Author Topic: 3MA trackbike project  (Read 40569 times)

kischde

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Re: 3MA trackbike project
« Reply #345 on: February 13, 2018, 01:44:46 PM »
If I remember right (which can be wrong, as I am now aged 45+) SP was the Sport Production Class (nowadays known as Stock-Sport Class) and FIII was the "open one". In the SP they've been running also the NSR etc against the 400cc four stroke. The bikes had to be more or less stock.
In the FIII they've been running without airbox etc...
These bikes where also running at IoM for example, and in a country I can't remember they've organized a cup with the 3MA's (SP Class).

BTW, this was the reason for me to go with TM32 (no SS) and open airbox.. I hope these values in the sugo manual will be a good way to start jetting
TZR-3MA3 1990
RD-350 YPVS 1WT 1988
TZ-500J 1982
TZR-3MA track bike in progress

casal-fan

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Re: 3MA trackbike project
« Reply #346 on: July 24, 2018, 02:08:32 PM »
Found a video of nice 2strokes at the Assen TT circuit.
The 3MA flooding Assen with engine sound. Pushing 3rd-4-5-6 from 1.52 to 2.05
Some really nice bikes at full revs (-P)

https://www.youtube.com/watch?v=8GH8XKevtRQ
« Last Edit: July 24, 2018, 02:13:44 PM by casal-fan »

casal-fan

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Re: 3MA trackbike project
« Reply #347 on: February 01, 2019, 01:53:27 PM »
Other project trackbikes taking longer to complete then expected.
This means that the 3MA Will get yet another chance, sooner then expected...
We'll see how IT goes...

Mikuni parts arrived - the closest one can get to sugo setup without the sugo needles, wich mikuni No longer can deliver.
Setters, needles, original mikuni pilots.
I Was lucky enough that Maccas found a set of original air adjustment screws wich he sent to me, so now the carbs can not be blammed, All original mikuni stuff inside.

Crossing my fingers...
While the bike goes good when IT finally gets going, IT can not accelerate when the flag goes down, because it has gotten charged Up with fuel on the grid.
No good at All, frustrating and dangerous...
Will update as I go... Slowly (-P)

jools

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Re: 3MA trackbike project
« Reply #348 on: February 05, 2019, 03:39:30 AM »
Hi Rui,

how close are those 6EN11-56 to the SP needles ? (in your opinion)

regards

Jools
Plus ce la change, plus ce la memchose

Louis

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Re: 3MA trackbike project
« Reply #349 on: February 05, 2019, 07:29:34 PM »
Hello Rui,

On my road going 3MA I ride with P8 and stock (3MA1) needles on lowest position (leanest possible)
The charging up with fuel is almost gone, that sounds nice but it is just a indication how lean this setup is.
For road going purpose you can control it, by monitoring the EGT closely. (give some throttle and let it pull if its getting to high)

But I don't know how it goes when you have a fast corner at the circuit and you slow down on the throttle at about 10.000rpm
Do you use the oilpump or premix?

King off all twostrokes ''TZR250 3MA''

casal-fan

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Re: 3MA trackbike project
« Reply #350 on: February 06, 2019, 11:09:34 AM »
Louis, yeah... my 3MA also responded very good to a drastic lean needle/needle jet combination that I had the year you and your dad came to Assen... This was with std. jetsetter and a series 7 or 8 mukuni needle wich is much larger then 6 series that are used as standart.
This was a bit too lean because I was lean related throttle response, but this was different then the charging up problem, but it was for me, a test that provede that a lean needle setup can help.
Unfortunetly it was a short pleasure, because the crank, as you know, went west after some laps ::) ::)

Jools, haven´t run the data for the SP needle.
Don´t think it is present on the mikuni chart I got from mikuni germany.
I did compare the 3MA1-needle to the Sugo needle, and the sugo needle compared to the 6EN11-56.

The 6EN11-56 on the full rich notch on a P2 setter compares very well with the leanest sugo setup possible.
You can see a study on them here.
 http://pure2strokespirit.net/forums/index.php?topic=5684.0

We´ll see how it goes...

jools

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Re: 3MA trackbike project
« Reply #351 on: February 06, 2019, 11:39:52 PM »
Rui,

I probably already have some 6EN11's somewhere but I went ahead and ordered 3 pairs and some P# needle jets too from Allens to be delivered to my son's house in Spondon, where the bike lives.

(I'll have to teach him how to put a 2 stroke back together to save me time when I get over there ^-^)

One thing that I have just considered is the effect of removing the intake adaptors I made up to suit the 3XV Sp carbs and which effectively space the reed valve 10mm away from the cases.
Plus ce la change, plus ce la memchose

casal-fan

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Re: 3MA trackbike project
« Reply #352 on: March 17, 2019, 12:39:06 PM »
The 3ma can trully be a bike that pushes the limits of human perseverance.
Drained for fuel before storange... But it still manages to drip ;D
« Last Edit: March 18, 2019, 09:48:13 AM by casal-fan »