Topic: Marissa's 1972 CB500

[Marissa]

Your carb jetting changes are going to be way off very likely. Simply upsizing jets due to velocity stacks is not all thats required, and I doubt very seriously whether 3 sizes up on the mains is fully required, and 2 up on the idles is probably very large too.

Did you buy true Keihin brand jets, or were they aftermarket? Are your carb needles in the stock clip, or did you move them to an enriched setting?

Yes, you are right and 3 sizes up was a bit too rich. But I am also not trying to install everything at once. I'm trying to put one different component on at a time so I can more accurately gauge the results of it. I'm assuming I will have to move the needle; I haven't yet so technically they should be in the factory placement but who knows. That itself should be an interesting task; when I first tried to take the needle assembly apart I couldn't get a good grip and angle on the screws and almost stripped one of them. I'll try soaking them in pb blaster next time I guess. And yes, they are Keihin jets! Dave told me to stay away from aftermarket whenever possible.

[DaveBarbier]

Nice work so far, I was actually going to shoot you a text the other day to make sure you're still around, haha. I agree with Cal as far as you'll probably have to raise the needle a clip position or two. You'll have to do some plug chops to see what you need as for jets. Which screws are you taking about? The little ones attaching the arm to the bottom of the slide? Are you using actual JIS drivers, I think I remember you saying you did buy a set.

In the oil filter housing are you pointing out the sludge? I can't see any large pieces of metal. Sludge is normal as far as I know. I wouldn't worry about it.

If you have fuel flow or overflow problems in the future, consider removing all those connections to the overflow tubes. From factory there's just one tube coming off each bowl down behind the motor. You've increased the likely hood of all bowls being unable to overflow and vent properly if that one tube gets clogged. Many people just use windshield washer hoses. It's cheap and will hold up fine with the amount of fuel it sees.

Is there an in tank filter sock? If so, you don't need an additional filter.

Nice side cover panels. How's the "feet touching the ground" issue?

Agree with Cal with the truing stand. New spokes and you should be good to go. Unless of course there's damage from an impact like the PO got rear ended. But it doesn't seem like there's any damage like that.

Again, nice progress!

[Marissa]

Nice work so far, I was actually going to shoot you a text the other day to make sure you're still around, haha. I agree with Cal as far as you'll probably have to raise the needle a clip position or two. You'll have to do some plug chops to see what you need as for jets. Which screws are you taking about? The little ones attaching the arm to the bottom of the slide? Are you using actual JIS drivers, I think I remember you saying you did buy a set.

In the oil filter housing are you pointing out the sludge? I can't see any large pieces of metal. Sludge is normal as far as I know. I wouldn't worry about it.

If you have fuel flow or overflow problems in the future, consider removing all those connections to the overflow tubes. From factory there's just one tube coming off each bowl down behind the motor. You've increased the likely hood of all bowls being unable to overflow and vent properly if that one tube gets clogged. Many people just use windshield washer hoses. It's cheap and will hold up fine with the amount of fuel it sees.

Is there an in tank filter sock? If so, you don't need an additional filter.

Nice side cover panels. How's the "feet touching the ground" issue?

Agree with Cal with the truing stand. New spokes and you should be good to go. Unless of course there's damage from an impact like the PO got rear ended. But it doesn't seem like there's any damage like that.

Again, nice progress!

Hey Dave,

Yeah, I'm talking about the screws in the bottom of the slide. I think I was going to try putting the housing in my bench vise but I didn't want to risk damaging it externally. How did you go about removing them? And yeah, they're JIS.

Also, it is just sludge in the oil filter housing, but it literally feels just like a glob of aluminum anti seize, and totally looks like it too. Is that normal? There was also traces of that stuff on the sides of the cam, and a little bit on the bottom of the breather assembly thing on the top of the valve cover assembly.

I replaced the overflow hoses as they were completely dry rotted and stuck, and we actually found the the overflow tubes were PACKED with varnish. I found this out when I was soldering the cracks on them and certain ones kept smoking. We took the smallest drill bit to it that we had, and it fit perfectly through and cleared them out.

