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1971 SL350

At least you found something to explain the failure to run. It's such a relief to run into something so obviously wrong, but it also makes you know you are going to have to review everything because the PO did that. On my K0 so many fasteners in the swing arm were easy to unscrew I figured the guy had the bike fully apart and just slapped it back together for some reason. That meant I had to check everything carefully for tightness. It's better than having everything rusted or corroded together so you can't get it apart, but not much.
 
I put the bike back together this morning and gave it a kick....and we have fire on both cylinders! I haven't adjusted the carbs yet but it seems ok. It is puffing a little smoke from that right cylinder. I'm not sure if its burning something off, it's just cold out, or if there is something else going on. No bad noises that I hear.

So I think the engine will be ok. I think I'll go ahead and drain the oil/clean the oil filter and do some additional testing on electrical and warm compression before I begin pulling the bike apart for restoration.

 
Other than it sounding like one cylinder's idle speed is slightly higher than the other as evidenced by the sound of it decelerating to idle after a rev, the engine sounds good and you can sort out the carb adjustments later. If the dead cylinder was the right side it could explain the smoke, excess fuel buildup in the pipe and muffler mixed with some oil washed off the cylinder burning off what's collected in the exhaust
 
Glad to hear it run. Nice job on the headlight upgrade. If I rode mine more at night I would definitely consider doing that.
 
I warmed up the SL350 this morning to check oil flow to the cam (good), charging with the new Sparkmoto unit (good), and to drain the oil/check the oil slinger (not so good). To start it off, the oil plug must have been installed by a gorilla. I had to take a big breaker bar to free it up. The o-ring on the oil plug might be OEM, who knows. Anyway, the oil was fresh but the drain plug had black something in it that had settled into the plug. Then I pulled the oil slinger cover (yes, that's right, the one with the messed up screws) off, and the retaining clip fell out with the cover. Apparently, the retainer was installed wrong or not installed at all (can't imagine except for my experience with the slow jet).

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The oil slinger was relatively clean, I assume the PO had cleaned it off, but there was more black something in there that I couldn't tell if it was plastic or metal.

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I have been waffling on whether to do open up the top end when I pull the engine. I think at this point I need to open it up just to check condition and replace to cam tensioner as a minimum. Can't wait for the next surprise!
 
Stripped down mostly, I should be able to pull the engine in the next couple days when I get a chance. I guess I'll plan on laying it down and lifting off the frame.

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Pulled the engine today. It came out pretty easy laying the frame on its side and lifting the frame off. The one thing I didn't expect is that the engine frame I built for my 1972 CL350 wouldn't fit the 1971 SL350.....duh

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I guess I'll just use a 2x4 to rest the front of the engine on...

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That's peculiar, I thought the mounts would be identical. I see FB post of people sticking CB350 engines into K1/2 frames and K1/2 engines in SL350K0 frames. In fact Aaron and I have one of the latter in storage right now.
 
That's peculiar, I thought the mounts would be identical. I see FB post of people sticking CB350 engines into K1/2 frames and K1/2 engines in SL350K0 frames. In fact Aaron and I have one of the latter in storage right now.

That is odd....I'll have to go check it out closer. Wouldn't be the first time I goofed....
 
That's peculiar, I thought the mounts would be identical. I see FB post of people sticking CB350 engines into K1/2 frames and K1/2 engines in SL350K0 frames. In fact Aaron and I have one of the latter in storage right now.

I agree, I always thought the lower motor mounts were the same myself.
 
It looks like the front mount on my 1972 CL350 is just shy of 5 1/4 inches out-to-out.

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The out-to-out on the 1971 SL350 is about 6 3/4 inches on mine.

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Seems like you could put a CB/CL 350 into an SL K1 with spacers, but a SL350 into a CB/CL would call for some mods. I guess it wouldnt be an issue on a SL350 K0.
 
Thanks for the measurement. Wasn't something I was aware of, but the difference in the lower case of the SL350K1/K2 is much more obvious now. I suspect it's because the K1/K2 frame is double downtube where the CB/CL350 and SL350K0 frame is a single downtube version that splits into 2 tubes under the engine.
 
