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Discussion Starter #1
One of the guys suggested I document the engine removal and rebuild process. I did a search on the forum and did not see a detailed engine removal and rebuild thread, so I decided since I'm doing this again - on the blue bike this time - I might as well publish the photos. I take lots of photos when I disassemble things to make sure I have a reference to put them back together. So here goes. I'll post photos as I go along.

The story begins with the red SL350 that I restored. The engine was not running when I bought the bike, so I just tore right into it and completely rebuilt it, cylinders by Bore-Tech, cam by Delta camshaft, head work by Action Cycle and new Barnett clutch bits. So the red bike runs very well.

When I bought the blue bike, I needed to get the lost title process started, so I just restored everything on the bike except the engine since it was running when I bought it. Clutch was stuck, but I got it freed up OK. I just painted the engine and tossed it back in. After got it registered and re-assembled, I started riding it and tuning it up, but quickly discovered it has low compression, 120 on the left cylinder and minimum -150 - on the right jug. So I just rode it, until the rain started here in the Puget Sound and now I'm taking it apart to get it running like the red bike's engine. Right now, when I ride the red bike, there's just no comparison with the blue engine - that blue engine is just not putting out! While timing the engine and finding TDC, I could hear the compression sliding past the rings into the crankcase on the left cylinder, so I figured it's time for a trip to Bore-tech for these cylinders.

I am not an expert on motorcycles, Hondas or the 350's, so please chime in with your tips, tricks and traps - everything I show here I learned the hard way or by reading this forum and the manuals, your comments are greatly appreciated and welcome. For you noobs out there, I believe you can easily take one of these engines apart, have the machine work done by a good shop and get it back together with an excellent chance of success, if I did it, anyone can do it! And if you screw something up, or forget something, you can always take it back apart! :D

So here goes, first step is to get the engine out of the bike - so, drain the oil:



Disconnect everything that is attached to the engine.



Put the associated bits into baggies and label them. I've done this once before, so I have an idea of what goes where, but on my first time, I was looking at photos a lot wondering where that specific bolt went and where I was going to find it. Keeping everything together and taking lots of photos reduces the head-scratching time significantly!

Disconnect the stator plug:


Remove the carb clamps and remove the carbs:


Remove chain and sprocket:


Remove clutch side cover because it drains the rest of the oil and you can remove the clutch and other heavy components while the engine is till fastened to the bike and you can put some torque on the various nuts without rolling the engine around the shop with your breaker bar:


Oil draining:



More later...
 

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Discussion Starter #2
Now for getting the clutch bits out, first you must remove the oil filter, housing nut, housing and drive gear before you can remove the clutch assembly.

Remove the snap-ring holding the filter housing cap in:


You can see the filter housing/drive gear retaining nut down inside the housing. The nut is captured by a lock washer tab that you need to bend down with a screwdriver before you remove the nut.


Using a screwdriver to jam the gears to keep the crankshaft from turning, I insert the special nut socket into the nut with my 3/8 drive extension:


The nut removed (this is why I like to do this before I take the engine out, sometimes you really need to put a lot of torque on these nuts to get them out:


Drive gear slides off after removing the filter housing:


With the filter and drive gear out of the way, the clutch can come off - first the spring retaining bolts come out (they can also be stuck pretty good):


Bolts washers and springs removed, the clutch discs come out:


Followed by the clutch actuator plunger thingy (the clutch pushrod pushes on this actuator:


Remove the snap-ring holding the clutch basket on the shaft:


Remove the clutch plate carrier after you get the snap-ring off:


Before you can pull the clutch basket off the shaft, you must remove the oil pump attach bolts so that the pump can come off with the clutch basket:


Clutch basket and oil pump coming off:




With the clutch removed, I get ready to remove the engine...
 

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Discussion Starter #3
So, you can see in the photo below that the mechanism underneath the clutch basket can look a litle scary to the uninitiated - like some crazy clockwork mechanism. Believe me that now is the time to take a lot of photos so that you can put it back together correctly the first time:



Take some good close-up photos like this so you can stare at it while you scratch your head and wonder where that part might be hiding, maybe in the bottom of your solvent bucket?



