First project- '75 CB550 beater in Orlando

cbertels

New Member
Hello everyone,

I'm a long-time lurker and just joined up. I've built and restored a number of classic cars but I'm new motorcycles. I'd love to meet up with some other members and learn as much as I can from all the knowledge here on the forums.

I recently acquired a '75 CB550 project another guy had started a cafe' build with but didn't really finish. Its in good shape overall but definitely needs some work to get it to level I expect. Any suggestions on where to start, it would be appreciated. I'm currently trying to get it running right and stopping properly. Given all the prior owners mods, I'm still figuring out whats still CB550 and whats aftermarket, modified, donor parts, etc. A lot of stuff has been done already that is frowned upon here (160 rear tire, knee dents, terrible welds, etc.) that will need looked over too. Overall, the dirt cheap price may make it worth while.

I welcome anyone interested in coming by to swing wrenches or have a few beers anytime. I'll start a proper build thread when the tedious stuff is finished and the build begins in earnest.
 

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Welcome in mate ;) sure lots ya can do with these Honda's and plenty of room to put your own spin on things colours /style seat etc :p just get it running well n stopping shouldn't have trouble with those non stock twin rotors on the front :eek: always here for Q&A's :p
 
Loctite77 said:
What is going on with the shifter linkage there? That looks kinda ghetto.


Yeah Son!

That shift linkage is SO ghetto. Its two pieces of steel poorly welded together. It broke while attempting to shift with my hand.
 
After a new battery and some wiring corrections, I've got in running, albeit terribly. It only runs with a wide-open throttle, idling at about 2k. Let off the throttle and it dies immediately. :eek:

Per the prior owner, "The short block is original and in wonderful condition. The head i had ported and installed new in/ex valves and dual valve springs with new seals and retainers. I also installed larger jets due to the increased air flow. It is also running a new electronic dyna ignition with new wires and plugs."

Next step is going to be to pull the carbs and sort through them. A rebuild may be needed. Without the stock airbag and original exhaust, its going to be a batter to get it tuned and running even somewhere close I think. Thoughts on where I should begin?
 
Pulled the carbs off today as well as the in-line fuel filters. The filters have what looks like a ton of rust in them. I pulled one of carbs apart and the gas that came out was VERY brown. The seals and gaskets looked like a rebuild was done not long ago.

I've drained the tank and gas didn't look great there either. Looks like I'll either need to clean and seal it or look for a new one. Given the prior owner doing the less than even knee dents in the tank, I'm not sure which route I want to take. Any suggestions?

Given the rust, should I go ahead and do a full rebuild or would running some new gas through them be enough?
 
I'd just shoot carb cleaner spray through the jets if the gaskets etc look good. Sounds like the problem is in the tank.
 
So I pulled the carbs apart and found tons of rust and dirt in all the passages. I've soaked them in a mild cleaner. and dropped the bodies off to get powder coated and will have the hardware zinc plated. I'm currently waiting on a jet kit. I noticed that the carbs had different sized jets between them, which I thought was weird. Likely makes syncing them impossible.

While thats going on, I'm tackling the rear brake. The wheel has been swapped with a wider wheel and disc, from Harley I think. The swing arm is from something else I believe, maybe a CB750. What I hadn't noticed is the rear caliper bracket doesn't fit AT ALL all and is just resting on old mount.

Any ideas on whether I can snag a factory mount (CB750, HD) or if I'll have to fab something?
 
Here are the photos of the bracket.
 

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Got all my carb stuff back from plating/powder coating and the look AMAZING! I got them assembled and bench-synced according to all the great tips on this site. It fired up pretty quickly but I thought it was running rough. Fuel is misting out the intake side as well. Cylinder 1 and 3 are not firing. The exhaust was significantly cooler as well. I pulled the plugs and they were a bit damp and no soot. Cylinders 2-4 are running VERY rich and soot build up on the plugs after only a few minutes of running.

I pulled the float bowl drains and fuel came out in equal amounts from all carbs so fuel is getting to them. The plugs are all getting spark when turning the engine over with the kick, so I don't believe it to be a spark issue. Really only leaves a carb issue but I can't seem to track it down.

Any thoughts??
 

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Guess you know why the carbs were jetted differently. Have you done a compression test?

I'm not far from you up in Daytona, once I pick up my project I'll have to hit you up!
 
I would give the motor a complete once over. Change the oil, check and set ignition timing, fit new plugs and do a compression test. And I'd start with the compression test.
 
teazer said:
I would give the motor a complete once over. Change the oil, check and set ignition timing, fit new plugs and do a compression test. And I'd start with the compression test.


What Teazer said, plus, regardless of what the PO says, I'd look at the valve clearances too.
 
Thanks for the input everyone! :) :) I attempted to check compression but keep getting inconsistent results. The tool I have is for VW air-cooled stuff and isn't fitting the bike too well. I'm gonna snag something that works a bit better. I checked the valve clearances and only a couple were off, and by a fractional amount. It was real tough to check those with std. feeler gauges so I'm gonna pick up some bike specific ones I've been recommended as well.

I changed the oil and plugs right after I picked it up. The oil looked good after running it through a strainer and the plugs that were in it were brand new so no clues there.

I'm fighting a cold thats going around the house so work is slow. While I realize all the issues still point to carb issues, I can't help but think something electrical is going on. Its got Accel coils and the Dyna S ignition installed from the PO. The wiring has been butchered and I've been debating scrapping it all and redoing it. The diagnosis work on this thing is getting real old.
 
Well the bike has been on the back burner for a couple weeks. Got back into itwith fresh eyes. Went through the ignition system and was wired correctly, although the quality wasn't great. Replaced some wiring and cleaned the rest up. Set the timing and put in new plugs. Still no change.

Checked the compression and 1-3 had almost none, while 2-4 were 80-90ish. Not promising. The prior owner said some "headwork" had been done by the guy he got it from, which is likely the issue. I'm going to check the valves for proper adjustment hoping that is the issue. If not, I'm betting its got worn rings/cylinders.

As always, any thoughts or suggestions are appreciated.
 
Honestly, I don't know if it does or not. I've been chasing engine gremlins and haven't gotten too far beyond that.

After checking the valves, most were WAY too tight and I couldn't even get my smallest feeler gauge in there. I was hoping this was the issue. I adjusted all valves, kicked it a few and rechecked. Checked compression again and no change. Oh well, it looks like I'll be tearing the top end off.

I'm torn between having the head checked out vs simply getting a new one given the PO's claimed P&P job and valve/spring upgrades on it.

In terms of pistons/cylinders, I'm hoping I can simply hone the cylinders and replace the rings on the stock pistons. Hoping to avoid boring and new pistons. Any thoughts?
 
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