aprilia rs 125 premix

[matyboy1]

hi i have a 2002 rs125 which is running on premix oil,the oil pump has been blocked off,the guy i got of gave me a jug and said 125ml of oil to £5.00 fuel so around 5 litres just wondering if this sounds correct and what sort of oil i should use any help would be appreciated thanks

[truslack]

Sort the oil pump out, it would be much easier in the long run.

From a previous thread on the topic, Kickstart reckoned the pump meters between 50:1 and 100:1 fuel:oil
( https://www.bikechatforums.com/viewtopic.php?t=210381 )

£5 at 1.28 a litre gets you 3.88 litres so your 125ml of oil is giving you a 31:1 premix so too oily.

Like I said, MUCH easier to sort the oil pump.
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Current: Suzuki RG 125 Gamma, Honda H100, Triumph Tiger 800XC, Suzuki SV650 (minitwin)

[Blau Zedong]

I'd be wondering why a bike that is otherwise standard is running premix. Also the pump should be removed and the drive blanked off, plus main (and possibly pilot) jet changed. 30:1 is ok as a starting point for premix, although with modern oils you can probably get away with 40 or 50:1.

[Kickstart]

Hi

Trouble with pre mix is that you land up with an oil supply that is directly proportional to the fuel used. So to have adequate oil when stuff all fuel is being used (throttle shut at high rpm) you need a rich mixture, which will be unnecessarily rich when a decent amount of fuel is being used.

The mix you have been told does sound a bit rich, but probably within reason.

Personally I would agree with Truslack and say to fix the oil pump.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[matyboy1]

hi i was told it was the full power version and the only modification i can see is a full endy exhaust system,whats the best 2 stroke oil to use thanks

[Kickstart]

Hi

No reason a full power one should need to run on premix. On most models the only real difference is that restricted models don't have an operating power valve (normally a blanking plate instead).

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[stirlinggaz]

[matyboy1]

hi m8 its a full endy system,as for the oil pump ive got a haynes manual so im gonna have a crack at it.i did ask why the pump was blanked off,it was when the exhaust was fitted thats what i was told so i dont no if it works or not i have the pipes,and tank for it,i was thinking of getting a replacement just incase off ebay as they are cheap.

[stirlinggaz]

hi,
ditch the endy, it does nothing for performance. (i actually think the bike suffers due to it, no power below 5k, + powerband up at 10k? f*ck that)
the likes of jm,arrow or jim lomas exhausts are a vast improvement.
or the cheaper option : fit an arrow, or even an oe aprilia spanny (cat-less) & any bling end can.
theres absolutely no reason why the oil pump should be removed, when fitting a sports exhaust.
whoever did this, for that reason, should have set the carb up properly instead & adjusting the oil pump is 1 screw/nut.
i'd recommend downloading the rotax 122 manual & the aprilia wsm, both available on-line, & starting from scratch.
install the oil pump, set it up (its as easy as hooking up the cable & aligning 2 marks up)
strip the carb, & see whats what. (might need to buy a couple of jets)
install desired exhaust. plug chops & enjoy. (for a few thousand miles before its rebuild time,lol)
cheers,
GAZ