I'm working some on the frame today getting it ready to sandblast. I'm not a good welder, but some of the welds on this frame look pretty poor even by my standards.

One area to fix is where the PO drilled though the fender support tube to mount a make-shift fender support. Here is how it was when I bought the bike, and the correct mount (still looking for a better chrome piece)...

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I prepped the hole that the PO drilled....

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And used a small MIG to weld the hole shut...

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Not the best but better than it was.....
 
That's an interesting bit of info on the lower case mounts. There are a number of differences from the SL350 K0 to the K1/K2. That makes it all the more interesting to hunt parts for a 1969/1970 K0 which is now a 52 year old, single year motorcycle. Lots of things are similar in appearance at first glance, but totally different in reality. Some examples off the top of my head are the taillight bracket, the front fender mount, the center stand (none on the K0), the carburetors (vacuum slides eliminated on the K1/K2), the kick starter, the RH switch pod, the headlight ears, the ignition switch and key, the fork lock sleeve, and more.

I know the K1/K2 bikes are supposed to be a big step up from the K0 bikes, but -- as an older guy, I appreciate the idea of the electric leg on my K0, and I really don't care if it is heavier. I won't be doing motocross with it.

Thanks for the great video. I played it a bunch of times. I hope I hear mine make a similar noise before too much longer.

I will follow your build with interest.

Ray

{Edited to add this} Nice job closing that hole in the rear of the frame. Since you are a welder, you can "spot weld" with your mig if you want to get rid of those little bolts on your air filter housing. If you hold a piece of smashed copper tubing up against the inside hole that you drilled and then hit each hole with your welder, it will end up looking spot welded (not that it will show anyway, but it will get rid of the worry of the bolts migrating to the wrong spot).
 
That's an interesting bit of info on the lower case mounts. There are a number of differences from the SL350 K0 to the K1/K2. That makes it all the more interesting to hunt parts for a 1969/1970 K0 which is now a 52 year old, single year motorcycle. Lots of things are similar in appearance at first glance, but totally different in reality. Some examples off the top of my head are the taillight bracket, the front fender mount, the center stand (none on the K0), the carburetors (vacuum slides eliminated on the K1/K2), the kick starter, the RH switch pod, the headlight ears, the ignition switch and key, the fork lock sleeve, and more.

I know it won't matter to you because you won't be climbing a hill or riding a trail and stall the engine, but the K1 and K2 also have primary kickstart which eliminates the need to find neutral before kicking the engine over. And you won't be looking for the nearly unobtanium left switch (horn only, made entirely of plastic except for the tiny little board with contact on it and the spring for the button) that most sellers think they can ask from $125 to over $200 for. Carbs are smaller (24mm) and the camshaft is different too, for more torque and a flatter powerband as well as a lower redline along with it. And you won't have to search for another nearly unobtanium part, that silly little twist-lock toolbox cap that didn't lock very well and is missing from nearly every one you see. It always surprised me that Honda didn't eliminate the electric start area of the upper case on the SL175 like they did on the SL350K1/K2
 
This is all sort of related to Juneaudave's thread, so I'll jump in here one more time and then I'll butt out.

I know it won't matter to you because you won't be climbing a hill or riding a trail and stall the engine, but the K1 and K2 also have primary kickstart which eliminates the need to find neutral before kicking the engine over
If I am ever climbing a hill or riding a trail or stuck at a traffic light and stall the engine on my SL350 K0, I will not even think about finding neutral so that I can use the kick starter. I will just pull in the clutch lever and hit the magic button for the E-start. As you know, it will work just fine with the bike in gear, because it spins the crankshaft directly via the sprag clutch. The bike doesn't care if it is in neutral. Coincidentally, guess what the USPS brought today from Partzilla? Yep -- brand new OEM springs, caps and rollers for my sprag clutch!

Dave, on the other hand, doesn't need to worry about rebuilding an E-starter or a sprag clutch, so there is that advantage!

