Topic: Starting a rusty '77 CB550K

[Tvag]

It's coming along, slow and steady.

TT, some answers to a previous post of yours regarding 3 not firing and 4 misfiring.

#3 not working.  You need fuel, compression, and spark.   What is missing?
Remove spark plug, lay plug body on engine and look for spark (across the gap, not just near it).
Assuming it sparks.... 
Compression is fine and it sparks across the gap.

Turn on kill switch to prevent engine from firing.
Apply full choke with the fuel petcock on.
Crank engine through ten-twenty revolutions.  Pull #3 spark plug again.  Does it smell of gas?  Does #4 plug?
Niether 3 or 4 smelt of gas (afterthought: should I have opened the throddle during this process). This could be a false negative as I had spilt some gas on the floor making smelling gas on the plugs more difficult. The plugs were definately dry though.

If #4 is wet with gas and #3 is dry, your carb is not providing fuel.  (Or, you have intake valve issues that a compression check should identify.)

#2 overflow.  Unless you still have a fuel contamination issue.  Sticky floats may go away with some regular operation.
No float sticking problems this time.

#4 backfiring. (Was this at idle?)  Lean mixture, or exhaust header leak and rich mixture.
Started the bike and 4 was still backfiring. It occured at initial start up straight through operation.

Furthermore, after running the bike for 10 minutes (reving throddle at times) I cut the engine and immediately afterward took a wiff from the 4 pipes. 1 and 2 smelt fine. 2 was dripping some fluid that was NOT gas. I think it was water. 3 and 4 definately smelt of gas.

Thoughts? Suggestions? Condolences?

[InaneCathode]

Your carbs are crapped up and or not adjusted right.
If you can get it to idle adjust the idle mixture on all four carbs, see if that fixes your running issues. How thoroughly have you checked your sparky sparky system? I'd clean the plugs really well and ohm out your wires. They should all be right around the same ohmage as it were. It might spark across the gap but you have no idea what the spark looks like inside the cylinder under compression. When you ohm your wires out you know that they're contiguous from electrode to coil. I'd also check your coil connections, make sure the spades are clean and tight.
That being said i doubt your running issues are spark related, generally those are either spot on or dead off. It sounds like your carbs are crapped up and or not adjusted right to me.

[TwoTired]

Given what you've told us, I think you are looking at another carb adventure.
Turn on your petcock to allow the carb bowls to fill.  Then turn it to off.  Use the drain screw on each carb bowl and measure how much comes out of each one.  Make a note.  They should be equal.

If there are differences, then you need to address float height the next time you remove the carbs.
With what you've told us, I'd guess that either your carb bowls aren't filling properly, or you still have idle fuel circuit blockages.
probably time to pull the slow jets, clean them, and then endure that each and every orifice and passageway is clean and clear.
Or, maybe your slow jets fell out.

Cheers,

[Tvag]

Given what you've told us, I think you are looking at another carb adventure.
Turn on your petcock to allow the carb bowls to fill.  Then turn it to off.  Use the drain screw on each carb bowl and measure how much comes out of each one.  Make a note.  They should be equal.

If there are differences, then you need to address float height the next time you remove the carbs.
With what you've told us, I'd guess that either your carb bowls aren't filling properly, or you still have idle fuel circuit blockages.
probably time to pull the slow jets, clean them, and then endure that each and every orifice and passageway is clean and clear.
Or, maybe your slow jets fell out.

I was afraid you'd say that, but that's what makes the most sense. Listen I'm absolutely POSITIVELY sure that my slows are not gummed up. They are as clean and clear as they could get. I've pulled and cleaned them twice and was meticulous beyond measure. It's not the jets. So, assuming it is an idle fuel circuit blockage and its NOT with the slow jets, where should I be looking for the issue?

[TwoTired]

Each carb body has a slow circuit with 4 exit holes.
1, where the slow jet goes.
2. the air jet at the carb throat entrance
3. The Idle Mixture Screw (IMS)
4. the delivery hole in the carb throat.

To verify there is no blockage in the bare carb bodies, I squirt carb cleaner into each hole, in turn and block two of the others.  This verifies that the entire passageway can deliver fluids.

A technical point.  You may have verified that the slow jets were clear when you last saw them.  Since that time you introduced fuel to them.  Can you be 100% certain, and bet all future income that there is NO possibility of foreign matter getting to the newly cleaned jets?  It only takes a spec about 0.016 in diameter to plug those tiny jet holes.

And, you still haven't told us if the all the carb bowls have gas, or the correct level of gas in them.  Number 3&4 cylinder do NOT get gas from 1&3 carbs, you know.  If you want all the cylinders to work the same, each carb must deliver the same amount of fuel to each cylinder at any throttle position.

