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1971 SL350

Juneaudave

Juneaudave

Veteran Member
Joined
Jul 20, 2020
Total Posts
531
Total likes
11
Location
East Helena,MT,USA
I braved fearsome storms to bring this 1971 home this morning...it's heavy on patina but is straight and rust free. Last registered in 1995.

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Wow, nice find indeed. I'm only slightly envious :sad: and as expected, the toolbox cover is missing. Hope the original mufflers are in decent shape since they're outrageously-priced unobtanium
 
ancientdad said:
Wow, nice find indeed. I'm only slightly envious :sad: and as expected, the toolbox cover is missing. Hope the original mufflers are in decent shape since they're outrageously-priced unobtanium
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The mufflers and headers are brand new....I can't tell that they have even been through a heat cycle. The PO said that he bought it like that. I think they are repops of some sort as I can't see any HM stampings. The tins are original paint...can't see any dents at all on the tanks, fenders, headlight, handle bars or gages. Tank is clean inside, someone took pretty good care of it. Still...the patina is pretty heavy from age and miles...the odometer says 12,500. It's going to take some effort from what I see so far....but that's ok for what it is.
 
I thought the first order of business would be to get it running and see if I could tell why it was parked. Starting with the battery...it was dead and looked like it had been overcharged and boiled dry. Case wasn't cracked like it had been frozen. Fortunately, someone stole a fuse from their mom's Subaru and wired it in. I'm thinking a new Sparkmoto rectifier/regulator, some wiring and a good battery might be the ticket. While I'm at it...maybe I can find an alternative for the tin foil heat shield!

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Very nice find, just like my first new bike when I was 18. The air cleaner housings are fairly regularly available on eBay and they reproduce the air filter element also. First thing I would do is see if the kick starter engages correctly, that gear is hard to find and if it's bad that would be my first priority in locating. I think AD posted something a while back on someone reproducing them now, a little pricey but available.
 
1973gts said:
Very nice find, just like my first new bike when I was 18. The air cleaner housings are fairly regularly available on eBay and they reproduce the air filter element also. First thing I would do is see if the kick starter engages correctly, that gear is hard to find and if it's bad that would be my first priority in locating. I think AD posted something a while back on someone reproducing them now, a little pricey but available.
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The kickstart (and the title) were the first things I checked and they seem to be ok. Another hard to find unobtanium seems to be the the stupid horn switch. The only one I've found so far is this one 35250-312-671 OEM Honda Horn Button Switch NOS Sl350k1 SL 350 K1 Genuine for sale online | eBay May have to pass on it....but I'll find one somewhere. Seems like you could substitute a CB or CL switch (or something else) and not worry about the signal part.

I did order a new tool box cover from Retrocb.com. The Jiff Peanut Butter cover was distracting....

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Yes, the separate, single-purpose plastic horn button assembly is as unobtanium as the kickstart idler gear, I've seen them for half that ridiculous price at $250 and that is already well beyond highway robbery for a piece of plastic with a single contact to a ground wire. The XL250 and maybe a smaller SL or XL also used it.
 
ancientdad said:
Yes, the separate, single-purpose plastic horn button assembly is as unobtanium as the kickstart idler gear, I've seen them for half that ridiculous price at $250 and that is already well beyond highway robbery for a piece of plastic with a single contact to a ground wire. The XL250 and maybe a smaller SL or XL also used it.
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I sold last winter's project Bighorn this fall and bought the SL350 due in part to the difficulty in finding good parts. The ability to find parts is really one of the nice things about these Honda twins IMHO...
 
1973gts said:
Very nice find, just like my first new bike when I was 18. The air cleaner housings are fairly regularly available on eBay and they reproduce the air filter element also. First thing I would do is see if the kick starter engages correctly, that gear is hard to find and if it's bad that would be my first priority in locating. I think AD posted something a while back on someone reproducing them now, a little pricey but available.
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Jay, aka Jays100, is working on getting these into production. Re-engineered from an OEM NOS gear I found.
 
WhooHoo! I put a new battery and plugs in it and she fired right up. There is serious popping out the exhaust on the right side, but the left side runs smooth. It shifts well and runs up and down the gears so that seems ok.

This weekend, I'll see if I can find the source of the popping cylinder....check the ignition, valve settings, and compression. I can't really tear into those carbs as I haven't got carb kits yet. My thought is that if I don't find anything serious, I should be able to maybe just rebuild the engine top end including a new cam chain tensioner, and maybe take a look at the condition of that kickstart idler gear. I did see that there is a crack on the right cam cover where the tach enters in.

Interesting...the left side had a NGK B8ES plug, the right side had a NKG BP7ES plug (humm). And...I didn't see any smoke from the pipes but there were some from the poffs of smoke out that breather hose. It's pretty chilly out so maybe the smoke was more apparent than it normally would be...

Anything else I should be checking on that engine before I start teardown?
 