And you won't be looking for the nearly unobtanium left switch (horn only, made entirely of plastic except for the tiny little board with contact on it and the spring for the button) that most sellers think they can ask from $125 to over $200 for.
No, but the K0 RH switch pod is unusual because it has the magic button for the previously mentioned E-start, AND it uses a black kill switch knob -- not the run of the mill red one. (I have a new repop one that is OK by me, but I probably paid too much for it. I also have the original one, but that is another story.)

Carbs are smaller (24mm) and the camshaft is different too, for more torque and a flatter powerband as well as a lower redline along with it.
And here, Dave has the advantage with his K1, if he is out doing whoop-dee-doo's and landing hard. He has no vacuum slides to slam shut from inertia and bog the engine. If he is racing, nobody will crash into him from behind. I understand this was the reason for going to the other carbs on the K1/K2 models.

And you won't have to search for another nearly unobtanium part, that silly little twist-lock toolbox cap that didn't lock very well and is missing from nearly every one you see.
No, but I have a K0 toolbox which I have blasted and painted, and it is complete with its hinged door. It is identical to the CL350 box, so it is easy to find. Ironically, it will be almost completely hidden behind the large plastic side cover that is nearly impossible to find. I do have a pair of the repop side covers from Randy Marbles, as well as the badges for them, but I hate to admit what I paid for them. I bought them early because I was afraid he would quit selling them by the time I am actually ready to use them.

Someday I may start a build thread on my SL350 K0 bike, and I apologize to Juneaudave for interrupting this good thread he has going. Maybe though, some people will enjoy reading about some of the differences between the models that we have discussed here.

For comparison, here is what the K0 should look like in gold:

 
Someday I may start a build thread on my SL350 K0 bike, and I apologize to Juneaudave for interrupting this good thread he has going. Maybe though, some people will enjoy reading about some of the differences between the models that we have discussed here.
OK, we're waiting for this thread to start
 
I pulled the top end off this morning. For a baseline, the engine has 12.5K according to the speedometer, and I thought it sounded ok after I got it started. My compression was 145 psi cold on both sides. I didn't take hot readings.

One thing I was concerned over was the condition of the cam chain tensioner as I saw black in both the oil filter and the bttom of the oil plug. As I suspected, it is coming apart and will be replace in the rebuild.

UOBOBSK.jpg



With 12.5 K, I was thinking before hand that it waould be nice to send the head off to Shumann Motor Works to have it reconditioned. But it doen't seem too bad and I'm worried a bit about how many $$$$ to stick into the engine. I think it need to compete against cam work and possibly having new pistons/boring.

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The cylinders looked good. I need some measurements to make a decision on boring. No real scratches, but pretty glazed over, so minimum honing and rings.

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The cam has me a little bothered...particularly as I don't have a good feel for how bad is bad. One lobe (on right) has some funky wear/pitting as it breaks over. It looks ok at fully open, but the pitting looks like it occurs as the valve is closing. The other lobes look great. I would welcome any thoughts on the SL350 cam as well as priorities.

sS1tXNr.jpg


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It definitely needs to be bored w/new pistons. I can see the etching in one cylinder wall.
The cam is in need of work, once they are pitted it progresses eventually destroying the rocker and lobe which means metal in the oil during the failure.
Power is lost or gained in the head and valve job. Valves all appear to be standing proud which means the seats are still serviceable.

For pistons I would go with these https://www.cruzinimage.net/2017/08/17/70-72-honda-sl350-1-0mm-oversize-pistons-set/ although I'd rather see .75mm over using 1mm over rings so the end gap can be set to tighter spec. Sometimes their rings are at max spec. or over.
I haven't been able to source a new or excellent used K1 cam yet so Oregon Cam doesn't have a master to use. That leaves Delta, Web Cam (916-369-5144) and Mega Cycle (415) 472-3195 as choices. I'd call the last 2 and ask specifically about the K1/2 cams because they are different from the CB/CL series. Rockers are the 312's so those can be sent to RAU to be repaired.
The cylinder head is specific to the K1/2 engine so the eBay offerings by Chris won't work right even though they'll fit, intake ports are different(smaller).
Horsepower is lost unless the valve job is done correctly, a poorly done one can rob 20% of the power. I would send the head to Chris to get it right.
 
