Topic: cb550 been setting a while (6 years) -- compression low?

[Hondawggie]

The engine starts and runs but it's been in storage 6 years and I set about doing a tune up.

Came to the compression test.   Since the exhaust system is out being cleaned I just did the compression test cold. 

Each cylinder was right around 100psi, +/- a few psi (less than 5 psi either side of 100).

Carb choke was not engaged.  And I opened the throttle fully.  And used the electric starter to turn it over until the gauge stopped increasing.

I actually ran the bike once around the block last week after pulling it out of storage so it has not run much after coming out of its hibernation.


I can do the 'warm' compression test and the 'oil-in-the-cylinder' test later -- the bike has around 22k miles.

For a cold compression test, is this reading low?

[joeyvans]

If you are using an automotive tester with a somewhat long rubber hose.... those numbers are probably normal.  I've been told that you should be more concerned that the numbers are all within 10% of each other.  I would imagine your numbers would come up with a warm test.  Then.... if you put some decent mileage on this summer... your numbers could come up even more.

I recently tested mine with an Actron automotive tester and was around 125-130 for my warm test (dry & wet).

As far as your question about normal numbers for a cold test... I can't help you.  Have never done a cold test.

[dusterdude]

You might have sticking rings too,ride the hell out of it and see if they improve

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[alacrity]

Put some sea foam in a tank of 91-gas and do the Italian tuneup... Ride it for at least 50 miles...

Then do a compression check again.

Dollar to donuts the compression gets better on all 4.

[Scott S]

 I don't think those are bad numbers. Tune it up and ride it.

[RevDoc]

On a cold test for an engine that has been sitting for years those numbers are fine. Do an oil & filter change,and follow the suggestion Alacrity gave you for the "Italian Tune-up". Run around the block a few times to get it up to op. temp. and then find some open road where you can redline it through the gears. Do that a few times and then see what an improvement you'll have.

[Hondawggie]

Sounds encouraging.  It had been sitting for a while when I bought it in 2010, 6 years ago, I'm not sure for how long, but it's encouraging that my numbers might be okay.


I'll do the oil/filter change and I'm also going to check valve adjustments.

I checked the points, one side, 1 and 4, was off; used a point file to clean 'em, set them to spec  (.04mm at TDC according to the Haynes manual).


ONE QUESTION.  I cannot find a circlip removal pliers with long enough bits to reach down and remove the front disc brake's master cylinder circlip. 

I've bought 2 different sets;  in the store I say "yep these are plenty long enough" but the plier jaws are getting in the way, I have already bought the rebuild kit for the master cylinder.

Anyone know of a tool that will reach down in there far enough?

[jonda500]

Can be teased out with an o-ring pick or a dental pick
John

[BomberMann650]

I checked the points, one side, 1 and 4, was off; used a point file to clean 'em, set them to spec  (.04mm at TDC according to the Haynes manual).

After doing points adjustments multiple times (in the shop and on the side of a busy highway)  I've found that doing the points timing "by the book/by the numbers" hasn't given me the greatest results.

It is a good baseline.  But fine tuning by "feel" is what I've found to give some pretty exciting results!

The method to time points by feel is buried somewhere in this forum.

[Hondawggie]

Can be teased out with an o-ring pick or a dental pick
John

There is some oxidation there -- I spent 1/2 hour tonight with several pointy tools and had no luck.

Having done several master cylinder rebuilds, this one is the toughest I've had.

Usually I can get the circlip to rotate in its groove.  This one?  won't budge.  It will not rotate, even with some significant force.

The piston moves fine in the bore -- just leaking a bit, the round rubber 'wiper' must be compromised due to being old/stiff.  But I expect the bore to be fine -- the master cylinder works, the front brake functions, it was just leaking out of the piston bore a little (not good for the paint on the bike).

So there is probably oxidation inside the groove that contains the circlip.

I've got it soaking overnight in penetrating oil.


I can only apply so much force on the circlip with any of the point tools I tried tonite.
But with a circlip pliers I could most probably apply enough force to get it out of the groove.

But both my circlip pliers have their pointed teeth or picks, whatever they're called -- just too short.

[Scott S]

 Just go to David Silver Spares and order a replacement master cylinder. Not much more than a rebuild kit and work awesome. Look original, too.

[Duanob]

You might have sticking rings too,ride the hell out of it and see if they improve

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+1 it's way more fun that tearing it apart, trust me. 

[Hondawggie]

I found on Amazon.com several 'long reach' snap ring pliers and ordered a couple for my tool chest.

My already-purchased master cylinder rebuild kit has a new snap ring, so.................
I busted out some righteous pointy tools and got the snap ring out. 

After removing the old master cylinder piston, the bore is smooth so I'm in good shape.
My purchase last week of the master cylinder rebuild kit was not for naught.

I'll need the 'long reach' snap ring pliers to install the new snap ring.

Righteous pointy tool set from Harbor Freight......