Total newbie question, where would the tank sock filter be within the tank? The petcock has that screen but otherwise I haven't seen or know of any filters internally. I actually found some particles in the inline filter I was running, but like I said, it was definitely creating flow issues, so I'm not running it anymore. I also cleaned out my tank a month ago or so, but apparently not well enough! Is it worth it to purchase that Red Kote tank coating and cleaner? My tank has little to no varnish or surface rust, maybe a couple spots the size of a penny.

I can touch both feet on the ground, just on my tippy toes haha. I'm a little worried once I get some ride time in that I'll manage to fall parking it somewhere, sometimes it's a little difficult turning it or moving it on a slight incline. Guess we'll see what happens. The side panels sit flush unlike the factory panels, I fabricated them from some spare sheet metal, wasn't a fan of the look, so I put 1" foam on them and upholstered them with heavy duty vinyl, and installed the old school Honda badges on. They're also attached via heavy duty velcro, so they're study sitting, and should be fine while riding, but I'm sure a test run will show results.

I don't think there's any rear end damage, but I'm curious if the PO ran over something, got air born for a hot second, and maybe fell off the bike after? It would explain the bent spokes in the rear, and the bent fins I have on the side. Otherwise the bike is in good condition visually. I agree, I should really get a truing stand, but at the moment I'm still catching up on a ton of other things. Financially I don't think I will be able to ride this season, maybe if I'm lucky in October I could get a run or two in?

I did compression readings recently and I freaked out over my results. Across the board, I measured 90, 80, 70, 90psi on my cylinders... Granted, this was on a harbor freight reader, and I never used it before, so I can't deem it accurate or inaccurate. Either way, it measured them at a consistently low level, so I got really upset and irrationally decided to tear the top end off, as I pulled the spark plugs and found cylinder 1 was burning oil.

Luckily (but also frustrating?) I found no visible damage anywhere on the valves, pistons, or cylinder walls. I noticed my valve seals are bad on a couple, but again, not a compression issue. There were crescent shaped rust spots where the head gasket sits on the outer areas of cylinders 1 and 4, so that definitely indicates a blown head gasket right? The gasket was seeping externally, but very minutely.

I did find one of the head studs is torn off though, a lovely surprise. I'm going to have to find a way to remove that. I'm assuming it's reverse threaded, and I don't want to tap it if I don't have to. I was thinking about welding a pipe onto the top of it, creating a T shape, and using that for leverage and freeing it from the block. Thoughts on that?

Anyways, so since I have the top end off, I definitely decided to get the Vesrah gasket kit (heard it's better than oem?) and, I also want to get the top end bead blasted and powder coated. A place I went to for an estimate quoted me $200 and also said it might be worthwhile to leave the fins unfinished and I don't really know if I like that idea at all. That price isn't including the tappet covers or any hardware, as I want to go with a stainless steel kit.

I also may be purchasing another cylinder jug soon; mine has two huge cracks in the fins by the exhaust, not to mention every corner is either bent, cut, or lightly chipped. So, I'm not sure if I want to just hone the "new" jug when I get it, or just say screw it and bore it out to a 550, get new pistons, etc. I would like to get this powder coated as well. I really wasn't looking for a power build with this project, but I don't see any reason not to at this point if I'm already in there. Side note: I have a mix of marvel mystery oil, pb blaster, and wd40 sitting in the cylinders, and cylinder 4 has virtually no mix left in it. All others are full. Does this definitively say the rings are bad on 4? Like I said, there is NO scoring anywhere. Could it just be that the ring gap is right below the pool of the mixture (bike is on the side stand) on 4 and gravity is just working it's magic?

It was also only at the point of total removal that I realized timing could be the main culprit.. We static timed the points.. but I totally forgot to time the bike itself.. So mad at myself but lesson is learned.. I guess in a way it gives me peace of mind knowing the internals are decent. If I had just timed the bike, I probably would have been on the road by now...

[calj737]

Yeah, I'm talking about the screws in the bottom of the slide. I think I was going to try putting the housing in my bench vise but I didn't want to risk damaging it externally. How did you go about removing them? And yeah, they're JIS.

