CB550K1 - that Gulf bike

Ringo

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I took another stab at the cylinder studs, with a little hatred this time. I bent them over at the base which gave me some solid leverage, and most eventually twisted out this way. A handful snapped off, and I welded old studs onto the ends protruding from the block. Most took a few cycles of welding/breaking/welding to come loose, and two of them I had to just hold the TIG torch on them to get enough heat down in the threads to break the bond. But they all came out.
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Pistons got cleaned up and new rings installed. The cylinders got a light hone as well, while we’re on the subject.
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APE cyl studs and pistons in their places. I will say, using APE’s recommended torque of 20-22lbs when torquing down the head had my skin crawling a little. That feeling when you know you’re going too far…you’re amazed the threads are doing what they‘re asked by the torque wrench. Twelve of those feelings.
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Jugs installed
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Head and 650 cam in place.
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An interesting find in the oil pan. Sand. A fair amount of sand. This baffles me—there’s been no sand anywhere near this engine while it’s been open. Maybe carelessly removing the oil fill cap with debris stuck around it? But still, it’s a lot of sand for that. Oh well, cleaned out and moving on.
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Ringo

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The stock carbs are really just a clusterfuck, aren’t they? It has me thinking about alternatives. So I’m not going to do anything with them right now, I might not even install the new ITG filter—it’ll just get smashed against the frame down tubes.
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I hate to say it, but I think I’m going to go back to a stock sprocket cover. It works a little better with the bike, visually. Sorry Lee!
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And lastly I fitted a new Hindle exhaust. I’m still planning on making a stainless exhaust myself, but don’t have time this year. Still have to figure out an end can, and modify it a hair to clear the side stand mount.
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irk miller

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The stock carbs are really just a clusterfuck, aren’t they? It has me thinking about alternatives.
I run the dual carb setup for the 550 from Murray's Carbs. Twin Mikuni VM34. He ditched the welded intakes for cast intakes, so now they're a much better fit and finish. I love what the setup does for these inline fours, especially on the bottom end.
 

Ringo

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I run the dual carb setup for the 550 from Murray's Carbs. Twin Mikuni VM34. He ditched the welded intakes for cast intakes, so now they're a much better fit and finish. I love what the setup does for these inline fours, especially on the bottom end.
That’s a neat option. From the photos on his site, it looks like the 2-1 manifolds clamp on to the stock intake runners? How’s the throttle response with that? I’d like to shorten the runners anyways, whichever route I go, so I’ll probably fabricate them. There’s a couple cool setups with four vm26/28s over on sohc4…buuuut I just keep circling back to “why am I doing this to a slow old bike?”

I was just looking at prices on CR carbs. They’ve almost doubled since I last owned this thing!
 
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irk miller

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That’s a neat option. From the photos on his site, it looks like the 2-1 manifolds clamp on to the stock intake runners? How’s the throttle response with that? I’d like to shorten the runners anyways, whichever route I go, so I’ll probably fabricate them. There’s a couple cool setups with four vm26/28s over on sohc4…buuuut I just keep circling back to “why am I doing this to a slow old bike?”

I was just looking at prices on CR carbs. They’ve almost doubled since I last owned this thing!
Twin VM34s with a well tuned intake should get you a slight hp bump- maybe 2- 3hp, plus better low end torque. They're very happy cruising 55 - 60mph. It's a worthy argument to question the investment on a vintage bike, but to me just the ease of maintenance would be enough to consider the option. I absolutely despise the Keihin 4 carb racks from the 70s. Add in a better throttle experience for the VM and it's an easy decision for me. I've done it on 3 Honda inline 4 engines so far. I'll probably do it to most every one I build. If you can make your own intakes, that covers half the price. I love the performance of the VM and TM on the overhead cam engines.
 

john83

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I also had a Murrays dual Mikuni setup on a CB550 and loved it. So much easier to deal with, started on 1st kick every time and better bottom end throttle response. They're not cheap but my OEM carbs were pretty worn out and it was worth it to me to have something much easier to deal with.
 

Ringo

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Interesting, thanks, I’m going to look into this. Did you guys run pods, or make an air box? Did it alter the intake sound? Got any pics of the set ups?
 

irk miller

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I'm running UNI filters, which I prefer over most. I've also run them with the K&N oval filters.

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