Ain't no body got time fo that.-or- I got the CB-Jeebies. A refresh on a Honda CB650 cafe-rat.

Okay, so with the bike nearly all together, I started working on the air filters.

The center two go on with no issues but the outer two have frame in the way.

So I ordered a silicone tube with a 90 degree bend and gave it the chop.

Then I bent a little piece of stainless steel into a circle and glued it all together.

Hopefully they will stay attached? I never have much faith in glue, regardless of how "industrial" it is.

So, she's back together! (Mostly)

So I popped a temporary fuel tank on it and cranked... and cranked and cranked...

Not a damn thing, checked spark, checked fuel, squirted some started fluid, all fine, no pops, no nothing.

Then, I noticed a missing vacuum line that was part of the fuel cut-off. BUT, it was blowing air out...

So I googled that issue and immediately found this reply...

So...............yeah. When you look at the timing marks on the crank, it looks like this.

But what you should be looking at, is this.

See that little 2.3 down there? Yeah, that should be a 1.4. You know, like it says in the manual.

Well, could be worse, nothing went into automatic self clearance mode.

So I tore it all down, moved the Cam a quarter turn and bolted it all back together. At least my 4 year old was excited about the extra work...

But, can't complain too much!
 

OH Yeah!

So after the initial victory, I noticed this.

that's not a small leak.

After a little poking around on the internet, many people said they had leaks like this from the little discs that cover the head studs. Also, when I tightened the head covers down, one of the bolts stripped and wouldn't get up to the torque specs, right near where it was leaking.

So I pulled it all apart... again.

The one bolt hole was completely stripped so I prepared it to use a heli-coil. lazily.

Yeah, I really could have done better than that. for starters, I should have put some plastic down over the remainder of the engine and then there would have been no chance of getting spare aluminum in it.

Oh well, I'm kind of dumb sometimes. I think I was able to vacuum all of the bits out, these are chips made by a drill and tap and not dust so...?

Anyway, I got it back together, adding the thinnest layer of gasket sealer where I had sanded those dents earlier(also right near the leak)

And? It still leaked just as badly.

Then I found the real culprit.

This large bolt and to a lesser extent the two allen bolts behind it. Good news was that these were very easy to fix, The big bolt needed the washer replaced with a copper crush washer. The allen bolts needed to be pulled out; there is an O-ring around them that was a bit worn down.

And now! it leaks way less! It still leaks a bit... Which I am worried is the result of using the bargain gasket set. Oh well.

I made a plug for the missing vacuum hose.

And then I bolted it all back together. Including the seat and tank this time. I rode it up the driveway and back a few times because it doesn't have any plates right now.

Seems like I need to do a lot more tuning now. It starts up super fast, like second crank, and idles really nicely. However, just reving it up in 1st gear, it misses a lot and struggles.

I know I need to sync the carbs but what else needs to be done to get it running right after a rebuild?

In reply to 914Driver :

Ummm... thanks, I think.

This morning I adjusted the dynamic timing and synced the carbs, mostly.

I don't have the adjustable restrictions for this tool so the needles bounce around a lot. I ended up just revving it up to 4k so that the needles would be still enough to read.

Also, that's the before picture.

After that I got it all back together and rode it up and down the nearby parking lot a few times. Everything is way better but there is still a tiny bit of hesitation around 3K. I've heard that this can be from the accelerator pump but I cleaned and adjusted it when the carbs were out.

Here she is looking presentable.

I still need to rebuild the front shocks and I am going to shrink those front turn signals.

After that, I am thinking a triangle shaped saddle bag to fill that spot under the seat and some flat green paint...

Jetting is probably off due to changes in both the exhaust and intake (read: air filters) from factory.  I know from my GS500 days that going from the factory air box to pod filters required a not-tiny amount of enlarging the jets.  I can't provide much in the way of numbers to suggest as it was years ago and GS500 != CB650.

It might be cool to have a little compartment under the seat where that open area is now.  Saddle bags would be bigger and provide more space and such which might be nice as well.

