CB350 Four scrambler projet + brat?

tahitianrider

Been Around the Block
So few months ago I picked up a 73 CB350F that had been sitting for about 30 years, along with a second engine with carbs and a second frame.
They have not been stored in great location during all those year it seemed... lot of humidity and corrosion about everywhere.

My main project was to build the first CB350F as a 2 seater scrambler, and later on maybe sell the extra engine & frame, but I now had another idea, since I have tons of leftovers parts (tanks, shocks, etc.) from other projects to build a second bike with those parts.

I managed to restart the bike by rebuilding the carbs & ignition, and then completly rebuild the rest of the bike: re laced wheels with new rims, tires, changed the fork seals, made a handmade scrambler seat, treated the gas tank, etc. so it's starting to look cool IMO.
Only things lefts to do are "finish up" work like installing turns signals, new drive chain, pods (carbs already re-jetted) and final tune (carb sync, etc.)

For the second engine however I'm not quite sure if it seized or not... It sat for a long period without spark plugs, nor carbs & exhaust... I tried gently turning the crankshat nut behind the points cover but it didn't move and the bolt quickly broke inside, luckily I was able to remove it entirely so I just have to install a new bolt. I then spray some fogging oil in the cylinders, left it for a day. Then I tried to connect 12v power directly on the starter and it did crank a bit and I could feel (wind) from the spark plug hole so I guess the piston did move in the cylinder. I sprayed a lot more fogging oil then left it as is, haven't tried anything else yet since my priority is to finish the Scrambler build first.
But if I can get this engine to run again too I think a brat build would be cool, or maybe a cafe racer but I'd like those bike to be 2 seaters.
 

Attachments

  • cb350F 1.JPG
    cb350F 1.JPG
    93.1 KB · Views: 337
  • CB350F 2.JPG
    CB350F 2.JPG
    99.1 KB · Views: 325
  • CB350F 3.JPG
    CB350F 3.JPG
    73.6 KB · Views: 505
If anything like the dohc 750s, you turned the wrong bolt. On these, you turn the bolt on the alternator rotor. Either way, you should remove the valve cover and put assembly lube (or at least motor oil) on the cam lobes. Personally, I'd fill the cylinders with oil and let it set for a week, then bar it over gently ~1/2 stroke, refill cylinders and let it set another week. Then bar it over to get most of the oil out followed by starter motor to get the rest down to just a coating. Did this with a '79 CB750F that had set in the open since 1999 with good success.
 
It was the correct bolt because I have the service manual and it is bolt used to rotate the engine when setting the ignition timing, it is the bolt I use when I set ignition timing on my working 350F engine.
Thanks for the tip on removing the valve cover, I hadn't think of it and I have extra engine oil laying around, that's what I'm going to do!
As for the oil in the cylinder, I actually put fogging oil (similar to marvel mystery oil) since I heard it could help a lot free'ing up pistons, but maybe I'll try the engine oil in cylinders too.
 
So the blue bike now is the red bike, looks great.
 
WhyNot said:
So the blue bike now is the red bike, looks great.

Exactly! blue wasn't the original color anyway, it was olive green at first, I noticed when scratching paint. Thanks :)

The second bike is just an engine and a frame a the moment, but I already found a complete rear wheel, and a complete front end off a CB250G (similar to the CB360 but only use by the army in France at the time) I'm waiting to receive
 
First 350 Four is now finished, I am just still waiting to receive its registration to test ride it which is pretty frustrating lol

And still gathering parts for the second 350 Four project, also waiting on oil sitting in the cylinders of the second engine to maybe unseize it, I might try to pour in petrol with 2 stroke oil mix inside the cylinders too.
 

Attachments

  • 350four2.JPG
    350four2.JPG
    86.1 KB · Views: 271
  • 350Four1.JPG
    350Four1.JPG
    116.3 KB · Views: 293
Man, that looks nice. Wish I could get mine even going......darn carbs.

Did you have to change the carb. jets with that exhaust set-up?

Never mind, see you have pods on there.......
 
Thanks! I still have to fix one small leak on one of the carb that is still leaking a bit via the overflow tube, I'll try to swap the other bowl with one I soldered.

What's wrong with your carbs?

Yeah I did changed the jets with the pods & exhaust, if I remember correctly, I put 38 slow jet and 80 main jet. I also sync the carbs. I will adjust the fuel mixture screw when I'll be able to test ride it on the roads.
 
tahitianrider said:
And still gathering parts for the second 350 Four project, also waiting on oil sitting in the cylinders of the second engine to maybe unseize it, I might try to pour in petrol with 2 stroke oil mix inside the cylinders too.

Try mixing ATF (transmission fluid) and acetone 50/50 and putting that in your cylinders. Its the only thing I've found that will actually penetrate past rusted rings on a seized piston.
 
advCo said:
Try mixing ATF (transmission fluid) and acetone 50/50 and putting that in your cylinders. Its the only thing I've found that will actually penetrate past rusted rings on a seized piston.

You mean something like that? because I just happen to have some
huile-de-boite-et-pont-motul-gearbox-80w90-1-litre.jpg


Nevermind I just found out that ATF means Automatic transmission fluid, I'll just get some on amazon then along with some acetone! thanks!
 
Absolutely gorgeous build. I love the choices you made in you blackout, and the ruggedness.
I'll get some pics of my 68' CB350 project up soon and share. Thanks for the inspiration


Sent from my iPhone using Tapatalk
 
^^^^^^Cool^^^^^inspiration......and absolutely agree....!!!!

