Silver Century project, shipload of questions

[joe28]

This is on a 1975 Silver Century non gearbox lower unit.
My "list of parts" I had going my kids stole from the clipboard, and ordered, (my Father's Day Present! At last something good), all came in, (if I had know they were going to to this, I'd made a BIG list)!
Had some time yesterday afternoon and thought I'd start on the re-ringing.
Figured I tear it apart, spend the week, giving "IT" a good exam, poking, cleaning, getting it done, NOPE!
First the headbolts...........
I was READY for the battle, torch was out, 2 cans of rust penatrate on the bench, a beer, (this was run in salt water and looks like it wasn't well taken care of).
The bolts were jjuusssttt snug!? they were really easy to get out!
Looks like the head gasket was leaking.
The water jackets were filled with rust "gunk" and some rust chunks. (A ice pick, coat hanger wire and a pressure washer got them cleaned out). It'll run a lot cooler now!
All together, checking, tinkering, looking at how it's make, taking my time, it took 2 1/2 hours to re-ring.

Hey MR Sea Gull! If'n your reading this, put a slight bevel at the base of the cylinder! It'll make putting the cylinder over the rings a lot easier! Check out how motorcycles do it! Please!

Bushings for crank bearings??!! Anyone ever try to retro roller bearings?
How about porting the transfer slots?
I HAD thought I could get a little more out of it by some grinding but the 1 common sense brain cell told me to back away from the grinder!
So, I listen to it and broke the glaze on the cylinder instead!!
(My reasoning that won over was that I don't know the "window specs, and can't flow test this cylinder, so leave it alone-clown)!
I had thought about the 25:1 conversion, but after seeing the bushings, I WANT as much oil in the bottom end as I can get!

I also applaud the engineers for the designing the top of the piston rod! most bikes I've worked on have a 1/8" hole for wrist pin lube. This has a nice big slot! I LOVE IT!!

Presently when I left "IT" last night, I have it all re assembled, but the "jug"? "cube"? (I like that, "cube"), bolts are hand tight, the head the same.
On the base gasket I used Silicone "gray" (high torque silicone), and orange "high temp" silicone on the head gasket, (first time i ever used ANY type of sealer on the head gasket)!
A put a really thin coating on both gaskets.
Looking at the lower unit and the real questions...........
1). the screws..... dis similar metals in salt water, heads are rusty, best way to get them out? (heat and tapping, then a impact screw driver)?
Chances of getting them out in 1 piece??
The lower unit is dribbling oil. Like a good British machine should (I think of my BSA)!
I want to replace the bushings and seal.
Best way to get the bushing out and drive the new one in?
(I'm 99.99% sure I'm going to do a gear box swap , but want to refresh this unit)
Any tips, things to check whilist I'm in there?
Best way to break in the motor after I fire it up?
Thanks to all!
Joe

[Niander101]

Remember if it aint broke Don't ...you know the rest!
These cranks last forever ...don't need rollers.
Im sure there is a bevel to aid the rings/piston going in.
Is there something wrong with the gearbox?[they are very strong]...if not why change it?
"How about porting the transfer slots?" Yes there are folks that race them. They will know all about the porting.
There are also high compression heads available.

[joe28]

Nope, no bevel on the "cube" sleeve. I thought it was strange, but I've had??? something that didn't, (old air cooled Montesa trials bike, something like that).
I LOVE how "beefy" the rings are too!! and the fact that they really overlap at the edge at the pin. Very little compression get by the rings!!
I used a hose clamp on the top ring, and was able to "sneak the bottom one in.
The old rings were in perfect shape too, I think it was a head gasket issue. The head bolts didn't go in deep enough. I had to chase the threads (dunno if was rust or??).
If this motor is "re-ring once a life time well I'm done!
I wouldn't touch the lower unit, 'cept for the tiny puddle of oil I find on the floor, (my '68 Century doesn't "mark it's territory").
My fear is the once the shaft starts to spin it'll pull the oil out.
I bet the P.O., didn't dump the oil when he should and "IT" has got bushing or seal play.
I want to swap it out so I have forward, reverse and a neutral, (might as well have it all)!
It makes docking easier! (in case the big motor ever sheets the bed).
If I ever pick up a "cube" cheap for one of these motors, I'll go nuts on the grinding and see what happens.
I sure looks "choked" up to me, small square edge windows, small transfer slot, (only 1 too?), small carb inlet port.
But, that being said, they sure seem simple and dependable!!
Another question popped into my head........
Spark plug for this motor?
I have a Champ 24 in there now, but the '69 runs a Champ 9??
Thanks!
Joe
That's always been my problem.........
"This is running AWESOME!!!, let's try................. I'll do this til it runs like sh** and them I get all ticked off!

