Author Topic: 73 CB500 Boston Cafe (Read 8485 times)

lajos · « **Reply #50 on:** June 06, 2015, 04:34:53 PM »

Stripped the paint off the upper half of the crankcase (damn she looks ugly now) and cleaned off the remainder of the gaskets. Aircraft stripper is pretty insane stuff. Tomorrow I hope to strip the bottom half.

lajos · « **Reply #51 on:** June 06, 2015, 06:31:57 PM »

In the carb body under the throttle slide there is a tiny hole. It's closed up from gunk in some of the carbs. What does that little hole do? Is it ok to clean it out with a small drill bit?

lajos · « **Reply #52 on:** June 09, 2015, 02:17:15 PM »

Plastigaged the crankshaft last night, all of them are ~0.0015", one a tad bit smaller.

Tightening the case felt good, almost like putting things back together.

MickB · « **Reply #53 on:** June 11, 2015, 01:00:28 PM »

Lajos what's happening with the stud?

lajos · « **Reply #54 on:** June 11, 2015, 02:08:15 PM »

I managed to get it out in one piece ( the post is on previous page at http://forums.sohc4.net/index.php/topic,148166.msg1691159.html#msg1691159 ).

In the end I needed more heat- got an oxy/mapp torch that I used to heat the stud to red glowing, and a regular mapp torch to heat the case around it. After a couple tries of this, it started turning with hardly any torque. Then I wiggled it back and forth until it turned all the way out.

I got the APE heavy duty studs in the mail to replace the old ones.

I'm still waiting for my big bore job to be done, in the meantime I'm prepping for engine paint and cleaning carb bodies.

calj737 · « **Reply #55 on:** June 11, 2015, 02:13:41 PM »

Over in the FAQ section, there's a handy little thread about riggin up a home made soda blaster suitable for cleaning your carbs. I know you mentioned previously about your neighbors lynching you, but this might be discreet enough to use on your carbs and contain the mess.

MickB · « **Reply #56 on:** June 11, 2015, 02:39:45 PM »

I takes a lot of heat that's for sure, I remember mine I was worried about the case being damaged, but it took the lot.

lajos · « **Reply #57 on:** June 11, 2015, 05:41:42 PM »

@MickB: Yes, I was also worried about melting the aluminum. But then I figured this cannot be pure aluminum but some sort of alloy, so it shouldn't melt that easy. I have an extra head that has super pitted unsavable valve seats, so I used that as a test piece with the oxy/mapp torch and I couldn't melt it even after heating it for a good couple minutes. But the oxy/mapp torch had a much tighter flame, so I could really heat the base of the stud (with the regular mapp torch I could get the welded nut glowing, but I guess the case sucked all the heat away from the screw part).

@Cal: Thanks for the suggestion for the small soda blaster. I was thinking about it myself, but at this point I have the carb bodies pretty clean having used simple green hd and pinesol in a small ultrasonic cleaner. Attached a picture below of the worst carb body I have. I can clean the small leftover alu oxide spots with a brush. The rest have no pitting or very little pitting. Is it worth using this carb body, or should I get a better one?

calj737 · « **Reply #58 on:** June 11, 2015, 06:07:02 PM »

That looks usable

lajos · « **Reply #59 on:** June 17, 2015, 09:29:37 AM »

Picked up my bored cylinders along with decked and valve seat cut head from the machine shop today! There's definitely no rust spots left in the cylinders after taking out 3mm

calj737 · « **Reply #60 on:** June 17, 2015, 10:09:16 AM »

What pistons are you planning on?

lajos · « **Reply #61 on:** June 17, 2015, 10:18:05 AM »

I have the 61.5mm cruzinimage pistons from ebay. The cylinders were bored to those with 2 mil clearance.

lajos · « **Reply #62 on:** June 22, 2015, 06:25:59 PM »

Finally got the crank cases painted.

After stripping the paint with aircraft stripper I spent a bunch of time cleaning with wire brushes, filed and sanded off a lot bumps and whatnot from casting, scuffed with red scotchbrite pads and some 4" 180 grit drill brush from HF. Then acetone washed and masked.

Cutting the masking tape around the edges was challenging at first, but then I used a small flashlight as a backlight which made finding the edge and following the shape with a small xacto knife a lot easier.

We don't have a garage so I was going to paint in the basement landing, but I found an old tent and used it as a paint booth. Worked pretty well, natural light and the mesh kept dust out.

Lint is evil. I did the masking on a painters drop cloth and the edge of the masking tape picked up a whole bunch of lint. I didn't see it until I sprayed the primer, so I stopped after priming, redid the masking on plastic sheet and all went well after that.

Used VHT engine primer, VHT cast aluminum engine paint and VHT clear gloss.

lajos · « **Reply #63 on:** June 26, 2015, 07:30:24 AM »

I started stripping paint off the cylinders with aircraft stripper and soon realized that it's just not going to work. Not sure if Honda used a different paint than the crank case or if the paint burned on there from the heat, but the stripper hardly softened it. I also found it near impossible to get between the fins even with small tube brushes to scrape the paint off. And it was way too messy.

I decided that it was time for soda blasting as Cal suggested. I picked up a 15lb soda blaster from HF along with a bag of medium size soda media.

