Topic: Dialing in the CB500, input request

[JBMorse]

My 500/4 engine is back together, and I'm in the final tuning stage (finally!!!). I'd love some help with the tuning.

Here's the status:
CB500 jugs honed, new rings
all new valves, valve guides on one side,
 complete valve job (thanks MReick for his awesome work!),
all new top end gaskets.
Last time I checked compression it was excellent on all 4 cylinders.

The carbs have been apart and cleaned, here are the settings:
Stock CB500 carbs 627B with stock 100 mains and #40 pilot jets. Idle screws 1.5 turns out, needle clip in the middle, carbs all synchronized using my trusty carbtune.

I've got a good UNI filter and a cruddy old Mac or something 4 into 2 exhaust.

Here's what's happening: I think the bike is rich across the whole rev range. It won't idle or run with any choke. It seems low on power and the throttle response is not so good. Riding today I noticed when I go to downshift, if I try to blip the throttle there is often nothing there. Twist the grip to blip and there's just a gasp.
It also sounds "gargly" to me, not as smooth as I remember (but it's been six years so feel free to ignore that....)
Finally, it's not very smooth. It's much buzzier than I remember at 60 MPH.
The plugs did look very sooty, but I re checked the timing and they're better now, still not great.

I've done all the 3k mile tuneup stuff. Tonight I pulled the carbs off again, and everything looks clean and orderly.
Here is what I'm thinking: Take out all the main jets and needles and replace them with my original Khein brass. I'm not sure this would help because I rode like 15,000 miles with the stuff that's in there now.

Any ideas on what to check? I'm sort of lost. The bike runs and goes, just not at its best.

[JBMorse]

Ah yes I should explain. I first bought this Honda in 2008 as a semi running project. At that time I rebuilt the carbs with some aftermarket kits, keyster or kl, can't remember. I didn't know about the bad quality of the brass parts at the time.
Well after a couple years riding around and a summer long trip, the Honda was parked due to a first gear problem, and I've only recently put it back together.

So the top end rebuild is recent, and I also did brand new oem gaskets in the carbs when they were off.
I like the suggestion of new plugs. It would be good to get a fresh start there.
Tonight I checked everything and put in the original Keihin needles, clip in the middle. When I get it all together I'll try the clear tube float check. Sounds helpful, I've been just measuring the heights with a metric ruler!

[alacrity]

Show us your spark plugs...

[JBMorse]

Thanks for the tips guys. I haven't had much time to work on this, but I've done a couple of things since I last posted. New plugs, gaps checked, and valve clearances, points and timing, and cam chain were all checked. And, I opened the carbs back up, checked the passages, cleaned everything, checked float heights, and swapped the original Keihen needles back in. Everything else was stock. I also adjusted the idle screws to 1 turn out.

So after all that it ran better, but is still showing the same symptoms. Rough idle, low on power (though it got better after the adjustments), and it still never wants choke, even when it's cold. And poor throttle response pretty much through the rev range.

Things I have yet to do: check the float levels by the clear tube method (didn't have the right stuff for this) and replace points. I'm running the best points I had. The 1-4 set is a cheap aftermarket one, and the 2-3 set is a used original but a little pitted. Soon I'm going to buy a brand new oem set.

Here are what my plugs look like today. Besides the float level check and new points, anything else I should look for?

Edit: I forgot to answer cal's question. For The valve job by MReick (whose work is fantastic btw) we used standard sized valves. They're aftermarket valves by Vesrah or something like that. He also did new valve guides on the exhaust side.