I understand you're dreading carb removal and installation.  That's why I usually do many checks with the carbs in place.  However, if you weren't meticulous with the carb cleaning regimen last time, or went to extraordinary lengths to feed the newly cleaned carbs with super clean fuel, you get to practice carb removal and installation again.  Like many skills, practice makes you better at it. 
And, typing on the computer, though far easier,  won't make the bike run better.     (I have several bikes that prove that last statement.)

Warning notes about the IMS. 
1. Behind the screw is a spring, a washer, and an o ring.  These aren't happy where they are and will find the most difficult to access place in your repair area, if you don't practice escape prevention.
2. NEVER overtighen the IMS. 
3. Did I mention NEVER, in #2?

Why is #2 so important that it rated an additional #3?
Since you asked, the needle taper is very shallow and will wedge into the metering hole rather easily. In fact, it will wedge in there so tight that it will break off rather than extract and leave the slow circuit delivery hole blocked, defeating the entire slow circuit operation.  This will make the effected cylinder NOT WORK!

Any more questions?  Good, now get to work and report back your findings.  We want to hear that you got a nice ride out of you machine and have successfully added another SOHC4 back into the working population!

Cheers,

[Tvag]

Aye Aye.

[playinsafe44]

Tvag, i had a problem with my cb450 carbs. i dipped them in carb dip, soaked them in simple green, and then scrubbed them with a brush under running hot water. i thought they couldn't get any cleaner and wondered why everyone was saying that getting them completely clean the first time can get tricky. i took off every peice of linkage, jet, float, needle...everything and scrubbed each individual peice. when i put them all back together with new carb kits and installed them on the bike, it ran, but not the best. when i asked what the problem was everyone said it was the carbs. well after arguing with everyone and thinking i was right and they were wrong, i took my carbs off again. on both carbs the tiny little tube that sits inside the top of the choke throat was clogged. it even took me a little while to get carb cleaner to squirt out of them nicely. but after that was done they worked perfectly. this was just my personal experience. hope this helps

[Tvag]

Tvag, i had a problem with my cb450 carbs. i dipped them in carb dip, soaked them in simple green, and then scrubbed them with a brush under running hot water. i thought they couldn't get any cleaner and wondered why everyone was saying that getting them completely clean the first time can get tricky. i took off every peice of linkage, jet, float, needle...everything and scrubbed each individual peice. when i put them all back together with new carb kits and installed them on the bike, it ran, but not the best. when i asked what the problem was everyone said it was the carbs. well after arguing with everyone and thinking i was right and they were wrong, i took my carbs off again. on both carbs the tiny little tube that sits inside the top of the choke throat was clogged. it even took me a little while to get carb cleaner to squirt out of them nicely. but after that was done they worked perfectly. this was just my personal experience. hope this helps

I'm ok with pulling the carbs again. I'll do whatever it takes to get them right. I'm getting close. Now just to get 3 and 4 on track.

[Tvag]

I'm ok with pulling the carbs again. I'll do whatever it takes to get them right. I'm getting close. Now just to get 3 and 4 on track.

I examined a spare set of carbs. i never removed the springs and orings from the idle mix screws assembly. I'll be sure to remove all of that this time. I was thinking of leaving the #1 and #2 carbs alone since they were operating properly.

Talk to you,

[Tvag]

Ok, carbs pulled and cleaned, again. I stayed away from 1 and 2 because they were firing fine. The float heights on 3 and 4 were approximately 1mm lower than 1 and 2. I've got a pretty crude means of measuring however and it's not that accurate. A small metal mm ruler. I took about an hour and a half measuring and remeasuring to be sure I was as close as I could get. Lets see if that helps.

The jets were completely clear as I expected but I blew more carb cleaner and compressed air through them again to be sure (main and slows). Also made sure all the passages were flowing. More spray carb cleaner and compressed air. I used a pen light where I could to make sure all passages were clear. I have to tell you I'm very very skeptical that the problem is the jets or the passages. I have 3 sets of carbs and this set looks immaculate compared to the other two.

While these are off anyone have any suggestions? I was going to throw them back on today and see if there was any improvement.

Otherwise wish me luck that it was the float height or something else I arbitrarily fixed.

Tvag

[Tvag]

Carbs back on the bike for he 3rd time. We've made some improvement i think. There is some good news and some bad news. Let me give you the run down before we get to that.

Put the carbs back in and opened the petcock. It was around 50 today so after turning the engine over with the kickstart a few times to get the oil circulated I tried the starter. I've always kickstarted the bike but the starter (to my amazement) worked. The bike started up on the 2nd attempt. Mind you I have not tried to synch the carbs yet.

