Topic: Pinhead's CB650

[Pinhead]

I've been amassing parts for my CB650 project that I started HERE. I'm going to rebuild the engine with new cylinders, pistons, rings, cylinder head, and valves. Everything will be re-painted and the aluminum parts will be polished.

With Soos working on my pistons, I figured I'd get my bike ready to rebuild. I took about 3 hours and tore the bike down almost to the frame.

The beginning of the project has already had one problem... One of the head bolts snapped; there's about a half-inch of bolt sticking up above the block. It will be soaking in penetrating oil for a few days before I even try to take the rest of it out since I don't want to snap off what is left.

Where can I get a set of new head bolts for my 650? Are heavy duty bolts/studs available?

What's the best way to clean the tranny/block now that I've got the cylinders off? Do I have to worry about getting degreaser inside the engine?

[Alan F.]

This should be a good build to follow, your writing is entertaining and you're going pretty deep with your rebuild. Personally I'll be paying extra attention to your elecrical system (again).

What's the best way to clean the tranny/block now that I've got the cylinders off? Do I have to worry about getting degreaser inside the engine?

I'd stuff clean shop rags into the crankcase holes around the connecting rods, this will prevent foreign matter (or small flying parts) from falling in there.

I wouldn't worry too much about a little degreaser getting into the engine, but prevent it as well as you can and use something that'll evaporate if it does get in.

To clean the cases and all I used 'rags in a box' and brake cleaner, and a stiff plastic bristle brush for the rough spots.  I'll be repainting anyway so whatever original paint or clear that comes off this way is ok.

Cheers and best of luck with the head bolt/stud, reply #4 seems to be the standard to go by: http://forums.sohc4.net/index.php?topic=6846.0 I wonder if chilling a pair of  visegrips in the freezer for an hour will improve anything?

-Alan

[Pinhead]

Thanks for the compliment and the link! Hopefully the busted bolt will be the first and last screw-up of the build. 

[Frankenkit]

....huh.  Pinhead, I didn't know we were about the same age. Crazy. 
Good luck with the bolt thing, I'm just excited to watch your build, here...

[Pinhead]

You're only 79 years older than me. 

[Frankenkit]

[Soos]

Ahh, tearing into it already?

Your pistons will have valve pockets monday or tuesday, but the motor shop will not be done with the cylinders for about a week they say.
I meant to take one of your pistons home to take a pic of it, but forgot it at work.

Any pics of your headwork?
I bet you need those valves back too huh?



l8r

[Soos]

If you need another head bolt, I might be able to spare one.


l8r

[Pinhead]

Ahh, tearing into it already?

Your pistons will have valve pockets monday or tuesday, but the motor shop will not be done with the cylinders for about a week they say.
I meant to take one of your pistons home to take a pic of it, but forgot it at work.

Any pics of your headwork?
I bet you need those valves back too huh?



l8r

I'll need the valves back to put into my engine. If you can, you ought to make a set and try them in one of your rebuilds.

Yeah I'm tearing into it but don't worry; I've got a lot of work to do before I'm ready for the pistons. Tripple tree first then lots and lots of cleaning, painting, and polishing. You've got plenty of time.

[Pinhead]

My bike is in my friend's shop an hour away so I can't just go look... What size exactly are the head bolts, length, diameter, and thread pitch? I wonder if some other un-related bike uses the same bolts that might be available as a "heavy duty" alternative...

[Alan F.]

you can look it up at www.motogrid.com they also have a feature that allows you to see which other bikes it was used on.

[Pinhead]

I got the stud pulled finally, and Soos is finishing up on my pistons and cylinders. I've started working on the intake ports on a spare head (cutting PowreLynz) which is taking a lot longer than I expected, about 2 hours per port. Hopefully once I get done with this head I'll be "good enough" to do it to the head that I'll be installing on my engine. Pics will be posted when I get them.

[Ecosse]

so, are you doing a stocker more or less or do you have more extravagant plans?

[Pinhead]

"Extravagant" would be a good description.

I'm building a full Surface Turbulence motor.




