Author Topic: High altitude 73 CB500 daily driver ( 5/20/17 update ) (Read 32806 times)

calj737 · « **Reply #50 on:** April 26, 2015, 04:29:02 AM »

You could have saved the time and money and simply refreshed your current boots. Winter Green oil and water mix, boil the carbs in a pot of that for about 15-20'. Presto! Supple like your newborns backside

It's odd to me that you're running lean (notwithstanding the vacuum leak) with 100s. Even 98s would be too lean in my opinion. You're at elevation, much less O up there, right? Should be the opposite and make you rich and not lean. I'd think you'd have to drop closer to 90s to reduce fuel sufficiently for a decent AF ratio. But-

If you ride at lower elevation during your travels, you're going to be too lean at say 1,500-4,000 feet of elevation once the O recovers to normal aspiration levels. And Lord help you if you dropped down near sea level- This static tuning of carbs is the only misgiving about them if you live in moutainous terrain and ride up and over and down again for the best scenery. Your bike will run well, then bog, then cough, then be healthy.

You might Ping Hondaman for some thoughts on a good all-around tune configuration for your geo. I'm certain he's dealt with this and has unique insights and invaluable recommendations for you.

Desert Dan · « **Reply #51 on:** April 26, 2015, 11:52:19 AM »

Im also perplexed by the lean condition, I did a few plug chops and the plugs came out a grayish white indicating the lean condition also supported by some what elevated engine temps. The elevated engine temps could be caused by the extra friction of the rings breaking in. I would have gone for the restoration of the air box boots as I have read many times about the wonders of winter green oil but the problem is not a lack of suppleness with the boots, the last owner of the bike tore up the ends of the 2&3 boots so that they don't fit exceptionally well on the carbs, 4into1 wants $16 a piece for the 2&3 boots or $60 for the set while DSS only offers the full set for $60 as well. I don't need the full set but at $35 I might as well replace all 4 and keep the old 1@4's as spares. My theory on the lean condition is that the head porting causes the engine to draw more air through the carbs making it so the current mixture set up cant supply enough fuel to make the proper AF ratio, combined with the torn and ill fitting boots letting air by the engine runs lean. The engine isn't heating up to dangerous levels and I believe my altitude is keeping the mixture near the proper ratio but its still not producing the pretty brown plugs that I prefer.

calj737 · « **Reply #52 on:** April 26, 2015, 11:54:06 AM »

Pretty decent synopsis. The higher engine temps occur from riding, or tuning in the garage?

Desert Dan · « **Reply #53 on:** April 26, 2015, 12:17:41 PM »

I haven't measured the temps yet except for the old spit and sizzle method but it gets hotter just idling than riding, which doesn't tell me much since it's air cooled. Using the valve cover end caps as a gauge when it idles for more than a few minutes I can't even touch them but after riding i can hold my hand on them for a couple seconds before it gets uncomfortable.

calj737 · « **Reply #54 on:** April 26, 2015, 12:48:55 PM »

With no air circulating, it will be much hotter.

Desert Dan · « **Reply #55 on:** April 28, 2015, 04:26:10 PM »

I put the new 98 jets in the carbs this afternoon and holy smokes what a difference they made, the bike really woke up and took me by surprise when I went to accelerate to highway speeds. I have to admit my earlier diagnoses of running lean was due to me reading the spark plugs before they had time to build up enough carbon on them for a proper reading, I checked again before I put in the new jets and they were all looking pretty rich. Im thinking I could safely go another size smaller on the jets but Ill need to do a couple plug chops to see where the mixture is at this point in time. Im also quite pleased to report that 75 miles in to the ring break in that there are no oil leaks and the head and base gasket are holding up nicely.

calj737 · « **Reply #56 on:** April 28, 2015, 05:43:13 PM »

Loud round of cheering!!!!

