Cam chain broken, what to look for

[Discus]

Hi everybody, I am new to the motorcycle world and looking for advice.

I am in the process of fixing a 1982 CB750 custom (1 bent fork tube and flasher issues so far, I rode the bike up to 30 m/hr before taking the fork apart). I guy not too far from my place is selling the same model as mine. He states that it is in "great condition" but "not running because a broken cam chain".

What should I look for when I go check it out. It could be a good parts bike or another project. What am I looking at to fix it? Is it worth it to fix? The bike has 80 000 km or 50 000 miles and was apparently running last summer.Looking at the pictures, the bike looks very clean.

Thanks in advance!

[TOOLS1]

I am not very familiar with the DOHC engines. But if I were looking at buying the bike. I would just assume it was junk, and buy it as parts. Priced accordingly.
TOOLS

[sgtslag]

Once the cam chain broke, the valves would be out of time, and they are likely bent.  Unless you are highly skilled as a motorcycle mechanic, and the price is right (buy it for parts-only price...), it is not worth fixing, unless the valves are intact -- only way to know is to tear the engine down, once it is removed from the frame.  The cam chain could have also damaged the crankshaft, as it connects between the crankshaft, and the cam's.  It could have salvageable parts within the block, but I would buy it more for the transmission, and everything but the engine.

The airbox is valuable to anyone who might have tried to install pod air filters on each of the carbs...  The rectifier/regulator is a pricey piece to replace, as is the gas tank (if this one is in good shape).  The plastic side covers are highly sought after, as they have a tendency to fall off while traveling down the roadway -- they typically sell for $50+ on e-Bay, especially the left side cover.  Cheers!

[LukeM]

I just got a shudder and a bad flashback reading this thread.  My 79 model broke its long cam chain (from the crankshaft to the exhaust cam), and the Sergeant is correct. The engine needs to come out, and be pretty much un-accesoried (starter, side covers, alternator, clutch, carbs, other stuff) in order to swap it out.  Depending on the age and condition of the motor, it may be worth it to overhaul it (new rings, bearings, valve guides and seals, new chain adjusters).  Be prepared to spend a few dollars on parts, and quite a few hours on labor. For me, I could not justify the expense for a weekend hobby, and parted mine out for almost what I had into it.

You'll get good moral and technical support from this forum, and perhaps from some others on the net. Take your time, go slow, clean things twice, measure at least twice, and read the instructions carefully.  I wish you well.

Luke

[dave Esch]

My bike has pod filters since I bought it. I personally would like to go stock in that department. Are there any benefits to the pod filters? Any downsides?

[LukeM]

If your carbs have the factory jets in them, using the stock air box will give you better response. The carbs are a constant vacuum design, and pod filters do not supply that as erl as the factory setup. If the carbs have been modified to run with pods, then there is no real reason to go back. It's your choice, but "choose wisely"as the knight said.

There are many threads on this forum discussing the benefits and pitfalls of pod filters. A few searches should yield a great many postings.

Good luck!
Luke M

[Discus]

Thanks for the advice... The guy was asking $600 and he came back with $400 tonight... I will wait a few more days and see. I need a fork tube and could maybe use 1 front flasher and who knows what else down the road. I could always sell some parts.

How much would you offer him?

It does seem like a lot of hours, more like a winter project then a spring one (I live in Manitoba Canada). Maybe this coming winter I can take it apart as a learning experience... who knows what I will need to do in the future on my main bike.

I'm sure I will have more questions but until then, I a few good rides!