Author Topic: 76 CB550F - The "as money allows" build thread  (Read 6984 times)

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Offline Mighty550

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Re: 76 CB550F - The "as money allows" build thread
« Reply #25 on: April 20, 2012, 04:35:19 am »
So after quite a bit of work, it seems like she is about an hour or two of tuning away from running as well as I can get it to. I replaced the points and condensers, reset the timing, adjusted the valves, cleaned, cleaned, and re-cleaned every crevice of the carbs, ditched the airbox for pods (I know, I know, but i like them) went up to a 110 main jet, and have the pilot screw turned 3/4 out.  Its pretty close, need to sync the carbs and get the screws set just right and I will be totally happy!  Now I can concentrate on getting rid of that ugly seat!!!

Offline Mighty550

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Re: 76 CB550F - The "as money allows" build thread
« Reply #26 on: April 20, 2012, 04:52:38 am »
Quick pic, and its amazing how much better those pipes look after they met Mr. Chopsaw!!


Offline db22

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Re: 76 CB550F - The "as money allows" build thread
« Reply #27 on: April 22, 2012, 02:14:44 pm »
Lookin' good.  Did you change your slow jets?  I went from the stock 38s to 40s when I installed pods on my '75 CB550K, am still fiddling with the air screw settings; currently set at 1.5 turns.  Did you adjust the float height? 

Your misfiring cylinder reminds me of a problem I encounter fairly regularly.  The float valves seem to want to stick in my carbs ('77 PD46A carbs on my '75 motor; who knows how they got there).  I have installed new float valves, polished the seats . . . they still stick.  This causes the bowl to overflow, and no fuel gets through to the cylinder.  Sometimes this is intermittent, as in one cylinder "misfiring", failing to run, as you are experiencing.  Sitting at idle seems to bring it on, as does leaving the bike on the side stand rather than the center stand.  The roadside remedy for this is to pull over someplace where you can set the bike on its center stand, and determine which cylinder/carb is not firing (touch the headers CAREFULLY, and watch your overflow lines for leaking fuel).  Close the petcock and drain that carb's bowl (mind the gas fumes; do this in the open air), close the drain and reopen the petcock, then watch the overflow tube.  If it pees gas, you're still stuck.  If it doesn't pee, start 'er up and see if you have gotten your cylinder back. 

At first I thought this might be related to possible sagging of the carbs -- with no airbox in place, they are supported by the rubber intakes and the cables only.  I make a carb support out of a couple of long zip ties, looped through the upper rear carb brackets, then over the frame.  You might consider trying this, if only to take the strain off your rubber intake boots.

Will be following your build -- good luck!
« Last Edit: April 22, 2012, 02:16:44 pm by db22 »
1975 CB550K (rider)
1975 CB550K (shaping up, slowly)
I may be goin' to hell in a bucket, but at least I'm enjoyin' the ride. . .

Offline Mighty550

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Re: 76 CB550F - The "as money allows" build thread
« Reply #28 on: April 23, 2012, 05:05:41 am »
I think (at least i hope) my misfire is a thing of the past.  I had it sitting at idle for about 5 minutes or so the other day, fiddling with the screws and all 4 headers were hot.  I did notice though, after i shut it off, about 5 minutes later, a little bit of gas pissed out of the overflow tube, just saw it out of the corner of my eye, not sure which carb it came from.  I had it on the center stand.  I will have to keep an eye on it.

I didnt change the slow jets yet.  I kept going back and forth whether i should or shouldn't, I decided not to yet, and just adjust the screws and see if i can get where i need to be.  Once i get it out on the road i may change my mind.  I kept the stock float height too.

Offline Mighty550

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Re: 76 CB550F - The "as money allows" build thread
« Reply #29 on: April 26, 2012, 04:42:24 am »
Well, got the carbs synced last night, if you EVER have to do it, get that tool, I dont have one and after last night, I will be buying one.  Seems like 1 1/2 turns out with the pilot screws gives me the smoothest idle, which surprised me.  Took it out for a 5 minute ride and noticed a couple things.  First, the throttle sucks, I keep twisting it and it seems like i never get to full throttle.  My last bike was a '09 triumph bonneville so maybe I'm a bit spoiled from that.  Also, it seems that these bike are really loud, or at least mine it.  My exhaust is rather loud, and Im not that happy with it, but that will change eventually, but besides that, it seems like the engine is rather loud as well.  Is that normal or is there something wrong with my bike?

But man, it was a good feeling getting out for a quick trip around the block, cant wait to really get rocking on this project!

Offline OneWheelDrive

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Re: 76 CB550F - The "as money allows" build thread
« Reply #30 on: April 26, 2012, 11:38:45 am »
Well, got the carbs synced last night, if you EVER have to do it, get that tool, I dont have one and after last night, I will be buying one. 

What tool are you talking about?  I've used a trusty 8mm crescent wrench that I bent at a 90 degree angle.  Then you can stick a flathead through the open end, hold the adjustment where it needs to be and tighten the lock nut. 
1975 CB550 cafe
1971 CB500 stocker
2008 Ducati Hypermotard 1100S *sold*
1973 CB350F *sold*
1975 CB550K Project "Keeper" *sold*
2010 Ducati Monster S4RS *sold*
1976 CB360T *sold*
1974 CB550K *sold*
1973 CB750K *sold*
1978 CB550K *sold*
2007 Vespa LX150 *sold*

Offline Mighty550

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Re: 76 CB550F - The "as money allows" build thread
« Reply #31 on: April 26, 2012, 01:01:53 pm »
Well that would work too, I used just a straight cresent wrench and it was a huge pain.

I was talking about this tool though: http://www.z1enterprises.com/detail.aspx?ID=4532

Offline Mighty550

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Re: 76 CB550F - The "as money allows" build thread
« Reply #32 on: May 16, 2012, 04:41:46 am »
Well, its a slow go, but I am making progress in baby steps.  Just replaced the fork oil, the old stuff was black, and man does it stink.  I was going to put small spacers on top of the springs to cut down on the sag of the stock springs, but the ones I made were like 1/32 too large, so I said the hell with it.  I will just get progressive springs later down the road.

I also decided to tackle the seat.  The big, king/queen seat i have i just hated, and spending over $100 for a seat that I will probably just get rid of when i take this bike from a simple rider to a full on cafe in the next year just doesnt seem like a good use of money.  So, 3 hours, $30, and a good bread knife later, here is what I ended up with.  Its not professional by any means, but it works, and its better then that huge thing.  Now I just need to figure out my hard starting issue.  Im thinking its float height, could I be right??