Soooo, a friend of mine decided to get another bike. He is sort of new, I'm kind of his advisor on the mechanical things he encounters. He test rode the brand new Rebel 500 and liked it. But he has a soft spot for Old School café racers and wanted to look for one. I warned him that with an old bike he would have basically 2 choices. Get one that has been gone through and pay a premium. In return it should be fairly reliable. Or, find one that needs work and make it a project. He built a Café racer out of a Ninja 250 previously and enjoyed it, so he was up for a project. We found a 1977 CB550 that had been partially modded. It looked good, had been recently in a shop for new plug wires, plugs, valve adjustment, carb rebuild, brake pads and tires. It seemed to run Ok although had a minor misfire and the front brake was dragging. I think the motor has been overhauled because it had little primary chain noise and no smoke. Owner didn't know it's history. Friend fell in love with it and bought it. He rode it 37 miles back home at 70 mph and it ran pretty good, although when we got home it had a very fast idle. I told him to check it out the next day, including riding around right in frond of his house to check out the idle and sticking brake. So, next day I get a text. He's 3 miles from home. Bike running horrible, super high idle, dying off choke, getting hot etc. He's throwing a tantrum and threatening to leave the bike by the side of the road. I asked why the hell did he ride it so far away??? No answer to that. While he had been sleeping all day, I was joining forums for SOHC Hondas and watching videos. Learned that these bikes have a history of cracking intake boot rubbers causing massive air leaks among other things. I mean it's a 43 year old bike. I suspect he has an air leak, easy to find, easy to fix. But he ran the bike all the way back home and now I see oil at the head gasket flange. I haven't told him yet that I think he blew the head gasket. He was in no mood to listen. So, I told him to chill out and when he's calm to contact me. We need to talk about the bike and his attitude going forward. I see 3 choices. 1. Sell the bike at a loss 2. Take it to a shop specializing in old stuff 3. Stick to the original plan, take things apart, make them good and learn a shit ton of things. His major flaw is he is incredibly impatient, when he want's something he just gets it. He's bad at listening to advice until it's too late. So, I'm in a holding pattern until I hear from him. I believe the bike has a good foundation and can be made into a very nice ride.
Idle: When USED becomes the topic, it reverts back to your first step before you put a dime in the vehicle. Hi, I came here to buy your bike/car/lawnmower/blower, but I'm going to help both of us by taking a compression test. Why? I'm going to raise a carb slide to compensate for a low compression cylinder. Oh shit the idle won't come down. 1. Set valves first. Why? Strange bike. Two ways to check, but practice your strokes so you are not 180° out of time. So watch the intake valve go down, and when it comes up, you then look thru the plug hole to see the piston come up to TDC (top dead center) and check both intake and exhaust rocker arms for up and down movement. A tight valve keeps the valve open is why you check or get a false reading at the comp test. 2. Compression test second. The percentage drop between cylinders shows a bad valve(s) to a head gasket leak. Say 10% drop between cylinders is extending the borderline. Say 15% between cylinders is rebuild time. Say 100psi at the gauge is a runner but don't expect much in; hard starting; power loss; runs rich. 3. Rebuilding a classic's compression to run is money wasted. Back in the day the metallurgy was soft material pounding each other out of spec. Guide wear means oil sucked thru the clearances so one down is to replace those. Next part is replace the valves with new. Last is hoping cutting new seats, the valve does not walk up the head and you no longer have the tappet hitting the valve but you screwed that almost out the rocker arm, are new seats replaced in the head.
Sticking brake is caused by the water in the brake oil. Water is heavier than oil so it drops to the bottom where the "quad" seal lives. This quad keeps the oil from leaking out the caliper or piston. So the 4 sides; seal the piston diameter is one, the other is the groove it sits in; is machined flat on those three sides is the groove. The water turns into a white crystal chunky type powder. You're suppose to replace these quads on teardown, but if you rub the powder off, does not leak when reused... especially when it's NA [no longer available]... you are stuck being very careful with the part. Next is to use vinegar and dip the caliper so that crust is chemically removed. The roughest tool used inside that machined smooth finish is a used toothbrush and paper towels. Take the clean caliper out and into the sunlight. There is an angle of ray where that groove is going to show where you missed removing the white powder build in the groove. Theory: Quad remains flat in the groove [] without brakes applied. Lever pulled, the piston moves out, the quad looks like this // under pressure. The brake lever is released, the quad moves the piston away from the disc and the quad goes back to memory []. With the crystal build under the quad, the rubber remains in this // angle > dragging on the disc. One more problem solved.
super high idle, dying off choke, getting hot etc.
Let's say the compression is decent and it's fuel related, not sync related. Idle hang is when the slide is shut closed, the idle comes down eventually. This is where the vac is sucking gobs of gas before the rpm comes down and passes that vac's pull over that hole of 3. Meaning, main jet, low jet, idle screw hole. The dying off choke says a closed jetting circuit hole(s). The getting hot is [sometimes] a retard ignition, to boiling so much of that gas ratio, it heats the engine up as if retarded. So a classic sitter with gas left in the carb bowl is to choke the jet hole that is least closed, to pull that circuit of the only gas traveling thru that one hole, not all circuits open to 'blend' the correct ratio. Close the choke arm and more air than gas enters and it stalls. When warm the idle is set so high so as not to stall the engine.
