Author Topic: 76 CB550F - The "as money allows" build thread (Read 6982 times)

Mighty550 · « **on:** March 16, 2012, 12:14:24 pm »

So I just picked up a 76 CB550F that "runs" for $900. I thought it wasnt a bad deal, not a steal by any means, but not bad. PO did a lot of things to it that I wouldnt do, but to each his own. There is very little rust, and it starts right up, but it doesnt run right, cylinder 4 misfires. I am gonna do full tune up on it to get it running tip top this summer, then over the winter, as money allows, Im gonna tear it down and rebuild it as a cafe racer. I got plans, big plans!

New to this forum, but not to bikes, this is my 7th i think. Love these old bikes, Im sure i will have questions, and from what I've seen so far, everyone on here is more than happy to help. Here is how she sits right now.

brooze72 · « **Reply #1 on:** March 16, 2012, 12:30:22 pm »

Congrats & welcome, post your progress as it comes along, we love pictures! Oh, there's a place somewhere for that K/Q seat...but I'm sure you have plans

Mighty550 · « **Reply #2 on:** March 19, 2012, 05:56:13 am »

It was so nice yesterday that i decided to go ahead and check/set the valve clearances. I got all done, and was tightening the last tappet cover and... snap. I broke the threads right off the cover. Thankfully the broken threads came right out, but now I need one tappet cover. Anybody got an extra one lying around???

Mcwilliams570 · « **Reply #3 on:** March 19, 2012, 06:01:03 am »

Hello mighty I might have one laying around or can take off a engine I have that sitting around. I see you are also not too far away from me..

Matt

Mighty550 · « **Reply #4 on:** March 19, 2012, 10:07:04 am »

No, no too far, about 2-3 hours or so. Let me know if you have one, and how much you want for it.

Mcwilliams570 · « **Reply #5 on:** March 19, 2012, 10:33:11 am »

Will just give it to you...PM your address and will send it out to you..

Matt

Mighty550 · « **Reply #6 on:** March 19, 2012, 11:07:36 am »

PM sent!

Tews19 · « **Reply #7 on:** March 19, 2012, 07:38:19 pm »

Welcome mighty! With your build, make sure you dont change the seat! You may not realize it now, but you will get all the looks!

Mighty550 · « **Reply #8 on:** March 20, 2012, 04:11:00 am »

haha, oh I know I will!

That thing is the first to go, followed quickly (hopefully) by that exhaust.

Just a little update, took off the carbs last night and fully cleaned them, man they were nasty. I was surprised that it started up and idled as well as it did. I think Im gonna try smoothing out the intake runners before I put the carbs back on. Anyone else done this? Any tricks to make it easier?

Mighty550 · « **Reply #9 on:** March 21, 2012, 05:12:09 pm »

somethings missing...

Got the carbs clean, gonna smooth out the insides of the intake runners and then reassemble.

Tews19 · « **Reply #10 on:** March 21, 2012, 07:28:14 pm »

Are you asking if somethings missing? Boots from the engine manifold to the carbs? Or the carbs themself?

Mighty550 · « **Reply #11 on:** March 22, 2012, 04:13:44 am »

No, I know whats missing, it was kind of a joke, a poor one at that I will admit.

Tews19 · « **Reply #12 on:** March 22, 2012, 10:29:45 am »

HA that was funny. Thought you were serious

Mighty550 · « **Reply #13 on:** March 23, 2012, 04:13:33 am »

So before I cleaned the carbs, my number 4 cylinder was misfiring, no much so that I could touch the pipes after it had been running for a few minutes. I cleaned they carbs (that one was a mess) and reinstalled last night. I didnt have a chance to sync them yet, but its still misfiring on cylinder 4. So far i've replaced the plugs, adjusted the valves (they sound much better now), cleaned the carbs, and smoothed out the inside of the intake runners. I still have to change out the points/condensers, and set the timing. Will this fix my misfire? This is what the plug looked like after a quick trip around the block last night (i checked, it has good spark)

Killer Canary · « **Reply #14 on:** March 23, 2012, 07:44:25 am »

Is it mis-firing through the whole rpm range?

Mighty550 · « **Reply #15 on:** March 23, 2012, 08:14:24 am »

Cant tell, it starts right up, seems like it idles fine but I can actually grab the header, while the others are flesh burning hot. After my ride around the block, i didnt want to touch it so i poured a bit of water on cylinder 3 header pipe, and it sizzled right off, on cylinder 4, the water just ran down it, so i am assuming its missing quite a bit, but not completely. At least i think.

Tews19 · « **Reply #16 on:** March 23, 2012, 09:18:29 am »

HMM, is the spark plug cap on tight? May want to trim the spark plug wire and reattach the cap then try...

Mighty550 · « **Reply #17 on:** March 23, 2012, 10:24:43 am »

If i pull the plug and attach it to the cap and try to start it, I get really good spark, so I dont think there's any issue with the plug/wire.

TMHackCB500 · « **Reply #18 on:** March 23, 2012, 10:59:47 am »

Is there any fuel getting to the number four carb? Have you checked compression? Was the #4 plug wet or dry when you pulled it? It sounds like that carb isn't getting gas or isn't getting it to the cylinder properly. I know you cleaned the carbs, when you did, did you break the rack apart and clean the fuel tees? Did you at least do a bench synch?

Mighty550 · « **Reply #19 on:** March 23, 2012, 11:21:15 am »

Didnt check compression, the plug was dry when i pulled it. I bench synched them, but I didnt check the fuel tees. If i unscrew the float bowl plug for that carb and gas comes out, its safe to assume that carb is getting fuel and the lines arent plugged right?

Mighty550 · « **Reply #20 on:** March 25, 2012, 12:39:48 pm »

the bowls are getting gas, and i just replaced the points and condensers. Working on getting the timing set correctly. Swapped the plug wires from 1 and 4. Cylinder 1 ran fine with #4 wire, and cylinder 4 still missed with #1 wire.

Greggo · « **Reply #21 on:** March 25, 2012, 12:52:03 pm »

Only need three things to make these engines run...compression, spark, and gas. If you've got good spark, you've either got plugged jets in your carbs still, or low compression, possibly due to worn rings, or valves not seating. I'd start with going through that #4 carb again.

Killer Canary · « **Reply #22 on:** March 25, 2012, 12:58:46 pm »

Possibly a leak in the intake boot?

Mighty550 · « **Reply #23 on:** March 26, 2012, 05:47:17 am »

I am praying that its not a compression issue, but I think my worst fears might become reality. Im gonna pull the carbs again and double check #4, making sure everything is clear. Then maybe Ill get a compression tester (harbor freight had them for $20 this past weekend). If its bad compression, does that mean the piston ring is shot? I've never dealt with a problem like that before. Can that be fixed without removing the engine from the frame?

Killer Canary · « **Reply #24 on:** March 26, 2012, 10:03:55 am »

Low compression is ring/piston/bore wear or valve wear. Now you can pat yourself on the back for getting a 550 and not a 750 because you can do top end work on a 550 with the engine in-frame.
Sounds like you're on the case; it WILL reward you soon!

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Author Topic: 76 CB550F - The "as money allows" build thread (Read 6982 times)