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Discussion Starter · #1 ·
I just bought my first bike, a 1973 CB450 K6 and in order to get it up and going, I need to replace a gasket. The previous owner had this to say about it:

Since the oil leak is at the head gasket, it loses a lot of oil and is getting fuel into the oil, which has made it very hard to shift. The gasket is cheap, but the problem would greatly compound itself if you were to run it for an extended time period in it's current condition.
He also said this when I asked him to explain it further to me:
The engine runs. In these bikes the clutch, transmission, and engine all share the same oil, but since the head gasket leaks, it not only lets oil out, but gas into the oil, If you ride it while there is raw gas where there should be oil you will ruin a perfectly good bike. Its worse than riding it with no oil at all because gasoline is a solvent and it will dissolve all the other gaskets and seals. plus there is the risk of explosion due to the agitation and heat from all the gears. right now its a very simple fix, but that would seriously complicate the matter. I would only start it, rev it, and then shut it down. only to prove that once the gasket is replaced, everything else works fine.
He purchased the gasket and I'm picking it up in the next day or two. In the interim, I'm looking to gather any advice that you folks might have had or tips/tricks to pass along when performing this gasket swap procedure. Of course, i'm assuming that at least one person knows what he's talking about. *fingers crossed*

Really - this is my first attempt at anything like this, so any tips would be greatly appreciated. And if you don't think that it's something a novice should attempt, i'm willing and open to listening to that as well.
 

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bandanabandit said:
I just bought my first bike, a 1973 CB450 K6 and in order to get it up and going, I need to replace a gasket. The previous owner had this to say about it:

Since the oil leak is at the head gasket, it loses a lot of oil and is getting fuel into the oil, which has made it very hard to shift. The gasket is cheap, but the problem would greatly compound itself if you were to run it for an extended time period in it's current condition.
He also said this when I asked him to explain it further to me:
[quote:zi7ps0c0]The engine runs. In these bikes the clutch, transmission, and engine all share the same oil, but since the head gasket leaks, it not only lets oil out, but gas into the oil, If you ride it while there is raw gas where there should be oil you will ruin a perfectly good bike. Its worse than riding it with no oil at all because gasoline is a solvent and it will dissolve all the other gaskets and seals. plus there is the risk of explosion due to the agitation and heat from all the gears. right now its a very simple fix, but that would seriously complicate the matter. I would only start it, rev it, and then shut it down. only to prove that once the gasket is replaced, everything else works fine.
He purchased the gasket and I'm picking it up in the next day or two. In the interim, I'm looking to gather any advice that you folks might have had or tips/tricks to pass along when performing this gasket swap procedure. Of course, i'm assuming that at least one person knows what he's talking about. *fingers crossed*

Really - this is my first attempt at anything like this, so any tips would be greatly appreciated. And if you don't think that it's something a novice should attempt, i'm willing and open to listening to that as well.[/quote:zi7ps0c0]

That's a new theory on me. If a head gasket leaks then you'll get blow by and oil out of the leak but it's not going to put any more fuel in the oil than any other time. It's true that enough fuel in the oil will cause the oil to thin out to the point where it could damage things but I've never heard of that happening in a gas engine that had decent piston rings. Now, my Chevy Duramax Diesel had the injectors go bad and dumped a bunch of fuel in the motor (almost 1/2 gallon) but that was a whole different animal.

I can't begin to guess where the seller came up with that piece of logic.
 

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IF the head gasket is not seated properly (leaks), some of the intake charge can be forced into the camchain galley as well as to the outside of the engine....Hence, fuel in the oil.....
Bill2 (Bill Lane) is the 450 EXPERT...Follow his proceedure for engine reassembly/timing.... His annotated manual makes this much easier, and he has it available on CD.... Steve
 

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Bandit -

You have a lot of work ahead.
You'll have to pull the engine, break the cam chain, then replace the head gasket.
While you are in there you may as well check the cylinders/rings and valves, to avoid any unsavory "stuff" in the future.
Previous Owners always say the bike ran real well before you bought it - usually they're either lying or too stupid to know any better.
You'll need the rest of the top end gaskets, probably, and a new cam chain rivet link as well.

Check the compression before you tear it apart...... Honda says you need to see at least 164 pounds, or you're looking at top end work. This value will be slightly lower with a cold engine - Ideally you should get the reading with a hot engine, throttle wide open, NO CHOKE.
Later, we'll tell you how to check the valves.

Not to worry, all the knowledge you need is right here.
 

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Bandit,
Simple to sort out but make sure you read up on things first & before you split the cam chain wire it first with some welding wire or tie wraps and make sure you don't drop it all in the sump.Out of my five bomber engine rebuilds I've let two go into the sump.I've actually managed to fit a cam chain into a K0 engine with head on after engine was rebuilt despite manual saying you have to at least remove head.Regards Chris.
 

