A long CB/CL/SL 350 build

oldhondas

oldhondas

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I'm going to do a 350 twin build from various parts.

!972 SL350 frame, may hard tail.....still contemplating.

1972 CB350 bottom engine, looks like it hasn't been split

1972 CL350 engine bottom, that has been split and put back together with permatex..... ewwwww

1972 CB350 jugs w/ cruzinimage pistons .050mm over

1972 CB350 head, and valves

1972 SL350 cam chest w/cam, gear and, rockers

1973 CB500 front forks w/ CB350 19 inch wheel
 
oldhondas said:
I'm going to do a 350 twin build from various parts.

1972 SL350 frame, may hard tail.....still contemplating.

1972 CB350 bottom engine, looks like it hasn't been split

1972 CL350 engine bottom, that has been split and put back together with permatex..... ewwwww

1972 CB350 jugs w/ cruzinimage pistons .050mm over

1972 CB350 head, and valves

1972 SL350 cam chest w/cam, gear and, rockers

1973 CB500 front forks w/ CB350 19 inch wheel
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I can only assume you mean SL350K1 or K2 for those in bold above, since a K1 could have been titled '70, '71 or even '72 (though less likely '72) and a K2 could have been titled '71 or '72
 
ancientdad said:
I can only assume you mean SL350K1 or K2 for those in bold above, since a K1 could have been titled '70, '71 or even '72 (though less likely '72) and a K2 could have been titled '71 or '72
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Yea, I'd have to go out and check......off top of my head can't remember.

Frame is the dual down tube frame. Doesn't have the stamped frame on the rear.

Thanks for the info.....
 
This is the start of parts gathering:
 

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ancientdad said:
Gas tank is definitely SL350K2 by paint scheme
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Cool, thanks.......I;m really looking forward to you helping me out on this build. I read some, alot, of your post, and have been using them as my guide.

I read somewhere you of someone else recommended taking a page from the manual to the machine shop when I have the jugs bored and honed. Just can't find that info.

I'm planning on having them bored 0.50mm over.

Thanks in advance.

Also seems all the pieces slid over the studs and line up purdy well.....
 
Well, I'm more into the 450 but I've worked on my share of 350s over the years, just not nearly as much recently. All the top end parts will interchange but as I'm sure you're aware, the cams and rockers have to match up. The carbs and head port size are smaller on the SL350K1/K2 engine and the cam grind is for more torque. You can take the manual info to a machinist for insurance, along with the new pistons of course, when you take the cylinders to be checked
 
Page 40 of the later 350 FSM has the info for the machinist.
You probably want to fit the CB350 bottom end into the frame so you know in advance how much modification to the down tubes is required for starter clearance. Easier with a partial engine.
 
LongDistanceRider said:
Page 40 of the later 350 FSM has the info for the machinist.
You probably want to fit the CB350 bottom end into the frame so you know in advance how much modification to the down tubes is required for starter clearance. Easier with a partial engine.
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Thanks man......I actually did that,
 

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Well, I did some playing. Mocked up some stuff.
 

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Mix and match... those right side footpeg brackets on the SL350K1 and K2 were notorious for coming loose at the 2 mount bolts on the frame after lots of jumps and hard landings, they flexed too much and on really hard landings they tended to bend downward. Though it looks like the snout on the crankcase for the electric starter is really close to the downtube, it does look like it would work out with an e-start engine in it
 
ancientdad said:
Mix and match... those right side footpeg brackets on the SL350K1 and K2 were notorious for coming loose at the 2 mount bolts on the frame after lots of jumps and hard landings, they flexed too much and on really hard landings they tended to bend downward. Though it looks like the snout on the crankcase for the electric starter is really close to the downtube, it does look like it would work out with an e-start engine in it
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yea, it appears the foot rest has been welded at one time or another.

I think the starter will clear......I'm too overly concerned about it.

The thing I'm having issues with is the exhaust. This is a very very low budget......meaning no money, no money build.

Not sure how to go on that......those CB350 header pipes are in so good condition.
 
oldhondas said:
yea, it appears the foot rest has been welded at one time or another.

I think the starter will clear......I'm too overly concerned about it.

The thing I'm having issues with is the exhaust. This is a very very low budget......meaning no money, no money build.