Carefully. Apply some down force on the screw with the correct JIS tip,. and just try to "tweak" it to break it loose. Don't try to "turn it out" all at once.

Also, it is just sludge in the oil filter housing, but it literally feels just like a glob of aluminum anti seize, and totally looks like it too. Is that normal? There was also traces of that stuff on the sides of the cam, and a little bit on the bottom of the breather assembly thing on the top of the valve cover assembly.

I'd suspect its not AntiSieze, but is instead a type of Gasket Maker product. Not good to find it there. A pretty good indicator that you need to drop the oil pan, check the oil pump, and possibly purge the oil galleys too.

Total newbie question, where would the tank sock filter be within the tank? The petcock has that screen but otherwise I haven't seen or know of any filters internally. I actually found some particles in the inline filter I was running, but like I said, it was definitely creating flow issues, so I'm not running it anymore. I also cleaned out my tank a month ago or so, but apparently not well enough! Is it worth it to purchase that Red Kote tank coating and cleaner? My tank has little to no varnish or surface rust, maybe a couple spots the size of a penny.

The sock filter is above the petcock, on a plastic standpipe kind of thing. Your tank may have come to you without one. Don't coat your tank at this point, just run a gallon MetalRescue through it and give it a decent tumble. That should coat and protect it just fine.

I don't think there's any rear end damage, but I'm curious if the PO ran over something, got air born for a hot second, and maybe fell off the bike after? It would explain the bent spokes in the rear, and the bent fins I have on the side.

Probably unrelated events actually. Bent spokes can come from potholes, or poorly tensioned spokes that hit a decent bump, down a curb, etc... Bent fins are likely from being packed, transported or strapped badly, unless theres other indication of it hitting the ground, falling over, etc.

I did compression readings recently and I freaked out over my results. Across the board, I measured 90, 80, 70, 90psi on my cylinders... Granted, this was on a harbor freight reader, and I never used it before, so I can't deem it accurate or inaccurate. Either way, it measured them at a consistently low level, so I got really upset and irrationally decided to tear the top end off, as I pulled the spark plugs and found cylinder 1 was burning oil.

The actual number is not so important as the consistency of the readings. Performing the check requires the throttle to wide open, a strong battery, a quality gauge, etc. A bike that's sat for a while will read lower too than a daily runner as the rings can get gummed up and produce lower readings.

Luckily (but also frustrating?) I found no visible damage anywhere on the valves, pistons, or cylinder walls. I noticed my valve seals are bad on a couple, but again, not a compression issue. There were crescent shaped rust spots where the head gasket sits on the outer areas of cylinders 1 and 4, so that definitely indicates a blown head gasket right? The gasket was seeping externally, but very minutely.

So bad valve seals can actually produce lower compression too (see above). Rust spots aren't indicative or a blown gasket (there's no water running through these engines  ). They can just be indicative of water sitting from storage, and maybe not rust at all unless its on the surface of the sleeve as these are aluminum castings.

I did find one of the head studs is torn off though, a lovely surprise. I'm going to have to find a way to remove that. I'm assuming it's reverse threaded, and I don't want to tap it if I don't have to. I was thinking about welding a pipe onto the top of it, creating a T shape, and using that for leverage and freeing it from the block. Thoughts on that?

That method works. Gently build up the heat on the portion of the stud. Simply heating it enough to weld to it can release the stuck threads, but you'll still need a means of turning it out. Welding a Hex nut to it also is popular.

[DaveBarbier]

Looks like Cal's got you covered

Regarding the possible upgrade, an entire 550 motor will drop in to your frame. Might be cheaper to find a running motor with a crap frame somewhere (actually may be hard in CT) and just drop it in your frame. Price of new cylinders plus pistons and machine work...you decide.

Vesrah is not better than OEM. OEM is best but Vesrah is widely used on the forum so it's not bad. Generally, OEM is best for everything on the bike. The Vesrah kit you got probably doesn't come with the rubber puck sealing washers that go over the head nuts. Get OEM pucks. OR if the kit has them, measure the thickness and the depth of the seat and be sure they'll sit about 40 thousandths proud. Sometimes aftermarket rubber parts aren't the right size.