I've seen people complain about this soda blaster that it's a PITA to load through the 1/4" hole, so I also got a 1.25" black pipe and cap. Cut a hole on the tank and welded in the pipe that allows soda to be poured in straight from the bag. Painted the top with flat engine paint for color testing (that's the color that goes on the cylinders).

Damn this thing works amazing. I only wish I would've gone this route earlier. I cleaned up the cylinders, head and all carb bodies in an hour. I didn't have time to take pics of the parts because I was racing to get it done before a rainstorm moved in, but they came out amazing. Now on to paint prepping those parts.

calj737 · « **Reply #64 on:** June 26, 2015, 09:32:01 AM »

Who loves you, Baby!

lajos · « **Reply #65 on:** June 27, 2015, 07:38:34 AM »

Weather looked good today so the plan was to paint. But two studs on the carb side didn't come out of the head, one broke. Seems like groundhog day.

This time however washer and nut got welded, oxy mapp heated stud, whacked and liquid wrenched, and got both out in an hour. (Cal should write a book. I learned to just do what he says.)

calj737 · « **Reply #66 on:** June 27, 2015, 08:43:02 AM »

Please pass that wisdom along to my wife at your earliest convenience...

lajos · « **Reply #67 on:** June 28, 2015, 07:46:00 AM »

Haha. Wives are different. The only option is to compromise.

lajos · « **Reply #68 on:** July 05, 2015, 05:33:42 PM »

The wife gave me the day off so finally had time to paint a bunch of engine parts.

lajos · « **Reply #69 on:** July 30, 2015, 01:59:36 PM »

The engine is finally going back together!

My kids' summer vacation is taking a toll on my free time, but I try to work on it a bit every day.

I don't have much bench space so made an engine stand that holds the bottom crank case.

I have the kick starter and transmission gears in. Hope I put it together correctly, wish I would've taken a lot more pictures when I took it apart. The gear shift forks are soaking now, I'll test the gears when that's back in.

lajos · « **Reply #70 on:** August 07, 2015, 11:22:11 AM »

Built the shift forks earlier this week and checked the transmission. Did a quick test and seems to be shifting through all gears.

Put the crankshaft in today. Plastigaged the connecting rod journals, all check out below 0.0015". The crank bearings on the ignition side had a lot of pitting, but I couldn't find any new yellow ones. Salvaged green ones from the extra cb500 engine I have, the plastigage strip matches the other bearings pretty closely.

Timing chain is brand new, primary chain is reuse (couldn't find new one, but it seems fine).

lajos · « **Reply #71 on:** August 13, 2015, 09:58:25 PM »

Waiting for some orings and seals from partzilla before I can close up the crankcase, so finished cleaning the carbs and put them back together. The needle pins were in the second notch from the bottom. I moved them to the bottom position assuming that the 600cc kit will need more fuel. Hope that wasn't a mistake because it looks like adjusting the needle position is a major pita.

Wish I had a better before picture.

calj737 · « **Reply #72 on:** August 14, 2015, 03:49:54 AM »

That needle position probably won't work, and it's likely too much fuel.

Fuel ratios depend a great deal more on cam and valve specs than bore alone. You'd need a fairly high lift and duration cam to demand that much fuel, and these stock carbs probably couldn't truly keep up if you did. I would return the needles to stock, and maybe raise them 1 notch if you're running pods and a non-stock cam. Then tune with jets and plug chops to determine ultimately where the needles go. That extreme a start will make it nearly impossible to tune without numerous jet changes and fouled plugs.

lajos · « **Reply #73 on:** August 14, 2015, 10:08:48 AM »

Thanks for the advice, Cal. I'm using stock camshaft, so there won't be more air, makes perfect sense to not add more fuel. I am planning pod filters though.

I have put the needles back to where they were when I took the carbs apart, which is 2nd notch from the bottom. It actually wasn't too bad, took less than an hour now that I know where all the screws and springs and whatnots go.

lajos · « **Reply #74 on:** August 25, 2015, 12:01:40 PM »

I finally got the o-rings from partzilla, so I finished putting the bottom end together.

I didn't know that the hondabond is as thick as it is, it was a challenge even squeezing it through the applicator attachment. I put it on as thin as I could and wiped it off around the crankshaft bearings to make sure not to plug them up. A little bit still squeezed out around the case.

Next, I misread the torque spec for the 6mm flange bolts and I ended up stretching the 105mm bolt that goes up from under the oil pan. Good thing I stopped before it snapped and revisited the manual. Also sent a mental thank you to the honda engineer who made that bolt stretchy and not the crankcase thread strippy. Since I started with 2 dead engines I had an extra 105mm bolt.

I wanted to prime the oil passages and the best I could come up with was to strap the connecting rods with rubber bands to a bar above the engine and turn the crankshaft by hand with the alternator bolt. The oil didn't come at first, so I removed the oil pressure sender that helped the pump pick up the oil.

I know the engine is still ways away from (fingers crossed) running, but hearing the oil gurgle through the crank bearings for the first time totally made my day.

Next up is putting the pistons and cylinders on. I've chased the cylinder stud threads and have the APE studs to go on.

Question about the base and head gaskets. The package for the base gasket (NE brand) says no lubrication or sealer necessary for the gaskets. I've read many posts on this forum and found no consensus if it should be dry, oiled, hondabonded or gasket sealer sprayed. Should I just install them dry as the package says?

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Author Topic: 73 CB500 Boston Cafe (Read 8485 times)