Topic: Restoring a '75 750K - Lots of questions.

[Jayelwin]

So I just bought a 1975 CB350K which will be my winter restoration project. The bike runs but definitely needs work. It seems to bog down and backfire a bunch. But I haven't even begun to work on it so I think it's a good canvas to paint on, so to speak.



So the paint is this awesome Flake Sunrise Orange. But the finish is dull and the tank has a few nicks. And you can see the black areas around the emblems are rusted with some peeling. I'd like to restore this as best I can but possibly keep the paint intact as it's original. Any recommendations? Should I have a paint shop try to redo just the black areas and then clear coat the orange part of the tank? I can get a new white stripe decal kit. And I could probably get new tank emblems too.



The side covers have been painted in the past (to match a horrid orange fairing kit). I'd love to restore these to the original metallic look. They are currently a solid color and look very plasticky. How hard is it to reproduce the original paint?



I plan on getting down to just the frame and have the frame re-powder coated. It looks like someone might have rattle canned it black int eh past and it's peeling in some places and has minor bubbly rust. I got a powder coat quote for $140 for the frame and $40 for the swing arm. I'll probably redo the triple tree while I'm at it.

Now the exhaust seems in good shape except for rust. And the chrome all over has a lot of tiny rust markings on it. This includes the handle bars and fenders. Tiny rust areas can probably just be polished out with elbow grease and either Blue Job or maybe the Diet Coke and tin foil trick. That'll probably just take work. But the exhaust has large areas of rust that I haven't checked but may be through and through the chrome.



Rechrome? Just polish as best I can? I plan on having the pipes off so I might be able to use some kind of power tool to polish.

And in general lots of parts just seem old and can probably be replaced along the way. Like the switches and all the cables. Lots of the bolts (bolt kit? someone here sells them).




And the last question. The motor also looks sort of tired. Like old aluminum. How can this be refinished? I have no plans on splitting the case or even removing the jugs or head as the bike runs and doesn't leak any oil. So I won't have it down to individual parts. But it will be off the bike (as I want to redo the frame). So what can I do to clean up and pretty an intact engine off the bike? Can you safely soda blast an engine if you plug up the openings? Then what?



The tires are good but inaccurate so I'll probably replace them. And the wheels and spokes have a LOT of rust. I'm hoping this 10 lbs of oxalic acid I bought pays off. And lots of elbow grease too.

Sorry for all the questions. But this is the place to get answers. I've got my work cut out but I've got all winter and lots of enthusiasm.

-Josh

[martin99]

That's a nice bike Josh.

What you have there is what's known in the restoration business as patina - showing all the signs of it's age and, apart from the side panels, about as original as you can get from what I can see though I'm no expert.

One thing I've learned over the years is if you 'pretty up' one piece, it'll stick out like a sore thumb and you will end up giving everything a makeover regardless of your initial 'minimalist' intentions. It can get very addictive and very expensive. You will end up with a beautiful bike but you might shoot yourself in the foot if you're the sort that'l be afraid of leaving it out in the rain.

I'd think long and hard before doing anything cosmetic myself, and be confident that it is in good mechanical order first. Treat it to some fresh oil, new filter and 3000 mile tune-up as a first step. Maybe check steering head bearings and brakes. And have a look under those fork gaitors too.

Whichever way you go. enjoy!

[Jayelwin]

Thanks. I figure there are things I can do to improve the look maybe without doing an engine removal. That would mean not doing anything to the frame.

Definitely need to work on the chrome. And my wife says I'd be crazy to paint the tank. It really is in pretty good shape, just dull like there's no clear coat.

Mechanically I plan on making it spin like a top. That's a definite.

[Stev-o]

Hey Josh....welcome and nice bike.  First off, clean clean clean. Every part will look so much better if it is super clean, even bolts. Clean everything until it is spotless!
I disagree with oldskool and your wife, I'd paint the tank in your case. If it didn't have rust and you had the matching sidecovers, it would be a different case. You'll never be able to match the tank and covers, I been there and regretted it ['76 CB550].

I recently restored a K5 and painted the tank and covers and it made the bike look fantastic!





Good luck

[Schnell]

Nice bike, josh. I have the same one. Lots of elbow grease ahead. Clean. You can gradually refresh the engine case aluminum with a scotch bright scouring pad. No need to go all the way to super polished.

