1968 CB 350 Restoration / Upgrade

I picked up a basket case '68 CB 350 a couple of years ago, and I'm finally getting around to working on it. I purchased two project bikes around the same time just because they were so cheap, I couldn't pass them by. You can see the other here - http://www.dotheton.com/forum/index.php?topic=29346.0

On the up side the previous owner had engine and carbs professionally re-built, and I was given a pile of NOS parts. On the down side I was given coffee cans of nuts, bolts and brackets. Nothing was bagged and labeled, so figuring out what goes where, will take a little time.

As I finish the tear down and start cleaning up the frame and get ready for paint, I want to order some tires, so I can send them out to get mounted and balanced. I've done a lot of searching around DTT trying to decide what sizes to purchase, and there seems to be conflicting opinions. I believe the stock sizes are 90/90-18 Front and 100/90-18 Rear. I've seen a lot of builds where people are using 100/90-18 Front and 110/90-18 Rear, and even larger. I've read comments about how this effects handling. Is that true? How large can you go before they hit the fenders? Is it best to stick with the stock sizes?

If you want the best handling from the CB350, it is recommended to stay with the stock tire sizes, the bike was designed for these sizes. If you want to go larger for aesthetics, then you can go a bit larger but depending on how large you go the tire may rub the front fender brace or forks.

My recommendation is to run the stock sizes.

If you plan on keeping the rear fender and brackets and stuff im not sure a bigger rear tire will fit. Im running stock size with some nobbies and I had a hell of a time keeping them from rubbing on everything back there.

Thanks for the input. Any thoughts on what type of tires, and where to buy them? I've looked all over the place, and the only thing I can find in the 90/90 - 18 and 100/90 - 18 are the same Avons that I'm running on my Cb 175. They're great tires, but I wouldn't mind trying something else out.

http://www.bikebandit.com/avon-am26-roadrider-motorcycle-tire

There were a few different tires mentioned recently in this thread: http://www.dotheton.com/forum/index.php?topic=51388.0

I'm running 100's up front and 110s in the rear on my CB360, and they fit fine. I too had problems finding the stock size tires. I did find that the front brake hose bracket was bent, as it started rubbing with the larger front tire, so I bent it back into place and all was well. I'm not sure if this info would also apply to the 350, but I do believe that the front and rear wheel setups are similar.

Handling seems fine, but this is from only a few miles on the new tires and my comparison is to 37 year original tires. I suspect wooden wagon wheels would be better than those tires...

Also check into actual tire dimensions on Manufacturers sites as they vary in dimension from one manuf. to another and even in the same manuf but diff model. Avons 90/90 - 18 may be the same size as bridgestones 100/90 - 18 also you can maybe find a 100/80 -18 that will be very close in actual size as a 90/90. The sizing is height as a percentage of width and depending on the roundness of the profile the Actual heights and widths can vary quite a bit. Also check that the rim width you intend to use it on is acceptable to the particular model tire and size.

I've made quite a bit of progress as far as rust clean up and polishing. I'm sending parts off to my mechanic tomorrow. Getting the new tires mounted, fork seal and wheel bearing installed.

The tank was in pretty rough shape, inside and out. I decided to try the apple cider vinegar trick. I shook a bunch of dry wall screws inside to start. Then added the cider vinegar, and let it set for about five or six days. Ran the vinegar through some cloth to remove the large chunks of rust and sludge that came out. It was pretty nasty. About an eighth of a cup total. I was impressed. I put the vinegar back in, and let it set for another couple of days. Rinsed out the vinegar with water, then water and baking soda. Unfortunately I think the tank was just to rusted. While a lot of it was removed, I think there's still too much in the tank. I think I'm going to bring it to a radiator shop and see what they can do with it.

Today while I was cleaning the heavy grease off the frame in preparation for stripping it, I found a small hole. I'm hoping this is a fairly easy fix. I don't know anything about welding. Any ideas on what fixing a hole like this might cost? It seems to be pretty solid all around the hole. No soft spots or cracks.

Also on the opposite side of the frame the foot peg bar bracket looks like it might be bent. The frame around it looks straight, and the bracket looks square to itself. it just looks twisted. Is this correct?

More pics.

I did some calling around, and it looks like it would cost 150 bucks to get the tank cleaned up at a radiator shop. Not quite in my budget, so I think I'm going to give POR-15 a try.

jakeZ70 said:

I did some calling around, and it looks like it would cost 150 bucks to get the tank cleaned up at a radiator shop. Not quite in my budget, so I think I'm going to give POR-15 a try.

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Metal rescue works amazingly. Ive used it to clean up some tanks and they come out spectacular. Its a little expensive but your tank only holds two gallons, I think it would end up running you $40. Plus you can reuse it after on other other parts to make better use of your money.

jakeZ70 said:

I did some calling around, and it looks like it would cost 150 bucks to get the tank cleaned up at a radiator shop. Not quite in my budget, so I think I'm going to give POR-15 a try.