HondaMan · « **Reply #57 on:** April 28, 2015, 06:49:41 PM »

Quote from: Desert Dan on April 28, 2015, 04:26:10 PM

I put the new 98 jets in the carbs this afternoon and holy smokes what a difference they made, the bike really woke up and took me by surprise when I went to accelerate to highway speeds. I have to admit my earlier diagnoses of running lean was due to me reading the spark plugs before they had time to build up enough carbon on them for a proper reading, I checked again before I put in the new jets and they were all looking pretty rich. Im thinking I could safely go another size smaller on the jets but Ill need to do a couple plug chops to see where the mixture is at this point in time. Im also quite pleased to report that 75 miles in to the ring break in that there are no oil leaks and the head and base gasket are holding up nicely.

Dan:
ride by me this weekend if you want: we can do some tuning!
Call me for my address, if you don't have it. I'm in Lakewood, lots closer than the shop where you came earlier.

Desert Dan · « **Reply #58 on:** April 29, 2015, 02:55:22 PM »

Thanks Cal! And it would be great to get a day of tuning in Mark I'll email you to set up the details. I got my synchrometer on the carbs today and got them dialed in so they have almost the same exact readings across the board, it is so much easier to balance the carbs when all the cylinders have good even compression.

Desert Dan · « **Reply #59 on:** May 01, 2015, 06:01:38 PM »

So I did the 100mile break in oil change and tune up the other day and everything is looking good and kosher engine wise. There was a good amount of magnetic sludge stuck to the magnets on the oil filter and magnetic drain plug indicating good ring break in, in total there was probobly 3-4 teaspoons of sludge between the oil pan and magnets. I didn't see much in the way of black rubber sludge from the break in of the new cam chain slipper and guide but I suppose it will take a little more than 100 miles for those to wear in properly. I re-tuned the carbs since I had the gas tank off just so I could get more control of the rpm using the idle adjust screw on the carb rack, I then went on a quick 20 mile jaunt. I am tickled pink by how well the bike rides after all the work Ive put in to it, the engine is so smooth the cheap Emgo mirrors I installed don't vibrate enough to make the view in the mirrors blurry until I get over 6k rpms. What are everyones thoughts on the second oil change? I was going to do it at 1500 followed by every 3k after that.
Just for fun I took a few gratuitous driveway pictures of the bike. I don't think it looks half bad considering many of the cosmetic parts came off of wrecked bikes from the local bike yard.

This is my syncing set up for the carbs

HondaMan · « **Reply #60 on:** May 01, 2015, 07:14:04 PM »

What a beauty, Dan!
Looking forward to actually 'touching' it. Come on Sunday? (Shelves are on Saturday.) I'll be here after "church hours", about 2 PM or so.

SOHC4 Cafe Racer Fan · « **Reply #61 on:** May 01, 2015, 11:30:18 PM »

That's a beauty, Dan.

Desert Dan · « **Reply #62 on:** May 02, 2015, 11:53:18 AM »

Thanks for all the kind words everybody, I definitely couldn't have gotten the 500 put together and running so well just in time for riding season without the help of everybody on the forums. I'd also like to Thank Mark aka Hondaman for all the help and knowledge he gave me the head he worked on came out beautifully and is working great. I'de also like to thank Andrew K who is a member of this great forum and gave me the great deal on the 550 head, cam shaft and valve cover. And Mark Im excitedly looking forward to bringing the bike down to you sunday so long as this nice weather we are having holds up.
This morning was a gorgeous day in Colorado so I took the 500 out for a 60 mile round trip cruise to Red Rocks park and amphitheater where I took a few more beauty shots amongst the amazing rocks of the Morrison formation

HondaMan · « **Reply #63 on:** May 02, 2015, 06:49:50 PM »

Next you'll have to get shots at Milner Pass, top of Mt. Evans, and all along my favorite, the Million Dollar Hiway!

Desert Dan · « **Reply #64 on:** May 02, 2015, 07:16:22 PM »

Thats hopefully the plan! I want to ride this bike all over Colorado this summer with a few multi day trips to the furthest corners of the state mixed in. Im starting out with short trips to build up confidence in my riding ability and my confidence in the bikes reliability. In my VW bus if I take it on a trip further than 100 miles one way I usually toss a to-go tool box in the back incase of breakdown, but storage space in the bike is somewhat more limited

.

HondaMan · « **Reply #65 on:** May 04, 2015, 05:15:19 PM »

Dan's done a GREAT job of bringing this poor, abused 500 back to life. It looks better in real life than in the pix, and runs fine!
Y'all ought to see it someday, it's cool!

