Aprilia RS 125

[2TInstitute]

Sorry Lozza, pretty cool though. Maybe someone should start a thread about "Old" two strokes / events / pics / memories etc - pretty cool subject !! and would be great place to pass down / preserve / share some great knowledge and experience..

Just shit stirring Pete, but that is a great idea

[2TInstitute]

Went for a little spin on the 125 today, some castor in the tank makes some nice smell, rides a absolute treat with roll on HP, 7000 it's party time untill 11,000, very 'un-125-like' to ride on the road. Running a tad rich in the day time on top but coming back into the zone in the night
All's well for the addition of the Aprilia GP 125 spec pipe.

[2TInstitute]

ran the same time with same top speed (head scratch)

[Jeram]

what was different on the bike this time?

[CrashDummy]

I ate a Quater Pounder, fries and drank a whole lot of Coke before getting to the track.

I'll let 2TInstitute explain what changed inside the engine. I'm not entirely sure. Anything I say now would be a lie.

Since the rebuild the main things that I changed for this night was the fitment of a shift light and home made quick shifter.

That works fairly well. I had a bit of difficulty getting it tuned precisely. I ended up going with the tuning that gave me the most consistent shifts. I settled for 80ms cut time which I think is still good. Good enough that it's one less thing I have to think about when I want to shift up in the heat of the moment.

While at the track I tried playing with the gearing and much to my surprise my drag spec gearing wasn't giving me an advantage. With the road gearing on the little RS was just as quick and if anything picked up .8mph on the top end.


There is my RS125.

This needs more GP pipe to wake this bike up. While the Tyga pipe I have on there is a significant improvement over the standard Aprilia trombone being a couple of kilo's lighter as well has having more grunt in the power band it is still lacking. It's great for "street" riding though with oodles of grunt easily accessible.

To be continued...

[graham]

ran the same time with same top speed (head scratch)

what was the air altitude (Relative Air Density) both days.....If the base has changed, the same time/speed as last time may actually mean you may have a lot more (or less) power than last time.

Accurate records = Accurate conclusions

Graham

[2TInstitute]

Geez graham no need for facts to mess up a good story , we're lookin for some good excuses here:lol:

With the RAD chart I pulled a Rotax Max Kart rad chart that is basicaly the same engine and carb, the Aprilia consistently runs 1 jet leaner than the same temp/barro on the chart(and is a fraction rich at that) .
Some EGT data will be next, and a few carb trials the RM125 TMX-X.
One problem is the 10,500 power peak or replace the engine with one of these

http://racebikemart.com/adverts/APRILIA ... 749132.php

[CrashDummy]

I haven't any idea Graham. What I can tell you is last time I was at WSID the weather was a lot colder. Carby tuning isn't really more forte. I've done the carby tuning on the OEM principals of safe is good. It'll run with whatever fuel I put in it in any weather conditions. It's no doubt on the fat side. I haven't had a chance to get out there and do a proper plug chop WOT tune session.

So for the moment I have no RAD reference for tuning.
The only answer I can give is. Weather was warmer. Bike wasn't as happy.

My hesitation in getting the tuning leaned out stems from about a year ago I burnt a hole clean through my piston. It's hard to shake that fear.

[graham]

The track will normally show (as a altitude reference) the density at the time.

At Willowbank, all time slips have this printed with your time readout.

Graham

Well I suppose we are a bit more advanced this side of the border

[CrashDummy]

Comparing atmospheric conditions from 7th May to 24th September.

Temp.C 0 = 0
Rel Humitity 0 = 0
Absolute Baro 30.12 = 30.14
Track Temp 0 = 0

Sure is chilly in Western Sydney. That's really helpful isn't it

[Jeram]

grab yourself one of these mate !

http://www.ebay.com.au/itm/Semi-Pro-Wir ... 158wt_1139

they are soooo good, and can predict weather changes (sunny, overcast, rain)

not bad for 38 bucks!

[graham]

All joking aside, the track must be giving the data out during the day, tuning for a top fueller at 2:00pm at 28C compared to 8pm at 18C on the same day with humidity changes from 80% down to 45% at the same time.....which would be a perfectly normal change each and every day, requires accurate data.

Imagine Quatar with the 125's what the jetting changes would be for the twostrokes (RIP) from Practice during the day to racing at night......

The drag boys have been very good at using their version of RAD, and software to Quantify changes required before the next run. Only the twostroke GP boys would have been better at estimating.......and now that knowledge will disappear

The normal run of the circuit racer does not have a clue......

Graham

Now about fuel.................

[2TInstitute]

The knowledge WON'T disappear, just off the blower with a tuner who will spanner for wildcard at the GP this year and will get the goss on the Aprilia method of tuning to the enth degree.
Ah the 'fear of rejetting', increases exponentialy with the speed at which the seizure happens.
The usual rule of thumb is a 3% change in RAD is 1 jet size.
The best weather station around is the Brunton ADC pro about a $100US, that does the RAD calculation for you.

[CrashDummy]

Here is some footage from Wednesday.
http://www.youtube.com/watch?v=TtPGu547Unw

[EPApolice]

Is it just me or were you short shifting? Good job anyway