Paul's Yamaha 3MA track bike

[Paul]

i have swapped the slides with ones that dont have a cut in the back
i want to put it out there though that a popular choice of carb for the big manufactures is the TM series and their slides are like this



for me this opens up a debate because the slides let no air in when shut and must suck through this slot??

[Paul]

there was a change of plan
i combined the track bikes engine with the road bike i am so happy with
i dont have the sugo carbs on yet as im waiting for cables but i started it with the spare carbs i have
i am really chuffed to hear it fire up, i have bypassed the 3ma tap and am running the bike purely on reserve
so i am getting closer, enjoy

http://www.youtube.com/watch?v=DBYRNXZ1w_M

[Louis]

Hey Paul,

We can shake hands, I'm often Changing from the original plan .

That's a crispy 3MA sounds, really nice. Idles and revving good to

So you give your track engine a go in the road going chassis.
This could be handy to get a good base setup.

Will you leaf it like that, or when you have the track chassis ready you swap it back?

Cheers.

[Paul]

Hi louis
ja, half the fun is taking your time and seeing how many times you change your plan
it is a good idea to swap to tune the engine in your road bike, but not this time. i was going to sell the track frame with road engine cheap to get it out my garage, but it worried me as the road engine is gooooooood. so i sold the rolling chassis to a cafe bike enthusiast! i bring the engine and carbs home.
excellent!
i fitted 3YL throttle and cables, split the carbs (sugo's i won off yahoo.jp) and started it last night, dunno but it sounds more awake, they are 34mm

[Paul]

after some discussion with louis by email, thanks bud, i have aborted the solid/blank emulsion tube mod, the bike wont go, right down to 200 mains and it splutters, and thats with no airboxes, so not going to work IMO
anyhow, after another 6 runs with 1.2mm FAJ and i'm crackling now
pulled it to 9000 and its strong, took it to 10000 and it wants to go, but not yet, she must wait
350/360 mains, Q8 needle jet, 30 pilot, 1.2 FAJ, 1&1/4 airscrew, 34mm 3MA2 20 carbs, slide modded opening ramp by 2mm (we're rough as in SA) needle 6N4-63 middle clip
this is still in development and mains might go larger

[Louis]

Hey Paul,

Sounds you are going in the right direction .
Always difficult to lower the throttle when she wants to go, but its a wise dissension.

Let us know how she go's

Cheers

[Paul]

Always difficult to lower the throttle when she wants to go, but its a wise dissension.

you're right there
i am also running the orings on the heads with no restriction in the flow, so i am just building heat slowly.
so far okay, it goes nice, just had another ride
got a funny spot just on 1/4 i cant tell if its lean or rich, will screw in airscrew half a turn and see if its better or worse

[Paul]

been a bit slack with this bike, too much work and TZ
heavilly motivated after seeing edds beauty tearing around RSR
so i got back into the carb thats when i noticed a bit of dirt sitting comfortably on the bell inlet, like the dirt thought it belonged there.
i aint having that, open carbs with 3ma is not really advisable.
so, with my heavilly equipped workshop i reached in for the hacksaw, this is what i did, see pics

i have a nice colour on plugs on topend, she pulls quite wickedly and easilly to the 13000 mark

got some issues further down when rolling it on, typical 3MA, i cant tell if its rich or lean. it either feels like no fuel or it will feel like it is bogging, too rich.

[Neal]

That should help keep the grit out !

[Paul]

That should help keep the grit out !

yes and to be honest there is no noticible difference, just like when i put 'em on the MC21

right
with these "magic" airboxes my initial set-up was

needles 6N4-63 middle clip
360L/370R
Pwr jet 90
PJ 30
FAJ 1.2
Q8

so they say, one thing at a time, i sat and thought about the bikes behaviour
and that it is off the bottom and through the mid, now the powerjet effects from 1/4 gradually to 3/4 where it is full bull and mains tapers from 1/2 to 3/4 then its full bull (see pic), i did the following

needles 6N4-63 middle clip
370L/380R
Pwr jet 70
PJ 25
FAJ 1.2
Q6

and i have to say it is 100% better

i effectively cleaned up bottom to just over half and used the power jet to help here. it is fun when it works!!! 

[zoomzoom]

Airboxes look good paul. nice work.

[Louis]

Hey Paul,

Looking good , I see that you go from Q8 to Q6 do you want to try the Q4's from the 3ma3 to?

Did you feel any (power) change going from open carbs to airbox?

[Paul]

Hi Louis
I've got Q4's which I'll have to use up country when I go track riding.
Regards airbox. I think there could well be a difference between what I'm using and open carbs. What it is I don't know as I only got it running this well with the magic airbox and I ain't taking it off. There are too many little stones and sand particles that make their way inside the front fairing cavity. Even with tea strainers fitted I didn't like it.

[zoomzoom]

who made the filters for you paul?

[Paul]

who made the filters for you paul?

They're UNI pod filters off eBay in the US of A.
They have a big wire spring in them to stop them collapsing. Very well made.