Newbie to the CB World! (pics)

[KCReed]

Hey all! About 2 years ago my buddy picked up a broken CB750 off of craigslist for $300, and for another couple hundred bucks he had it running. I started looking for one, but didn't really have a place to work on it. I bought a house earlier this year, which gave me room to expand my hobbies and projects. This guy popped up on CL this week, and I couldn't pass it up!

It wasn't running when I got it, and the previous owner could never get it running over the 2 years he had it sitting (but he mentioned he didn't try very hard). I have already pulled off the carbs, and am making room on my workbench for the teardown and cleaning. I brought my buddy I mentioned above to make sure it was a fairly kosher bike, considering its condition. He was very impressed with it, said it was much more complete than his had been upon purchase, and is pretty sure once I get the carbs straightened out it should run just fine.

I have built multiple motors for cars, done wiring, motor swaps etc, but have never worked on a bike. I have also never touched a carburetor until this project.

He had POD filters installed on it, but luckily it came with a few boxes of spare parts including the stock air box. The limited reading I have done so far leads me to believe that I will be using this upon initial startup instead of the individual filters. I may try to install them at a later date, but who knows. I have to worry about getting the turn signals and lights working, as well as everything else to make it road-worthy, before I want to think about modifying anything on it.

On a side note, is this thing the SOS that everyone dislikes?

Can't wait to sink my teeth into this project over the next few months, and hopefully by spring I have a swanky fresh CB750C to scoot around on!

Cheers!

Reed

 

[amc49]

Yes. Ditch that valve and learn to turn the petcock off, biker rule #1.

Be advised that most of those engines never got the valves adjusted, they then run funky and 90% of the planet goes after the carbs to never get it running right ever. Not saying it's NOT the carbs but those alone are a handful even for people who rebuild them all day long. They commonly clog in places that most 'experts' never find.

The valves sink in head due to no lead fuel and then they close up clearances to then not run right, the clearances are also NOT what you get by direct measurement and another cause of them not running. You set valves at .005" instead of the service manual figure of .003" to have any prayer of long running. The valves can be shut to have zero compression at .002". Why one of the FIRST things one does is to run a compression check to find out where you are, MANY will have one or more cylinders down on compression, carb work won't touch that.

 

[KCReed]

Yea, I have noticed that with these bikes most people recommend doing a valve adjustment every time they change the oil. It was definitely on my list of things to do/check this time around. It looks like the transmission fluid was clean when I checked it, but I will still be doing a full fluid swap as well. I was going to try to check the timing also, but have read it is a little tricky. I should mention that all of my previous automotive experience is on Honda's, so I am fairly confident I won't have many issues in that regard. I have set timing on multiple Honda motors already, and exited to get this one uncovered to see what its all about!

 

[KCReed]

So where do I find shims? Ebay seems to be the only place really, will I need to have some extras with different thicknesses to do the valve job on this bike?

 

[amc49]

...............................cockpit problems

 

[amc49]

'...most people recommend doing a valve adjustment every time they change the oil.'

They're crazy. Set at .005" and them bedded in you actually can go as long as 20K+ miles but better not to. I'd say every 7500 or so check. You have to set them more often with the OEM suggested clearance, there is a reason why that number is garbage.

You have no idea of what shims you need until you run the clearances, surely you know that from the cars..................K&L Supply still sells some I believe. 25MM. diameter, thinking Yam FJ11/1200 fit as well as some Toyota too. Some shims can be moves from one place to another to make it good. Do NOT turn the engine with a shim missing! Shims are reuseable unless they have scratch damage on them.

Service manuals here....................join up for free and go to technical documents section.

http://www.cb750c.com/modules.php?name=Your_Account&redirect=viewtopic&t=301

Or here.............same rules

http://www.cb1100f.net/