Aprilia RS50 9 Pipe Test, the results page!

[LorryDrvier71]

Thug whens this santa pod thing happening? And where exactly is it?

[Modular Overrev]

if i was there with you Micah i could've volunteered to do the rejetting for every pipe test.

i see that your working on your own pipes now that's progress, it pays back big time to develop & sell your own pipe so you don't have to rely on external sources for you needs.

[Micah / AF1 Racing]

I appreciate the offer Overrev....when I get my new externally tuneable carb from PSI this will be very easy to do....100% of the jetting circuits can be tuned externally while the motor is running, even the needle is adjustable over 40 positions while the bike is running at speed on the dyno....kinda like mechanical efi. The powerjet has like 10 adjustment positions....you can even set it up to adjust on the fly at the track to match changing weather conditions or to repond to data from the onboard system like egt and detonation count.

Yes, building your own pipes has huge advantages like the ability to make them somewhat tuneable and to make a series of pipes with each having a special property to suit conditions.

[Modular Overrev]

wow i'm so envious of that, a high tech carb like that will be very handy for me as i hate to open up the carb everytime for a jet or needle adjustment.

how much for that carb?

[Micah / AF1 Racing]

My cost on them is $500 each....no shit! Contact Bruce at PSI Engineering in the frozen north if you are in need. They are a triangular bore for good throttle response but still 28-30mm wide at WFO for max airflow.

[Velo]

Originally posted by Micah / AF1 Racing
My cost on them is $500 each....no shit! Contact Bruce at PSI Engineering in the frozen north if you are in need. They are a triangular bore for good throttle response but still 28-30mm wide at WFO for max airflow.

Please post pictures or link.
This sounds interesting.

OT:
These heads are they for sale? I uses the same cylinder on my SR

[Micah / AF1 Racing]

They will be at some time in the not so distant future....but you will have to send a drawing precisely dimensioning the stud holes since it may be a little different than the heads we use on the GPR Derbi and RS50.

The carb link is here:

http://www.psiperformance.com You will have to search around, actually a lot of fun since these guys do some awesome snowmobile 2-stroke stuff. Just email Bruce at the psiperformance site about the smaller carbs, I am not sure if they are listed.

[Velo]

Originally posted by Micah / AF1 Racing
They will be at some time in the not so distant future....but you will have to send a drawing precisely dimensioning the stud holes since it may be a little different than the heads we use on the GPR Derbi and RS50.

If you have one.
I can go mesure my head and confirm / disconfirm the sizes.

[Micah / AF1 Racing]

At some point we will have these for most of the Pro Race kits for tuning for different tracks and conditions....just let me know the pattern for the studs, the combustion chamber offset value (how deep cc drops into cylinder) and stud hole size....I will check against what we have already built.

[Velo]

Originally posted by Micah / AF1 Racing
just let me know the pattern for the studs, the combustion chamber offset value (how deep cc drops into cylinder) and stud hole size....I will check against what we have already built.

I am not shure that I understand you.

The head drops 2 mm into the cylinder.
The distance between the cylinder pin holes (or what to call them) are diagonal 63 mm from inside to inside hole size is 7½ mm
the distance between to holes side measure is, 42,5 mm

The hight of the head (between cylinder and outerscull) is 17~ mm (,1 -,15)

[Micah / AF1 Racing]

My current heads are:

Combustion chamber drops 1.9mm
Combustion chamber diameter:47.48mm
Stud hole size: 7.48mm
Diagonal from outside edges of stud holes is: 66mm
Height from cyl to stud hole top is : 17.25mm
the distance between to holes side measure: 44.5mm

This head will not quite work with your cylinder....The Derbi heads will be finished in a few weeks, I can see if they will work at that time.

[RpR]

Though about using copper heads?

[Micah / AF1 Racing]

I have thought about copper combustion chambers but the aluminum ones we are using at this point are very capable of shedding the heat of combustion.

[RpR]

Originally posted by Micah / AF1 Racing
I have thought about copper combustion chambers but the aluminum ones we are using at this point are very capable of shedding the heat of combustion.

If you're already doing everything the best possible way, why not go all the way? Of course it would be a waste of money to do copper heads when still experimenting with the layout of the CC. Aluminum sure is a lot cheaper than copper =)

[Limey]

This seemed like the perfect thread to get some engine answers. I have a RS 50 with the following;

Top 75cc, 23mm Del'Orto, Heavy Duty clutch, Da Vinci pipe, Aluminum oval can, (#100 main jet, one step richer on the clip), fome filter and airbox in place, 14/47 gearing. I believe the reeds and manifold are stock. (I purchased the bike used and could not get paper work on the exact parts installed).

The problem: raced against Team Promotion's (east coast track day org) Riejus with Top 75 kits the Riejus walked away from my RS. The Riejus have the same motors but with Mikuni carbs, airboxes removed, and I believe Arrow pipes. They ran pump gas. I'm only 155lbs so it ain't my weight.

The question: How can I get some more juice out of my motor. I don't want to spend $1,500. I heard the Del'Orto cards are junk. What kind of difference would a 24 Mikuni with reeds and manifold, an aftermarket street ignition (for more midrange), and some porting make? I imagine the stock crank could handle this. I want to run pump gas.

I want to have to ability to put the bike on the street w/o swapping ignitions when my girl wants to ride it (I got it for her actually. Please hold the comments about a pipey top end only beast. We may get her on the track with it next year.)

I know there is an aftermarket crank out there that supposedly revs to 18,000 rpm! Can the top handle those revs?

Other then that I plan on putting a Bitubo on the back, some stiffer springs up front, track plastics, and some super soft 125 tires on my spare wheels, and race race race the little puppy.

Opinions and advice are welcome.