Here's the back of the clutch basket with the oil pump - piston is held onto the eccentric rod by a pin that will fall out if you're not careful. There are dimensions in the manual for the clearances on these pumps - oil pump dimensions are important, so measure everything to make sure it's going to have suitable output:


Also - none of the gasket kits I've bought have the oil pump gasket included, not even Bore-Tech's kit, don't ask me why, but you'll need to make sure you get one, frustrating when you're putting it back together and discover that the gasket you need was not included - or that the gasket kit you have is for an SL350 K0, not a K1 and the side cover gaskets won't fit the side covers!

Everything disconnected, ready for removal:


I re-install one of the top engine mounts backwards and connect my come-along to it with a wire rope to lift the engine:


I wrap protective paper around the frame tubes, put some rubber caps on the exhaust studs and lift the engine free. I've also done this with the bare frame laying on the table - either way works fine for me:


And we're out!


I set the engine onto a suitable table covered with Puppy Pampers that we had left over from house-breaking our 120 lb. 9 month old Newfie laying in the corner over there, bored to tears, the Puppy Pampers work great to soak up the oil mess during disassembly:


The plugs tell the story, nice color, but oil fouled - definitely ring problems of some sort, probably rusted cylinders as well:


Next - the teardown begins.
 

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Discussion Starter #4
Engine disassembly begins:

Stator and stator cover come off:


Points plate is next:


Remove the bolt holding the advance mechanism onto the cam - I keep the ignition related stuff in a seperate baggie to avoid confusion:


Advance mechanism should just slide off:


Loosen the bolt holding the cam tensioner and remove the tensioner housing - you can see the badly worn cam tensioner roller; you can bet the other roller looks the same:


Here's a view looking down at the carb mounts - notice how they are angled; I highly recommend you mark them left and right and top so you can re-install them exactly as they came off, otherwise your carbs won't go back on very well:


Here's a must-have tool for any Honda mechanic - a $2 garage-sale impact driver with #3 bit:


And here's what it's for:


I don't even touch a Phillips head screw anymore until I put the impact driver on it first - here I'm removing the screws holding the cam bearing covers to the cam housing:


Cam bearing housings come off both sides of the cam housing - some light tapping may be required to break them loose, I use a plastic mallet and sometimes a bronze rod:


Next, I remove the cam.
 

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Discussion Starter #5
The valve adjustment eccentrics come out - note the o-ring seals on the shafts:


Next the cam sprocket bolts are removed. There are two bolts, one shouldered and one not (that is, it's threaded all the way to the head of the bolt). note where each one comes out so you can put them back in their correct location:


Here's how I get a 10mm socket onto the bolts, I go through the cam openings in the side. A swivel socket works as well, or an open end 10mm wrench:


After releasing the sprocket from the cam - you must wriggle the cam out of the cam box. This is tricky and can be frustrating, so take your time, take a break and keep at it, eventually the moons and planets will align and the cam WILL come out. Getting it back in is even more fun!


After you get the cam out, you can remove the valve rockers, etc. then it's time to remove the head - remove the two bolts on each side of the spark plug holes:


And remove the head. It might take some judicious tapping, be careful don't tap on any fins or other fragile locations. Don't pry it apart with a screwdriver, just use a plastic mallet and a bronze or aluminum rod and tap against thick parts of the head casting to get it to crack open:


The head on my red bike was stuck onto the cylinders very tightly - I had serious difficulty getting it off, it was really glued on! I didn't break anything getting it off, but it took a few blows with the mallet to crack it open - just be careful!

The head doesn't look bad. I'll do an acetone leakdown check to see if the valves are tight:


So, here we are. So far I've spent three hours since removing the gas tank to get this far and now it's time to take the puppy for a walk and have some lunch.


More later as I load up more photos.
 

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Discussion Starter #6
The disassembly and damage assessment continues:

The pistons look OK, rings are all there:


As suspected both rollers are history, I'll be replacing those. You can see the tensioner roller axle and the two little rubber plugs that sit on top of the roller when it's in the top case. Those are fun to re-assemble, if you drop one down in the case, the case halves will be coming back apart:


Here's the other roller closeup:


Pull the lower pin out of the cam chain slider and remove the slider from the top of the cylinder:


The cam chain slider and lower pin:


As you disassemble the cam housing, cylinder head and cylinder block from the crankcase, you'll see these locating dowels - make sure you remove them (or they will fall out when you're not looking)


Here's a photo of the cam sprocket bolts, you can clearly see the shouldered bolt:


The camshaft showing typical wear. Delta camshaft in Tacoma, WA can re-grind your cam for $35 plus shipping. I was lucky enough to find a brand new SL350 cam on eBay for $70:


So, here's the primary problem - corrosion in the left cylinder (the one with 120 psi compression). Apparently, this engine was sitting for some time with this exhaust valve open, letting the moisture in and rusting the cylinder.


