Topic: High altitude 73 CB500 daily driver ( 5/20/17 update )

[riverfever]

I hate pulling the carbs off. I moved the needles with the rack on the bike. We've been getting hammered since I got home so I haven't done anything else.

[Desert Dan]

Pulling the carbs is my least favorite job, Ive done it so many times since I bought the bike Ive got the process down to a two hour job to get the carbs off torn down and back on the bike. When you did the needles on the bike did you have any issue getting the slides out of 2&3? It would be a huge time saver not having to pull the rack for the needles.

[Desert Dan]

I finally got ahold of the previous owner for some before pics of the 500
Here is how he bought it

Here it is after his restoration

And after I got ahold of it

You can see why I thought it would only need a quick tune up to get it back on the road, but I had no idea how much work I would be putting in to it when I bought it. I still need to rebuild the forks and replace the worn out fork gators but its 98% of the way there

[riverfever]

Dan...Cal was the one who originally suggested that I do it that way in the efforts of saving time. Getting those tops off the carbs (particularly the inner screws of 2 and 3) was a royal PITA. You cannot get a Phillips screwdriver on those. I ended up using a the bit from a multi-screwdriver carefully placed in the screw. I then used a finger to press that bit down and then used a 1/4" wrench to turn the bit. Worked great. Removing the slides wasn't horrible. It was definitely worth the effort. I hate wrestling with that stupid airbox and the boots.

[Desert Dan]

I took a look at doing that today but I didn't think of using the bit trick you described so I just left well enough alone. I cleaned my spark plugs with this nifty 80's spark plug cleaner I have laying around my shop, its this little black box that hooks on to a 12v battery, it basically sandblasts the plugs using graphite and does a half way decent job of cleaning them. I combine that with a little acetone and I can get 99% of the carbon off of the plugs. Im going to wait and accumulate a few miles on the plugs before I decide if I need to mess with my mixture any more, at the moment it seems to be running just right.

[Restoration Fan]

Sorry to hear you guys are having bad weather.  It's been over 80 hear for a few weeks. 

[Jerry Rxman Griffin aka MuthaF'er]

Sorry to hear YOU are having bad weather. 70's, sunshine, calm winds but the humidity is way up to 24% today. Now THAT sucks. I like our usual 15% much better. That even kinda eliminates mosquitoes. Aren't they the GA state bird ?! 

[Restoration Fan]

  Not where I live, Jerry.  It actually has been humid here.  But nothing a little wind therapy won't cure!

[Desert Dan]

   After cleaning the plugs Im getting a much hotter spark now and the bike has decided it wants to run lean  . It gets pretty hot now, and under hard acceleration I get a bit of backfire, under high load and low rpm I sometimes hear a little popping coming from the carbs. Im thinking I need to bump the mains up to 94's and bump the idles to 38's. It makes cense to me now that Im running lean as the 92's didn't give me an increase in power over the 98's. Besides that Ive now got 900 miles on the top end and it hasn't sprung a leak on me yet.

[Desert Dan]

    Long time no see every one, I haven't been posting much lately because I've been too busy riding the bike. Ive been doing a fair amount of work to the 500 trying to get the engine tuned just right. Last time I left off I thought I was running lean after cleaning my plugs, but after further testing I found my timing had slipped way off causing the engine to run hot. After much tinkering I found that all my timing issues were caused by the cheap diachi points I was using, it's just criminal that such junk parts are allowed to be marketed for these bikes. I put in a set of tech points and bingo, five minutes later my timing was spot on without having to do any shady modifications to get the timing right.
    This set me back on my quest to find the correct jetting for my altitude I had my #92 jets drilled out to 96's but haven't tried them yet. right now Im running #98 mains #40 slows and  I moved my needles to the second clip position from the top with a single needle shim, giving me the effect of half a clip position above the middle clip position.
I believe I am still running slightly rich as my gas millage is still somewhat poor, at an altitude of 8000+msl I get 37mpg and at 4000+msl I get 43mpg, I believe if I try #92 mains and #38 slows I may be as close to the proper jetting as I can get.
    I just finished doing the 1500 mile oil change after rebuilding the top end of the engine, Im glad to report there are still no leaks on the top end and my compression numbers are 150psi on all 4 cylinders using my cheap harbor freight compression gauge to check them. Ive been checking my valves and timing about every 300 miles to ensure everything is running smoothly. For the oil change I used BellRay EXL 20w50 mineral oil with a 1/3 of a quart of zinc ZDP additive. The BellRay oil seems to really agree with the engine as it seems to be quieter and the clutch no longer slips when taking off in first. I just ordered a bunch of parts to rebuild my forks and replace my unsightly fork gators. I also ordered new seals to replace the leaking ones behind the clutch actuator cover, driving air cooled vw's Im used to leaving oil spots where ever I park but I want the CB500 to be the exception. Ill try and take some good pictures of the fork rebuild to keep everyones interest. Besides that all I can say is Im having a blast riding the 500 every chance I can get and racking up the miles.

