Author Topic: Yamaha RS125cc  (Read 1731 times)

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Offline jimson

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Yamaha RS125cc
« on: November 14, 2013, 10:17:34 pm »
G,day viewers I have Yamaha RS125cc road bike engine in a milk crate. Are these engines any good? Are they anythink like a DT125? Jimson
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Offline SON

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Re: Yamaha RS125cc
« Reply #1 on: November 14, 2013, 10:39:01 pm »
RS or RX?

Offline cyclegod

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Re: Yamaha RS125cc
« Reply #2 on: November 14, 2013, 11:07:58 pm »
More like a CT3 or AG175 which coincidentally fits straight on  ;)
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Offline jimson

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Re: Yamaha RS125cc
« Reply #3 on: November 14, 2013, 11:17:25 pm »
I,ll get back to you on that. Thanks Jimson
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Offline vandy010

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Re: Yamaha RS125cc
« Reply #4 on: November 14, 2013, 11:50:39 pm »
Gearbox ratio's are very close to MX125a
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Offline Lozza

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Re: Yamaha RS125cc
« Reply #5 on: November 15, 2013, 07:40:38 am »
Is it a disc valve engine?
Jesus only loves two strokes

Offline OverTheHill

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Re: Yamaha RS125cc
« Reply #6 on: November 15, 2013, 09:06:11 am »
Have an RS125 myself [plus an RX125]. RS i looked after at work until the elderly gent gave it to me [after his grandson had "fixed it" haha]. Anyway--they're [nz version anyway] a 4 speed with neutral like an AG [positive neutral]. Porting is better than the RX i have but their might be two RX versions over their reign. My RX has quite restrictive porting and is 'all revs' and no torque, where the RS has good ports plus a squish type head. RX has a flat top piston & non squish head where RS is slightly convex plus squish. Be careful buying pistons as although initially look the same i suppose you'd have a low com model if fitting rx piston into rs head or conversely a high com using rs in a non squish rx head. Sorry, reads complicated doesn't it!! [my specialty 'that']. By the way--is [or should be] same mounts as AG175/AT1-2-3. Thanks.

Offline jimson

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Re: Yamaha RS125cc
« Reply #7 on: November 19, 2013, 12:04:57 am »
Okay stupid me. The engine turns out to be a 97cc LS3-014223 so different engine same question. Are these engines any good? Jimson
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Offline vandy010

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Re: Yamaha RS125cc
« Reply #8 on: November 19, 2013, 08:19:24 am »
Is it a cast iron barrel?
All those early Yammie donks are good.
Just need the obvious things checked/serviced etc
Parts should be easy enough to source as well
"flat bickie"

Offline OverTheHill

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Re: Yamaha RS125cc
« Reply #9 on: November 20, 2013, 08:53:26 am »
LS3's are good little bikes. Mate has one he's had since we used to race together to work in the morning [he's 70 something now], he put a bigger carb & a quiet chamber on, bit more comp & went like hell. I had an AT1 [piston port] so one day i fitted a CT1 [175] top end secretly and went past him changing up--haha, take that. Anyway, good little motors. At work we 'did' have one customer that had a 4 speed version, i think with neutral at the start like an AG but he was an asian student and might have bought it with him from overseas as only recall selling 5 speed ones. Thanks. ps, google image LS3's, should be heaps. Same mate--i bought two LS2 100 twins off a few years ago, they're neat too--still have them.