SL350s

EDIT: Big mistake - do NOT soak carbs in Simple Green.


Two weeks ago Rick and I rode Palo Duro and LBJ Grasslands.

Part of that trip was picking up 3 SL350s from thencameDonson.


I am overwhelmed. First thing I did was to get the CB err, SL350 with CB pipes together cause it looked almost ride ready. A quick carb clean (as opposed to a carb overhaul which it needs, a 30 minute charge on the battery, a couple of new plugs and clean gas - it runs! Lots of little things like crusty cables but I am happy.

Originally I did this because I wanted an extra engine for mine. Now I have 3 extra sl350s! I am shotgunning this and just sit down and start working on something different every day. Today was clean the carbs of SL350 (2). One was completely frozen up. They had been sitting in a bag of Pine Sol (thanks ADV Rider tip) and the outsides were pretty clean but still sealed. So I used vice grips to open the drain screw and fed a nozzle through that hole and shot a full bowl of WD-40 into it. WD-40 is not my first choice but after 2 weeks I had already run through 2 can of PB Blaster, 1 quart of MMO, 1 can carb cleaner, 1 quart Pine Sol, and just about every anti-seize and cleaning product left over from 40+ years of riding. I did have one bottle of Simple Green so after prying the carb bowl off by hitting it against a wood fire log, I put it all into a 1 gallon freezer bag with all the Simple green.



Here is the bike (2) this carb matches. It was used offroad as the lights are missing and the wiring harness severely cut up.



That side cover is jb welded and so I was looking at bike 3 for a good side cover (engine not air filter side cover). It seemed like the best donor bike since the motor was frozen. But I can't seem to leave it alone and the last few days I removed its engine and have it down to where I am about to bust the timing chain (seized) and take the head off. Still consider this a learning experience cause my original intent was backup for my original SL350 while I take it apart and do a cam chain tensioner. Until I do that, I am uncomfortable riding a 40 year old SL in the boonies. But I also have to resist the temptation to get all these SLs back doing what they were meant to do - DS.

More to come.

Hey, Mike, glad You got it running, but I changed My mind. Please bring it back, after You overhaul the carbs!
The little Honda Hawk You saw has gone to a new home, as did the camper i was in at palo Duro.
Dont know if I will see You guys at the Norton Rallye, as My friend, Dave Howe , crashed badly in North Carolina last week. Two collapsed and punctured lungs, crushed ribs, bruised brain, bruised liver, kidneys and spleen, and more.....He was AtGATT, but still been on a ventilator until yesterday. He is improving some, but may not ride again.

Don, really sorry to hear about Dave. Sounds like a bad wreck, hope he is back riding soon.

You know I am really confused - so many projects! I am like you, I want to see every vintage bike back doing what it was meant to - riding. This thread is where I will post the developments.

Bike 2 - the saga continues. The simple green worked and I was able to open the float bowl - arrgh! I took off the jets and put them and the bowl bag into the bag of Simple Green. Dang cheap Walmart freezer bags are dripping stinky simple green all over. After a day of soaking I think they might have damaged the slide. It no longer looks shiny and slick. I wonder if those slides are covered with some kind of seal?

Back to the bigger project, bike 3 with the frozen engine. Sunday I was having problems getting the cam out cause it was under tension and I could only get the top bolt off the cam. The answer I found was to take the box off the tach drive side of the engine. Doing that let me remove the rocker arms and when I did, the push on the cam was relieved. Now It looks like I will not have to break the cam chain. Tonight I plan to try to remove the other cam sprocket bolt out and remove the cam. Better get pictures first cause I will forget. Once the cam is out, this should get easier. So far, no indication of why the engine is seized although there were shavings in the oil.

Dang box on the tach drive had 3 of 4 screws come out with the impact and penetrating oil. The last one, and hardest to get to was a bear. It took an hour. First I tried the impact, then a punch, then a flat tip screwdriver, and finally got it off with the drill.

The wiring harness for bike 2 and 3 have been cut. I have been looking on eBay and the only ones I see cheap are the CB350 harnesses and all look like crud. That is a later problem. For now I need to get the chassis on 3 clean and paint or powder coat it.

I don't think simple Green was the best cleaner for the carb, particularly the slide. It used to feel slick and now it is porous. A guy on the ct90 forum suggested lubing it with PB or Rem Oil and I think I will try 3n1 cause it is just like Rem oil. Either way, I worried that I screwed up a coating or something and any oil I use will likely get dissolved by gas once it is running.

I have the head off and cam out of the sl350. One cylinder is free, the other seized. When I took the head off, I could see that the Marvel Mystery Oil (MMO) that I put in the plug hole of the stuck side is still pooled above the piston. I whacked it with a board and a hammer with no luck. The other side did go down when I whacked it but the cylinder raised up along with the stuck piston. I sopped up the MMO and replaced it with tranny fluid and plan to wait a week. It has already soaked for several days in the MMO.