Quote from Hondaman from this post: http://forums.sohc4.net/index.php/topic,122379.msg1438727.html#msg1438727

First, check the step depth of the head hole. Then, check the thickness of your seal. You need at LEAST .030" compression, .040" is better. The too-thin ones are only about .005" thicker, which won't seal when the head heats up and the hole becomes deeper.

What I would do, use this site: https://www.cmsnl.com/honda-cb500k1-four-1972-usa_model460/partslist/ to tell what the size of a given o-ring is, then compare it to the one you have from the kit. Mainly for the o-rings that go between the cylinders and case where the oil jets are (not sure if you're in that far) and the o-rings that go between the cylinders and the head on the outsides. That is a common place for leaks in these motors. Too small or too large of an o-ring isn't good.

Hope that helps!


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[SOHC4 Cafe Racer Fan]

What I would do, use this site: https://www.cmsnl.com/honda-cb500k1-four-1972-usa_model460/partslist/ to tell what the size of a given o-ring is, then compare it to the one you have from the kit. Mainly for the o-rings that go between the cylinders and case where the oil jets are (not sure if you're in that far) and the o-rings that go between the cylinders and the head on the outsides. That is a common place for leaks in these motors. Too small or too large of an o-ring isn't good.

CMSNL is a great source as well as the parts fiche to figure out parts specifications and part numbers.  Their parts and shipping prices are on the higher side.  David Silver Spares is also a good source, but make sure you are ordering (if you do) from the USA website and not the UK site.  They all ship from the same place, but the UK site charges you more for shipping. 

[Camrector]

Remember open motor = open wallet.
Cruzin image 605 kit and a cb650 cam swap with some mild porting really wakes these motors up, and keeps the money under control.
Hondaman has some experienced things to say about painting fins.

[RAFster122s]

Unless they closed the US address, they will ship from US on parts orders where they have stock.  If they are missing a piece from order they may choose to ship from the other site because the shipping costs from both locations pushes any advantage from shipping in USA out the door...so, cheaper to ship from the NL location at that point.

It would be interesting to see the shipping costs vs charged amounts for a year...that loss could influence a hike in shipping, etc. I am sure they would be looking at those figures.  There comes a price point where you will consider going elsewhere with your order if the cost is perceived as being too high.  The company might take a small hit on shipping at a loss when their sales volume more than makes up for that small loss.

Definitely support the USA warehouse if in US as it keeps it in business.

David
 

What I would do, use this site: https://www.cmsnl.com/honda-cb500k1-four-1972-usa_model460/partslist/ to tell what the size of a given o-ring is, then compare it to the one you have from the kit. Mainly for the o-rings that go between the cylinders and case where the oil jets are (not sure if you're in that far) and the o-rings that go between the cylinders and the head on the outsides. That is a common place for leaks in these motors. Too small or too large of an o-ring isn't good.

CMSNL is a great source as well as the parts fiche to figure out parts specifications and part numbers.  Their parts and shipping prices are on the higher side.  David Silver Spares is also a good source, but make sure you are ordering (if you do) from the USA website and not the UK site.  They all ship from the same place, but the UK site charges you more for shipping. 

[Marissa]

Disassembled further to see if there's any other evidence of damage.

The connecting rod definitely is not supposed to look that dry/dirty... right?

While the cylinder jugs are definitely stained, I don't think they have any significant scoring. I have yet to measure the piston rings to see if they are out of spec; but to my surprise every single one of them spun freely. Even the bottom set spun. I'm dumbfounded. I would assume if the gapping is too significant on the rings, they would score, correct? Could it be possible the rings are seating too much inward and letting blow by occur, thus affecting compression poorly and leaving no signs on the cylinder walls?

This wall was my biggest concern, though off the top of my head I don't remember if I could feel that residue or not. I haven't worked on the bike in a month and I just got back from vacation so I'm a bit foggy.