There is some uneven reving by the bike upon initial start up and warming up. I don't know if that's normal. So here is the good news, the #3 pipe was HOT after only a couple minutes. Actually #3 and 4 were both hotter than 1 and 2 which is the opposite of what was going on in the past. The bad news, #4 is still missing I think. I didn't run it long enough to really tell but I can hear a small but distinct noise that sounds like a match being put out in water. I can hear it from the carbs on the #4 side and I always assumed that noise is what it sounds like when it doesn't fire. I confirmed this what trying to synch the carbs. Whenever I heard the noise the mercury in #4 would drop far below the other gauges.

Finally, just in case this matters, I was testing to see what happens when I put full choke on once the bike was warm. The bike would rev hard if I did this. Not sure if that is an indication of anything either.

Soon I'll try again to synch the carbs and see if that doesn't rectify the problems I'm experiencing.

I'll try to get video or audio of how the bike is running and post soon.

Tvag

[Tvag]

Ok boys, this post isn't all text like usual. I've got something to show you finally. I caught a break in the action and decided to try and sync my thrice cleaned carbs.

1. #3 is firing again   
2. #4 will misfire but almost exclusively during the first couple minutes after startup. Thoughts?
3. I've posted a video of my most recent carb sync.   

[youtube=425,350]xi_5W3L0he8[/youtube]


And this is how she stands. I decided to put the tank back on. I'm planning to get a new battery this weekend so I may even be able to take her for her first test ride. Kind of really excited for it. 

[edbikerii]

She's a real beauty.  She reminds me of my own when she was new (to me).

[Tvag]

YES!! YES!!! F'ing YES!! 

Wow... guys I have to say I haven't been this pumped for quite some time. I went out on Sunday to get a battery for my bike. After filling and charging it yesterday I came home from work today and put it in my bike.... slight problem but we'll get to that later.

After getting it in, despite the fact that it was drizzling outside I just absolutely had to take it out for a test drive. I fired it up. It sounded great no signs of #4 missing but I wasn't paying that much attention I was so excited that it was for the first time running under its own power. I ran inside threw on my helment and some boots and came out to take it on it's maiden voyage.

I wasn't out for more than a minute with the rain and all but it was my first official ride on my project / first bike ever. Man, can I tell you how good I feel having brought that bike back from where it was without a clue what I was doing? Unbelievable.

So, my problems:

1. In my haste to get a battery for my bike I bought the wrong size. This battery is smaller, still 12 volts but I think it's only 7 ah when I believe it was suppose to be 12 ah? What does this mean for me? That it will die faster?

2. The front breaks are sketchy. They don't do a very good job of stopping the bike. I have to pull them down to the handle to get any real stopping power. crappy.

3. I have to adjust the rear break peddle as it is positioned too low.

4. I still have 20 year old tires on this thing. Best to get some new ones and some new tubes.

With that said the bike sounded and performed well. Got to fix those breaks!

I just wanted to thank the forum and everyone who supported me while I took on this project. It's not done yet and I'm not going anywhere but I just want you all to know how appreciative I am for SOHC.net and all those who make up it's community. Even those of you I don't like. 


 

[TwoTired]

Congratulations and well done on your work!

The brakes are particularly crappy when they are wet, even if they work perfectly otherwise. Did you use new pads?  They take a while to wear in and give good friction (when not wet).  For stock brakes I learned to ride in the rain with one hand on the lever, dragging the brake to squeege off the water and to keep the disk hot, keeping the rotor dry.

Your 7AH battery will wear out faster.  And, you may have trouble keeping it charged if you do a lot of idling around town, as that is when the bike's charging system can't keep up with the bikes' electrical load.

Rear brakes are your friend in wet weather.  Sometimes, it's 90% of your stopping power, until you can squeeze off the water on the front disk.  Adjusting it is easy.

Good tires never hurt.  But, I actually have some older tires (than yours  ) I'm still using on bikes that don't get ridden much.  But, I sure don't race with them, or tour with them, I keep the speeds way down, and I examine the sidewalls before and after each ride.

Cheers,

[OldSchool_IsCool]

CONGRATS T!!!

Great feeling, isn't it?!? 

[hoodellyhoo]

Congrats!!!!!!

It's been a lot of fun to read this thread (not that it's about to end). You've put a ton of work into that bike and now you get to start tasting the fruits of your labor. I probably would've given up on that bike long ago, but you kept sticking to it. In all honesty, it is inspiring. Be proud, because you certainly earned it!

[dagersh]

BRAVO TVAG!!!!!!!!!

Good for you!  It is about time you got some payoff for all your hard work.  I am really glad for you!

Gersh

[Tvag]

Tried to register my bike yesterday, turns out I owe my old town some car tax for a year in which I never lived there. They F'ed up and I'm pist off.

BRAKES!! God damn BREAKS! I decided to try a different master cylendar on my bike. I used on from the '79 KZ400. I get the same results.

I need help. Maybe I'm not installing the master cylindars correctly or bleeding them properly?