[HondaMan]

Sorry to hear the Daiichi bugs bit you, too! The only ones I have seen last at all were the ones I used to test my prototype Transistor Ignition back in 2006 or so. Since that removes all the loads, they lasted with no timing shift for 6 seasons before I did my rebuild. Then I put in new TEC, anyway. I'll probably never have to change them again?

How do you like rain riding? It's been so wet down here my shed is STILL full of water, now 7 weeks.
The garage got water last weekend under that big, black front that rained all Friday night, too. My bike is STILL where you last saw it, but at least it is dry!

[Desert Dan]

At the rate it's been raining it might not be a bad idea to fit floats and paddles to your 750 Mark. Ive been doing my best to avoid all the rain showers lately but I have been caught in a couple so far, one storm I got caught in dumped so much water I started to lose spark on my #4 cylinder. I believe the water worked its way in to the the spark plug cap and was allowing it to short to the cylinder head.
   Im taking a break from messing with jetting right now, its pretty darn close as it sits and Im beginning to over think it. My next focus will be upgrading the ignition system, Im thinking Ill save up for a set of dyna coils and one of Mark's transistorized ignitions. After that I think Ill sell a kidney or two so that I can afford a 4into1 exhaust .
   I just finished freshening up the front breaking system today with new pads, new brake fluid, and a general cleaning of all the different components. Im just waiting for my new fork gators to arrive and Ill be diving in to the fork rebuild within the next week.

[riverfever]

Over here we're supposed to have a bit of a break here these next several days.

[Desert Dan]

I went on a ride the other day with my buddy and his monstrous 1100cc Yamaha V-Star, we rode down to Deckers on the Platte and were going to ride on Foxton and county rode 67 to Sedalia but the river was so high it had closed all of Foxton so we had to turn back. It was a good ride though about 60-70 miles round trip. The bike ran great as usual, and I got a few good pictures of it at the scenic overlook on 126.




Ive noticed with my current jetting after a ride at lower elevation the bike runs smoother and the plugs have a better brown coloration, but on rides at higher elevations like the one the other day it doesn't have the same power, has poorer gas millage, and the plugs are black and sooty. Im hoping a set of dyna 5 ohm coils will give me better spark and compensate for the power loss at altitude. With the dyna 5 ohm coils which spark plug caps work best? The stock Honda resistor caps or should I go for a set of the lower ohm NGK caps?

[calj737]

My opinion: The higher you go in elevation out there, Dan, the worse your bike will run. If you're set up for 2,500-4,000' riding, then as soon as you cross 6,000' your carbs will begin running rich. Go to 8,000' or higher, and you'd best be pointed downhill to get home...

Chris (Riverfever) is suffering the exact same issues. He's running pretty darn close to perfect at 5,500-7,500, but as soon as he eclipses 8,000', here comes the soot.

He too is running Dyna S, 5.0Ohm coils, and resistor plugs. I don't think resistor caps will make much difference. These bikes with mechanical carbs just can't adjust the fuel and timing dynamically to meet the ever-changing landscape where you live. I have told Chris, find a place of happy compromise and live with a stumble at 1,000' and slight bogging at 9,000'.

I've got to believe Mark has the best advice and input for your region based upon his expertise and experience of being a resident. I just hope my opinions are not far off.

[SOHC4 Cafe Racer Fan]

Cal is spot on. With those altitude ranges, you need to adjust your carburetors to a happy medium that will work in the sweet spot range where you ride most.  Unfortunately, you cannot lean out the mix on the fly when you ascend.  EFI seems to handle the changes better, but has it limits, too.