[commando1954]

Be very careful if you decide to soda/bead blast the engine. Cut out some alloy bungs and fit them into the inlet and exhaust ports and silicone them in.Protect the o rings on the gear lever and kickstart shafts.Again silicone will do, as masking tape will let material past.I know from experience when I had a Commando engine bead blasted.

[PeWe]

Nice bike. You wrote CB350, I see a CB750.
If side covers are the original, buy new fresh and paint them. The old could crack without not much abuse. My did on a K6-76. A long crack in the middle of the cover (1979-1980)
Restoring the bike is very addictive and you will spend some money.
If frame has a dull paint and you need to fix it, the engine has to be out...when engine is out why not take it completely apart and replace internal chains, retainers, maybe some bearings, clutch.
Pistons out, need hone of the bores, new rings or maybe more if pistons are damaged. Head off, valves out make sure that seats are OK and lap the valves.
Complete gasket set with ALL o-rings and rubber stuff cost some too and most likely needed.

Keep it in original style can be better if you see it as an investment. Polish the rust and corrosion away, wax the paint will make a huge difference. New faces in the gauges, repaint the handlebar switches... Aluminum polished into chrome style is not CB750 original look.

For your own fun:
836 high CR pistons, ported head, bigger inlet valves, hotter cam + HD valve springs... 4-1 or a race style 4-4.... OOPS! >$3000US just flew away, just like that!! Plus new other engine stuff already mentioned.

$3-4000US will be spent just doing the obvious.

[acollin]

Congrats on the buy and welcome to the forum.

Not sure if this matters in the large scheme of your project, but if the bike is titled a 1975 the color and the fuel tank did not come with the bike originally.

The paint colors and fuel tank are from earlier models. For 1975 the petcock should be on the left side of the fuel tank. If memory serves me the original paint on your tank could be from 1973 or 1974. The emblems on the side covers earlier still. I believe the stock colors for 1975 were a red and a blue. As I said before depending on your planned outcome, this may not matter at all, but make your decisions informed decisions. It could save you some cash in the future.

It looks like a super platform but I personally would spend some time verifying exactly what you have there as it could make a difference down the road.

Good luck

[ekpent]

Your petcock right now is in the reserve position, pointed forward is off    See a later model front fender and as mentioned K1 style sidecover with a red jewel.  Can you post the frame number and engine number for us so we can see what year the stuff  really is . Sometimes even a 74 can be titled as a 75 if sold that year. Lots of engines were swapped around also as well as other parts. I see both 74 and 75 turns signals and other parts now etc.

[Dunk]

Nice bike, looks mostly there. Go through the carb and thoroughly clean them, probably gummed up from sitting. Clean or replace points and set timing, ensure advance is advancing and returning smoothly. Probably run fine after that.

Lots of cleaning and polishing. I use a variable speed buffer and wool and foam pads with coarse and fine compound to clean up aluminum and other metals. Works on bolts too if the coating isn't too bad. Wool pad and compound put bolt in vice and just hit it quick. If it doesn't clean up I sand blast and paint since I didn't want to take everything apart mixed up to get plated. Replacement bolts for other parts that are highly visible like fender and all the stuff around the top tree.

Check your wheel bearings and triple tree bearings. If in doubt replace them, major safety issues if they are worn. Relatively cheap and easy to do.

My spokes were a little rough so I sprung for stainless Buchanon spokes, worth it to me. If yours aren't bad you could probably polish them up but that would be very tedious with them laced.

I'm also in NJ, south near Philly. Shoot me a PM if you're in the area, need advice or need a part quick. I'm restoring my K1 currently, have a look at my project thread and start one of your own once you get into it. http://forums.sohc4.net/index.php?topic=125385.0

[Jayelwin]

So I decided to poke around the bike and figure out what year it really might be, as someone pointed out the color was off for a '75. The frame has serial # CB750-2537064



And the engine serial is CB750E-2419326



I was on reserve as I was running low - no need to fill up if I've got to remove the tank.

I'd love to get more info as tot he true provenience of the bike. Let me know how these numbers measure up.

[Jayelwin]

Here are some of the photos form the seller. They might shed some light on this bike.







The seat is a NOS replacement that the PO had just put on.

[Stev-o]

Its a K5, maybe the tank was changed?  Very common.


http://www.hondachopper.com/engine/engine_timeline/timeline.html

[Schnell]

Fuel petcock on your bike is on the right side. My '75 cb750 has it on the left.