Just for curiosity's sake you might check compression. And I'd be curious to see a picture of that crack in the right cam bearing cover
 
ancientdad said:
Just for curiosity's sake you might check compression. And I'd be curious to see a picture of that crack in the right cam bearing cover
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Here is that crack. Ididn't notice it till I was changing out that BP7ES plug. Hope that piece isnt JBWelded in....I'm beginning to think the PO was the creative sort...

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The closer I look at this SL, the more half-assed things I find. Here is a pic of the rear fender taillight/fender area. There is supposed to be a chrome mount/clip that goes over the top of the frame bar and bolts to that stand alone bolt towards the front. The mount holds a rubber bushing to isolate the fender sort-of. So on this pic...the frame bar should be on the other side of that plate, and the original mount went over the top.

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If you look a little further at where the inner fender meets with the aluminum outer fender, its jammed in there. I think the inner plastic fender should lap totally underneath the aluminum fender. So they either put things together wrong or something else is going on. I can't see where the frame is jacked in any way.... but it sure isn't put together right...

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I found a used mount and bushing on ebay so I'll put that on and see if I can get this straightened out.
 
No surprises so far to me, the SL's seem to mostly be either very clean(barely used) or butchered to some degree. There's FaceBook group for the SL's where people sometimes are parting out a bike that's worth looking into.
 
Hoo boy...Still more ham handed work.

I started the day planning on adjusting the cam chain tensioner, setting the valves and checking out the ignition timing. First thing I noticed when I pulled the points cover off was that the ignition was full of pbblaster, one of the valve adjustment screws was pointing in an odd direction, and I subsequently found the advance mechanizism crudded up and two of the four screws holding the points were stripped. Timing wise...it was off, and the valves were all off. Funny it ran at all.

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I was looking at the coils and plug wires(hard as rocks)....

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The tank was a mess but I have cleaned it out pretty good now....24 hour soak with Evaporust and 8 penny nails, fresh water rinse, alcohol rinse and dry, and diesel rinse to protect it from flashing for the time being. The fuel petcock is awaiting a new kit....the fuel petcock reserve path is plugged so I'm trying to get that cleaned up. New gasket for the fuel cap ordered...its toast. The bike had hideous red fuel filters on it. Now I know why!

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I swear...every little thing on this bike has been neglected or messed up by a ham fisted PO. I was cleaning the fuel petcock (and trying to figure out why the reserve was plugged). As it turns out, the reserve nipple(that holds the little inlet screen) was busted off and the screen was missing. No wonder it plugged up.

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Nice job on the tank…I need to do a bit of “Evaporusting” myself - hope my tank turns out as good as yours looks.
My petcock was also wrecked…(the pipe for ‘normal’ fuel flow was broken off and both the fuel hose mounts pulled out of the crappy metal housing).
I have purchased an aftermarket replacement.
Cheers
Mike
 
I found a rusted out fender bracket on ebay that was cheap enough. Seems like the nice ones I found were too expensive for my tastes. Anyway, I took a chance, soaked it in the Evaporust and gave it a polish. The shine came back but the chrome is definately distressed than I hoped. Guess I'll stare at it over the winter and decide whether to leave it, sand/paint it cloud silver when I paint the frame, or find a better one. I'm on the fence on this piece....at least it's better than it was....

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I'm going to spend today messing with and cleaning up the points. I got a new set of screws to replace the stripped out ones, so that is good. But as I'm looking at the points, it seems to me that the little bolt that holds the wire on the right contact is backwards (maybe it doesn't make a difference, I dont know)....but I can't really tell. Any thoughts on orientation?


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It is in backwards from how they are typically oriented, but as long as it clears the points cover and doesn't short on anything it will be fine though you could reverse it to better avoid the problem. The terminals on the wires are decently oriented to avoid the cover.
 
The next new issue is a broken mounting tab on the right air filter plate. Looks like metal fatique got it. Fortunately I think I can fabricate a solution for this that will be solid if I don't find another at a reasonable cost.


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ballbearian said:
Can you weld a washer to it? I love saving old parts and I'm cheap.
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A washer is definately a possibility! I'm sure I can weld, pop rivet, bolt or epoxy something up. I was thinking maybe a angle bracket...

Anyway, I've decided this bike is beyond "patina" bordering on "ratty"! At this point, I'm not really fixing anything yet, just trying to get it running good enough to get it hot, see what the compression is, and figure out how deep I need to go into the engine...
 
I suspect that while the old rectifier/voltage regulator was boiling the battery dry, it also blew out all the headlight and tailight bulbs. Replacement bulbs are expensive so today I worked on modifying the burnt out headlight to accept an H4 halogen bulb. Here is how far I got. I think its going to be tight when I fit it back into the headlight case as the SL350 isnt very deep. There is a sticky about doing this in the forum electrical section for 350s.