Not sure how to go on that......those CB350 header pipes are in so good condition.
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Yeah, the proper exhaust for an SL350 is the biggest stumbling block, and nothing else used on it looks quite right but for a budget build I completely understand. I think you'll encounter the need for modification with the CB headers though, based on the SL footpegs
 
I'm still considering doing a hardtail, but that's gonna to be further down the road, gotta get the engine work done first.
 

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That frame looks like it's been through a war. I can't say I've ever seen a Honda frame with so many cracked, broken or split spots before. It must have gotten thoroughly thrashed in its life before you
 
ancientdad said:
That frame looks like it's been through a war. I can't say I've ever seen a Honda frame with so many cracked, broken or split spots before. It must have gotten thoroughly thrashed in its life before you
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I think the same. Don't know the history on it.

I got it because of the tube frame, thinking it will be easier to hard tail, rather than a stamped frame from a CB/CL.

I did get ahead of myself though, installed a roller bearings in the head

I was gonna have this thing sand blasted, but I think I'll just spray it down with some air craft stripper, and prime and paint......not really going with anything show worthy.
 

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I've read some where's, when rebuilding these CB350 twin engines, it's better to use a different oil pump.

Just can't remember where and which oil pump was recommended.

Does anyone know? Thanks.

Haven't really done anymore physical work on anything.

Did order a lift table, as I have other projects happening, and these old 64 yo bones are a aching. Waiting on it to arrive.
 
Having a lift improves the situation for us older guys a lot. I've been working on the Harley I bought recently with it sitting on the floor and though what I'm doing isn't a big deal, it's still a lot less comfortable. As for a different oil pump for the 350, I'm not aware of anything out there except for the ultra-expensive and heavy modification required to fit Cappellini pump
 
ancientdad said:
Having a lift improves the situation for us older guys a lot. I've been working on the Harley I bought recently with it sitting on the floor and though what I'm doing isn't a big deal, it's still a lot less comfortable. As for a different oil pump for the 350, I'm not aware of anything out there except for the ultra-expensive and heavy modification required to fit Cappellini pump
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Thanks, I think now that I remember, was a CB360 build I read that about the oil pump.

Yep, I've got a Harley I'm about to take a dive into the cam chest, and have come to the conclusion that lift is needed.

Plus all these vintage Hondas will be easier to wrench on as well.

So win/win.......................!!
 
oldhondas said:
Thanks, I think now that I remember, was a CB360 build I read that about the oil pump.

Yep, I've got a Harley I'm about to take a dive into the cam chest, and have come to the conclusion that lift is needed.

Plus all these vintage Hondas will be easier to wrench on as well.

So win/win.......................!!
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Yes! And as to the 360 oil pump mention, I think you're remembering a mod to the oil filter relief valve - which can be done on the 350, 360 and 450 as well. I did it on my 450, since anything you can do to get a little more flow to the top end of a 450 is worth doing (if in fact it does help)
 
ancientdad said:
Yes! And as to the 360 oil pump mention, I think you're remembering a mod to the oil filter relief valve - which can be done on the 350, 360 and 450 as well. I did it on my 450, since anything you can do to get a little more flow to the top end of a 450 is worth doing (if in fact it does help)
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Yep, I know that mod, and am considering it, long way to go for that work though.

Got pistons in from Crusimage .050mm over. Gotta get them and the jugs to a machine shop.

Did a leak down test on the head, exhaust side leaked down quicker then intake, Guess I have to do the test again and take better notes, Not sure which cylinder leaked the quickest.

May just drop it along with the rest and have a valve job and decking done.
 

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Well, the last post I did on here was 2021. Had problems and had to step away. Back now, I turned the head into a motorcycle shop to have them check the head for me.
I told the guy, I was not in a big hurry........that was Aug 2021.

Checked with him yesterday, still not done yet.........just different excuses each time.

The head is there, and he started working on cutting new seats. Then he had to go, so he kicked me out, shut down the shop........

Hopefully I'll get the head back this week.
 
oldhondas said:
Well, the last post I did on here was 2021. Had problems and had to step away. Back now, I turned the head into a motorcycle shop to have them check the head for me.
I told the guy, I was not in a big hurry........that was Aug 2021.

Checked with him yesterday, still not done yet.........just different excuses each time.

The head is there, and he started working on cutting new seats. Then he had to go, so he kicked me out, shut down the shop........

Hopefully I'll get the head back this week.
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Fingers crossed.
 
I finally got the head back, looks nice. Guess 160$ was a good price.