Another view:


So, my experience with honing these cylinders to remove this amount of corrosion damage has resulted in honing the diameter too large to meet the required dimensions. These pits are probably 1 or 2 thousandths deep, maybe more, so .002" on the radius is .004" on the diameter - so at a minimum I'm looking at opening up the bore at least .004". Probably too much to go back in with stock standard pistons and rings. Worst case is that it takes more than that to get all the pitting out.

Also, and perhaps more important, is that the cylinders will probably measure out of round - honing them will not make them truly cylindrical again, so while I can probably get away with honing and tossing in a new set of rings, I made the decision to have them bored and honed oversize by Bore-Tech. They'll return the cylinders to me with the proper oversize new JCC pistons and rings, plus a top end gasket kit (since their gasket set does not have the K1 SL350 side cover gaskets).

I also ordered new cam chain and carb mounts from them, plus other stuff.

Here are some measurements I took of the cylinders and pistons - they are standard and not too badly worn:



The left piston, 2nd ring broke when I removed it, so it may have been cracked:


So now, I'm cleaning parts and shipping the cylinder to Bore-Tech. While I wait, I'll be removing the valves and cleaning up the head, then lapping the valves in. They passed the leakdown check :D


Stay tuned more later as I continue to clean and assess the condition of the transmission and bearing and crank components.
 

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The FSM does not require the removal of the side covers to dismount the engine...I assume you did it because it is easier to remove the covers while the motor is still mounted? Or is the clearance a little better?
 

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Discussion Starter #8
I did it to remove the clutch while the engine was still in the bike, I wanted it firmly mounted when I applied the torque to the filter housing nut needed to break it loose. Last time I took the engine out first, then had to hold the engine with one hand on the table while I honked on that nut with the other hand, it was stuck fast and was very awkward.

The nut socket also is tricky to fit properly on the nut.

Much easier with it in the bike to break that nut loose.

Jim
 

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That's what I thought. Makes sense. I have to change my bottom case. I think I will duplicate what you did. See? Your pics helped someone already. !!


Sent from planet Earth using mysterious electronic devices and Tapatalk
 

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What a great thread, very detailed photos that I'm sure will be a lot of use to a lot of people undertaking this with their engines. I know I'll be using it as a reference. Thanks.

Hope you don't mind, but I just sticked it since its such a good tutorial.
 

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Time to disassemble the crankcase:

First - before I forget, make sure you didn't lose the ball bearing out of your clutch mechanism that is stuffed down in the hole in the middle of the clutch arm, held in with grease:


Next, the crankcase needs to be split, first remove the nut and spring and ball bearing that engages the shift mechanism. It's located under the cap-like nut on the top, right rear of the case:


When removing the various pieces, be careful to check for washers and shims that may be oil-glued to the front and rear of some parts, like the washer stuck to the face of the kick start idler gear. There is another shim-like washer stuck to the back of this gear. Make a note or take a photo because you won't remember where it goes or, more likely, where it went after you put the gear back on the engine.


A magnet helps sometimes in getting some of the oily, slippery parts removed, such as this thrust washer on the crankshaft:


Remove all of the bolts holding the crankcase upper and lower halves together. Look closely all around both cases to make sure you didn't miss any semi-hidden bolts, then pop the case apart:


The innards sitting in the lower case. Don't be frightened, it's not bad after you get used to looking at it for a while ;)


The crank and shift mechanism inside the upper half of the case. This engine looks very clean inside - that's really good news!