I sent the top end to a shop to have it inspected and new valve seals installed, they said everything looks to be in tip top shape, which is helpful but I was hoping the valve seals would be the culprit. I guess I'll verify tomorrow whether or not they were including the condition of the valve seals in it as well.

I just want to ride. Shame on me for getting myself into this mess haha. I should have just waited longer for a running bike.

[Marissa]

Also, do you guys recommend replacing all of the head studs instead of just R&Ring that broken one? I'm in the mindset of "Already spent too much, might as well take extra time and money to make sure it's done right"
and don't want to skip any parts I might unintentionally.

Which also leads me to the question of: what do you guys recommend to do when the original paint on the engine is dirty and in rough shape, and every place I've talked to does not recommend to powder coat it because of the heat soaking issues? Do most of you just use as spray can engine enamel? Do you guys leave it bare? I've tried aircraft remover, the orange gel paint stripper, paint thinner, sanding, soaking it for days and it doesn't do a bit of removal on the paint. Is it worth it just to get it hot tanked and leave it bare?

Thanks in advance.

[Stev-o]

The connecting rods appear to have surface rust, most likely from moist in the motor when it sat.  That should clean up, try WD-40 and very fine steel wool. 

Remove the Pistons and take them and the cylinders to a competent machine shop for proper measuring. 
You might get lucky amd only need a hone and new rings. 

Personally, I would just replace the 1 broken stud, your not building a race motor, right?


The engine cases came from Honda painted, with a thorough cleaning and sanding where necessary, they can can be rattle canned with VHT Aluminum and look like new!

BTW - I've been through this twice in the last year, it can be frustrating but very satisfying when complete. 

[MauiK3]

Marissa
I am working on my K3 750 cases right now. I cleaned with simple green, wire brush on a dremel, etc. then I carefully washed with brake clean and acetone. I rigged a bag under it to control the runoff. I will be using POR15 aluminum for mine. Duplicolor aluminum is also good, as is VHT.
POR 15 is available at auto refinishing stores.
Steve

[DaveBarbier]

I agree to replace only the broken stud. Perfectly fine to use the existing ones.

If you want to spend more money but have the motor better than new, you'll have to disassemble everything, but send to Nils (Noblehops) and have him vapor blast it.

http://forums.sohc4.net/index.php?topic=164058.0

Finish ends up looking incredible and you can leave it bare. Heck, paint would make it look worse.

If you were getting low compression it could have just been from the bike sitting and the rings being a little stick/rusted. Normally in that case compression comes back up after putting miles on it.


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[calj737]

I agree to replace only the broken stud. Perfectly fine to use the existing ones.

Personnaly, 1 stud breaking is often an indication that more will too. The motor is apart now, remove all of them, chase the threads, install new studs, and never look back.

If you want to spend more money but have the motor better than new, you'll have to disassemble everything, but send to Nils (Noblehops) and have him vapor blast it.

http://forums.sohc4.net/index.php?topic=164058.0

Finish ends up looking incredible and you can leave it bare. Heck, paint would make it look worse.

Dave is 100%. Whomever declared powder coat is a problem on these engines is 100% incorrect. Perfectly safe, very common. Vapor blasting is an excellent finish, but will require some maintenance to keep it. Else, you can Vapor Blast then clear coat the motor afterwards to protect it. Aluminum oxidizes instantly and perpetually.

If you were getting low compression it could have just been from the bike sitting and the rings being a little stick/rusted. Normally in that case compression comes back up after putting miles on it.

I agree with Dave 100%. Compression is at best an "indication" not a determination. With new valve seals being installed, it would behove you to have the seats lapped and the guides inspected for tolerances.

[Lostboy Steve]

I agree to replace only the broken stud. Perfectly fine to use the existing ones.

Personnaly, 1 stud breaking is often an indication that more will too. The motor is apart now, remove all of them, chase the threads, install new studs, and never look back.

If you want to spend more money but have the motor better than new, you'll have to disassemble everything, but send to Nils (Noblehops) and have him vapor blast it.

http://forums.sohc4.net/index.php?topic=164058.0

Finish ends up looking incredible and you can leave it bare. Heck, paint would make it look worse.

