Topic: 75 CB550F -- "It burns less gas than my car, so let's get it running" project

[knochgoon24]

I'm Wes. Currently a Senior at PSU majoring in Aerospace Engineering. Picked this up from a friend that is moving to Texas. You guys almost lost me to the Suzuki GS crowd until he offered this to me for $250. Figured the deal was too good to pass up.

[knochgoon24]

The good:
-It was pretty cheap
-It was (almost) complete
-He kept it in his garage
-Most of the parts that need replaced on a used bike were recently done

The bad:
-His friend rolled it into his porch. So the tach, gauge bracket, headlight bracket, and front fender needed replaced.
-The looks need some TLC.

More good news:
-All these parts were included. 


So I started putting things together, just to see if all the parts were there. I really haven't had a chance to get things cleaned up, but I did put a new battery in it and all the electronics work. I also did an oil change and checked the spark plugs. Bled the brakes and adjusted all cables.

The only part that seems to be missing is the petcock. He threw it away because it was leaking... oh well. Once I get that, I should be able to try firing it up.

I hope to be able to start riding this to work and class instead of driving my 97 Eagle Talon Tsi AWD. Parking is free for motorcycles on campus. The parking for them is actually closer to the door of my building than the handicap spots.

Here's how it sits. I've had it about 36 hours at this point.   

[lone*X]

Nice find at a really good price!  How long from the last time it ran (or ran into the porch)?  Too long may require a good carb cleaning.

[CafeDawg]

Man great deal and looks way better already.  The gas crunch and poor gas mileage of my 4Runner is one of the reasons I bought mine as well.
Good Luck
Respect
CD

[knochgoon24]

It rolled into the porch while it wasn't running. He lives on a pretty steep hill and it got damaged while moving it from the upper shed to the lower garage.

He said he had it running 2-3 years ago. The registration stickers and papers suggest it hasn't been on the road in 6 years. I'm going to try firing it up today to see if I need to pull the carbs and clean them. He said he drained the fuel from the whole system before he stored it.

I got some cleaning supplies, so I'm going to try and get all the dust off it today, too.


A few other small problems have crept up since I started looking at it closer.

-Brake master cylinder needs rebuilt
-Rear brake light cover is broken
-Neutral light switch isn't working
-Rear lights don't light up as running lights

Still trying to track down a petcock. I found a thread that suggests that a 75-76 CB750F petcock would also work, so that's good news.

[Bankerdanny]

I'd pull the carbs and clean them anyway. It's only medium pain in the ass (tip: use a hair drier to heat the carb-manifold connector rubbers to soften them up) but will pay dividends later.

[knochgoon24]

He took care of it. 

After I saw that, I ran fuel through the bowl until it came out clear.
The fuel line from the petcock to the right 2 carbs was clogged. Unplugged that and it fired right up and ran beautifully.

It does need the electrical system all checked over though. I'm not getting any charging.

I washed it and degreased the engine. And he called me and said that he probably has the cover for the right side too.

[Bankerdanny]

I get that same brown silt in my carbs too. I installed a Mr. gasket galss filter with replaceable element as a supplemental filter until I am confident that the last of the gunk is out of my tank. I have several hundred miles with it in place and no negative impact on how my bike runs.

[knochgoon24]

It looks like it might have come from the spring that holds the one jet in. It had some very very light surface rust on it.

[Bankerdanny]

My later carbs don't have that spring. It's from the tank. It is fine enough to get past the built in screen.

[knochgoon24]

Well I won a petcock off eBay for $23 shipped. Once that gets here, I'll be one step closer.

I need to start cleaning electrical connections here sometime, but I'm working 96 hours in an 8 day stretch right now. The bike will have to wait. I barely have time to eat and sleep.

[knochgoon24]

I think I found the electrical problem...


I think that's the connection that grounds the stator. It looks like someone used a household wire cap to attach a piece of 18ga wire where 14ga wire used to be. I guess it couldn't take the load, got hot, and caught fire. It got REALLY hot at some point. The brass terminal on the end had the zinc evaporate off the outside layer. I'll try to repair the wiring and see if the stator didn't get fried in the mess.

And for some reason, 4 different ground wires a soldered together right before that wire cap. Time to track down a wiring diagram and figure out what's up.

[knochgoon24]

Electrical problem... fixed.
Rear brake light switch... fixed.
Fuel tank... cleaned.
Petcock... installed.
Fuel lines... replaced.
Front brake... fixed.

Insurance... check.
Registration/Plates... check.

Permit.... tomorrow.


I've now had 3 people come up and talk to me while I was working on it outside in the parking lot. They've all had stories about how they used to have an old Honda like mine and how they loved it so much. I talked to one guy for a good 30 min before he went back to helping someone move a few buildings down. When he heard me fire it up an hour later, he pretty much came running back down the parking lot to check it out.

Oh, and I picked up some side covers from Pain. It will be looking pretty sharp once those get here.

I would have taken some updated photos, but a surprise afternoon shower decided to roll through. It needed rinsed off anyway.

[knochgoon24]

Went to the DMV and got my permit this morning. Figured that I'd take the 550 out to a local parking lot to practice for a while. Well I got about 1 mile into the trip before I started having problems.

It wanted to bog out really bad. I had to start revving it to 3.5k and gingerly slipping the clutch to keep it from wanting to stall when starting from a stop. So I turned around, got it home, and the carbs are now off to be checked out.

Also, one of the floats seems to be leaking and I'm spilling quite a bit of gas, so I'll be checking that out too.