Front turn signals don't match the rear. (Different size/year)

Front turn signals are mounted in a new position, leaving an empty bolt hole on the ear.

[ekpent]

They had the tank on reserve also    If you change out the side cover emblems from red to orange someday make sure the wings are pointed in the correct position,see one is backwards. Did you ever say how many miles the odometer has on it ?

[Stev-o]

They had the tank on reserve also    If you change out the side cover emblems from red to orange someday make sure the wings are pointed in the correct position,see one is backwards. Did you ever say how many miles the odometer has on it ?

Hey Eric - don't ya love how we "nit pik" each other's bike!?

[ekpent]

They had the tank on reserve also    If you change out the side cover emblems from red to orange someday make sure the wings are pointed in the correct position,see one is backwards. Did you ever say how many miles the odometer has on it ?

Hey Eric - don't ya love how we "nit pik" each other's bike!?

Guess I'm getting worse than a little old lady.

[Jayelwin]

I'm trying to run it out of fuel so I don't make a mess removing the tank.

So I guess we are concluding that the tank is not what's original for 1975. As it's probably not worth replacing it'll have to do. Also I like the orange.

Now how to get the side covers to match. I figure the tank needs to be compounded, touched up, and re-clear coated.

As to all the little wrong parts I plan on doing a lot of replacing here and there. Ebay is a wonderful resource.

It has a Dyna ignition system which is awesome as this was going to be an upgrade I was going to make anyway.


Sent from my iPad using Tapatalk HD

[Jayelwin]

Oh, 30,378 miles on the odo. I want to send the gauges to a restorer too. They're pretty tired as well.


Sent from my iPad using Tapatalk HD

[Stev-o]

I'm trying to run it out of fuel so I don't make a mess removing the tank.



Now how to get the side covers to match. I figure the tank needs to be compounded, touched up, and re-clear coated.

How would removing the tank make a mess, petcock doesn't work?

So you want new paint on the side overs match 35+ year old paint on the tank? Good luck. 
Do it right, paint them all together. 

[ekpent]

I'm trying to run it out of fuel so I don't make a mess removing the tank.



Now how to get the side covers to match. I figure the tank needs to be compounded, touched up, and re-clear coated.

How would removing the tank make a mess, petcock doesn't work?

So you want new paint on the side overs match 35+ year old paint on the tank? Good luck. 
Do it right, paint them all together. 

In Planet Blue---Yummy    http://forums.sohc4.net/index.php?topic=116060.0

[Jayelwin]

I figure if I end up doing something to the tank it'll need to be empty. Less fuel in it would help. So no need to fill it above reserve. This way it will be easier to empty.

I know it will be challenging to match the site covers to it painted tank. But if I bring it all to a paint shop specialist (I have one in mind) I wonder if they'll be able to easily reproduce that wonderful metallic orange flake paint.

[ekpent]

Its a multi layer process with a silver base coat and the candy orange etc. There are paint kits for sale out there if your painter cannot match it. As Steve mentioned though the orange color had a tendency to fade out over the years which makes doing a match trickier.

[acollin]

If a 1975 color scheme is what you want or simply to,get side covers to match the tank you want to keep, there are plenty of parts people reading these postings that might be able to trade stuff or sell stuff. Like me, I'm certain that most people reading these posts, have plenty of stuff to trade and sell.

Also, as you well know there are plenty of sellers of parts out on ebay. I have matched painted pieces myself with making certain the part pictured is factory original paint. Sometimes you may have to pay up for it and there are the scammers out there, but finding what you want could be easier than you think if original factory paint is what you are hoping to end up with.

I would strongly recommend sorting out the mechanicals before spending energy and resources on paint. Invest in good tools and carb sync system and buy quality parts. The machine will love you back if you take care of the mechanicals. Even the funkiest looking cb 750 will return the love if you take care of her.

Good luck

[acollin]

If you are making a list.

I believe the gauges are earlier than 1975-- if this is true, you really don't know the mileage. This makes a mechanical shake down even more important.

Baffles are missing from your exhaust pipes. If the pipes are intact (not rusting), take care of them.

Look under the tank for the original ignition switch bracket. The switch was originally mounted on the frame below the tank.

We do love the nit-picking.
Be well