1. I connect a clean MC to the brake line.
2. I fill the MC with clean brake fluid
3. I pump the break handle carefully with the cap off till I notice no more bubbles coming from the holes
4. Pump the brake handle until the handle tightens up. (They both did tighten up but not to the point where I expected. I can still pull both of the MC's almost in contact with the throddle. I saw very little improvement from my MC to the KZ400's.)
5. Bleeding brake system. Pull leaver, open bleeder, close bleeder, release brake lever. Continue until no air is escaping brake caliper.

After I do all of this my front wheel will not spin free of the brake pad no matter what adjustments I make to the caliper adjustment screw.

I'm about to bring this thing into a mechanic OR beat it will a crowbar. I'm 50/50 right now.

WHAT AM I DOING WRONG? The KZ MC was working fine on that bike. Am I missing something!!

[OldSchool_IsCool]

Shouldn't that be:

- open bleeder
- pull lever
- hold lever
- close bleeder
- release lever
- repeat until no air

[Tvag]

OldSchool,

I've attached two snipets from service manuals. The second one describes the manner of bleeding the brake system I was refering too. It has you apply the brake, quickly open then close the bleeder, then release the brake. I've tried both ways and I think doing it properly. Maybe I'm not doing it long enough?

The FIRST snipet states "so there is a small clearance between the fixed friction pad and the brake disk." Does this mean that the un-fixed friction pad should be in slight contact with the disk at all times, because that's what's happening to me and it doesn't seem right. With my lack of experience though I don't know.

Also in the SECOND snipet refers to bleeding the break system. It states "Pump the brake lever a few times until it becomes hard." Well guys, this does not happen with either of my MC's. This is the primary indicator for my issue. I know the KZ400 MC is operating correctly because I just dismantled that functional brake system to use the MC on my CB. That lever traveled 1/4 the distance on that system that it travels connected to the CB brake system. So, my question to you is this...


Assuming I have a perfectly functioning MC, if the brake lever does not 'harden up' after a few pumps, what does this indicate?

[OldSchool_IsCool]

Let me start by saying brake work is not something I've been terribly successful with either.  If anything I write contradicts others, use your best judgment.

OK, if you are releasing the bleeder under pressure and closing it before the return stroke of the M/C, you should be OK.

The active pad will likely touch the disk, but only slightly.  Ideally, it will recoil into the caliper housing slightly, drawn in by the flex of the seal.

What are the condition of your brake lines?  You may be fighting internal expansion from deteriorated lines.

[Tvag]

What are the condition of your brake lines?  You may be fighting internal expansion from deteriorated lines.

Honestly, I've checked the lines to see if they bulge upon lever action with no visible signs. They are old lines and were sitting with gunked up, sandy DOT3 in them for years. At one point I used a spare set of lines I had to see if that was the problem but I thought I got the same results. They are an old set as well. Considering all the work I've done on the caliper, piston, and MC's, I'm thinking it has to be the line. Where do I get new (braded?) line?  Thanks for the help!

Tvag

[TwoTired]

If you are going to use the bleeder valve at the caliper...
You open the valve and apply internal pressure with the lever.

Before you reach the end of the lever's stroke, close the bleeder valve.  You want to close the valve while there is still positive pressure in the system that can force air out.

Let the lever return, while the bleeder valve is closed.

Open the bleeder valve and apply pressure again.  Repeat above, until no bubbles are present in the discharge.

It helps to position the hydraulic system so that the bleeder valve exit hole and the master cylinder are at the farthest distance from the earth.  Internal bubbles will naturally rise to this point where they can exit.

Large bubbles will travel faster than small tiny ones.  Flailing at the lever or putting very high pressure inside the system will make very tiny bubbles the easily suspend in place, going nowhere without a complete fluid exchange.

Don't expect to see old rubber brake lines expand.  Your eye cannot distinguish between a few thousandths of an inch change in diameter along its total length, even though such expansion increases the internal volume of hydraulic system.

With the caliper piston pushed back into the bore a small amount, the stationary pad should be adjusted for 0.006 clearance from the brake disk.  More than this amount will require excessive lever travel to firmly actuate the brake.

Try again...  With patience.

Cheers,

P.S. Have you read the brake caliper rebuild walk though in the FAQ?  There's another brake bleed description in there.

[Tvag]

I bleed the brakes again today. The brakes feel better with the KZ400 MC than with the original MC. Anyhow, took it for another spin and could feel the difference. I'm still not satisfied and will be purchasing some new brakeline. Probably SS if I can afford it. It looks to be a $60 investment from what I can find online and on ebay. Sadly that's not in my budget. I'll have to wait a month or two before making that a reality. Sad but true.

Meanwhile, Talked to the tax assessor in my old town and owe less than I thought. My car registration was never transfered over to my new town so... I own 2 years in back taxes. Also not in my budget and basically its costing me my new brakeline and a new battery for now. Oh well, all in good time.

Thanks guys. I'll fill you in some more in a bit.