heat dissipating dome coating. My question is that with 9k on the engine piston wear should be minimal.... Right? Is it worth investing in new pistons? I will try to get the head off tonight and post some pics so we can better access the situation. I am toying with an idea to have the valves coated in a thermal barrier / anti stick coating. I may port the head as well. While having it apart I want to make it as clean and durable as possible. Also, should I have a machine shop cut the head? and if so how much? Will boosting the compression up a bit increase my overall power? I'm not looking for a rocket-ship just something solid and strong.

Raef · « **Reply #1 on:** October 03, 2011, 07:40:51 AM »

Good questions, I have 2 550 motors down and a project waiting on one to get put back together, I'll be watching for opinions

Mark

Kermit · « **Reply #2 on:** October 03, 2011, 09:36:31 AM »

where those slick coating really come into play is on high revving motors running thin oil. I don't think you will get max benifits for your money with it on an older bike. But if you have it apart, and the resorces to have it done then more power to you, but remember you will never get the money back out of it.

Lostboy Steve · « **Reply #3 on:** October 03, 2011, 10:10:29 AM »

Yes, I was actually expecting that response. Thats pretty much what I thought, but like you said if its available to you it may as well be used. I'm not building this bike to sell it. I'm building this bike for me to ride and to pass on to my 3 month old son when he turns 17. If I was worried about getting the money back I would have stopped about a grand ago. lol. Good point though.

TwoTired · « **Reply #4 on:** October 03, 2011, 11:16:47 AM »

Honda made pretty strong and durable engine that stands up to most abuse pretty well. Neglect isn't an abuse well tolerated, though. If you want to buy parts for rebuild in 15yrears, that will add legs to the bike's life. But, with 9K miles the engine, it is just past the break in point. Take the head off if you must, But I think you should have run it another 100-200 miles to see if it would all seal itself up again after doing some real work rather than just sitting.

Kinda depends on why the comp was low on one cylinder. But, my 77 CB550F sat for 15 years. Had 8K miles and low compression on one cylinder, so I only paid $100 for it. I did the usual to make it run again, but never opened the engine, and 100 miles later all the compression checks came out equal. In fact, that thing seems to have more power than all the rest of my 550s. I don't buy the "while-I'm-in-there" snowball effect at rebuilding. It's a waste of time, money, and effort most times. imo.

MrGardman · « **Reply #5 on:** October 03, 2011, 11:26:04 AM »

Quote from: TwoTired on October 03, 2011, 11:16:47 AM

Honda made pretty strong and durable engine that stands up to most abuse pretty well. Neglect isn't an abuse well tolerated, though. If you want to buy parts for rebuild in 15yrears, that will add legs to the bike's life. But, with 9K miles the engine, it is just past the break in point. Take the head off if you must, But I think you should have run it another 100-200 miles to see if it would all seal itself up again after doing some real work rather than just sitting.

Kinda depends on why the comp was low on one cylinder. But, my 77 CB550F sat for 15 years. Had 8K miles and low compression on one cylinder, so I only paid $100 for it. I did the usual to make it run again, but never opened the engine, and 100 miles later all the compression checks came out equal. In fact, that thing seems to have more power than all the rest of my 550s. I don't buy the "while-I'm-in-there" snowball effect at rebuilding. It's a waste of time, money, and effort most times. imo.

Have to agree with TwoTired about the break in. When I was still wrenching on Hondas, we found most of the bikes , like the 350s and up, didn't start running really well until they had about 5000 miles on the clock.

Lostboy Steve · « **Reply #6 on:** October 03, 2011, 11:46:20 AM »

Again, I have mixed emotions as all of these things have been going through my head. Obviously I don't want to yank the head for a lack of better things to do. It is definitely an intake valve. During the leakdown test I had a steady stream of air coming out of the carb. The whole problem is, (as king custom pointed out in a previous thread during diagnostics) it won't idle right with the terrible leak on number 4. Syncing the carbs is near impossible and riding it like this although possible would be a pain in the ass. I have a good long winter ahead of me and if there was a nice day I would ride my Buell. I wasn't even going to have the valves cut if necessary. I was going to do a really good lapping on them and coat them in a teflon-like frying pan coating which is said to reduce valve adjustment frequencies and keep them from building all that grime over the hours / miles. I have a really good source for these coatings and he gives me really good prices because I am a nut and coat just about everything. I agree, made well, most Japanese bikes were /are. Technology has come a long way though. Just like electronic ignition is not 100% necessary because properly set points work well, CDI is just less maintenance, and I'm all about that. Remember that a left open valve for 20 years starts off as a really nice shiny surface that probably developed enough rust to not seal. I will definitely take all of these thing into consideration. Thanks for the replies and check back late tonight / tomorrow for pics hopefully.

Raef · « **Reply #7 on:** October 03, 2011, 05:31:34 PM »

Of the two motors I have down, one is a 76 f with 8500 miles on it, the only reason I took it apart, I put a hole in # 2 piston. I thought it was due to a plugged carb on a long trip, come to find out when I took it apart you could see where it had been full of water. # 2 cylinder still had water marks in it.

