TZR250 3MA HYBRID (race)

[Louis]

Its been a wile back since I had worked on the hybrid bike.
To keep my relationship healthy I had to do some work at the house
Now all that is done, so I can slowly pick it up where I left it.

Got the fairing back from the painter, and it starts to look a bid more like a racer.
Have to sort out quit a few thinks, but the end is close.
Can't wait to give here a go, on a deserted road.

Here is how she looks now.





Does someone know if these will fit the mikuni 3ma carbs? it looks to me that they could fit.
http://www.parkeryamaha.com/mikunineedlevalveset.aspx

[Warwick]

Looking good Louis. I'm pretty sure those needle valve sets will fit the 3MA carbs as all the big TM carbs seem to use the same basic body. Go for the 3.5s though, not the 1.8s.

[Neal]

Looking good Louis ! Good luck .

[tzr-v4]

Very nice Louis, but looking very black now 

[jcsnook]

Wow...very nice Louis!!  Sexy!!

[Louis]

Update:

Its a will back since I had time to work on my bike, but today I had time
What did I do.

Made all electrical work.
-tachometer
-battery meter
-temp meter
-ignition on/off switch (with control led)
-powervalve on/off switch
-kill switch
http://www.youtube.com/watch?v=Mo46pMK4uhM

This will probably not be the best solution as its a small display
But it will have o do for now , perhaps in the future there will be another display.

On the bike it self I did the following.
-Balancing the front wheel (old fashion way)

-Balancing the rear wheel

-changed the showa 1000 shock for the 600 shock (witch gives me a bid more clearance)

-tighten /check all bolds.

Starts to look more on a race bike


And last off the day I wormed her up to see if all is working
http://www.youtube.com/watch?v=CWlAURvppOw

Last thing to do is sorting out the carbs, this will be done with a few new ideas
Still waiting on some ordered parts

Cheers guys

[Warwick]

Looking and sounding great, Louis! 

[Louis]

Thanks Warwick, will get there.



For the ones who don't know it, I use on my hybrid bike primary needle tubes.
Original a 3ma has bleeder type needle jets.
For the moment I'm tying my home made primary needle tubes (with a brass tube around the needle jet)


But I like to try this, I have them at home.


You will get the idea, will change the emulsion tube in my lath to make it fit witch should not be that difficult
So you will have a solid (original) pimary emulsion tube.

Do some off you guys have a idea where to start with jetting with open carbs and primary needle jets.
I see that the tz250w 3lc has stock 450 mains with 38mm carbs.

I have 32mm Should i start with around 380 a 400 mains??

[Warwick]

Yes, that should work better Louis. Your home made primary N/J won't work so well because it has the ring around the needle jet itself. This means that it creates a seal in the carb body just below the tip of teh needle. this area should be open so that the air coming through the air jet can mix with the fuel as it exits the needle jet - just as it does on the TZ needle jets you have pictured above.

Yes, I would think mains around the 400 mark would be a good starting point.   

[EEKNOWS]

Looks great Louis,Brembos look like a good upgrade. Neighbours must realise what's going to happen when the video camera comes out 

[Louis]

Hello Lozza,

Neighbours must realise what's going to happen when the video camera comes out 

Yes, you see that right.
To hold the peace in the neighborhood I'll only let her run for a couple off minutes.
Ones I have sorted the carbs her at my home, will drag her to my parents house where I can properly worm her up and ride the first meters

Warwick,

because it has the ring around the needle jet itself. This means that it creates a seal in the carb body just below the tip of teh needle. this area should be open so that the air coming through the air jet can mix with the fuel as it exits the needle jet

You make me a bid confused , What space needs to be open?
The plan is/was to cut the top off, and machine the needle jet to the original 3ma size.
So you will have a primary needle jet pouching/sealing agents the original Q8 needle jet.
(like sugo 3xv ones)

As I sad that was the plan , now I'm thinking what needs to be open?
I'll let the carbs un toucht, so when closing the inlet tube on the carbs for the airjet's
I thought it should be good.

[Warwick]

Sorry, Louis. I didn't explain it well  .

What I mean is that I think you'll need to replicate the same overal external shape as the TZ-type nozzle/needle jet in your pic for it to work well? So if using the 610 needle jet you'd need to machine off the protrouding 'ring' that runs round the outside of the jet.

Does that make more sense

I'm planning on trying TZ needle jets in my own 3MA. I checked it out, and It looks like with a little modification to the cab body and/or Jet the TZ jet will fit in the carb with the jet tip at the same height as the 3MA jet. You might want to look at that too? A key advantage would be that it would be far easier to source different size needle jets .

[Louis]

Does that make more sense 

Ehh, i think

A picture says more then thousand words , so lets see if I understand you right.

Here you have the whole construction.


The idea is/was to machine the top off and make it the correct values to fit the 3ma carbs
Like this:


After that, when fitting the emulsion tube it will tighten the original needle jet. (like oem)
Ill plug off the original airjet inlet (from the side off the carb) and hold the little brass bolls in place.
So in theory I should now have a working primary needle jet construction.


I have looked at your idea.
When I fit the 633 needle jet, it looks like it to short


Of course I could retap the thread inside the carb body further to allow the 633 needlejet to fit on oem location.
But that will bring the main jet almost outside the bowl. Perhaps you can change the fuel level, but i doubt if you can get it up 6/8 mm.

A thought the needles seems to fit.

[Warwick]

Sorry, Louis. I have some computer problems just now, so it's hard to make an image to show you what I mean, but I'll try to explain a little more.

For the needle jet to work as it does in TZ carbs you need an air bleed for the needle jet. But instead of the air from the air jet mixing with the fuel in the emulsion tube, it forms a 'pool' of air that helps atomise the fuel as it exits the needle jet. This is why I think you will need to cut off or cut down the ring that runs round the outside of the 610 needle jet so that it can work like the 633 type does.

On the TZ carbs the air fir the air bleed is controlled by an adjuster screw. It looks like it would be pretty easy to modify the 3MA carb to use the same kind of adjustment, or you could just use a fixed air jet - or even use tha VAJ system to adjust the airbleed according to revs/throttle position?

As I mentioned, I've been meaning to try that kind of set-up for some time now, but other things keep getting in the way... I will get round to it though, so if you still can't follow what I mean, I will post up some pics and a report when I get round to it. Currently busy clearing some ground so that I can put up a workshop at home, so hopefully the bike development will get back on track in the next few months...

[Paul]

Nice work guys. I personally loathe the airjet carbs. I also do not know enough to try and convert them to primary carbs. Else I would. I reckon all my hassles have been air and it has cost me to learn what I have.
I watch with interest and hope you both succeed and share your results here.