1975 cb550... it's gonna take some time, and $$$$

jmemmert

Active Member
I sold my ducati monster two days ago, and decided I wanted to take some of the profit and find something different. My neighbor had a 1975 cb550 that he hasn't ridden in a few years.

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It's ugly, but $400 seemed fair.

What's good about it? Well...... It's got new tires! :)

Bad? it has lowish compression, rusty everywhere, side engine covers rashed, forks leak, rims rusted. Carbs need rebuilt.


I plan to go all out with it. Either a Benjies fiberglass Armadillo or dolphin set, or maybe a roc city cr style alloy tank. Obviously freshen up the engine, or find a good runner somewhere else. clean and paint everything. and who knows what else. Anybody got any Ideas or advice for me?
 

PHeller

Coast to Coast
Thanks, makes my bike sound like a deal! (CB400F)

First thing I'd do is squirt some ATF in the cylinders and let it soak for a day or so. That'll loosen up the rings. Not too much now or you'll have to drain the oil immediately. You want it to burn off real quick.

New sparks plugs and new gas. Put a filter on the fuel line/s.

Pull the carb, clean it out as best you can, check the condition of the diaphragms and floats. Make sure the pilot jets are clear. Once you've made sure they are clear....spray them some more.

For your first start, all you really need is pilot jets and good spark. Even on low compression, torn diaphrams, clogged main jets, leaky float bowl seals, and numerous other issues; you should still should get something.

Once you know it runs/idles, than you can tear everything back apart to start replacing worn/broken things.
 

SheepishLion

New Member
Not to jack the thread, but what does the ATF fix? The lowish compression?

Also, is that a German shorthair pup in the bike pic?

JoeN
 

PHeller

Coast to Coast
I had always heard that ATF can loosen up the piston rings, but will burn off faster than conventional motor oil. Some say that it also can break down some of the carbon build up on valves and pistons as its starts to burn, similar to SeaFoam treatment. However, like I said, you want to use a very small amount. Basically just enough to cover the top of the piston and get to the rings.

I've heard of some people turning the engine over a few times with the spark plugs removed to blow the excess ATF out of the engine.

ATF will pretty much destroy the viscosity of motor oil, so its not good for the bearings of the engine once it has made it past the rings. YOU MUST CHANGE THE OIL AFTER THIS TREATMENT.

FYI this is pretty much standard treatment on rotary engines that haven't run in awhile.
 

jmemmert

Active Member
SheepishLion said:
Also, is that a German shorthair pup in the bike pic?

JoeN

yep, a german shorthair that dosn't point worth a darn. A great pet though!

I've got evidence that it's sucked dirt, rather than take the time to rebuild, I've sourced a good running engine for $400 with 13000 miles on it.
 

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