[Niander101]

Its easy to fit F/N/R box to a silver century...got the T shirt grinding not necessary

[Charles uk]

No compression gets past the rings because there is no compression, in your model the best you'll ever see is 75 lbs & they'll still run at 45, so don't buy any avgas.

Normal plug is D16 or equivalent, 1/2" inch reach 18mm.

No seals in your lower unit only bronze bushes, give us the engine number so we can confirm that.

If you want it to work harder without self destructing, everything will have to be in an as new condition, the easiest way to a achieve this is a new crankcase & renew all the bronze bits in the lower unit & possibly the prop shaft if worn.

Depending on which model you have will tell if an FNR is a simple job.

[joe28]

Tanks!
I meant to get the # and plop them on here, but left for work before I grabbed the info book I keep.
Half the battle is trying to figure out what the P.O. did! Where the Champ D-21 came from is anyone's guess!
I got it started last night, (took more pulls than I like to, but we'll see if that changes as the rings seat in), seems to run nice, (I put the siphon tube on it, it really does pump well at low RPM)!
No seals only confirms my fears that the bushings are worn.
I had it running in a small trash can, after 1/2 hour, there is a pretty good oil slick on the water, (I do have 85-90 in the lower unit, the 140 oil is far away with the other motor).
I have motor mount issues on my boat, (the mount I had in the "Boat parts shed" that I bolted on doesn't raise the Sea Gull lower unit completely out of the water, broke my brand new latch pin finding that out), that has to corrected before I go to the next part of this project, a gear box.
A guy who used to sponsor me owns a bike shop, he has a "flow table" for porting cylinders. Some day when I get a spare "cube" I'll take it to him, let him "flow it" and see where it stands, THEN attack it with a grinder! The seed has been planted, I MUST try it, just cuz!
Joe
What would we do if we couldn't "tinker"

[Niander101]

I had it running in a small trash can, after 1/2 hour, there is a pretty good oil slick on the water,...Totally normal
some of the later Gulls [F/N/R]have oil seals in the gearbox and use thinner oil.

[phil]

In my opinion, the motors run cold and most of the ones I see are running way too rich, unless it's going to be doing long runs of over an hour at 3/4 - full throttle, it needs a D21 Champ., also I much prefer NGK ab6 or ab7 to a champion. All my old motors start much easier with NGK. By the way, I'm sure you will not be running it too rich as you know what you are doing with 2 strokes.

[Adrian Dale]

Don't forget that after 1/2 in a small bucket there will be quite a bit of exhausted lub oil draining down the exhaust that will also cause a slick, may not necessarily be a severe gearbox leak.

AJ

[joe28]

Tanks!
I'll pick up a NGK and see if it makes a difference.
For info the ser # isWSL1047FF5, June 1975 4.5 HP Silver Cent.
It wasn't 2 smoke oil film, but the "chocolate milkshake of gear oil.
Being anal, and not ever doing a lower unit, I'm gonna get the bushings (and I hope seals) and give it a shot!
This way I've got a "pretty new" S.G.!
If I do the gear box swap, I have the unit all fresh for my other motor.
Joe


'

[Charles uk]

The gear box swap on a WSL is not quite as easy as some say, first you require a drive shaft tube that has the ability to mount an FNR gear lever, then it will be noted that most of the FNR boxes were fitted on long shaft motors used the stiffer larger diameter except for the very top & bottom drive shaft tube, to prevent the drive tube bending under load & fowling the drive shaft!

So you will need everything below the powerhead that is not fastened to the cylinder, including a model 90 prop, & the model 90 transom bracket & rubber thrust collar.

Easy if you find a model 90 with a dead cylinder!

It might well pay you not to weaken the mixture very much, even though you will get a little more power as a significant amount of piston cooling & upper cylinder cooling/lubrication is provided by the rich mix in cross flow, deflector piston 2-strokes!

[joe28]

Tanks!
The gear box swap is an idea in the back of my head that is growing. Sure would be nice to be able to pull into the dock and hit N or R though.
I don't know enough about these outboards to start to "tinker and modify" "IT" (yet).
I would never cut the 10:1 mix down!
I had thought about the 25:1 conversion kit, but after seeing these motors have bushings instead of bearings for the crank, the more oil the better! (although my 1 gallon gas can can barely fit 1 gallon of gas and 12.8 oz of 2 smoke oil)!!
I'm not looking for speed, or power, it just has to troll 1-3 mph hours at a time! (The "Gear Head" in me wonder just what I can get out of it though)!
"IT" has to push a #1000 boat up n down the river.
But, that being said, because its "odd" and so far everyone has chuckled at it, (narrow minded people here in the States ), it HAS to be really dependable.
First time "IT" fails, I'll never hear the end of it!
Joe

[Niander101]

Don't worry about them...have some Balls