SOHC4 Cafe Racer Fan · « **Reply #66 on:** May 04, 2015, 05:23:14 PM »

Quote from: HondaMan on May 04, 2015, 05:15:19 PM

Dan's done a GREAT job of bringing this poor, abused 500 back to life. It looks better in real life than in the pix, and runs fine!
Y'all ought to see it someday, it's cool!

Heck yes! That's a unique re-spray of the tank and side covers. I like how the inset brown flows from the tank to the covers. Very 70's colors.

Desert Dan · « **Reply #67 on:** May 04, 2015, 08:48:17 PM »

I had a great time at Mark's on Sunday, I am in totall awe with the depth of knowledge he has with all things motorcycles. He has a very impressive collection of vintage Hondas and I even got the privilege of seeing his famous 750k2. Mark gave me several pointers on the cb500 which I imediately put in to use when I got home. I was really pleased to learn the proper routing of the clutch cable so that it no longer hangs out freely and even has a better and smoother pull now. Mark noted when he gave the bike a once over my spark advance springs were worn and weak and advancing the ignition timing too early, He prescribed cutting off the end hooks and bending a new end on to the spring to compensate for the wear.
Here is what the un modified spring looks like

Here is the spring after being shortened one winding.

This method was fairly easy and straight forward as the advance kicks in around 3000+ rpm as compared to the previous 2500-rpm. The only issue I ran into in doing this process to the advancer was it through my ignition timing way out of wack. It's most likely caused by a mixture of the shortened springs, an ill fitting points base plate, and the cheap diatchi points. I got the timing set correctly first statically timing the ignition then dynamically timing it. As it sits the main points plate is maxed out in adjustment and in order to get 2/3 timing correct I had to wallow out the sliding grooves in the 2/3 base a significant amount. The ignition is timed correctly now but Im not pleased with the compromises I had to make with the points plates, I ordered a used ignition off ebay that includes the spark advancer, points plates, points, condensers, and wiring all for ten dollars. I plan on mix and matching bits and pieces between my ignition and the used one I ordered until I can get my timing set with room on the plates to adjust further if needed later on. Ill be keeping my current spark advancer as when I had my engine apart I was able to confirm the advancer's TDC mark was right in line with the engine's true TDC.

HondaMan · « **Reply #68 on:** May 04, 2015, 08:57:29 PM »

If it pulled the timing toward the 2-3 (which is what it sounds like) then the inside of the points cam is also worn, or the shims at the base are long-lost (they were plastic) and the whole cam wobbles a little bit. I kinda suspected this when you mentioned having to "dial-in" the advancer back when you reassembled the engine, but I knew if this spring-shortening came out "way to the right" like this, the cam issue would show up. You can make new shims from sheet brass, if the ID of the points cam isn't torn up too badly - but, judging from the other problems you inherited with this bike, I would bet it was never lubed in its life, cauusing too much ID clearance now.

--but, you're no slouch in the wrench room! I know you can figure this one out.

Desert Dan · « **Reply #69 on:** May 04, 2015, 09:19:19 PM »

Thanks for the vote of confidence Mark, I would bet your'e right on the mark with the cam wobble. Ill compare and contrast my current advancer to the one Ill receive from ebay. If the ebayed advancer is good shape Ill just switch that one in, if not Ill just go ahead and make those brass shims. As far as the plastic shims you mention are those on the base of the advancer where the locating knob is or are they on the pivoting arms of the advance mechanism? On my advancer there are plastic caps on the inside of the pivot arms but the end of the mechanism that mates with the crank is just bare metal.

HondaMan · « **Reply #70 on:** May 05, 2015, 02:13:41 PM »

The shim are (were?) located on the bottom base pin, same diameter as the cam. They always had none, or 2 or more, because as soon as one is left, it munches it right up from movement. Most are gone these days. The Twins really suffer a lot from this, as they were styrene plastic and warped from being at the top of the engine, with predictable results!