'78 CB750 pistons modified by Soos. Mine are the four on the bottom.


I haven't taken pics of the intake ports yet, but they're getting a Surface Turbulence treatment as well, using a modification called PowreLynz

This obviously isn't my engine, but it illustrates the basics of the mod.


Final CR will be 10.7:1.

[Frankenkit]

that's so hot.   you need to finish it and ride it over here so I can butt-dyno it.

[Ecosse]

...so I can butt-dyno it.

1) slow as s#!t 2) half fast 3) tear @ss 4) kick butt...?


man, if you keep it shock looking, but with that crazy engine, it'll raise a few eyebrows!

[Pinhead]

It'll look close to stock, though I've got taller rear shocks, a different rear fender, and will go with lower handlebars. It will also have a "Viper" fairing on the front.

I will probably repaint the side covers with CB650ST or something similar, though.

[Soos]

Ok, So do I get to see a pic of the pistons valved and head all together soon of what?



Peace and grease





l8r

[Pinhead]

I'll probably get out to my buddy's shop this weekend and will get pictures and start putting the engine back together. This will be my first Honda SOHC rebuild so it will probably be a bit of a learning curve.

[Pinhead]

I just got my Ignitech programmable ignition in the mail today... All the way from the Czech Republic. I've been looking through the options in the software and there are more than I'll probably ever use. The CD came with two pre-programmed ignition curves optimized for the DOHC 750/900; one with the original centrifugal ignition advance enabled and one with the centrifugal advance locked in the idle position.

Also, the best part, is it is 100% plug-and-play. It came pre-wired to plug into the stock wiring harness and it can use the stock inductive pickups.

[Soos]

I just got my Ignitech programmable ignition in the mail today... All the way from the Czech Republic. I've been looking through the options in the software and there are more than I'll probably ever use. The CD came with two pre-programmed ignition curves optimized for the DOHC 750/900; one with the original centrifugal ignition advance enabled and one with the centrifugal advance locked in the idle position.

Also, the best part, is it is 100% plug-and-play. It came pre-wired to plug into the stock wiring harness and it can use the stock inductive pickups.

OOOOH!




VERY, VERY interested in how everything works out!!!




l8r

[traveler]

the mere fact that is dosen't "look" right, yet makes sense mathematically...more often than not means it will REALLY be something!

I really think you are on to something....turbulent air and backpressure mean ALOT of the street!

~Joe

[Pinhead]

I know it's been a long time since I've updated this post. I haven't had a whole lot of progress other than getting the engine painted, and piston rings, pistons, and cylinders installed. I was going to install the head but I seem to have misplaced one of the "alignment dowels" for the head (the spacer that goes around the cylinder head bolts that keep the head aligned with the pistons/cylinders). Does anyone know where I can get another one of these?

[Really?]

I just got my Ignitech programmable ignition in the mail today... All the way from the Czech Republic. I've been looking through the options in the software and there are more than I'll probably ever use. The CD came with two pre-programmed ignition curves optimized for the DOHC 750/900; one with the original centrifugal ignition advance enabled and one with the centrifugal advance locked in the idle position.

Also, the best part, is it is 100% plug-and-play. It came pre-wired to plug into the stock wiring harness and it can use the stock inductive pickups.

They make one of those for my bike but it is probably for more involed than what you will ever need but you might find this thread interesting.  They have been beating this thing to death to get it close to the ungoddly priced Yammy stock unit.

http://www.venturerider.org/forum/showthread.php?t=40414&highlight=ignitech

Not trying to scare you or anything, just though you might find it interesting along with what they did with the software mapping.  You may need to create a temporary (free) account to see the pics and videos.

[Pinhead]

Luckily the CB650 uses a mechanical advance/timing instead of a "brain box" so the wiring and programming on it is much simpler than in that thread. If I want to use the "stock curve" all I have to do is program the timing to 0° BTDC all across the operating range; the IgniTech module will follow the stock centrifugal advance and fire the coils as soon as it gets a pulse. After I get it running I can easily switch between a "programmed" curve and the stock curve. Then I can add vacuum advance (MAP sensor) later on.