HondaCB650

Our bikes were designed to run regular 87 octane fuel. They're designed with 9:1 compression. However, years of leaky rings may have built up carbon deposits on the pistons which has likely both increased the CR and created hot spots which could raise your octane requirements. If your bike pings und...

There are no drop-in pistons for the 650, unfortunately, unless you can find some NOS stuff from the early '80s.

I'm running '78 CB750 pistons but they had to be machined to fit the combustion chamber. The work was done by a forum member who I haven't heard from in a couple of years...

I'd bypass the aged wiring harness by running two additional wires to the battery terminals. Attach one directly to the positive terminal of the battery and the positive output of the rectifier. Attach the other directly to the negative terminal of the battery to the negative side of the rectifier. ...

You're certainly a whole lot closer. It still seems like your electrical system has some kinks to be worked out, though; even with all of the lights on you should still be able to charge the battery at everything above 3,000 RPM. You said, "even with full output the system still does not charge...

Yeah, Volker, the rear shock look to be the same ones that I have on my '79. Taller than stock but also quite a bit stiffer. They soften a bit after a while, though.

Clogged emulsion tubes?

I've never actually seen or even read of a stator going bad in one of these bikes... I guess if yours is bad there's a first for everything!

Since it charged to 13.6v at a relatively low RPM, the rev test indicated a bad rotor.

As long as the stator's wires read below 1 ohm across all three, the stator is usually good. I've never actually seen a bad stator; the weak link is the rotor.

cb650 wrote:I have found a few roads around here that are open range and no matter the surface the fresh cow pies are the worst.

I've heard the term "slick as cow shit on a doorknob."

I had to try to find a rogue bull tonight after work so I figured I'd putt around the pasture on my '79 CM400. I didn't realize how big and rough the neighbor's pasture was, though (I found out tonight that it's 2 full sections). Worst part was when I ran out of gas in the bottom of a dry creek bed....

64,569 miles on my '79 as of today. EDIT: As best as I can tell, in '07 when I joined the forum I had around 43,000 miles on it. 21,500 miles in 5 years is about 4300 miles a year which isn't as much as I expected lol. EDIT: I just realized that it sat for two of the 5 years so that brings it up to ...

Volker_P wrote:

Pinhead wrote:...the Haynes manual didn't tell me to turn the engine backwards with a wrench while adjusting the cam chain.

Attention, you have to turn it forward!

That's the second time I've said backward when I meant forward. Duh!!

Sorry for not responding to this thread in such a long time; got a new job and moved so I haven't been on the 'net much since January. When I get some free time I'm going to build the "test circuit" that Lou used to design the ignition and I'll see if I can get the 4-prong system working. ...

I didn't know screw-in idle jets existed in the '79 (mine are press-fit).

You may have a set of carbs that has been modified by a previous owner. If so, I'd start by finding what size you need and cross-reference newer carbs to try to find the correct thread...

Any reg/rec that has been attached to a bad rotor is suspect. Either an open or short in a rotor has an uncanny ability to fry regulators. Once you get a new rotor and have a known good reg/rec (you may want to check out my "cheap regulator/rectifier" thread), I would bypass and/or augment...