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CB550F2 another cafe racer project

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Topcat:
Hi All,

This is the first project I've been worked on and if I'm being honest, the first bike I've actually done any work on at all (thinking I've bitten off more than I can chew at times).

Its been a while since my introduction post, and a couple of questions on the forum as I've had some pretty busy few months with family things so I haven't been able to work on the bike much at all, but thought I'd give a run down of where I am and problems I've got at the moment and perhaps throw up some pics and a quick video of the bike idling (some advice on this would be welcome).

Here is the bike as I picked it up, nice looking decent condition from my noobie view point at least, managed to get the bike up and running if a little clunky and it wouldn't idle at all.

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The carbs were pretty gummed up so first task was to strip and clean these, they were pretty bad, it was extremely difficult to disassemble and remove the jets and floats. a couple of the floats broke off during this process as they were seized solid as were the jets.

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Once I got these all removed I popped them in for an ultrasonic clean which is one noisy machine.

https://youtu.be/rODUkeJwIKM (video of the ultra sonic cleaner).
 
They came out pretty clean and then I rebuilt them with new jets (cheers to nurse julie on advice on where to buy jets), floats o rings etc.

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One of the slides was a bit damaged and I had to bodge it by sanding a pretty big burr.

The original bike was missing a number of pieces of the airbox and the airbox in general was falling apart so I decided for the moment I'll be running Pods (while I work on it) but will be putting velocity stacks on it eventually. So based on information I've seen here and on other forums I've jetted with 40 pilot jets and 115 main jets.

I've also noticed the solenoid for the starter is broken so will need to replace that (just waiting for the new one to arrive). So at the moment I'm kick starting the bike. After reattaching the carbs I must confess I did make a bit of a stupid error by not attaching the throttle cables and wondered why it wasn't starting :(

However now I've got the bike starting with full choke and sort of idling. It seems a bit clunky, originally it was only firing on 3 cylinders but threw in some new sparks and its firing on all 4. However when I close the choke the engine revs go up quite significantly and won't come back down.

Other problems I seem, the number 1 and 2 pipes are quite discoloured, 3-4 aren't discoloured at all, however this is the case from when I picked it up.

Also the bike seems to be running pretty hot with smoke coming off the pipes after idling for a few mins (I'm assuming this could be some oil that has leaked in the past but not really sure).

https://youtu.be/eShcfpoUhUY

Any help or pointers of where I start to look for these issues would be great.

Other bits and pieces, I'm stripping the bike down as I intend to get the frame blasted and powder coated, but wanted to get the engine at least running smoothly before getting to far in to the cosmetics.

I do plan on re doing all the electrical components as quite a lot of it appears to be either falling apart of held on with chewing gum.


Cheers
Topcat

MarkCR750:
I would strongly recommend that you fit an original air box or go straight to velocity stacks, it’s notoriously difficult to set up pods, I believe that this is because pods do not provide a smooth airflow into the carburettor, on the CB750 the standard air box contains 4 rubber velocity stacks, they weren’t put in there by Honda for fun, they straighten/smooth out the air as it enters the carbs, I don’t know if Honda use a similar set up on your bike but no doubt the air box has design features that smooth flow, you’ll probably save yourself a lot of time if you go straight for a standard set up, good luck with your build.

mickwinf:
that number one exhaust has been seriously hot at some time to be that blue! I would advise to go through all the normal servicing items first then re-visit the carbs. i too would recommend a standard air box and new rubber connectors as it sounds like it is running very weak. I have a used airbox and filter box if needed.

Topcat:
Cheers for the replies guys, I think its running extremely rich at the moment I assume due to the fact I'm mostly running with the choke on.

I popped out a spark plug just to check the state (these are brand new just been installed) they were a lot darker than in the picture (think this was after I got rid of some of the blackening)

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I'll pop my velocity stacks on it next to see how much of a difference that makes, I also might take a look at the air screw.

For the seriously hot front pipes, what would that normally indicate? exhaust valves? timing incorrect?

Cheers
Topcat

Trigger:
What are the plugs you are using ?

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