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Discussion Starter · #1 ·
First of all, a big hello to everyone one on the forum.
I've been rebuilding a CB750 for over two years now and have recently purchased a "quick project bike".

I believe its a '74 CB200, engine no. CB200E-1023XXX

After removal of the engine, the first problem I face is a free spinning Sump/Oil Bolt.
Is this common?
Whats the best method for removal?
(I though perhaps attempting to weld a T-Bar to the bolt head and pull whilst twisting.)

Once removed, is there a simple fix?



Frame, which I plan to have Sandblasted and Powder Coated Gloss Black.


A bit of work ahead, engine currently does not turn over...

 

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Hey looks better then mine when I started! Do you mean removal of the centrifugal oil filter?

[attachment=0:eek:5thv6mw]IMG_2038.JPG[/attachment:eek:5thv6mw]

I tried the bolt method but ended up using a screwdriver in the holes you can see inside the cap. Just had to wrench on it until it started moving. The o-ring inside mine had hardened and the alloy cap had bound itself to the 'cup/cylinder' mainly from corrosion... took a while to get it out, but got it out eventually!
 

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Discussion Starter · #4 ·
Thanks for the tip, I'm sure I'll look at the Oil Filter soon..

I actually mean the bolt on the base of the engine, used to drain oil when the engine is in the frame.
This is spinning, not coming loose or tight. Appears to have destroyed the thread.

Whilst I'm not looking forward to getting new cases, if it has to be done then so be it.

My primary concern is leaking oil everywhere during tear down.
 

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Discussion Starter · #5 ·
As I mentioned my engine is seized, I was unable to remove the head without taking drastic steps...
(Documented below).

As you can see, the pistons look to be pretty stuck...
Whats the best method for removal of the barrels/cylinder??
Its on very tight and I would prefer not to break fins, the manual does not cover much regarding this process.


After removal of the tensioner bolt I had to cut the primary chain, makes a good video!


The head removed...







Piston & Sleeve


Piston & Sleeve
 

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Discussion Starter · #6 ·
I got frustrated and decided to be nasty.
Went back the the garage and wacked the parts of the cylinder front and back where I'd do least amount of damage to the fins.

I've now confirmed why the engine was seized... One of the pistons is stuck in pretty tight, although I could have guessed that looking at the photos. (see earlier posts).

What is the best method for cylinder removal, "wacking" does not shift the stuck piston. :cry:


After a few good *WACKS*



Weapon of choice...
 

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You could also hang the engine a few inches over a pillow, suspended by the jugs. That way every time you whack it out of contempt, gravity will do the work for you.... :twisted:
 

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Since you have the jugs lifted a bit, you might be able to place wood shims between the cylinders and the case. Then use a soft drift (aluminum or brass) to drive down the stuck piston. If you can drive it down, you can then rotate the engine, letting the jug come up with the stuck piston. Use a thicker wood shim, and repeat the process. The piston is toast anyway, so the concern would be to salvage the cylinders. Haven't ever tried this myself, but I read this tip in the book, "Building Budget Brits", by Mike Brown.
 

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Discussion Starter · #10 ·

Setup and ready for a beating. I'm using a sledge hammer, and a handle from a brick hammer I got from the hardware store.
The tape is to prevent the handle from splitting.



I made sure the crank/rods were about 1/4 on the down stroke, so with each wack I was not causing parts to move undesirable ways, other than the sudden impacts onto the piston...



You can see its on its way!!!
This was about 1.5 hours in...
It was hard work, took 2 hours.



At least now I can remove the barrels. I'll get the remainder of the piston pressed off when my new ones arrive.
I purchased NEW 0.75mm oversize pistons (eBay), hope they will be OK! The pistons will take a few weeks to arrive to Australia from the UK.



More tear down whilst I wait for parts to be delivered.



Note to self...



Muck from the 70's.



The front of the Oil Filter was very difficult to remove. As you can see luck me broke an 8mm bolt off in the shaft.
I'll have to take it to a machine shop ones its out for bolt removal. I had to use colinCBerg screwdriver method to pry the front open.



Looking better...
 

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I had kind of lost track of this thread. Looks like you're making progress. I'm happy to see the method of lifting the jugs off the stuck piston worked out for you. Hope there was no damage to the cases.
 

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Discussion Starter · #12 ·
Thanks for the heads up burke...

After requesting others to keep their project logs up to date I've kind of let mine slip...

Here's a little more on progress thus far...
No shiny parts yet, just engine work whilst I wait for all the couriers to arrive.

I've purchased a number of things since my last post, you'll see them come together over the course of the project.

The engine is getting done, i'm taking my time trying not to make any mistakes along the way.
Doing the basics like replacing seals and bearings etc.

Managed to find .75mm oversized pistons, so the barrels have been bored and honed to suit.
Hopefully this has removed any pitting caused by the stuck piston and associated belting! Visually it looks 100% Ok.

Here's a few photos anyway...

A before shot..
Scroll down to see the after shot.



Cases split after finally removing the stuck piston! Hooray!



I sent the cases off to get soda blasted. Here is some of the residual left behind before giving them a good clean and soak... Its amazing how clean they came up, very happy!



Giving them a good soaking and clean.



Cases and parts sprayed with VHT Engine Enamel - Universal Aluminium.
Dont worry, the engine was cleaned well after the paint curing with oven cleaner that is possibly more toxic than the paint fumes... :?: :?: :?:



Coming back together.



Buttoned back up, bolt heads and threads cleaned to within an inch of their life.
My after shot.






Sizing the amount of stud height that should protrude throught.
What is the recommended amount??? I can not find this in any of the service manuals! :?: :?



Amazing the difference a clean and coat of paint makes!





I'm guessing here, any reccomendations?


This one wont any further into the crank case. Assuming thats ok and buffer it out with washers?
I'll run a tap down it to make sure there is nothing wrong with the thread.



Valve removal using a "G Clamp" and a bit of 20mm diameter steel pipe.
Got the idea from here: http://gstwins.com/gsboard/index.php?topic=13672.0









Now onto the shocks... Removal of all but two of the seals was easy. Some hot water and vice grips got the job done.








Next Up...
The Head...
 

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I cannot say for sure (never built a 200), but based on my experience with 175's (very similar engine) I would position that "longer" stud at the right rear position (oil feed up to the head) as it gets a thicker copper gasket/washer anyway......I go to the extreme of polishing the "oil-feed" studs after altering them (reducing diameter) very slightly for ease of oil passage.... (175's have two, your engine uses only one).......I don't recommend that for a novice, but it can be done.....
 
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