Author Topic: High altitude 73 CB500 daily driver ( 5/20/17 update ) (Read 33093 times)

Desert Dan · « **Reply #25 on:** April 02, 2015, 06:11:32 PM »

Ill see what I can do, since the valves are installed its some what difficult to get a good picture of the port's shape.

Desert Dan · « **Reply #26 on:** April 03, 2015, 10:16:16 PM »

Ive been unable to find much in the way of info on the installation of the cam chain tensioner, from what I can visualize in my mind when installing the tensioner will keep the cylinders from sitting on the block until the head is bolted on forcing the tensioner assembly to "bow". If some one with experience rebuilding these engines could chime in and describe the installation process I would be extremely grateful. If all else fails Ill remove the pistons and try dry fitting everything to see how the tensioner is supposed to fit.

goldarrow · « **Reply #27 on:** April 03, 2015, 10:30:15 PM »

Recommend that you download HSM here's the page you need

Make sure tensioner is seated properly when pushing the cylinder block down, drop oil pan and see from bottom.

Desert Dan · « **Reply #28 on:** April 04, 2015, 11:06:39 PM »

Quote from: goldarrow on April 03, 2015, 10:30:15 PM

Recommend that you download HSM here's the page you need
Make sure tensioner is seated properly when pushing the cylinder block down, drop oil pan and see from bottom.

Thanks, I actually had the HSM printed out and in my shop, I was just on a roll assembling everything and was working out of the clymers because everything was going together smoothly up to the point when I discovered the chain tensioner wouldn't seat properly with the head installed. I tried for a couple hours to get the tensioner installed without removing the freshly installed head and cylinders but there was no possible way to get it to seat properly in the case. I could get the adjuster nut and fastening bolt lined up fine but it wouldn't be seated or I could get it seated and there would be no way to get the adjuster bolt through the cylinder block hole. It just seems to me the distance from the slot in the case to the adjustment hole in the cylinder block is about .75 inches shorter than the distance the from the bottom of the tensioner to the adjuster bolt.

Greggo · « **Reply #29 on:** April 05, 2015, 11:48:15 AM »

Nice work on the bike so far, and nice van! My dad's been working on VW's for about fifty years.

HondaMan · « **Reply #30 on:** April 05, 2015, 10:57:25 PM »

Not the best pix, I'm afraid!
Here they are, though. I think the lighting in the garage wasn't good enough for my camera to full-field focus that day.

This was after the face mill, but before the final finish. The tool marks can be removed with 80 grit emery paper if you do yours to completion, use your fingertips in there. The small sanding drums on Dremels will sorta work, but they don't follow the contours very well.

Desert Dan · « **Reply #31 on:** April 06, 2015, 07:11:04 PM »

Thanks Mark, I couldn't get very good pictures of the port job with the valves installed and like you suggested I went in and finished up the intake sides with 80 grit then polished smooth the exhaust sides followed up by a thorough acetone and q-tip cleaning.

Thanks Greggo, Ive been working on old air cooled VW's for about 8 years. The bus was my very first project that I built when I was 15 and has made transitioning to the Honda engine pretty easy.

SOHC4 Cafe Racer Fan · « **Reply #32 on:** April 06, 2015, 11:00:49 PM »

Pretty decent shots when you enlarge the image. Thanks, Mark!

Desert Dan · « **Reply #33 on:** April 08, 2015, 01:54:01 PM »

Ok so I did the dry fit of the cylinder block and head with the tensioner installed, some how the little m6 tensioner bolt is able to withstand the pressure of the head and cylinders forcing the tensioner in to place. Installation was pretty easy without pistons and gaskets but it will make the actual process of assembly a bit more of a PITA.

When properly seated the tensioner keeps the cylinders about half an inch off the block

Initially there was barely enough of the studs sticking out to get the head bolts started but they slowly drew the cylinders down on to the case

Everything installed and the assembly lightly torqued down

Hopefully Ill have the replacement bits in this week and Ill have the engine together by next Monday.

