TM250 carburation question

[ninjamk]

Right, I understand that.  I am just looking for a good place to start if someone is running something similar.  I assume that I will need to be a few sizes richer than stock.  Otherwise I will start way rich and work my way down.

[Freakshow]

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.

Mate  im just telling you what i ran on a TM 250 1974/75 model and it worked and won more than a few titles and that's flat pinned.  if as you say your just putting around for fun, you wont be lean unless you dont plan on changing gears. a quick look at the pipe tells me its set up for low revs, so it wont rev out anyway.

Forget what the Japanese book from 35yrs ago says your not in Japan and your not i assume 45 kg.  

If you put a standard MUk 32-34mm carby on there which is what you will need to do to make the bike run properly and be legal then thats where i would start.  Once you have done your first plug chop then you can take it from there. it will reveal all.  it will take you 10 mins to find all this out.

2 of us are now telling you what the jetting is and its under #200.   NO offence but Make it simple on yourself and just follow the advice, we are trying to help you.

[ninjamk]

Thanks,
I do appreciate the help. Just curious, how can you tell the pipe is set up for low revs? I have a basic understanding of how expansion chambers work but dont really know enough to tell what it is set up for.  Also what did you mean by "so it wont read out anyway."

Thanks and sorry if these are stupid questions. 

[oldfart]

Think freaky is saying ....  "Rev Out "
 

[Freakshow]

yep rev out. stupid ipad shit.  Im going back to the PC to compose emails or wording responses in forums least it my spelling that sux then and not being changed to other words entirely.

Yer its a long pipe in many sections specially that front cone and the tail, so it would be more a low down reving pipe.  althogh the last cone is quite fat and visually short but because of the turn it would have a bit of volume in there.
you find the light switches are generally compressed fronts.  NO big deal be good for what your doing as you say 'put puting' about and you WONT have to ring its nuts out just to get the clutch to take off.

But if its a bit soft you can easily cut an inch or so out the straight section with the springs either side and see if it brings the total tuned length into spec that suits that hybrid motor. because you working with so many strapped on parts its going to be a work in progress till you find how it all works best together.

[ninjamk]

Well, I must say, you guys know your TMs.  I just put in a 30 pilot and a 180 main.  The needle still needs adjustment or a switch out because the mid range is way too rich, but once it gets on the main the thing takes off.  I think the 30 pilot is a little lean, and 40 was too rich so I am going to pick up a 35 and see how that is.  I am used to the riding the bike in stock TS configuration with slightly low compression, I was not expecting that big of kick when it took off 

[Freakshow]

easy to ask, but some times you gotta have some faith and listen to the answers

drop the needle one and see how it goes, it might flatten the middle out for you.

good luck, its all sailing from here.......