Wifey has the kitchen remodel going, so minimal time on the bike(s)
 
oldhondas said:
I finally got the head back, looks nice. Guess 160$ was a good price.
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That depends on what you can't see - did he assemble everything (valves and springs in), or can you see the valve seats to tell what kind of work he did? I mean, 2.5 years for some head work is more than enough time to do it right. :rolleyes:
 
Once in a while, I stopped in to check on it, he would show it to me and explain what he was doing to it.

He once said he was waiting on a tool to cut the seats, and it wouldn't be in for a while.

So, some my fault, most his fault taking that long.
 
Got the head back, looks good. Getting the engine put together. Getting the timing mark and the cam lined up was a pain. Also getting the two sides on the cam box.

Hope I lubed them up enough.
 
Just don't get much time to work n this thing.........

More sanding on the frame of the CB/CL/SL350 build. Got a loooonnnngggg way to go.

Gotta get to the store and buy oil for the engine, I just rebuilt and finally got the side covers on. Planning on Rotella T6 synthetic. Just as break in, then I'll go back to 10/40 Honda Motorcycle oil.
 
oldhondas said:
More sanding on the frame of the CB/CL/SL350 build. Got a loooonnnngggg way to go.
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Down and dirty for me. Scrape thick chunks with knife/screwdriver, degrease with brush and gasolene, hit choice spots with SOS pad then hose it, grind rust spots with course wire wheel drill brush, spray rustoleum black gloss engine paint , recoat areas as needed.
Fall is coming, clock is ticking, only pretty where it needs to be.
 
Well, had to go to my family reunion up north, so more time taken away.

I will do as you say and just make the seeable areas neat. The rest will get the minimum service.

4 years is really stretching it.

Now that both knees are replaced, and shoulder next month, should have it done by the end of next year.

Let's hope...................................!!!!!!!!!
 
I need a parts manual for a 1972 SL350.

Anyone know where I can get one?
 
Re-reading this thread, I'd guess based on the gas tank in the early pics that you mean SL350K2. The only part book we have for an SL350K1 and K2 is for Australia, but I can't imagine too many important parts being much different if at all. Here's a link to it good for 3 days

Online Backup for PC, Mac and iPhone | IDrive

Shared with IDrive
www.idrive.com www.idrive.com
 
ancientdad said:
Re-reading this thread, I'd guess based on the gas tank in the early pics that you mean SL350K2. The only part book we have for an SL350K1 and K2 is for Australia, but I can't imagine too many important parts being much different if at all. Here's a link to it good for 3 days

Online Backup for PC, Mac and iPhone | IDrive

Shared with IDrive
www.idrive.com www.idrive.com
Click to expand...
Thank you, this exactly what I needed.
 
Can't find the number for the paint.

Got her up to a rolling chassis, with engine installed. Well, sort of, still tweaking some bolting up issues, and starter clearance.

Looks good though. I could actually make this bike look like a real SL350, with the right part orders.

Buuutt..I didn't actually want to go that way. Just seems I'm not in the mood to beat and bang and make an accessory box , and seat.

Working with the wiring harness, and two different controls for the handlebars. I can work it out, just not liking the cool weather coming our way.

Plus the Honda control I have for the right side need to be rebuilt. I want to do it, but can't find diagrams for assistance,

All I can do is stay focus, I suppose.

Can't get the puter to recognize the phone to download pictures. Maybe next time.
 
I ordered a wiring harness for CB/CL/SL bike, Plus L&R hand controls, throttle/speedo/Fr brake/ and clutch cables.

I think I ordered the wrong rec/reg. Guess I'll have to relook that order.

When received, I will wire it up, and finally have it at the firing stage.

I still need an original starter wire, I'm using a make shift wire at the moment.

I Hope.
 
Well the wiring harness I ordered is for a SL350, it doesn't have the starter system. oops.

So reordered a CL350 harness, got it, now just to wire it up.

Ordered a front wheel for a CB350F with disk and speedo, buuuut, it won't fit.

So, back to the drum wheels, 19" or 21", I'll be making that decision soon. Fender I got for the front won't fit either.

May use it as a rear fendert6u, with some mods.
 
On ebay of course..........I just forgot I had a starter engine, and turn signals and such.

Also can't find a right hand control, that has the starter button, shut off and light switch with the brake lever slot.

I don't have much room on the handle bar to put a separate control, and brake lever perch.

So may have to do without the shut off switch on top of the control.
 
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