I have the c clip off but it was a bugger to remove the oil filter cap.



Then again, everything looks clean, maybe it is time to stop cleaning the insides and finish the bore and piston.

No more progress on the seized piston. A couple more days soaking and a couple hundred more whacks at it have not helped. Brother said to toss dry ice on the piston then whack it. That is probably next but I have considered taking it to one of the guys here on the board with a shop.

More pics from the SL350s in various stages starting with the rusted mufflers and bad weld problem of my first sl350 and main ride.

Get a bigger hammer.....

I am still at this stage and getting tired and need to show progress or I will forget/lose.

Here is what I am thinking after yet another week of soaking the cylinder:

Any thoughts about starting a gas fire in the cylinder?

http://www.smokstak.com/forum/showthread.php?t=37566

I am suprised that piston is so stuck......How about a dry ice/ heat with torch cycle to get the metal to moving? Never had to do that Myself, but.....Who sold You that thing?

Haha. I think I am going to give it another week before I give up on this engine and start pulling parts. The progress on the two others is great - one just needs a battery and air filters to ride. I think it is ready for inspection if I want to go that direction.

What I want to do is start working on my original bike and fix the cam chain. These sl's were just back up parts for it. But it did not take long to find a good use - one will keep the aggressive knobbies and another be the street rod.

The carb to air filter rubber hoses are gone on the old SL's. I think I am going to fab one set out of radiator hose since one of these SL's have one carb like that already. I could do the pods and since I have no sidecovers, that probably would look better. Wish these were available OEM cause I won't buy one off eBay that is 40 years old no matter how good it looks.

I know what You mean. I am restoring a 1975 XR-75, and the rubber intake runner is missing. When I called the XR-75 people to order one, they laughed and said "good luck". Still not sure what I am going to do, there.

thencamedonson said:

I am restoring a 1975 XR-75, and the rubber intake runner is missing. When I called the XR-75 people to order one, they laughed and said "good luck". Still not sure what I am going to do, there.

Click to expand...

Easy. Get a block of fuel-resistant rubber and a really sharp whittling knife, then just carve away everything that doesn't look like a '75 XR-75 intake runner.

hee hee

Man, I hate it when I stumble upon an unobtainable part, right in the middle of a restoration project. Actually, the above advice is not far from realistic; of course it helps to have a fully-equipped machine shop and piles of stock materials.

I wish it was that easy GP. The intake is a rubber runner fused somehow to a aluminum intake flange. I could gob-smack something together, but i am working toward a show restoration.

Ah, yes, composite construction. Lovely. Well, you just need to search high and low to find replacements, or find the closest match you can. Otherwise, you can make the two parts and fuse them with modern epoxy.

JB Weld is My Friend.

Go read up on Randakk site for Goldwing restoration. His tips on carbs are invaluable. You may very well have terminated the carbs with the Simple green. You boil them in water, straight distilled water, out side on the propane turkey fryer.
WD40 is your enemy around "rubber" parts. It makes them swell and then you can not reuse them or they stick your pistons in the calipers when the seal swell up and locks everything in place.

I'vve never bothered with other solutions since I discovered Berryman's Chem-Dip in one-gallon cans for carb cleaning. It's unparalleled.

SL350 said:

I am still at this stage and getting tired and need to show progress or I will forget/lose.

Here is what I am thinking after yet another week of soaking the cylinder:

Any thoughts about starting a gas fire in the cylinder?

http://www.smokstak.com/forum/showthread.php?t=37566

Click to expand...

Maybe the crank is stuck.

You need more whackage on that stuck piston. I went through the exact same thing with my '67 305 (CL77)

Don't be shy, you aren't going to hurt anything. Expect broken rings when it's all done, that's just the facts.

+1 on more whackage.

Well I was not dainty about it. I whacked it good enough to put a huge crack through the cylinder even though the sleve looks ok.

About the Berrymans - I am really trying to get away from the strong chemicals. One dip I bought 10 years ago from O'Reily was so strong that when I took my gloves off after handling carb parts - all theskin on my hands were pealing. Went right through the gloves. Could not get anyone to take it either - it had been classified as EPA hazardous.

I make too many mistakes for the strong stuff. Now for cleaning tanks I have gone to vinegar.

Wondering now about cutting the piston away from the cylinder just to see if the crank and lower half are good. It is still on the table but soon will be put aside to start the work on my current rider. It needs a new camchain tensioner before it wrecks itself.

A look at the new crack:



Is this too far gone?

SL350 said:

A look at the new crack:

Is this too far gone?

Click to expand...

Can you point out the crack? I see some stray casting & machining lines, but no obvious crack...

The diagonal line dead center in the picture. It was not there when I started whacking. It crosses the top to the sleeve but not deep on top. On the side it goes all the way down to the bottom of the jug and the left side of the crack is about 1/64" higher than the right side.