Thanks Jim...I'll take your advice. I'm guessing that unobtaininum sprocket should be looked at too while I'm down. I vaguely remember someone talking about having them re-bushed although I'm not sure what that entails....
 
Thanks Jim...I'll take your advice. I'm guessing that unobtainium sprocket should be looked at too while I'm down. I vaguely remember someone talking about having them re-bushed although I'm not sure what that entails....

Need to talk with Jays100 about these gears, he's done the engineering and last convo was he was going to send it out for getting some made. So not unobtainium.
 
You’re well on the way to the slippery slope I went down over the last 12 months!
My advice is to brace your wallet for what’s coming.
Cheers
Mike
 
"in for a dime, in for a dollar"

I keep telling myself that I'm gaining a great deal of enjoyment, pride and personal accomplishment when I do the best I can on one of these projects. Anyway, my wife doesn't mind the money so long as I'm out in the garage....

BTW...I did talk to Chris Schumanm (Schumann Motor Works) about getting the cylinder head reconditioned. He's all about it, and impressed me as a very interesting and knoweledable fella. I'll box it up and ship it out after the Christmas rush is over...
 
BTW...I did talk to Chris Schumanm (Schumann Motor Works) about getting the cylinder head reconditioned. He's all about it, and impressed me as a very interesting and knoweledable fella. I'll box it up and ship it out after the Christmas rush is over...

He knows his stuff, and it's refreshing to see a guy who is 20 years younger than most of us be as interested in vintage bikes as he is.
 
Well...here's the bad news on the rockers.

Left exhaust....probably the best but dished

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Left intake....pitted and dished

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Right exhaust...pitted and dished

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Right intake...Something and dished

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I guess the question is whether to have them repaired, or buy new ones at CMNSL @ $50.88 a pop.... Does anyone have a cost from Rockers Unlimited?
 
I don't know what Rockers Unlimited's price per rocker is, but I'd be tempted to go with new now that CMSNL has them at that price. The very recent information about Delta Cams re-ownership by one of the original owners is promising because they did good work at a really good price at one time, and they're going to make things right for Scootman so maybe they can be a possibility in the future.
 
That's good news.

yeah, depending on how much material is taken off the cam, not sure if an NOS rocker would even work... probably still going to need material added to the rocker pad to make up for the material ground off the cam. Unless you get an NOS camshaft along with some NOS rockers.. they're still floating around if you want to go that route.
 
The Rockers Unlimited use hard-face weld?
They should last the life of the bike when maintained with good oil changes and regular valve adjustments.

That price is much less than Mega-Cycle which charges over $70.
 
The Rockers Unlimited use hard-face weld?
They should last the life of the bike when maintained with good oil changes and regular valve adjustments.

That price is much less than Mega-Cycle which charges over $70.
That's the only kind of welding used on rockers, it's a special rod or wire that's used.
 
yeah, depending on how much material is taken off the cam, not sure if an NOS rocker would even work... probably still going to need material added to the rocker pad to make up for the material ground off the cam. Unless you get an NOS camshaft along with some NOS rockers.. they're still floating around if you want to go that route.
NOS rockers are easy since they're 312's but finding an NOS K1 cam for a decent price hasn't happened yet. I would have bought it so Ken could make a master for regrinding. SL350K1 & 2 use a different cam than the other 350's
 
That price is much less than Mega-Cycle which charges over $70.

Actually, when they repaired one follower for me back in 2017 it was $99, at the time it was the same price for a NOS follower from CMSNL (not including their $25 shipping for that single follower then)
 
Go get it champ!

:lol:

That is a bit crazy! I'd probably opt for a later Camshaft, all the associated parts and call it good enough...unless he's going for a full 100% original restoration, that Cam is'nt worth $1100 to me.
Honda suggested a similar conversion for Fat Cam bikes in 1970
Honda parts bulletin.jpgHonda Special Notice.jpg
 
Or to anyone in their right mind. It still amazes me they have the stones to charge that kind of money for something that probably sold for around $80 to $100 new, if that much.

You're absolutely right...if you look at that sheet from 1970 a new cam cost $19.68 back then, adjusted for inflation over the years, that equals about $145.54 today's money... how do they sell it for $1100? how do they get this price?
 
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