Dave is 100%. Whomever declared powder coat is a problem on these engines is 100% incorrect. Perfectly safe, very common. Vapor blasting is an excellent finish, but will require some maintenance to keep it. Else, you can Vapor Blast then clear coat the motor afterwards to protect it. Aluminum oxidizes instantly and perpetually.

If you were getting low compression it could have just been from the bike sitting and the rings being a little stick/rusted. Normally in that case compression comes back up after putting miles on it.

I agree with Dave 100%. Compression is at best an "indication" not a determination. With new valve seals being installed, it would behove you to have the seats lapped and the guides inspected for tolerances.

I didn't declare it was a problem, but the jury is still out for me on mine. Not the cases but the cylinders. I have noticed a lot of Harley's leave their cylinders and head bare but do the case. My buell was like that too.

Anyway, you're still the authority on small block hondas to me Cal. If you say it's ok, I feel better about it.


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[calj737]

I didn't declare it was a problem, but the jury is still out for me on mine. Not the cases but the cylinders. I have noticed a lot of Harley's leave their cylinders and head bare but do the case. My buell was like that too.

Anyway, you're still the authority on small block hondas to me Cal. If you say it's ok, I feel better about it.

I'm confused...? Are we talking about powder coating the cylinders being a potential problem Steve? If so, not an issue. The fins promote cooling due to air flow. Powder coat is not so thick that it will trap heat or prevent flowing air from drawing the heat away.

Remember your day in physics: heat moves towards cold. Internal heat radiates toward the exterior due to atmospheric temperature drawing it. Just like AC in the summer draws summer temps towards your inside room. You're keeping summer heat out (because it's colder inside) and heat inside in the winter (because it wants to seep out) due to colder air.

Works the same way with engines and exhausts. Pipe is colder than the exhaust gas, therefore the heat moves toward the surface, heating it. That's why you burn your fingers; they're colder than the pipe 

[DaveBarbier]

Pipe is colder than the exhaust gas, therefore the heat moves toward the surface, heating it. That's why you burn your fingers; they're colder than the pipe 

So what you're saying is if you don't want to get burned by the pipes, grab a handful of coals off the grill first, then touch the pipes. Got it.

[calj737]

Not exactly. But, Dave, I'd like you to try immersing your hands in water, then bring it to a roiling boil (keeping your hands immersed) then grab the exhaust. My thesis is you'll be fine since your skin will have been brought up to temperature by the boiling water.

If it doesn't work out, at least you have a good start on veal stock for supper 

[RAFster122s]

Do you like your eggs poached or fried Cal?

[DaveBarbier]

Not exactly. But, Dave, I'd like you to try immersing your hands in water, then bring it to a roiling boil (keeping your hands immersed) then grab the exhaust. My thesis is you'll be fine since your skin will have been brought up to temperature by the boiling water.

If it doesn't work out, at least you have a good start on veal stock for supper 

"This veal soup is great, there's more fingernails than I'm used to but it's still nice."

[PeWe]

Also, do you guys recommend replacing all of the head studs instead of just R&Ring that broken one? I'm in the mindset of "Already spent too much, might as well take extra time and money to make sure it's done right"
and don't want to skip any parts I might unintentionally.

Which also leads me to the question of: what do you guys recommend to do when the original paint on the engine is dirty and in rough shape, and every place I've talked to does not recommend to powder coat it because of the heat soaking issues? Do most of you just use as spray can engine enamel? Do you guys leave it bare? I've tried aircraft remover, the orange gel paint stripper, paint thinner, sanding, soaking it for days and it doesn't do a bit of removal on the paint. Is it worth it just to get it hot tanked and leave it bare?

Thanks in advance.

Hi Marissa, I hope you do not mind details about CB750. I guess this cover all bikes.