Your buddy with the monstrous VMax probably wished he had your tossible middle weight bike when you got into the twisties. 

[riverfever]

I was just there there other day Dan! I have never seen the river like this before. I made it to where they've started putting in new asphalt and turned around to head back to Deckers but saw several houses under water. The day after I went they shut the river down.

Just for reference...yesterday I went for a ride. You and I are pretty darn close in altitude. I wanted to run over to Cripple Creek. I have a slight boggle at just a hair above 1/4 throttle where the motor pops ever so slightly. Give it just a hair more throttle and life is good. Back off just a hair and things are fine too. Cripple Creek is probably 9600ish' but there's a real good drop down into town and it's gotta top out at a bit over 10 before the final descent. Well the closer I got to that spot the worse things got at that 1/4 throttle. It was really popping and losing power the higher up I went. I suspected it was doing this because it was rich at that point but didn't know for sure. I was worried about dropping #4 so I turned around and headed down again and within a few thousand feet everything was back to normal. Then I decided to run down to Colorado Springs and see what happened at that same throttle spot (CS is around 5500'). By the time I got down there the motor didn't pop at all. So it was interesting only in that it confirmed some things for me. Within an hour I changed 5000'+. Sometimes I wonder if I should have a different bike but a difference of 5000' is huge. I believe Cal is right and I think I'm real close to being at a compromise with the carb settings.

[Desert Dan]

Right now I'm still running the stock points and coils but I want to upgrade to the dyna coils and Mark's transistorized ignition in oder to squeeze out all the performance I can out of the ignition system. The stock spark plug boots are something like 10k ohm's while the ngk's are 5k ohms, so i was just wondering which set of boots work best with the 5ohm dyna coils.
   I've been batting around the idea of upgrading my 4into2 exhaust to either a Carpy or Lossa engineering 4into1. I've heard mixed reviews on 4into1's on the 500's as they can cause more trouble than they're with if they aren't designed correctly. I'm also wondering if the 4into1 will flow any better than the 4into2.
   I think I'm being a little too picky with the jetting because I don't have any stumbling at idle or bogging at WOT. I just feel like the performance isn't there for an engine that's been freshly rebuilt with ported,polished, and decked heads.

[brett_bike]

River fever and DesertDan,

We should get the 500's together and compare notes.

I've been chasing a stumble since installing the MotoGP werks exhaust. It's better but I'd like to see what others are experiencing.

[riverfever]

I would love to get together and ride and see both of your bikes. I'd also love for someone else that rides a 500 to ride mine and see what they think. I think it's pretty close but this is my first bike so I don't know much better. Brett where are you? Is there a place we all could maybe meet up?

[brett_bike]

I'm in Arvada and my riding is usually around the metro.  I've wanted to ride out 285 and over Hoosier pass to Breck to see how altitude affects my settings, but with the two little ones I haven't had much time to myself to get a good ride in.

[riverfever]

With Dan in Evergreen I wonder if we could meet up for a ride and lunch in Bailey area??

[Desert Dan]

I'm right in the middle between you two, I'd say Sedalia might be a good mid point between Woodland park and Arvada. Either way I'm game for meeting up regardless of distance.

[calj737]

Dan - you'll find (especially after riding Chris' bike) that the 4:1 exhausts are more free flowing than stock. Usually, these systems trigger the need for a larger main. If your a tad rich, it might be a solution. If you're already lean, it will worsen that situation.

As for ignitions, I believe most use NGK 5.0 Ohm caps with the Dyna coils.

When you 3 get together, the rest of us need lots of pictures to admire!

[Desert Dan]

I went on another ride with my buddy and his v-star, in total I did roughly 210 miles today problem free on the 500. I met my buddy in Castlerock where upon we took back roads all the way down to the springs and took a cruise through the garden of the gods.

I also think Ive fine tuned my mixture to an acceptable level. When I got home from my ride I drilled a extra holes in the baffles of my Jardine 4into2's, the exhaust note is slightly louder but after a quick test ride around town all my plugs turned a nice dark brown. I think Im now just slightly on the rich side at high elevation and will have the correct mixture or be slightly on the lean side at lower elevations. I also ordered a set of dyna 5ohm coils to add to the bike to improve my spark and performance.