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Use vinegar......works great, smells bad............but works great. And cheap.....

I tried using vinegar. See above. I think the rust was just too heavy. It removed quite a bit of it, but not all.
I'm a little hesitant to use Metal Rescue. The 350 tanks actually hold almost three gallons, so I'd be looking at almost 75 bucks. I've heard mixed reviews. I'm assuming people that haven't had luck using it were dealing with as much rust as I was.

I have used Kreem products on all 3 of my bikes tanks. What I do differently is I use the acid etch full strength. You have to keep it moving around though. the last one I did looked like yours and came out looking great with Kreem. I know some people are down on it and I do not know why. I have one tank that was kreemed 18 years ago and it is still looking great.

I have used hardware inside a tank to scratch off the rust. It takes a long time and allot of shaking. In my opinion, this is the best way to remove the heavy rust in a tank. After washing out all the dust, the remaining rust can then be chemically removed. You can buy a gallon of distilled white vineger for a buck. A 3 gallon tank will cost $3 which isn't much. Vineger is dilute acetic acid so it isn't very strong and shouldn't be further diluted. I should mention that I haven't used vinegar and I bet it takes a long time to remove any rust. Phosphoric acid, now that's the stuff!

Before rust removal is started, there probably is a thick coating of dried gas residue in the bottom of the tank. This 'varnish' can keep the bottom of the tank from getting cleaned properly. A good wash with cheap carb cleaner or other strong solvent will melt this varnish so it can be scrubbed away with the hardware shake.

Tom

jakeZ70 said:

I tried using vinegar. See above. I think the rust was just too heavy. It removed quite a bit of it, but not all.
I'm a little hesitant to use Metal Rescue. The 350 tanks actually hold almost three gallons, so I'd be looking at almost 75 bucks. I've heard mixed reviews. I'm assuming people that haven't had luck using it were dealing with as much rust as I was.

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If you have a 78 and still have the original square tank... they hold 2 gallons, I have one. In 71 they changed to a rounder tank which expanded it to 3gal.

moetrout said:

I have used Kreem products on all 3 of my bikes tanks. What I do differently is I use the acid etch full strength. You have to keep it moving around though. the last one I did looked like yours and came out looking great with Kreem. I know some people are down on it and I do not know why. I have one tank that was kreemed 18 years ago and it is still looking great.

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I dont like kreem, ive used it, and it was done with acid but it just doesn't hold up with the new gas. If your going to line it, use POR15.

TomTerrific said:

I have used hardware inside a tank to scratch off the rust. It takes a long time and allot of shaking. In my opinion, this is the best way to remove the heavy rust in a tank. After washing out all the dust, the remaining rust can then be chemically removed. You can buy a gallon of distilled white vineger for a buck. A 3 gallon tank will cost $3 which isn't much. Vineger is dilute acetic acid so it isn't very strong and shouldn't be further diluted. I should mention that I haven't used vinegar and I bet it takes a long time to remove any rust. Phosphoric acid, now that's the stuff!

Before rust removal is started, there probably is a thick coating of dried gas residue in the bottom of the tank. This 'varnish' can keep the bottom of the tank from getting cleaned properly. A good wash with cheap carb cleaner or other strong solvent will melt this varnish so it can be scrubbed away with the hardware shake.

Tom

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Tifun on here actually put roughing stones (or nuts and bolts if you want) in his tank and put it in his dryer to spin. Put a large comforter in the dryer and smash the tank in the middle of it. Put some extra blankets around to make sure its good and tight. I believe he ran it though a cycle or two, turned the tank around and then ran it through again. It turned out really good and might be something to try if your having a hard time and dont want to go a more expensive route.

Someone else used a rotisserie from a gtrill to strap the tank to and let it turn turn turn.

I tried to talk my fiancee into letting me use the dryer for tumbling, but she came back with a pretty quick and emphatic no. I tried to explain that there hasn't been gasoline in this thing for over 30 years. That didn't matter.

Using the drywall screws and the cider vinegar definitely helped quite a bit. A large amount of nasty gray sludge came out during while rinsing. I just don't think the acid is quite strong enough for the amount of rust in my tank.

Phosphoric acid sounds like it would do the trick, but I'm not sure I want to deal with that nasty stuff.

Are you in a hurry?

If not, fill with vinegar, drywall screws (count them to ensure you get them all out) (ask me how I know).

Shake, cause you want to get in shape., let sit after you're tired.

Next day, shake some more (cause you want to get in shape). Let sit cause you're sore and tired. (ask me how I know)

Do the above for about a week, then have the wife tell you, you look stupid, say "oh well, and do it again for about 4 or 5 more days............ensure you drink beer while you're doing this telling yourself, at least I'm exercising.

Results::::::::::runk and happy, cause you have a clean tank, and all it cost you was........oh you'll see.