Desert Dan · « **Reply #71 on:** May 05, 2015, 09:57:56 PM »

Hmm thats a vexing development, one of the problems of diving in to an incomplete project is you never know about the small things you're missing until some one points them out to you. When I was modifying the advance springs I carefully inspected the "peg" on the bottom of the mechanism and the hole it is inserted into on the crank for wear and there was non visible to the naked eye. There didn't appear to be any wear on the base of the mechanism either as the machining marks are still clearly visible on the base, with that said there is a certain amount of wobble to the advancer cam when the bolt and slotted nut are not installed and holding it in place.

Also Mark, I read through your entire build thread you did for your 750 in 2013, after which I did some searching on E-bay and came across this
http://www.ebay.com/itm/13-NOS-CB750-Valve-Guides-Sandcast-K0-K1-12027-300-330-12035-300-300-/251922470916?hash=item3aa7bfd804&vxp=mtr
It would appear to be early K0 K1 valve guides, which if I understood your explanation of 750 valve guides correctly means they are made of your highly prized stellite. There isn't much of a description the title just reads, "13 NOS CB750 Valve Guides Sandcast K0 K1 12027-300-330 12035-300-300". So I imagine there would have to be a bit of a discussion with the seller on whether or not they are stellite guides for the 750.

Desert Dan · « **Reply #72 on:** May 06, 2015, 10:11:53 PM »

I managed to get a few test rides in today in between rain showers to see how the shortened advance springs worked, sadly they caused a flat spot in the 0 to 3000rpm range. This creates a bit of a wall where the engine doesn't develop enough power to accelerate the bike past 3000 rpms unless I coax it along with the clutch. Though on the bright side it does seem to make the engine run smoother from 4000 to 5000 which is where I do most of my riding. I think when I get the used 550 ignition Ill try swapping a shortened spring for a stock spring so I can keep the new found smoothness while losing the low rpm flatness.
I also got the new air box boots from Germany so as soon as the new jets arrive Ill install those. I could only find #92 jets online, I would have preferred 96's or 94's to replace the 98's Im currently running so hopefully I don't go from too rich to too lean. If I end up on the lean side Ill either drop a needle position or take the 92's to this harley shop down the road from me and see if the guy there has some micro bits to drill them out to 94's or 96.
There's a vintage bike get together going on tomorrow in Denver that I just learned of so Im going to try and ride the 500 to it. The flat spot shouldn't be an issue as it's easily overcome with the clutch but it has been raining off and on for the past week which would be the only thing preventing me from going. If I do make it Ill see if I can get any cool shots to share on here.

HondaMan · « **Reply #73 on:** May 07, 2015, 11:12:55 AM »

If the carbs are still running rich, the flat spot will be "stronger" with the cut-back springs because it is too much fuel to burn. Once you get that air filter and the mix right, you may well wish to 'revisit' this spring issue, as it will make a nice difference.

I wouldn't spend too much time and effort on those jets, either, until you get the air filter right-otherwise, you'll be right back on this 'page' again after all that work, once the engine can breathe easier.

Desert Dan · « **Reply #74 on:** May 07, 2015, 09:25:46 PM »

Mark your knowledge of the intricacies of the Honda motorcycle astound me, I re-jetted the carbs with the 92's and the flat spot seems to have disappeared. I didn't get a full test ride in as it rained all day today up in the mountains but I did take the bike up and down the driveway and I see any signs of the flat spot.
Since it rained all day I was unable to go down to Denver to check out the vintage bike "show", but I did get the new jets in from 4into1. I spent most of the afternoon re-jetting the carbs, putting on the new air box boots, and fixing a small fuel leak. The fuel leak was caused by a pooched o-ring on the 1-4 fuel T and would drip 1-2 drops of fuel a minute. I also took Mark's expert advice and ditched the unifoam air filter and made my own. I simply bought a circular paper Fram air filter and cut it down to size to fit in the unifoam's plastic box, altogether the modification cost me six dollars and I have enough filter element left over to replace the current filter once it gets used up. Hopefully there will be an hour or two of sunlight tomorrow to go on a proper test ride and see how today's tune up worked.

News:

Author Topic: High altitude 73 CB500 daily driver ( 5/20/17 update ) (Read 32806 times)