50cc Sidecar Scooter

[Rex Schimmer]

A Jackson Pollock Bonneville scooter!!! Neat!

Rex

[Nortonist 592]

I thought that's where he did all his work.  At least his canvases look like that.

[revolutionary]

Made some test runs with the 72cc Athena jug and head today. it definitely needs a new pipe. It is falling off at 9000rpm and should go a bit higher than that.

Ran a decent 57.9mph. Strong cross wind and struggling not to blow over. Still fun. I swapped on the turbo and made a warm up pass then in the middle of getting up to speed. put put chug.. out of gas. done for the day but I saw I was getting just 1.5 psi boost and it wanted a bunch more jet. I was running a 98 on motor then just put in a 102 for the turbo and it acted lean still.



swapped on the turbo

[sofadriver]

Made some test runs with the 72cc Athena jug and head today. it definitely needs a new pipe. It is falling off at 9000rpm and should go a bit higher than that.

I sure agree with that.  It looks like your head pipe is about a foot (or more) longer than it should be.  Taking that much length out is going to mean a re-mount of everything else but I think you're going to have to.  See if you can find some pics of the Buddfab streamliner's exhaust and turbo set up. 

[sofadriver]

http://www.apriliaforum.com/forums/attachment.php?attachmentid=260425&d=1408300386

Buddfab's 50cc motor.

Pipe is shorter, fatter, smaller stinger i.d. and wrapped to make heat (gas waves move faster).

All your power is in the pipe.  The turbo will just be the icing on your cake.   

[revolutionary]

Below and bottom is the pipe I have been using as compared to a street "high performance" pipe. I used the dimensions provided by the 2 Stroke Wizard software. It picked up about 5mph overall using my ugly pipe over the best of 3 other pipes I tried.

I thought the chamber seemed really small also, but it seemed to work. I think it is about 2.5"ID. Also, I tried cutting the primary shorter and adding length until I got to what worked best, which ended up at what the software recommended.

The stinger is actually quite small at 1/2" ID and 5" OAL but I put a larger diameter extension  and turnout on it to connect to the turbo.

I'll work on the software today and see what they say for the new bore size.

The buddfab system is awesome for sure. If I was starting from scratch I would use a Minarelli engine at the get go. Significantly better overall and gets rid of the power robbing CV system. This is the "fun" project that is "supposed" to be low buck and low effort. How do we keep having scope creep on these projects???

[rgdavid]

Your pipe has not enough volume,
I can send you some dimensions if you need,

What cylinder head do you use ?

Did you work on the crankcases ?

What carb and reed valve ?

David,

[revolutionary]

Below are the specs I used. Do they seem right?

[sofadriver]

Rev, the pipe you're using almost looks backwards from your computer wizard.

Note the very short B2 length on the Wizard.  This has a huge impact on RPMs.  As is, I doubt it will make power over 10,000 as it will take too long for your gas pulses to get back to the exhaust ports.

As David said, a fatter pipe will give you more "hit" and the taper after the fat belly will help determine the length of your powerband.  How many speeds does your scoot have?

You've probably seen this before.  I use it as an occasional refresher when I start to think in a rational manner (like 4 stroke people) 
http://justyamahard350.com/articles/eric.htm

[RGV]

This is a pretty good read, helps you get your head around 2 smoke pipes.

http://www.rgv250.co.uk/forums/index.php?app=core&module=attach&section=attach&attach_id=23788

I tried the "2 stroke wizard program". Lets just say I didnt go through with the pipe it designed.

Dave

[rgdavid]

You could try a program by "bimotion" .
Works quite well,

I have a decent pipe here if you want some dimensions,
Ill try and get you some other dimensions from freinds who do scooter drag racing,

If you want help we need to know more about your moter,

Ps , rgv, i have an aprilia250.

[revolutionary]

Looking forward to advice...

Internal engine work - just cleanup and smoothing of the ports


Stock crank and rod. 41.4mm stroke
Athena 47.6mm bore (stock is 39mm bore), no work done but it is much wider than stock and tapered oval instead of square
Athena head - static compression appx 12:1
VForce3 reeds
21mm OKO carb (I have a 24mm also, if needed, but was too big for the old 50cc)

[sofadriver]

Try telling that program that you want to make 15hp at 14000rpm and see what it says.
Need to know your gearing/transmission.

[revolutionary]

9:1 final gear ratio, CVT primary (2.45-0.85:1), 90-10 tires

[RGV]

Ps , rgv, i have an aprilia250.

Nice bikes. Italians build very pretty bikes. (And women  )

Dave