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A Broken Cam Chain, A Broken Heart & A New Start

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McFloobles
honda305.com Member
Posts: 3
Joined: Tue Apr 07, 2009 12:54 am
Location: Los Angeles, CA

A Broken Cam Chain, A Broken Heart & A New Start

Post by McFloobles » Sun May 10, 2009 10:51 pm

Hello All,

firstly, I would like to thank you all for building this website and this community. I have been using the vast resources of your communal knowledge to work on my CB77 that I bought last Fall.

I am a younger guy with no previous mechanical knowledge and I hadn't intended to buy a bike that needed so much work, but I just fell so in love with the bike when I saw it, that I had to have it.

The work and the learning curve have been nothing but a joy and I was able to get the bike running and have been driving it around simply with the factory manual, the help of knowledgeable friend and a whole new set of tools.

Now although it had always been my intention to try to do a proper resto job on the bike, I had hoped to do it this Winter, after a fun first summer of riding and getting more involved in bikes. However, this has sadly been pulled up short on me as, when driving in the third lane of the freeway at 55, my engine suddenly lost power, giving me a minor heart attack and sinking sensation all at once.

So, it is time for the full restoration of my bike! And in that spirit over the next few weeks, I am going to post pictures of everything I do with my bike in the manner I have seen Spargett and others do so successfully.

To start with though, I would like some advice on Cam Chains.

This weekend, I pulled apart the whole top of my engine, when after a process of deduction, we realised that the Cam Chain must have broken and after pulling it apart, it seems we were right.

It looks like one of the screws that was holding the internal part of the cam chain tensioner had vibrated its way loose (?!?) as it was no longer attached. The second screw was also barely finger tight.

So, my first question is... Is this something anyone else has ever heard of or seen before?

Fortunately the loose screw does not seem to have caused any visible damage to the inside of the engine and was found, slightly damaged sitting in the oil at the bottom of the motor when I took the bottom plate off.

Happily my cylinders look very clean and my valves all seem in good condition too (although I will be posting pictures of all these part for conformation) and this tragedy may not be the end of the world after all.

So, my second question is... what new cam chain should I buy? ServiceHonda seem to have an OEM one in stock. Should I go for that one? Or should I get a rivetted one? (This is something my friend who is familiar with bikes but not my CB77 suggested I ask)

Once again, I am really pleased that this site exists and is so active and I am REALLY excited to work on getting my bike really beautiful.

And, my third and final question is... Should I rip apart the bottom of my engine to look and see if there is anything wrong with it like there was at the top? My friend who is guiding me says that we don't have the tools to reassemble the bike if you do this it is necessary and so I would also need advice on finding a mechanic is the California who could help me with this.

Thank You All In Advance!

A very excited McFloobles!

joeweir1
honda305.com Member
Posts: 761
Joined: Wed Mar 08, 2006 9:35 am
Location: middletown,pa

Post by joeweir1 » Mon May 11, 2009 6:59 am

You really do not need any special tools to take the bottom end apart.I did it with the few tools I have in my garage and I never split the case on a bike before I got my 305.

Phil-UK
honda305.com Member
Posts: 229
Joined: Thu Oct 19, 2006 7:04 am
Location: ENGLAND

Post by Phil-UK » Tue May 12, 2009 3:05 am

Hi

I''ve heard of cam chains going but not especially on CB72/77s etc., someone with more experience
of them would be best placed to say.

When I rebuilt my CB72 I used a cam chain with a soft link ( not a spring link ! ) and I think this was
how they originally were
Q. - anyone confirm/deny if early CB750 used a soft link as its the same chain ?

An endless chain is theoretically stronger but more awkward to fit. I'd be tempted to wait
until you have the engine apart and can see where the old chain broke before deciding.
You might also then be able to see why a loose adjuster would have caused the chain to break ..
did somthing jam ?

good luck

Phil

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