Topic: VIDEO: CB550 compression and leak down test

[bochnak]

I've worked on a few CB500/CB550's in the past few years and they all had low compression due to carbon build up on the valves.

Here is a 20min video I put together that takes both compression and leak down before and after a top end "refresh". The "refresh" consisted of disassembling the engine down to the cylinder base gasket (the head gasket was leaking as well). After it was disassembled, everything was soda blasted, piston ring end gap checked, valves lapped, cam tensioner inspected for cracks, and then resealed with new gaskets.

Compression and leak down video:

Before "refresh" compression was 117, 97, 140, and 140 psi. Cylinder #2 with 97psi had over 30% leakage! After, the compression jumped up to 150-170 per manual specs and leakage down to 4.5%.

Some pics:






So anyone working on bringing their CB back to life should definitely start by checking compression!

Let me know if you have any questions.

Thanks,
Matt

[Deltarider]

To decrease the chance of carbon build up on inlet valves I recommend good gasolines like Shell V-Power or BP Ultimate.

[yellowjacket]

Looks awesome.  I am exactly at the same spot.  78 CB550.  Lots of carbon build up.  Yours looks great, what did you clean it with?

[bochnak]

Looks awesome.  I am exactly at the same spot.  78 CB550.  Lots of carbon build up.  Yours looks great, what did you clean it with?

Oh man, the gaskets were a bear to clean up. I have never seen such stubborn gaskets in my life! I ended up soda blasting everything, including all gasket material. The soda cuts through carbon like butter. Worked great! I'm using a HF cabinet with armex soda @ 80psi.

You can see my setup pictured in this post:

https://www.howtomotorcyclerepair.com/dustdeputy/

[Duanob]

Vids are a great way to see how things are actually done instead of reading from pages. As long as its done correctly (referring to a certain vac sync vid that gets posted every now and then).

A little Berryman's goes a long way to clean up carbon deposits. I use it to clean the chambers, piston tops, etc. Also throw a bit in the gas tank every couple of fill-ups as well.

[strynboen]

a common problem 500 engine problem are weared valve shafts on erly types engines..it  give that, the valve adjusting fails after a fev rotations of the engine..it gives a big power loss..the problem vas gone in the later modells.with fixed shaft..so a refit of a k3 valve cower 77/78 fix all problems..

i did all the stuff you did...for 3 years ago..the engine runs perfekt,,,often no need for thange all parts...just the veared parts. and a good klean up..and you got a almost as new engine for low cost..importment is to get the camchain tensioner to fit perfekt in bottom..alvays take the oil sump aut by install and kontroll ot right fit..
a vaccum cyncro make the final thoutch..and make the engine to a seving machine

[bochnak]

Vids are a great way to see how things are actually done instead of reading from pages. As long as its done correctly (referring to a certain vac sync vid that gets posted every now and then).

A little Berryman's goes a long way to clean up carbon deposits. I use it to clean the chambers, piston tops, etc. Also throw a bit in the gas tank every couple of fill-ups as well.

I have a CB500 on my lift right now with low compression and oil leaks (head gasket, maybe the pucks, or both). I also have seafoam & berryman top end cleaning products. It would be interesting to see how much compression can be restored w/o taking the motor apart?

[colvinry]

Great vid! What's the YouTube link?


Sent from my iPhone using Tapatalk

[MandEms]

I just bought the 550 rebuild video.  It is really good.  Thanks.

[Duanob]

Vids are a great way to see how things are actually done instead of reading from pages. As long as its done correctly (referring to a certain vac sync vid that gets posted every now and then).

A little Berryman's goes a long way to clean up carbon deposits. I use it to clean the chambers, piston tops, etc. Also throw a bit in the gas tank every couple of fill-ups as well.

I have a CB500 on my lift right now with low compression and oil leaks (head gasket, maybe the pucks, or both). I also have seafoam & berryman top end cleaning products. It would be interesting to see how much compression can be restored w/o taking the motor apart?

Are you thinking running the product through the motor or removing the head? If oil leaks out the sides of the head or through the pucks you should probably remove the head and replace the HG and the orings at the oil passages. No big deal. soak the head in Berrymans and scrub with a nylon brush. You will be surprised how much crud comes off. Also soak the tops of the pistons. Replacing all the gaskets and rubber is a big help in renewing a SOHC4 motor. 

[bochnak]

I just bought the 550 rebuild video.  It is really good.  Thanks.

Much appreciated! Thanks!