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Discussion Starter · #6 ·
Where is the annotated manual? Sorry if it's uber obvious, I just joined last night.

I'm going to take a look at it and see if I can figure it out. Otherwise, I'm going to see if Bill2 wants to take a trip to Seattle hahaha.

I'm seeing a skype conference call function on this forum in the future!

Thanks for all the input.

1st step is figuring out how to drop the engine. I really am a newbie to mechanics in general.
 

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This is my KO manual but things go the same way for a K6 so follow steps 1 to 10 & lift out from left side.I always find it easier to remove ignition switch,coils, & horn completly out of the way as well to give more manoevering space.Also don't forget to disconnect the battery live wire before you do anything with electrics.
Regards Chris.
 

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Discussion Starter · #8 ·
Thank you so much. Alright! I'm going to follow this to drop it and then check back for the next steps per Bill2.

Thank you again.
 

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When you get to step 11 chock someting under engine to take weight of engine before you undo all engine mounting bolts ,I use a nice solid block of wood.If you don't do this engine will fall lower in frame and scratch it and be more difficult to lift and remove.There's a bit of a nack to lifting & leaning to get it out so be careful and watch what your'e hitting.Get a mate to give you a hand out with it,its so easy to catch frame with engine and pull all bike over when trying to lift out.These are quite heavy little beasts or should I say they are when your'e 58. Regards Chris.
 

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You can do but be prepared for it to be a bit wobbly that way.You don't need to find the centre of gravity with a good block of wood or worry about the wobbles.Quite easy though if you'e got an extra pair of hyands on the job.
 

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bandanabandit said:
Noted.

How about using a car jack?

BB -

It's not really that hard.
Bike on centerstand.
Remove the pipes, chain, engine mounts, wiring, footpegs, etc.
Leave the kick start on so you have something to hold on to.
Straddle the frame in normal riding position, feet on floor, chest on frame tube.
Lift the engine straight up a few inches, move it to the left, and it's out.
Actually it's one of the easiest Honda engines to get out, no wiggling or contortions required.
I'm old/frail and I can do it in a couple of seconds.
The engine weighs about 140 pounds, but you're not bench pressing it or anything, just lifting an inch or two.
 

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Get old/frail Bill to come and give you a lift or at least hold your right leg whilst you swing to the left to place it on floor.140 lbs in English money is still 10 stones.Bill is that with or without the oil.Regards Chris.
 

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GAMD5 said:
Get old/frail Bill to come and give you a lift or at least hold your right leg whilst you swing to the left to place it on floor.140 lbs in English money is still 10 stones.Bill is that with or without the oil.Regards Chris.
Yuk, yuk - you Brits and your stones.
Actually, I work for a British company named Severn Trent - I'm sure you know who they are.

I do have long legs and arms (ex-basketball "star", sort of), maybe that helps???
Seriously, it's a snap.
 

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Its easy to us but probably a shade difficult when youv'e not done it before.Yes know S.T.W.A. well used to be one of my customers when in the electrical wholesale business and is still my local water authority. Chris.
 

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Chris -

I forgot to get back to you on the Bomber Manual, sorry.
Due to domestic financial calamities, I'll have to put it off for a while.
Can't really afford to mess with the outrageous shipping right now. Maybe at the end of next month or so??
 

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Bill my mate Geoff wants to know whilst your'e lifting engine out straddled above the frame how you move youre right arm through the frame and drop the engine to the floor he says you must have rubber arms or are they as long as your legs. If you go totally from left side in this position I'll see you in hospital with a slipped disc. Regards Chris.
 

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Discussion Starter · #18 ·
Just in case, I wanted to put the motor pic in here so you could see if you thought it was something different.
Not even sure that you can see it, but there are the splatters.



more when I get the engine out
 

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GAMD5 said:
Bill my mate Geoff wants to know whilst your'e lifting engine out straddled above the frame how you move youre right arm through the frame and drop the engine to the floor he says you must have rubber arms or are they as long as your legs. If you go totally from left side in this position I'll see you in hospital with a slipped disc. Regards Chris.
\

Chris -

Once you lift the motor up and move it to the left about halfway out, you can simply balance it on the lower frame tube for a second, step to the left of the bike, stick your right arm through the frame to grab the kickstart, then complete the manuever to lift it out and down.
 

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After draining the oil I laid my bike down and unbolted the engine. Then lifted the frame off of it. Worked for me.

You really should buy a copy of Bill's annotated CB450 manual on CD. It's worth every penny!

GB :mrgreen:
 
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