If you can determine why the stud broke, replace the broken one only. (If you can find one). All if all look bad. The heavy duty studs are rather brittle when over tighten them. I broke an APE cyl stud due to a bad torque wrench. Honda studs are more flexible. The reason to use APE or Kibblewhite studs is the less flexibility. Max torque 22.5 ft lbs, I do  just under it 20.65 ft lbs (28Nm as I did with Honda std)

Rattle can motor paint worked fine for me. I did my CB750 with Motip (color alumin) which is rather durable. Fuel from carbs when changing jets did not ruin the paint. Easy to add some additional spray when it has got some scratches. It look more std than the 2k painted CB750 cases I have seen. Those have thick layer of 2k paint, Mercedes type. Look like engine has been dipped into it. Rattle can paint I use look closer to Honda OEM with all casting marks visible.

I sprayed cyl and head with it later on. My last cylinder is not sprayed since it has nice fresh glass beaded surface. I believe that thick layer of paint can cause higher temp in a hot climate. Hondaman has mentioned that in an old thread.

I have 3 cans more. I'll use same paint on my next project, CB750 K2. I need to remove old protective black paint first.

I washed the cases with naphta first. Then dish washer powder for dishwasher machines in a deep stainless sink with hot water. Dipped the entire case and brushed it. Dried and cleaned with acetone before some additional quick sanding with a paper. Wiped with acetone cloths again. Some axes were still in engine. Last time with most of the gearbox still in. I sprayed the steel quickly with WD40 to protect against flash rust.
Sprayed and let it dry

[SOHC4 Cafe Racer Fan]

That's a great example of how good the spray cans can deliver a nice finish.  Ideally, you should Harden the paint by "baking" it in an oven, but that's not the healthiest thing if you cook food in the oven.  You can also treat it by lining a cardboard box in aluminum foil and using a heat gun to heat up the box.  If you can't do either of these methods, the paint will harden after a few heat cycles running the bike, but until then it will be easier to damage.

Powdercoat is great, too, but requires very extensive cleaning after coating to make sure all of the oil passageways are free from blasting media.  You cannot be too cautious. People have washed their engine parts, blown water and then air through the passages and then even still found grit.

[PeWe]

Paint got time to harden since I painted in July 2012, assembled the engine several months later.
Here a photo of how the case looked before repaint. Whats left of Honda's paint. I did not paint the cases in the 80's despite I pulled engine several times that decade. I think the paint left mostly when sitting in a barn for 19 years.

Good thing with the way I did it is that some axes can be left in cases when washing it. If beading the surfaces all holes must be plugged and no gearbox or other stuff still mounted.  Save some $$ too. Hard corrosion can be brushed off.

I used Caustic soda to clean my hubs and valve cover.
It loves aluminum oxide! Bucket with a few liter of rather strong solution, 2 dl caustic soda in 3 L if I remember correctly. Part in bucket (outside for fresh air and not gas people!) use a dish washer brush and work the solution all over the surface. It react hard so use glasses and long sleeve rubber gloves. The corrosion will turn to black, let it work for a few minutes. Not too long, check after 2 minutes. Leaving it for hours can make the part to dissolve completely I have heard stories about missing heads and cases only steel thread parts left

Rinse with water and remove the blackened corrodes surfaces with steel wool. The surface will turn to a nice old aluminum grey that can be polished further. The heavy alu corrosion disappear very quick and easy.

Photos to show and encourage others.
Note! covers only cleaned with caustic soda and water, finally steel wool. Not sanded at all. The sanding tool on phote for something else.

[Marissa]

PeWe,

Thanks for the examples and the photos of what you did to your 750. Those photos have helped me determine that I think it's best if I just go with a VHT spray engine paint. I've actually used VHT bright aluminum paint on my valve covers for my 300zx and it came out well. I think it will be better for now anyways since I need to save a bit of money on this project.

Still waiting on the top end to come back from the shop. I've been working on polishing a lot of the shinier bits on the bike and trying to restore them to fill up my time without spending more money. But of course it led to me buying a stainless steel Allen bolt kit  hoping to update the thread with some real progress next time.

[Davez134]

I used VHT engine enamel on my 750, and it has held up great so far. I used the wrinkle black and cast aluminum, I don't see a chip on it yet. I might be stating the obvious here, but prep/clean, prep/clean, then do it again before applying the paint. (I also used the VHT primer on the bare metal first) and make sure to heat/cure it before any contact with gas or oil.