My carbs are leaking somewhere's between 2 and 3, I thought the fuel line but looks like something else. I've got them pulled just gotta stop being so lazy and do something with them.

Where did you get the jets from? I've looked at different places, but like to see where others shop.

I've got that exhaust on mine, using the straight pipe that's offered with them.

Have yet to hear how it sounds, with the carb issues giving me fits..........!!!!
 
supernorml said:
Absolutely gorgeous build. I love the choices you made in you blackout, and the ruggedness.
I'll get some pics of my 68' CB350 project up soon and share. Thanks for the inspiration

Thanks!!

WhyNot said:
^^^^^^Cool^^^^^inspiration......and absolutely agree....!!!!

My carbs are leaking somewhere's between 2 and 3, I thought the fuel line but looks like something else. I've got them pulled just gotta stop being so lazy and do something with them.

Where did you get the jets from? I've looked at different places, but like to see where others shop.

I've got that exhaust on mine, using the straight pipe that's offered with them.

Have yet to hear how it sounds, with the carb issues giving me fits..........!!!!

I think your carbs could either leak from the fuel line from the fuel tank, it actually needs to go ALL the down and it can be pretty difficult to stick the fuel line all the way down to the bottom. This would be the good option, or the bad option: it probably leaks from the "T" fitting between carbs 2 & 3 which has 2 orings. Most likely the orings are busted, but it is a PITA to take apart because you actually need to take the 4 carbs aparts to reach this T fitting.

Those jets are difficult to find indeed, got mines from 4into1, they're cheap, about a dollar the jet, plus $26 dollar shipping to France ::) ;D

Those Delkevic 4 into 1 pipes sounds really good! just wait for it... !
 
By the way,
Is there any other way to try to gently crank or turn a CB350F "seized/stuck" engine aside from the the "special nut" used to turn the cranckase for ignition timing, which is kinda "fragile" or the kickstart lever, which is difficult to operate and put force on when the engine is not in the frame and just resting on the ground.
Maybe putting it in 5th gear and try to turn the sprocket with a chain?
 
If the sprocket is worthless, put 2 longer bolts in it to stick out.

Slide it on the shaft, with it in a gear, and use a pry bar in between the 2 bolts.

Be gentle with them, not to break the bolts off. Do a back and forth motion like it was on the bike.
 
There's really not a great way, other than the big nut on the end of the crank. I don't even like to put a lot of force on that either.

You'll want to soak the cylinders for at least 2 weeks. The last stuck engine I rebuilt I just ended up pulling the head off and bashing the piston down with a block of wood and hammer.
 
Oh okay, thanks for the info, I will pour the acetone/ATF mix in for the moment then wait a couple weeks.
When pulling the head off to hammer down the pistons, ins't it a problem to hammer just one piston ?? wouldn't it be better to hammer for example piston 1 & 4 at the same time? and 2&3 together too ? since they are syncronized?

I guess it would be better to know somehow which pistons are in their compression stroke to not hammer those ones?
 
I finally managed to to my first road test today (was waiting for the license plate)

I do have some issues to solve:

- The battery isn't charging at all, I installed a new reg/rec combo much more modern that the old units, a cheap one off ebay, I don't know if this is the problem or the stator.. I think I'll have to run a kind of stator test to know which component is faulty, but I guess a stator that has been sitting so long in a barn bike might have some problems? Is there an easy stator test I can do using a ohm meter on the connector pins of the stator?

- Clutch is slipping a bit, especially at higher RPMs, for $50, I think I'll just but new clutch plates & springs.

- When I laced the wheels, I did not true them well enough, so I have a nasty vertical wooble past 35 mph... feels like sitting on a washing machine. I guess I should be able to correct that without have to remove the tires of the wheels and just puting the bike on a stand?

But this baby sounds beautiful!!
 
tahitianrider said:
- The battery isn't charging at all, I installed a new reg/rec combo much more modern that the old units, a cheap one off ebay, I don't know if this is the problem or the stator.. I think I'll have to run a kind of stator test to know which component is faulty, but I guess a stator that has been sitting so long in a barn bike might have some problems? Is there an easy stator test I can do using a ohm meter on the connector pins of the stator?

- Clutch is slipping a bit, especially at higher RPMs, for $50, I think I'll just but new clutch plates & springs.

stator test is an easy one. 3 leads from stator. We can call them 1,2,3, Set meter to ohms. Read at the plug 1-2, 1-3, 2-3. They should all be around 1.0 ohms. If not, AND you have very sharp meter tips. Push the tips through the wire insulation close to the stator body itself. Read all three again. If it tests good here. Then start looking for the broken wire. Usually between the stator and the bend where it comes through the plastic seal. If you find the break you can then re-solder w a new wire. If it reads 1 ohm through wires 1-2, and nothing 2-3 and 1-3 then you know its wire 3 thats broke. Because 1 and 2 both read good.

FWIW. I just replaced mine w one of these Emgo.
https://www.ebay.com/itm/Charging-System-Stator-For-72-77-Honda-CB350F-CB400F-CB-250F-400F-Super-Sport/372256368264?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D20131003132420%26meid%3D09206c93684348c89735cd799d1913e6%26pid%3D100005%26rk%3D2%26rkt%3D12%26mehot%3Dlo%26sd%3D182381367553%26itm%3D372256368264&_trksid=p2047675.c100005.m1851


Yes new clutch discs and springs is a pretty easy job. Be sure to measure the steel plates while you're in there. Also, I use Rotella in the blue bottle in all my Hondas. Some oils can be too slippery causing slip issues.
 
Back
Top Bottom