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I did the same for my Dream and it's cramped for space too. the male spades are wider and hard to find so I bought cheap pig tails and ditched the block, added heat shrink sleeves. Now it just barely fits with the wires nestling around the speedo cable.

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ballbearian said:
I did the same for my Dream and it's cramped for space too. the male spades are wider and hard to find so I bought cheap pig tails and ditched the block, added heat shrink sleeves. Now it just barely fits with the wires nestling around the speedo cable.
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That looks really good. Have you had any issues with heat? I wondered if there would be some sort of heat issues without the ceramic H4 socket....
 
Getting ready for a new Sparkmoto regulator/rectifier. The old regulator is located under the battery cage, so I pulled that and repainted with VHT engine paint. It only had about 50% of the original paint left, hopefully the new paint will hold up better.

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The old rectifier is mounted high and held on by one bolt. I'll need to either fabricate a mounting plate to mount the new unit up high, or maybe mount it under the battery cage if it fits and the leads are long enough. Not sure what others have done on SL350s.

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If you wish to make the VHT paint a little more resilient then baking the finish per the cans instructions will help. I think it is usually around 200F for 1 hr and it makes it more impervious to the oils and volatile chemicals. A BBQ is a good option for outside heating, or the oven with SWMBO's approval.
The smell isn't terrible in the oven, yet it is there. ;)
 
Hi all
I purchased a fair bit of gear from Charlie’s Place (Charlie has been great answering multiple questions from me - his gear isn’t the cheapest, but the quality is high), including a new reg/rec.
I intend to place it here:

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I am building a new harness, using a kit from Vintage Connections. I really love the quality of crimp you get using the correct tool (wish I’d have purchased a proper crimping tool years ago). Here is an example (that is one of the pins that goes into the male side of the ignition switch connector)…
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Cheers
Mike
 
I went ahead and mounted the Sparkmoto to the battery cage where the old regulator was mounted. The Sparkmoto reg/rectifier has two mounting holes and I just had to open the mounting holes on the cage slightly with a file to fit.

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There is plenty of clearance between the regulator/rectifier and the tool box. The wiring harness will reach except to the black sensing wire. It will need a spice.

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LongDistanceRider said:
2 voltage regulators? Charlie's and Matt's
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If I had bought Charlie's....I think I would have mounted it up high with the single bolt like Mike did. But I was already committed to Matt's, and that unit seems to belong under the battery box.

Anyways, I've still got to do some tinkering with the air filters and lights yet, then I should be good to start it up and hopefully get it up to temperature for a compression test before I tear the bike down for restration. Seems like there has been a lot of little stuff to fix on this bike.
 
I fussed with the right air cleaner today and repaired the end mount as best I could. Ended up cutting a piece of zinc coated angle and attached it with some small bolts. Not the best solution, but I think it will work. I'll have to be careful to make sure those small bolts don't come loose and get sucked into the carburetor (n)

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Both frames get new filter material as the PO didn't do a very good job fitting and glueing up the Unifilter material.

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Fit the H4 Halogen 35/35 headlight into the bucket today. Surprisingly enough, it fit ok without any problems...

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And wow....the light is alot brighter than the stock light on my CL350. Be interesting to see it at night....and if there are any heat issues....

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Juneaudave said:
Fit the H4 Halogen 35/35 headlight into the bucket today. Surprisingly enough, it fit ok without any problems...

And wow....the light is alot brighter than the stock light on my CL350. Be interesting to see it at night....and if there are any heat issues....
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That looks good;much brighter than stock.
I didn't know the SL's have 12vts
 
I hooked everything back together this morning and and started it up. The bike is still just running on one side (with the non-firing side just popping horribly with gas dripping out the header/muffler joint). Spark seems bright and good, cold compression readings on both sides are 145 PSI by my gage, no wierd noises...While I had it apart, I set the timing chain tensioner, set the valves and the ignition. The side that is firing sounds great.

So I guess my next step is to take apart the carburetors and chase down that rabbit hole. I didn't do that before because I knew to PO had them apart to clean and I assumed they were relatively correct. My bad.

Should I do any other tests now before cleaning the carbs? Thoughts?
 
Hummm....Seems like my issues with the right cylinder not firing are definately carb related. I pulled the carbs off, opened up the non-firing carb, and found the slow jet laying in the bottom of the float bowl. At least its relatively clean. Its off for a long soak in the Berrymans can. The float is also bent....I don't know how you do that. Not sure I even want to look at the other carb at this point....

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Was running a little rich LOL. Funny it is a threaded in slow jet too, as some of the early ones in carbs are a press fit and I have seen those fall out from inexperienced work being done. Pull the other one apart for sure and that knock kneed effect on the floats isn't a big deal, as long as the two float are parallel to each other on the horizontal plane and the back support bar isn't deformed. Good time to recheck your float levels too while it is apart.

It should be singing a good tune again soon. :)
 
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