UPDATE:
I feel like a fool. After getting the carbs off (there has to be an easier way than what I did) I realized that the one hose had a weak spot and wanted to collapse. So basically what was happening was that everytime I gave it some throttle, I had 2 cylinders dying on me from fuel starvation.

The carbs look really really clean inside though.

[jacquesleclochard]

I've now had 3 people come up and talk to me while I was working on it outside in the parking lot. They've all had stories about how they used to have an old Honda like mine and how they loved it so much. I talked to one guy for a good 30 min before he went back to helping someone move a few buildings down. When he heard me fire it up an hour later, he pretty much came running back down the parking lot to check it out.

That's great. I love it when that happens. Glad to have you on board!

[knochgoon24]

Well, while putting the carbs back on, I spotted another section of bare wiring. I thought it was just a little 2" long section that may have chaffed against the frame.

Wrong. It's the ground wire that runs from a fuse box all the way up to the ground point on the frame near the coils. It was toast the whole way.

So this is the fun I had yesterday. I got that all fixed, but now the high beam isn't working again.

[knochgoon24]

Well, the problem I'm having with the high beam has been traced back to the starter button. The low beam still worked because the same guy that did all the other crappy electrical work also ran a wire from the fuse box directly to the low beam power wire inside the headlight. And since this is a '75, the switch is that plastic style. I tore apart the right hand controls and the little switch is cracked. I guess the connection to make the starter start is good, but the headlight circuit is weak. It worked while I had the switch soaked in electrical parts cleaner.

[knochgoon24]

First photo is what's left of the starter switch.

The other photos show the fix. I replaced it with a switch from Radioshack. I had to use a file on the switch to make it a little bit narrower. It's a very snug fit.
There's a little black button cover that goes over that peg and makes it look alright. Doesn't look like a hack job at all, actually.

All the electronics work much better now that the wiring is fixed.

[knochgoon24]

Got the new side covers in the mail.

For now, the tank is just going to have to stay dented. It adds character.  Otherwise, there isn't too much more to fix.

[knochgoon24]

Guess it's time for an update.

I got the bike all together and running for about 5 months. Ran great and I put almost 3000 miles on it in the short time I had it in condition to ride.



But as time went on, a knocking sound started to develop. Adjusting the valve lash didn't fix it, and it sounded like it was coming from the bottom end. I suspected a shot rod bearing.

So in November, I started the tear-down, expecting the worst.








No noticeable play in any of the bearings. No metal in the oil pan. No signs of any wear anywhere.

At this point, the only things I think could have been making the noise are the primary chain or the cam chain. Both were worn, but not enough to contact anywhere inside the case.


And the kicker. This is the frame, front fork, both fenders, and both wheels all in my little hatchback ready to be transported to my parents' place for winter storage while I rebuild the motor.



So while I'm in here, anything else I should do? The hone marks are still visible on the cylinder walls. I figured I'd clean up the piston tops, rehone the cylinders, and put some new rings in it.

I'm going to replace the rubber carb to head boots with silicone couplers. And the intake to carb boots with silicone couplers and aluminum velocity stacks inside the stock plastic air box.

While everything is apart, I'll be repainting the frame, replacing all the engine bolts with socket cap bolts, and installing new throttle, speedo, and clutch cables.

[SHELLFISH]

Nice looking bike and good luck with the rebuild!

[Greggo]

Just wondering...why put metal stacks inside the plastic box?  Good work so far!

[Greggo]

BTW, that knocking could have also been the 'clutch rattle' if it was loudest with the clutch lever released.  Be sure to sync the carbs when you put it back together - it can make a huge difference with smoothness/noises.

[knochgoon24]

It's been almost a year and a half, but I finally have the time, and possibly enough money to get this back into riding condition again. I've since graduated, failed to find a job in my field, and decided to go back to school and pick up an mechanical engineering degree. Just one more year of classes. Apparently, most of the jobs I'm interested in are more mechanical than aero. Wish I knew that 6 years ago... Anyway...

I've spent all that time, lurking on here, eying up builds, and trying to figure out what I can do to get this back together. Unfortunately, I need to play the budget vs. reliability game. So I've spent many many hours trying to figure out what parts would be fine to reuse, and what parts should be replaced, just because I have the case split.

The biggest breakthrough has been stumbling on the thread(s) about using a 650 primary tensioner in a 550 case. I knew I'd need to replace the primary chain, but $150 for a new OEM chain is a bit steep. Everyone points to the lack of a tensioner as one of the weak points of this motor. I sourced an oil pan, pickup, and tensioner off eBay for $70 shipped. All the parts are from an 81 CB650. I found a lightly used chain for $29 shipped on there, too. It's off a CB400 with less than 4,500 miles, and it looks brand new. All of it is on the way, ETA May 14th-24th.

My next big decision is about gaskets.

I found the same kit that DSS sells, but already stateside, for $87.  So I'll probably go that way, but what should I do about the oil seals. This motor has almost 35,000 miles on it, so replacing ALL the seals is a must, IMHO. Where to source these?


In fun news, I picked up a buffer at Harbor Freight, and some more wheels and compounds from a local hardware store. It's not a professional finish, but it's enough for me.  Photos soon.

I also bought 150' of wire in a variety of colors. Plans are to rebuild the whole wiring harness with new stuff. I'll run a few automotive relays to keep from running as much power through the starter button and ignition switches. I also plan on switching to a modern fuse panel with ATM fuses. The contacts in my current panel are damaged from the previous owner using stuff, other than fuses, to complete the circuits. I'll probably go with Weatherpak connectors since I've used these on my car with success.

For the most part, everything after that would purely be cosmetic, and could be done at another time.