We need to talk about the bike and his attitude going forward.
The mind has to enjoy the challenge. The wallet has no lips; if you throw more money at it than it's worth.
I see 3 choices. 1. Sell the bike at a loss 2. Take it to a shop specializing in old stuff 3. Stick to the original plan, take things apart, make them good and learn a shit ton of things
1. Hard decision. I just bought a can of carb dip. NAPA is cheaper than a-zone. Flash your aaa card and get it cheaper still. I tried the vinegar trick for a few days soaking. It's a single cylinder flat slide carb. New main and low jet installed. It was hard starting, needed the choke to run, had the idle set high, the idle would hang, then come down to an idle and stall. Dipped the body in the can of carb dip, and let it sit while I broke for lunch. Put it all together, started it and ran the idle down when all was warmed up. I told my buddy that it was better he started it cold, so when he came to pick it up, it took him 3 kicks and it idled off choke so fast, I said nothing about pushing the choke in. What a difference using that dip. Lesson learned.
Remember, rubber has to be removed using the dip or vinegar; either way or it swells. So the tubes between carbs have orings to transfer gas to the other carb is one; the float needle may be rubber tipped too. The idle screw might have an oring or not. If they are all metal, then dip the carb bodies in the can as an assembly. Wash the one half bank, and flip the other two in the dip. Keep the jets in place, the float too... once you know the needles are steel tipped. The idle is now repaired. If you're helping and can take the carbs apart then no problem. Tell me the letter/number of the carb somewhere on the body, I may have a spec book page on the bike. Data like valve lash, float level, how many turns out on the body screw, etc.
2. No. This sounds like a few hours work. The shop will just let it sit in a corner, and when they have time for it... we'll call you after the season rush. If they know their shit, they walk out with a single cylinder comp on a comp basis, letting you know if it's worth even throwing their time at it. And their hourly rate to stay open is what, $90-$100? One day's work is $700 worth of hours thrown at it? See where this is a home project kind of bike? Shit is too easy where I'm sitting.
3. Now we're talking. It's not going to be that hard looking back. These puppies were/are bulletproof. No recalls, nothing. Rubber carb boot wise, smash some goop glue down the cracks. Shrunk orings between head and carb boot? Cut rubber orings the size of the groove, cut the ends of the rubber ring so each end is sliced at this / angle so they lay over each other and goop glue them in between the slice anshit. Take a hair dryer and heat the rubber boots before you tag team pushing the carb body back in place. Some ut vid has someone softening up the boots. Search carb boots or something like that. If those boots use allen heads, you may not be able to whack them with that tool you hammer the phillips tip with. Ruin that X in the head at those boots, used is fucked. Either pull the engine or goop glue around the boot and head. Goop can take the heat.
Shit, I remember pulling these of the crate, assemble them, get em 'wet' and taking them around the block. One time without trying, the back tire lit; it was so greasy back in those days. I almost lost it is why I remember these when they first came out.
Tormenting the motorcycling community one post at a time
Hub good points. Like I said , he was impatient and we weren't in a position for a compression, carb investigation. It ran good all the way home. What changed between then and the next morning I'm not sure yet. And you are correct about taking it to a shop. There are a couple of shops around here that specialize in bikes like this and do good work. If he is going to continue to melt down when things go wrong, then even several thousand dollars to have a good running machine are worth it. I am all for diving into this bike. After all, that was his reason for buying an old machine. He will learn a lot, and once complete he will be comfortable dealing with whatever comes up. Plus he can build it exactly the way he wants it. But if his impatience and temper make it a miserable experience, he should just cut and run now.
Also, the carbs were stripped and completely rebuilt and synced right before he bought it. I don't know yet if they changed the intake boots. Haven't inspected the points or whether it has an electronic ignition conversion in it. Haven't checked the ignition timing which I know is important on these bikes. It does have brand new spark plug leads and plugs.
I can relate but could it be universal? I had a trickle of frustration, known to throw things at one time. I grew past it and began to appreciate the whole experience. Where I think it's theory that begins the tantrums. You're so puzzled throwing whatever you know at it. I usually walk away from it and come back a day later. The hindsight looks you straight in the face and on to the next practice in the art of... 'It only goes together one way'. Theory comes later where the abstract of 3 variables is all you need is fuel/spark/compression.
Well, you can run the quickies at it. Pop the points cover and see if the advancer can moved with your fingers. Spray the rubber boots with brake clean near the head and see if it stalls. You'd hear the valves tick if they were tight. And then back to basics is to check valves, compression, before you attempt the sync. The heads would seep due to the gaskets. Leak on the ground is a gasket change; weep/seep after a few hundred miles is let it ride. Very common for the product and its era of models by said brand.
Tormenting the motorcycling community one post at a time
I usually walk away from it and come back a day later.
This is the best lesson learned I always tell younger engineers, usually comes to you later that night or the next day. There is a bunch of theory on intuitive thinking that has demonstrated this technique helps in solving complex problems.
Very wise you both are!
Perfectly Set up '06 dead and gone New BBW '14 14R
Well, haven't heard from him yet. I am planning on locating the possible air leak along with checking the ignition components and timing as a first step. But I guess if he never calls me I won't have to worry about any of that.
