Topic: 78 CB550 Project

[Beep Bop]

Cant seem to attach the photos so I've attached a Google Link to the 4 fuel levels :

https://goo.gl/photos/mVNQEE44i3WAMVRTA

[calj737]

1 is high
2 is perfect
3 is perfect
4 is high

[Beep Bop]

Okay, so I need to adjust 1 & 4.
In theory is this going to solve the leaning out issue or is this another beast altogether?

[calj737]

I would not characterize your issue at the moment as one of "leaning out". Starving for fuel, sure, that's more accurate.

I want to ask a question, but I am doing so very gently and respectfully: Are these carbs the very carbs rebuilt by James? I find it miraculous that they are that far out of adjustment having been in his hands. He is known for dead-on, perfectly rebuilt and factory spec carbs.

If these carbs weren't rebuilt by him, send them to him so he can properly rebuild them.

[Beep Bop]

Cal,

Thanks for the reply.

The carbs are 100% rebuilt by Harrisuluv/James and I have been reluctant to touch them in any way.
The reasoning here is that I understand there are only going to be more variables with getting the bike started if I have to worry about the carbs.
I agree and like to think that with James' work eliminates any questions of issues with the carbs.

With that in mind, i did try out some new rubber boots between the carbs and intake manifold and it does seem to have helped startup.
I let it run to the point it warmed up and a new issue emerged where it started backfiring - indicating ignition.
Other observations as it warmed up was that it would occasionally (once or twice) be able to start without choke.
The Revs would surge when throttle was applied.

I am waiting on a shipment of 78 airbox rubbers from Paul Gabor which I will put on this weekend and report on.

[Beep Bop]

Attached a video of her warmed up and idling.
What is the ideal idle speed for these? Also will it just be a case of tuning based on Idle Mixture screw?

If I try to rev it without choke on, it dies.

https://sohc4-forum-attachments.s3.amazonaws.com/VID-20170506-WA0009.mp4

[Beep Bop]

Well folks, she lives and is better than ever.
For anyone who is going through something similar I've come back to leave some feedback.

Turns out it was very much a case of needing a top end rebuild, Cyl. 4 needed new rings and a new piston as it was only holding compression when wet.
New set of rings and now she runs sweet.
Theory on how this happened was that the PO had destroyed the threads on the sparkplug for cyl4.
Letting the bike get exposed to the elements and rain corroded out was left of the rings.

I was fortunate that the cylinder walls were some how in great shape and only needed a hone.

Anyway, hope this helps. Glad after nearly 2 years I now get to ride.

Other things that got done since the last update, forks have been rebuilt, cleaned up the electrics, front and rear brakes including BMC rebuilt and fixed up the turn signals and rear brake lights.