BirgerBuilder said:

 

 

See that little 2.3 down there? Yeah, that should be a 1.4. You know, like it says in the manual.

Well, could be worse, nothing went into automatic self clearance mode.

So I tore it all down, moved the Cam a quarter turn and bolted it all back together. At least my 4 year old was excited about the extra work...

 

When I was in college, I did a light rebuild (bearings, rings, hone) of my VF500 on the kitchen table (as you do).  Got it all together but it leaked oil out of the countershaft seal, which required splitting the cases to replace.   Argh.  All buttoned back up, it wouldn't start and I eventually brought it to the Honda dealer, tail between my legs.  It took the mechanics no time at all to figure out I had mixed up the intake and exhaust cams.  Sigh.

So I fixed that and it started right up.  The dipstick wasn't spun in and it shot out of the motor.  That's when I noticed the kinked vent line that caused the countershaft seal problem the first time.

They were going to hire me that summer as a bike builder/general lackey but changed their minds.   :)

pres589 (djronnebaum) said:

Jetting is probably off due to changes in both the exhaust and intake (read: air filters) from factory.  I know from my GS500 days that going from the factory air box to pod filters required a not-tiny amount of enlarging the jets.  I can't provide much in the way of numbers to suggest as it was years ago and GS500 != CB650.

It might be cool to have a little compartment under the seat where that open area is now.  Saddle bags would be bigger and provide more space and such which might be nice as well.

I was just watching someone's video that suggested bigger jets to go with the open exhaust and intake... so that's tempting.

And yeah, the 'saddle bag' would be more like a storage pocket that fits inside the frame.

The other fun is how any number of people could have played with the jetting before you got the bike.  So going through the process of identifying what jets you have and then trying to play around a bit would probably be useful.  Or really frustrating!  Probably both to some degree.  

When cleaning the carbs, a torch tip cleaning set  is a lifesaver,  It is just a series of finely sized wires to poke through tiny orifices (plural) to break up any deposits, then the cleaner of your choice will have a much easier time of it.   Maybe $5 from Harbor Freight.

My 72 CB750K did not have the vacuum assisted diaphragm slides on top, but the VF750 Sabre did.  DO NOT get any cleaning solutions on the diaphragms.  It can mess with the rubber badly.  You can wash them with mild soap and water.  If there are needles at the bottom of the slides, you can raise the needles slightly by shimming them with tiny washers.  It gets you onto your main jets sooner.  Are all the carb adjustment screws the same number of turns from fully seated?  All their o-rings replaced?  Float valves all set to close at the exact same height?  Replace spring loaded fuel valves and seats if you can.

To rough synch the carbs, get those pods out of the way and very carefully eyeball the throttle plates just off closed and closed... microscopic motions... eyeball the bottom of the plate...just as it seats and a hair off closed.  You would be surprised how close you can get it like that before using the gauges.   Are all of the slides lifting evenly as you rev the engine.  Eyeball it. Are there tiny little idle bypass holes in the floor of the carb throat?  Torch cleaning wire works a treat there too.  and all the little holes in the sides of the emulisifier tubes, and through all the little passages.

Is your fuel tank valve gummed up and starving the engine?

On a reassembled engine, I'd definitely set the valve clearances.  Too tight and you burn valves.

How does this engine handle ignition advance?  Springs/weights or solid state?  Regardless, drop a timing light on #1 and make sure you ae getting advance from idle up to 3k or so.  You can even dial in the full advance number on a fancy gun to shoot the timing marks at full advance.  I always had good luck with accell coils and yellow jacket wires.

I jetted my CB650 from the stock 35/90 up to 42/120 plus a needle shim. It runs pretty dang well now, though probably a bit rich because it barely needs any choke now.

Some good advice fellas, Now that everything is back together I'm not sure I want to pull it apart to mess with the jets anymore. And with a few other projects looming it seems like the CB will be chilling in the back of the garage till spring time... If I had plates for it, I'd be riding it a bit but I'm not so sure it's worth the trouble just for a few weeks of nice weather.