Desert Dan · « **Reply #34 on:** April 15, 2015, 11:42:33 AM »

I have run in to another considerable road block, I got the replacement head gaskets and I assembled the top end with the cam chain adjuster installed correctly this time or so I believe but..... I cant get the adjuster bolt to spin clockwise or counter clockwise and something is binding in the engine making it difficult to turn over. The spark plugs aren't installed so its not compression keeping it from turning over and the cam chain itself is not binding up so i believe the issue is the adjuster itself is binding on something. The motor turns over well enough for about 340 degrees then I can feel something rubbing for the last bit of rotation but its still stiff enough where the kick start lever doesn't have enough torque to turn the engine over at all. Here is a somewhat grainy and out of focus picture of the cam chain adjust in it's slot in the engine case.

I can see the adjuster making its way up to the base of the cylinder block but I cant see any thing that it might be binding, the adjuster worked fine prior to installation and I am currently letting my nerves cool. I want to fix this issue WITHOUT pulling the head and ruining another gasket set. Im in desperate need of advice I have most of today and tomorrow free if more pictures are necessary.

Desert Dan · « **Reply #35 on:** April 15, 2015, 11:47:00 AM »

Here are some pictures of the latest assembly of the top end so if you spot some critical error I may have made durring installation let me know.

Desert Dan · « **Reply #36 on:** April 15, 2015, 02:36:47 PM »

Never mind I figured out the issue and fixed it, I had a mild brain aneurism though fixing it. If you notice on the 4th image down on my last post the cam chain guide was installed backwards so I had to un-torque the head separate it from the cylinders a 1/4in and reposition the cam chain guide. Im hoping Im lucky and the head gasket holds even though I torqued it once the head separated from it cleanly and there was no damage to it. With the guide fixed the engine now turns over freely and the adjuster works again so now I can dial in the cam and hopefully get this spiteful thing running.

Desert Dan · « **Reply #37 on:** April 21, 2015, 08:32:06 PM »

Im beginning to think this bike is cursed or some sort of jinx, I got the engine all put back together and the darn thing refuses to start. The issue appears to be the engine not getting any fuel, so I dropped all the carb bowls and cleaned out the jets and passages with carb cleaner but it is still not getting gas to the cylinders. I rebuilt the carbs a few months back and had them tuned and working well prior to the top end rebuild. Ive got good spark to all four plugs. Prior to the rebuild I had the ignition timing spot on so I didn't think it was necessary to re-time it for the first start, but Ill check and or adjust that tomorrow.

I spent an entire day measuring the cam with my dial gauge indicator and I couldn't get the hang of it so I decided to use the stock cam sprocket for now and revisit the adjustable sprocket later on down the road. I set up the cam with the notch lined up with the top of the head facing the exhaust side of the engine with the engine at tdc. Setting the valve lash went smoothly and when #1 is at tdc and on its power stroke the valves are fully closed with the proper gap, as I rotate the engine forward from there the exhaust valve opens and closes until Im back at tdc followed by the intake valve opening then closing.

At this point I was pretty sure the cam was properly set up so I did a quick compression test and with a cold engine and the new rings yet to be worn in and properly seated. I got 60psi across the board, I only kicked the engine over 4 times for each cylinders compression test so I felt that was adequate. Seeing as there is still no fuel getting to the cylinders Im beginning to think there is not enough compression/suction to pull the fuel in to the cylinders. Im going to redo the compression test tomorrow and Im hoping the new head gasket seated correctly and Im not loosing compression past it. I may be overthinking the fuel problem and it will probably end up being something simple but hopefully some one will chime in with some ideas on what I should do next to get this sucker to start. Even with all my careful planning and preparation this motorcycle has fought me every inch of the way since I bought it so Im considering naming it Old 666 after my great Uncle's B-17 that he flew during the war.

goldarrow · « **Reply #38 on:** April 21, 2015, 09:36:09 PM »

How did you hook up your gas supply? Post pics?