The other, I bought sight unseen with 23,000 miles on it, it was very tight, nearly locked up, it to had been full of water.

I am torn about what to do, once the parts had been cleaned up nearly everything it both motors is well with in factory specs.
The only thing I am not sure about at this time are , both set have some discoloration hear and there I have yet try to hone them.
7 of the 8 pistons and rings seem to be useable.

It just don't seem right putting a motor back together when you had to pound it apart.

Mark

KingCustomCycles.com · « **Reply #8 on:** October 03, 2011, 05:41:32 PM »

Everything back into manual specs with a quality gasket set. Standard new rings if the bores are nice after deglazing. Valve guides if the wobble is over .004, valve grind and lap if you need new guides, pistons reused if they measure per manual. I would do what we call in aviation an overhaul. Everything in the top end is cleaned, inspected, measured, replaced or repaired as necessary, and reassembled with new gaskets and seals. I can't comment on the coatings as I have no experience.

OldSchool_IsCool · « **Reply #9 on:** October 03, 2011, 05:51:57 PM »

I agree with TT and MrGuardman, the engine needs run to see if the valve cures itself or if it's maybe bent or it's face rusted.

If, after a few more miles, a topend rebuild is called for, you'll need to replace all gaskets down to the base, all O-rings, pucks and seals too. Check the action of the valve chain tensioner. The tensioner slipper rubbers should be checked for signs of age cracking. If the cam chain has any deep rust or stiff links, it will need replaced. You can break it and put a softlink in if you want to avoid splitting the cases.

As for any high performance modifications, you'll need to ask your accountant.

Lostboy Steve · « **Reply #10 on:** October 03, 2011, 05:55:23 PM »

Here come the pics!

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Lostboy Steve · « **Reply #11 on:** October 03, 2011, 05:59:14 PM »

The pistons look great as do the bores. The valves are in need of serious lapping and de-carbonizing! I hope i can get away with just that. King i'd like to know your thought on cutting the head.

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KingCustomCycles.com · « **Reply #12 on:** October 03, 2011, 05:59:57 PM »

Yep, thems some engine parts alright............................There is little to be gained from pics of dirty engine parts for me. A micrometer, thickness gage, and dial indicator will be worth a 1000 words. If the head is warped, have it machined, otherwise, keep your ability to run pump gas and not have to worry about stressing parts due to increased heat. The problem with performance upgrades is they always lead to compromises and the need for more changes at the cost of longevity and reliability. A good tight engine, in stock trim, is very quick and satisfying. With 30 years since most people have cracked their engines, most have never experienced even close to original factory performance and power.

Lostboy Steve · « **Reply #13 on:** October 03, 2011, 06:16:08 PM »

That is well appreciated i dont know how to check head warpahe other than a standard flatedge. I am no engine buff. I will measure the bores and anything else you would like. I can say that other than the carbon buildup and valve faces the engine looks really clean. The cylinder walls have NO marks or scores.

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illrational · « **Reply #14 on:** October 03, 2011, 06:21:30 PM »

Hey King where can i find the specs on things like springs and camshaft or crankshaft run out and the sort?

Raef · « **Reply #15 on:** October 03, 2011, 06:31:10 PM »

go to the web site portion of this forum and you can download the whole manual

thehammer · « **Reply #16 on:** October 03, 2011, 06:37:27 PM »

My understanding is that these aluminum heads warp pretty quick. A flat edge is a close enough check as long as it is as long as your head. shaving down the mating surface and a rinse in an acid bath should cost about $40 at a machine shop. One thing I would do after lapping the valves . . . while you're in there.

Lostboy Steve · « **Reply #17 on:** October 04, 2011, 07:22:34 AM »

So I called a few machine shops around here and they told me to kick rocks. (The actual words used were "not interested") I am getting the jug and head coated. I was hoping to do that before the head got cut this way the baking process doesn't affect straightness. Regardless I think that lapping the valves is my only option.

Lostboy Steve · « **Reply #18 on:** October 04, 2011, 07:55:55 AM »

Some more pics after minor cleaning. I found a shop to do the head and valve job for 150$.

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thehammer · « **Reply #19 on:** October 24, 2011, 09:46:48 PM »

that looks good!

bryanj · « **Reply #20 on:** October 24, 2011, 10:01:31 PM »

No need for rings unless they are badly corroded (doubtful) or out of spec--Highly unlikely. but be sure that all bits of old gasket are cleaned oout of the oil ways ESPECIALLY below the dowels holding th erestrictors.

READ THE MANUAL CAREFULLY about re-fitting th evalve cover or you will be doing it all again 'cos of bent valves

Lostboy Steve · « **Reply #21 on:** October 25, 2011, 06:50:46 AM »

I already bought a ring set on ebay so they are goin in. Otherwise, as soon as i get my head back from powdercoating / valve job I'll post some pics.

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Author Topic: Engine rebuild thoughts. 77 cb550k. While I'm in there I may as well...... (Read 1941 times)

KingCustomCycles.com

KingCustomCycles.com