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Author Topic: 69 SL90  (Read 345 times)

Offline Rat_ranger

  • Posts: 310
69 SL90
« on: Sep 05, 2018, 03:02:16 »
So the other day I picked up a pair of 69 SL90s.  One is mostly complete, the other not so much.  So my plans are to do a restomod on the red one.  Stock parts that I don't have are the tail light, handlebar controls, kickstand, and battery cover.  So a relatively short list of parts.  The engine was locked up, I got the cylinder off today, it did come with spare cylinder done up for a 54mm "big bore" and a clean looking head. 

My plan is to do the big bore, some port work, and refresh of gaskets and seals.  The frame and tins will get repainted to look factory.  Otherwise I'll leave it alone, I figure being a one year only model and being almost complete it should be easy to bring back.

The blue one has no engine and is missing some other bits.  It'll probably get something like an atc110 or ct90 engine with the autoclutch, that way my wife can learn to put around on it.
Xs650

Offline Hurco550

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Re: 69 SL90
« Reply #1 on: Sep 05, 2018, 11:43:15 »
Nice get man. Always thought these were neat and a little quirky with the way the cylinder sticks out through the front of the frame. I've often wondered if an over zealous kid in the woods ever broke the head or cylinder off with a spirited pop over a log haha
"If you just picked up a drug habbit instead of a kawasaki triple at least you could get high while you waste money"
~ bradj
1988 tw200, the swamp donkey: http://www.dotheton.com/forum/index.php?topic=75455.0
2006 Suzuki DR650 Adventure monowheel trailer build: http://www.dotheton.com/forum/index.php?topic=75033.0
1976 BMW R90/6 farkilitious: http://www.dotheton.com/forum/index.php?topic=74349.msg882477#msg882477
1975 RD350 Road Racer: http://www.dotheton.com/forum/index.php?topic=70652.msg833688#msg833688
1976 GT250 Rebuild: http://www.dotheton.com/forum/index.php?topic=64973.new#new
Full Custom Pit Bike: http://www.dotheton.com/forum/index.php?topic=66954.new#new
1971 Yamaha 90cc twin HS1: http://www.dotheton.com/forum/index.php?topic=70498.0
"much ingenuity with a little money is more profitable and amusing than much money without ingenuity" - Arnold Bennet

Offline advCo

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Re: 69 SL90
« Reply #2 on: Sep 05, 2018, 12:10:29 »
Awesome! I"m always in for a little SL action.
"He broke the mirrors off his Cadillac, 'cause he doesn't like it looking like he looks back."

74 CB360 - Luna - http://www.dotheton.com/forum/index.php?topic=63294.0 - Sold
82 GS550L - Tracker-ish - http://www.dotheton.com/forum/index.php?topic=67229.0 - Sold
74 XL350 - The Turd - http://www.dotheton.com/forum/index.php?topic=70252.0 - Sold
Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
73 Suzuki RV125 -http://www.dotheton.com/forum/index.php?topic=73875.0
'97 BMW F650st - http://www.dotheton.com/forum/index.php?topic=75732.0

Offline Rat_ranger

  • Posts: 310
Re: 69 SL90
« Reply #3 on: Sep 05, 2018, 20:49:51 »
It's possible, but I think the header would get smashed first.

These are quirky little bikes, and I think once done are a better choice than a pitbike.  I was actually searching for a cheap pitbike when I found these.  I wanted one just to mess with and have some fun, but these will fit better and be just as fun.

I did get the cylinder off, it must have sat with the intake valve open, lots of rust in the cylinder and head.  But thankfully nothing got past the piston.  The insides look nice and clean, so the cases will be cleaned up and new gaskets.  It came with a cylinder bored a little under 4mm over, so a "big bore" piston will be used.  It does have an aftermarket header that'll get cleaned up and used with a new muffler.  Other than tracking down stock parts I think I can get this bike back to its former glory for under $1k total.
Xs650

Offline Rat_ranger

  • Posts: 310
Re: 69 SL90
« Reply #4 on: Sep 08, 2018, 22:24:08 »
Wwll the big bore puston came in today.  Amazingly the cylinder is bored and honed just right.  Measuring it up there is .0015 piston to wall clearance.
Xs650

Offline Rat_ranger

  • Posts: 310
Re: 69 SL90
« Reply #5 on: Sep 11, 2018, 22:43:00 »
No picture today, but the engine is fully torn down.  Next up is cleaning everything to get it ready for new gaskets.  Every fastner on the engine will be replaced with allen head bolts since they are rusty and half stripped.
Xs650

Offline Rat_ranger

  • Posts: 310
Re: 69 SL90
« Reply #6 on: Sep 13, 2018, 22:44:01 »
Well I was wrong.  I thought the center cases had been painted black, turns out there was just a very heavy coat of dirty old oil.  Some time with degreaser and scotchbrite pads and things are looking better.  Still needs more scrubbing, but I have time.  I also checked the speedometer, the bike only had 800 miles before the street parts were stripped off.
Xs650