[bochnak]

Vids are a great way to see how things are actually done instead of reading from pages. As long as its done correctly (referring to a certain vac sync vid that gets posted every now and then).

A little Berryman's goes a long way to clean up carbon deposits. I use it to clean the chambers, piston tops, etc. Also throw a bit in the gas tank every couple of fill-ups as well.

I have a CB500 on my lift right now with low compression and oil leaks (head gasket, maybe the pucks, or both). I also have seafoam & berryman top end cleaning products. It would be interesting to see how much compression can be restored w/o taking the motor apart?

Are you thinking running the product through the motor or removing the head? If oil leaks out the sides of the head or through the pucks you should probably remove the head and replace the HG and the orings at the oil passages. No big deal. soak the head in Berrymans and scrub with a nylon brush. You will be surprised how much crud comes off. Also soak the tops of the pistons. Replacing all the gaskets and rubber is a big help in renewing a SOHC4 motor.

I agree the HG needs to replaced along with everything else. The purpose of running product through the engine w/o disassembling is to see if it would work.

The CB500 on my lift has 30k on the clock and needs a ton of work all around. The owner may be looking at sourcing another motor as a project.

I use to soak & scrub parts in the past, that is until I found the power of soda blasting and ultrasonic cleaning!

[Duanob]

Soda blasting has some nice results. I guess it depends on how for your customer wants to get into this thing. @ 30K I might go in thinking of replacing the rings and checking the cylinder walls but after checking them first. My first 550 had a stuck ring. It smoked pretty bad at high RPMs but I just changed the oil, poured Berrymans into the plug holes and rode the piss out it. The ring finally let go, it never smoked a bit after that. Had plenty of power too. Later I replaced the head gasket mostly because of the oil leaks but it ran fine before that. The cylinder walls were in fine shape so I never even pulled the jugs. A lot of guys just start tearing into these motors  to rebuild them but most cases its not necessary.

[bochnak]

Soda blasting has some nice results. I guess it depends on how for your customer wants to get into this thing. @ 30K I might go in thinking of replacing the rings and checking the cylinder walls but after checking them first. My first 550 had a stuck ring. It smoked pretty bad at high RPMs but I just changed the oil, poured Berrymans into the plug holes and rode the piss out it. The ring finally let go, it never smoked a bit after that. Had plenty of power too. Later I replaced the head gasket mostly because of the oil leaks but it ran fine before that. The cylinder walls were in fine shape so I never even pulled the jugs. A lot of guys just start tearing into these motors  to rebuild them but most cases its not necessary.

Very true. The owner tinkers as well, so he may do the job himself. I have yet to determine where the leak actually is. I have some UV dye that I use to find those pesky leaks.

[Duanob]

You know just a thought: make sure the vent tube isn't kinked or plugged. That can force oil out of places its not supposed to.

UV dye? That's pretty high tech!

[rotortiller]

I'd take the differential tester with a grain of salt since it can lead to money poorly spent. Lots of factors to consider, especially for an engine sitting. Your engine can give low readings and still be serviceable. For example cylinder defects below TDC or below the rings are not monitored. A compression tester is the better choice supplemented by a power check on the road.  Valves can leak in a temporary manner. It is a tool to be used carefully and considerately. If I had a bike I'd drive it for a bit then evaluate. Not saying it can't evaluate a bad engine but it can also incorrectly evaluate a good or bad engine. Here is a interesting article: http://www.aviationpros.com/article/10388599/cylinder-differential-compression-testing-subject-to-interpretation
BTW, cool video.

rt

[Redline it]

I do have a question. I was going to build a leak down tester, looking at youtube videos arrangement of styles, I noticed one thing, the use of a regulator onto the tester was almost present. One of the compressors I have has a regulator, regulating pressure output. So theoretically I can use that regulator instead of adding another one to the leak down tester, right? Then just couple the restrictor to the reg, right? thanks. I hope one day I can get the patience to really use it. 

[strynboen]

yes you dont need 2 regulators.
..often there is 2 auttake on kompressors..one regulated ...and one direkt to tank.(..a long air line can give some problems..if pressure builds up in it,,so often ve use a regulator close /direkt on the air Tool)

[Redline it]

yes you dont need 2 regulators.
..often there is 2 auttake on kompressors..one regulated ...and one direkt to tank.(..a long air line can give some problems..if pressure builds up in it,,so often ve use a regulator close /direkt on the air Tool)

cool thanks!