This little black rubber ball is important, remove it ( I use a pick to fish it out) and don't lose it, it needs to go back in to provide proper oiling:


Take a photo of the gears before you pry them free and lift them out so you can study it when the time comes for re-installation. Getting the gears and shift mechanism back together properly is relatively easy, but can be a bit of a puzzle - you can never have enough photos:


Take photos of the shift mechanism to help you get the shift fork installed on the shift shaft the right way round:


Play with the transmission, turn it and shift it through the gears to see how it works, it can be fascinating if you've never seen a motorcycle transmission before. (no synchros!??) See that roller bearing trying to escape its race on the right side of the rear shaft? It will hop off and roll away if you're not looking:


The inside of the lower case showing the snap ring you must remove to get the kick start shaft out:


Sorry about this being an SL, there's no electric starter on this model, so you folks out there with electric starters may have results that differ.

Here's another clever bit hiding in the bearing bores, two of these in the transmission, the hold the bearings in place and are usually left behind in the case when you remove the gear mechanisms:


The main crank bearing block - make note of it's orientation to make sure you get it back in right way round, remove the four bolts:


And remove the crank. Now you can finally free the cam chain. Buy a new cam chain - using the old one will break your heart when it fails shortly after spending all this money to rebuild your engine:


Remove the dowel pins that hold the bearing in place in the case half:


Here's the crank removed. This one looks really good, nice and clean, the bearings are very smooth, so I see no need to go any further with the crank assembly. I truly never want to have to disassemble one of these and it appears to be a real pain:


So, I just wrapped it up and set it aside.

Next, I'll do some assessment of the removed parts for wear and then some cleaning. More later.
 

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Disassembly continues.

The main crankshaft bearings look really good on this engine - you can see part of the inner race in this photo - very nice!


Now it's time to remove the shift shaft, first you need to remove the clips and pins that hold the shift forks in location:


I use a thin screwdriver to pry the clips out:


Then a magnet to coax the dowel pins out of the fork holes, a little shaking and tapping usually frees them up and they come right out on the end of the magnet:


Here are the shift forks, pins and clips removed next to the shift shaft. With the forks freed from the shaft, the shaft just slides out of the case:


Now you can go over each of the cases and remove any parts left in, like these dowel pins in the bearing bores, I think there are three of these:


Remove the old seals, I like using a lady's foot for this, but a screwdriver works just fine:


I remove all of the oil seals in the engine and keep them so I can take inventory when I get the new seal kit. The seal kit from Bore-Tech did not include the big aft shaft seal, I had to order that separate, I guess the SL engine is the only one using that large seal:


Don't forget the tach drive seal in the right cam bearing/cover:


When I went to clean the right side clutch cover, I found this errant shim/washer stuck to the inside of the case - it goes on the kick starter shaft. It almost got away!


Here's the SL350 K1 side cover gasket sitting on top of a normal CB 350 side cover gasket - not the same. In the middle is the oil pump gasket that does not come included with the gasket kits I've bought:


Everyone has their own favorite method of removing gaskets - here's mine. I use a heat gun turned up to a thousand degrees and I literally heat them up so hot, they just fall off - well, almost. They do come off very easy and clean up is light brushing of residue off the mating halves:


So, here's a problem - the right side cam bearing appears to have been starved of oil at some point in its life, you can see the molten aluminum in the bearing bore and the signs of aluminum on the cam bearing in the background - not good!


Another view of the damaged cam bearing showing signs of heat discoloration. So, I bought a one in good condition on eBay tonight for $20. I'm not worried about the cam journal because I have a new cam :D Life's Good!


Did some cleaning of the case halves, but that's all for now because the Big Puppy says it's time for dinner!
 

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Great pics, nice work! How was the kick start idler, they seem to be wobbly.
 

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Discussion Starter #19
captb said:
Great pics, nice work! How was the kick start idler, they seem to be wobbly.
It's good on this bike, surprisingly. The red bike's was wobbly and chipped. The replacement I got for it wasn't chipped, but not much tighter on the shaft. This engine is very good in the bottom end, a pleasant surprise!

I wonder why that right cam bearing spun like that? Oiling problem at some point? Maybe somebody cranked and revved it before oil could get up there? Something missing or maybe wrong or backwards gasket?

Jim
 

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Discussion Starter #20
xHoladay40x said:
i like the way you use to remoze gaskets i am going to need to try that next time i need to remove one
I think it makes getting those cylinder base gaskets off easier, don't have to scrape around all those studs as much, that's a tough place to remove a gasket!
 
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