Desert Dan · « **Reply #39 on:** April 22, 2015, 12:30:42 PM »

Well I am feeding the worst at this point as the is still no sign of ignition. I verified that the carbs are filling up with fuel properly but that fuel is not traveling to the cylinders. I think when I had to lift the cylinders to flu the cam chain guide I ruined the sealing property of the head gasket and pressure is leaking between the cylinders because i can't get a pressure test above 60psi.

Also I reset the ignition timing and something is off with the 1-4 points as they turn which ever coil I hop up to them in to an electromagnet and kill the spark to the corresponding plugs. I took the entire points assembly all the way apart to get a fresh view of what is going on with them and discovered there is significant run out on the bolt screwed in to the crank .025in so that's another issue I need to figure out.

Desert Dan · « **Reply #40 on:** April 22, 2015, 02:00:31 PM »

Thanks for the reality check I was getting a little frazzled with all the issues going on. I put the points back together and statically timed them now I have spark on all 4 again. I then did as you said and put about a tea spoon of oil in each cylinder and compression rose to about 160psi on each. I'm using a harbor freight compression tester and it's not designed for motorcycles.

Desert Dan · « **Reply #41 on:** April 22, 2015, 03:35:59 PM »

Ok so I took off the airbox and intake plenum on the back of the carbs and I got it close to firing by spraying starter fluid in the carbs as I crank it. I'm taking a break for today and will pull the carbs tomorrow to really clean them out and reset the float heights. I can confirm they are getting fuel to the bowls as when I first turn on the fuel the over flow tubes drizzle some gas for about 5-10 seconds.

I need to re address the spark as I will get a good strong spark on all 4 plugs then they will randomly quit sparking. I'll pick up new condensers on my way home tomorrow and see if that helps

Desert Dan · « **Reply #42 on:** April 24, 2015, 11:24:06 PM »

Good new everybody! She lives and runs great! Thanks to calj737's advice I went through piece by piece and got it figured out. Unfortunately I don't know exactly what was causing the non start issue because I did multiple things to it before starting it, instead of trying after each different fix. I took the valve cover off to verify that I had installed the cam correctly which I had, this also entailed re adjusting the valve lash. I also took the carbs back off and verified the float heights were still set correctly and cleaned out all the jets and passageways with carb cleaner. I drained the gas tank and refilled it with fresh 87 octane from the nearby gas station. I replaced the condensers even though Im 95% sure the old ones were fine, the coil issue was caused by the blue trigger wire on the 1/4 coil grounding out on the coil bracket when ever I installed it.

So here it is in all it's glory, this isn't it's first start as I wasn't expecting it to start the first time it decided to fire up so I didn't have my camera ready.

Stev-o · « **Reply #43 on:** April 25, 2015, 08:51:10 AM »

Congrats - bike sounds solid! Kudos to Cal, he's helped get another one running.

Desert Dan · « **Reply #44 on:** April 25, 2015, 06:03:32 PM »

Thanks Steve-o and Cal, I did a number of test rides to break in the rings and the motor felt stronger after each ride. I put about 50 miles on it today and I plan on doing the first oil change at 100m Im using standard 20w-50 motorcycle mineral oil in combination with a zinc additive. Its running a tad on the lean side right now with stock 100 manes and 40 idles with the stock air box set up and a uni-foam filter. I think the boots that go from the air box to the carbs are letting air by causing the lean condition so I ordered new boots from Germany for $35 U.S including shipping, It'll take an extra week to come from Germany but its worth it to save paying the additional $25 4into1 and David silver spares wants for their boot kits. Once the new boots are on Ill continue to dial in the carbs Ive got 98 mane jets standing by incase they're called for. Before the rebuild I had the needle clip set in the middle position (3rd from top or bottom depending on which way you count) I had tried the 2nd from top which was too lean and second from bottom which was too rich so Im thinking second from the bottom with the 98's will be the ticket.

Desert Dan · « **Reply #45 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.

Desert Dan · « **Reply #46 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.

Desert Dan · « **Reply #47 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.

HondaMan · « **Reply #48 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 #49 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.

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Author Topic: High altitude 73 CB500 daily driver ( 5/20/17 update ) (Read 33093 times)