Yamaha LS3 "The One Hundred"

chambers · Mar 1, 2013

Hi guys,

I've been lurking for a while finding lots of inspiration and thought it was about time I started a build thread!
I'm a welder fabricator living in Brisbane, Australia.

So I'll start with a question... Does any body know anything about the Yamaha Ls3? As far as my research has shown it is near identical to the rs100? My bike is from 1972 I think... Its a 97cc single, two stroke, The styling is similar to the Ls2 but with a bit of closer inspection they are quite different

Here's my bike the day I bought it, Not running fuel tank full of rust etc.

chambers · Mar 1, 2013

Re: Yamaha LS3

The advertisement translates from French to say..
"the engine adopts a valve intake, intake of seven transfers and five lights to exhaust"

Which kinda makes sense i guess? I used Google translate so if anyone actually reads French and the translation is wrong please let me know

.....

So far I've had the engine running after a carb clean, new plug, points adjustment and a little re-solder on the condenser 8)

I was stoked for about 2 mins until I realised i had a leaking crank seal and VERY loud crank bearings!

chambers · Mar 2, 2013

Re: Yamaha LS3 100

So I tore down the engine, Removed the bearings and seals and cleaned it up a bit.

I also decided I would put some knee indents in the tank, remove the battery holder and old very blocked oil tank.

p.s sorry about all the crappy phone pics I don't know where my camera is.

kopcicle · Mar 2, 2013

Re: Yamaha LS3 100

We see the LS3 here in the states as an RD 100 usually but I have seen it called other things . If parts get too hard to find I have an excellent machinist and parts hoarder here locally . I do realize that most often the shipping far outweighs the cost of the part but I thought to offer . I would agree that these little things perform and last outside of all expectations . The only thing is we run all the tiddler two strokes in the family on Amsoil 100:1 synthetic in the tank at near 200:1 as well as using Spectro 2T in the injection tank . It gives us a bit of warning and far less damage should the oil injection quit for some reason .
Keep at it I think you'll find it well worth the effort .

~kop

chambers · Mar 2, 2013

Re: Yamaha LS3 100

Thanks for the reply Kopcicle!
I thought the rd100 was a twin for some reason but I could be wrong, I used to have a couple of rd50's about ten years ago and they are singles... Thanks for the tip on the oil injection.

Parts are pretty scarce but most are fairly generic, Thanks for the offer though I may still take you up on it at some point ;D

chambers · Mar 4, 2013

Re: Yamaha LS3 100 (rd100?)

Hey can anyone see my pictures? I logged on on my phone at work and couldn't see my pics? ???
9 photos all up at this point...

Thanks

bradj · Mar 4, 2013

Re: Yamaha LS3 100 (rd100?)

looks good man

stroker crazy · Mar 4, 2013

Re: Yamaha LS3 100 (rd100?)

Photos all good, chambers!

Looks like a fun project, keep up the good work with piccies as you progress.

Crazy

chambers · Mar 4, 2013

Re: Yamaha LS3 100 (rd100?)

Cool thanks guys ;D

catsy · Mar 4, 2013

Re: Yamaha LS3 100 (rd100?)

Im jumping on board, gotta love our low displacement bikes!

VonYinzer · Mar 4, 2013

Re: Yamaha LS3 100 (rd100?)

Good stuff. Keep the updates coming.

DreadRock · Mar 4, 2013

Re: Yamaha LS3 100 (rd100?)

I'm in looks real close to the LS2 maybe head fins look lil diff !

chambers · Mar 5, 2013

Re: Yamaha LS3 100 (rd100?)

Yeah that's what thought at first... Ls2 is a twin and the engine is a structural member of the frame, The Ls3 is a single with a full frame but he tank, bars , seat etc all look identical

*edit* of course you know most of that since you have an Ls2....

chambers · Mar 8, 2013

Re: Yamaha LS3 100 (rd100?)

Here are a few rough mock up pics of the direction Its heading.

Still left to do

Fabrication
-head light bracket/ indicators
-expansion chamber
-new bars (currently bicycle bars

)
-cut down guards
-new oil tank
-new seat (cardboard template at the moment)

Engine
-New bearings/seals
-port/ polish

misc
-new tires
-speedo
-paint

Man that list is longer than I thought :

** Also the fork angle is actually a bit steeper than it looks cos there are no bearing cups in the stem in the photos**

stroker crazy · Mar 8, 2013

Re: Yamaha LS3 100 (rd100?)

Don't forget to add new seals to your list!

Forty year old seals are untrustworhy.

Crazy

chambers · Mar 8, 2013

Re: Yamaha LS3 100 (rd100?)

Ha yeah thanks they were in my mental list just not the physical one! Especially cos of the amount of white smoke billowing when she was running breifly

Added now.

silverwolf · Mar 18, 2013

Re: Yamaha LS3 100 (rd100?)

I just got a "72 LS3..looks like the red one in the photo..have to get it running but suspect it might need crank seals..are they hard to get to?

chambers · Mar 18, 2013

Re: Yamaha LS3 100 (rd100?)

funny you ask, one of the reasons I started this thread was to get info on parts availability etc....
Unfortunately no one seems to know anything about it ??? :

Anyway as far as I can tell they are the same as the early rs 100 and possibly the LT3 100 which both are fairly easy to get , I haven't bought mine yet so I cant tell you for sure if they fit .

Good luck and let me know if you find anything out 8)

stroker crazy · Mar 18, 2013

Re: Yamaha LS3 100 (rd100?)

If you can't find parts CMSNL could be worth a try. Not cheap, but they have lots of stuff.

http://www.cmsnl.com/yamaha-motorcycle_model16707/

Crazy

chambers · Mar 18, 2013

Re: Yamaha LS3 100 (rd100?)

Thanks crazy,

I have tried there and they have no Ls3 specific parts ???, But as I say I'm pretty sure they are the same as the rs100.

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