Topic: '72 CB500/4 : Project WTF was I thinking!? ...Time for some updates!

[Scott S]

 Heck no...they're long gone. I think I did sell them, so somebody wanted them.

[streak09]

Bike looks great! Some good work goin on there. How are those K&N's workin out for you? Did you find a dual flange filter that matched the distance between carbs? looks nice.

[Scott S]

 Yes, those are dual flange and are listed to fit the `81-82 carbs. I've only had the bike idling in the garage so far and haven't ridden it yet. The carbs seem very responsive and snappy, though. I don't think I'll have too much trouble dialing them in, but I have some fuel leaks to fix first.

[Stev-o]

Congrats on firing her up! Where are the fuel leaks? I've had a couple bikes leak after a start up but worked it's way ok after normal running. During short idle testing, I sometimes turn the petcock off for a bit to prevent fuel from leaking if a float is sticking.

[Scott S]

 I know I have a leak around an Idle Mixture Screw O-ring. There are some leaks around the bowls, too. I have some needle jets, gaskets and O-rings on order.
 I think I'll make a jig and run some fuel through them while they're off the bike and make sure I get them all.

[Stev-o]

Check your float bowls too. I had one with a cracked overflow tube...

[scottly]

 He mounted the Pamco circuit boards on the 650 plate. Since he used some existing tapped holes, the timing was slightly retarded. We had to file the points plate a little to get it to full advance.

Is that the 650 plate I sent you? If so, another thumbs-up goes to geminimotors, who originally donated the plate in the interest of science.

[Scott S]

 It is! I still need to file the adjusting slot just a little more. The timing is currently on the left of the two II hash marks at full advance. Maybe just the width of the line is all.
 Pete used the existing threaded holes to mount the boards rather than drill and tap new ones. That placed the transistor a little too retarded. It would probably be fine right where it's at, but it would bug me to death knowing that it's retarded 1/2 a degree!

[Scott S]

 The chain finally showed up. I went with a 104 link (stock CB650) and a 40T rear sprocket. If the chain stretches too much over time, I'll have to remove a link. I'm on the second to last mark on the swing arm. The CB650 has a longer swing arm than the 550. It's fine for now and a few more adjustments, though.

 That enabled me to adjust the rear brake, get the sprocket cover back on, and change out the charging rotor (now that I can put the engine in gear and hold it with the rear brake).

 The 400F pegs do, indeed, work with the 650 shift shaft.

[Scott S]

 We also worked on mounting the Hall Sensor for the speedometer drive.

 My Dad whipped up this neat bracket, and we used longer bolts from the hardware store.


 I used a little silicone as well as the C-clip to attach the magnet to the bracket.

[Scott S]

 While I replaced the idle mixture screw O-rings, needle jets and float bowl gaskets, Dad fabbed up another simple bracket to mount the pick-up for the sensor.

 I found out that the carbs have 102.5 mains in them already, and I think stock is 100. I ground back the tabs on the idle mixture screws and set them at 2.5 turns out, versus 2 1/4, which is what the manual lists. Maybe that's why the carbs sounded so crisp! And no more fuel leaks. Yay!

 Anyway, back to the sensor....

[Bankerdanny]

Nice job on the sensor. you wouldn't know it didn't come from the factory that way.

[Retro Rocket]

I wonder if the 2 longer bolts and the plate  will unbalance the wheel...? 

[Scott S]

 Nope, not that I could tell on a short test ride.

 The speedo works, too, but I still need to enter the proper tire diameter and change it to MPH.

 I also installed a 10K ohm resistor inline on the tach wire to get the signal down.



 That got the tach reading correctly, but it has a little noise in it. The bars would jump up one or two bars over the actual idle speed. We twisted up about 10 feet of wire in my drill to make a homemade capacitor and prove a theory. That took ALL the noise out of the tach signal as made it steady.
 I tried wiring in a capacitor from Radio shack, but the smallest one I could fid didn't remove all the noise. I have half a mind to re-attach the coiled wire and just hide it under the tank somewhere.

[Retro Rocket]

Nope, not that I could tell on a short test ride.

Just be aware that being out of balance may not show up until a certain speed, it has to reach its resonant frequency before you'll feel it, it may not happen but generally putting the slightest bit of weight off center will put a wheel out of balance....

[Scott S]

 The bolts were just long enough to fit through the magnet plate, which is 2.5mm thick and very small. Any extra threads on the other side were trimmed off flush with the nut, just like the stock bolts.
 This unit weighs very little and is close to the center of the wheel, but I'll keep that in mind and see what happens at higher speeds.

[Godffery]

Some pretty nice work there.!

Currently I'm punching out a CB550 motor to 600cc for a customer; I would have rather just dropped in one of these 650's.   8 /

[Scott S]

 I took it for a short ride yesterday, just up and down the block.

 The clutch still needs some adjustment, and maybe the idle mixture screws. It's not quite as crisp rolling off the throttle as I'd like, but hard to tell with the clutch out of adjustment. It pulls hard after it gets moving, though.
 
 I'm supposed to pick up my seat today. I'll fine tune the clutch and carbs and see how she feels. No leaks so far. I may need to add another capacitor inline or a larger one to get a little more of the noise out of the tach signal. I'm getting close, though....very close.

[Scott S]

 Got the seat back from the painter today. Re-mounted the seat pan. I think I might have to come up with a better form of attaching the seat to the frame. Our method works but is a PITA. It's really a 2 man job. Luckily, it only has to come off about once a year for valve adjustments.

[Scott S]

 While the K&N filters respond well to carb adjustments, they interfere with the side covers. The RH side is worse than the left. I'll have to re-examine this. I could run Uni pods, but I'd rather make these work.




 Speaking of carb adjustments, we were able to tune the Idle Mixture Screws and get rid of 99% of any hesitation, popping, etc. at idle and low speeds, especially once the engine is warm.
 I still think it's too lean on the top end. This sucker is STRONG and pulls HARD, but I don't like the way the plugs look. Below is #1 on the left and #4 on the right. Oddly, #1 looked like #4 earlier, before adjusting the IMS. I don't know why it's so clean here...odd.
 The bike has 102.5 mains in it (stock is 100). I have an assortment to choose from: 110, 112.5, 115 and 120. I think I'll try the 112.5's next.

[Scott S]

 Another thing that worked better after a little heat in the engine and carb tuning was the tach! I'm getting almost zero noise in the signal now.

 I still need to program the speedo and make a change on the main jets, then figure out what to do about the side covers. Other wise, I'm ready to put some miles on this sucker!
 Here she is with her new look!

[rb550four]

That 500 looks fantastic! Nice job!

[Godffery]

You could trim the side covers like we did on this one:
http://www.vinmoto.org/gallery/v/VinMoto-Garage/album03/Godfferys-Garage-123/Thomass+Cafe+project/TTCB+033.JPG.html?g2_imageViewsIndex=1

[Scott S]

 That is an option. You have the single pods and I'm running the dual throat filters. I do have a couple of extra side covers....Hmmmm....
 Uni Pods are an option, too.

[Godffery]

K&N's are the BEST filter on the market, I would stick with them.