TM250 carburation question

[ninjamk]

Ok, so I am getting to the point where I am ready to start tuning my TS250.  I am running a 73 TM250 top end and cdi with a TM34 carb and foam uni pod filter.  Exhaust is a pro-form chamber with circle-f silencer.  I am really paranoid about getting the jetting correct and not running lean.  Is anyone running a similar configuration on their TM and if so what does your jetting look like.  Also, what is the determining factor to switch to a leaner or richer needle rather than switching the emulsion tube or vice versa.  Thanks

[Dono113]

Mikuni carburetor jetting.
 
Mikuni needle jet orifice diameter.
The chart below lists the inside diameter of the needle jet in millimetres, ie an N-6 is 2.580mm ID.  This is true for every series of Mikuni needle jet, ie every N-6 is 2.580mm ID. Obviously the needle jet range is from N-0 as the leanest up to R-9 as the richest. Note that not every size is actually available in each and every series of needle jet -- this is just a size reference. 
There are some other sizes and markings used, ie #224 series are numbered AA-0, BB-0 etc, and they are not shown here.
    -0   -1   -2   -3   -4   -5   -6   -7   -8   -9
N   2.550   2.555   2.560   2.565   2.570   2.575   2.580   2.585   2.590   2.595
O   2.600   2.605   2.610   2.615   2.620   2.625   2.630   2.635   2.640   2.645
P   2.650   2.655   2.660   2.665   2.670   2.675   2.680   2.685   2.690   2.695
Q   2.700   2.705   2.710   2.715   2.720   2.725   2.730   2.735   2.740   2.745
R   2.750   2.755   2.760   2.765   2.770   2.775   2.780   2.785   2.790   
http://cid-407d7ef0965d3991.skydrive.live.com/browse.aspx/Racing%20Model/RM%20Owners%20Manuals some carby tuning info in here
 

[ninjamk]

Thanks for the info.  I have the Sudco Mikuni manual, but it wasnt really clear about that part of it.  Both my TM34 and the stock VM32 have Q2 needle jets.  Would you go up a size or two on the needle jet or just start with raising the needle a clip or two?

Thanks again

[Freakshow]

#180 main and #30 pilot, it will be close as close and you can mess about from there.

apart from that call Ian williams tuning as he is the mukuni guru ( he is on the net)

he would still have my TM specs there as well.

[Freakshow]

dont fork with the other stuff leave the Q's in there till you are really fine tuning if you have too.

Q2 will give you enough pipe to send it to the Main.

ONLy if its blubbering and you can fix it on the main then mess about coming down.  but you wont need to go up unless your white lean and your out of supply to your main.   Basically thats only the case if that nozzle has less internal diameter than the main your supplying and your Q will certainly not leave you short.

[oldfart]

Are you still running the slinger and oil pump ? or have you done the case mod and removed the slinger.
I'm running a Circle F pipe and running a NEW  34mm carb with Std needle and have played with the jets along  clip setting to suit my motor of which has had the oil pump removed.

[ninjamk]

I am running the TM oil pump, not sure if it was any different than the TS but all the charts in the manuals made it look like it pumps a slightly larger volume.

[ninjamk]

#180 main and #30 pilot, it will be close as close and you can mess about from there.

apart from that call Ian williams tuning as he is the mukuni guru ( he is on the net)

he would still have my TM specs there as well.

So I just checked the TM manual and apparently stock, the TM has a 260 main jet.  I am going to assume that you meant to go with a 280?

Thanks

Oh, and I just got the pipe and everything fitted, here's some pics:

[Freakshow]

nah im prity sure it was a #180 in there it was a 75 model TM 250 with a 34mm Round slide Mikuni carb.   any more jet and it loaded up.

Just so you know also you cant run a flat slide in pre 75, before you get too carried away with jetting and stuff.

[ninjamk]

are you talking round or hex jets? Also, I do not plan on competing on this bike, its just for fun.
My manual is showing stock TM250
Pre 74:
Main: 260
Pilot: 20

1974-1975
Main: 230
Pilot 40

So I am assuming that with the bigger carb and aftermarket pipe I need to be bigger than 20 and 260.

[Dono113]

Nice pipe champ

[Suzukal]

From the Suzuki parts catalogue..
TM250 hex main jet
72-73 .. # 230
74 .. # 200
75 .. # 210

pilot jet
72-73 .. # 40
74-75 .. # 35

My TM250 runs #35 pilot & # 190 main, anything big like # 260 & it runs like the choke on.

[oldfart]

By the looks you have a flat slide

[ninjamk]

By the looks you have a flat slide

Yes I do, as I said in the first post.  I am starting to get confused, I can accept that the bike runs best with a 180~190 main jet, but why are all the jet specs in the mid 200s?

[oldfart]

As we are all quoting figures from round slides....and your Tm manual would be refering to round slide also.