120 main jet. why?

[rjteeter]

I'm a bit lost on my carbs. I have a tx650 titled as 74. It appears it has 73 or earlier carburetors. They have 125 stamped on the butterfly(what does this number mean?), a pilot jet of 42.5 and a main jet of 120?

Back to the main question, why a main jet of 120? From what I see this was not a factory jetting?

 

[5twins]

Someone obviously put the wrong one in there. It should be a 130. Look closely, maybe you're not reading the number right.

As for the # on the butterfly plate, I'm not exactly sure but it might designate the angle of the bevel on the top and bottom edges. It's certainly not the diameter because later BS38s with the same bore use a 120 and the BS34s which are even smaller use a 135.

 

[rjteeter]

The butterfly diameter should be around 38mm. I'm assuming that is why they are called bs38's? Of course I am questioning my self after you have questioned me and opened up the option of mis-reading the jet but then again I did check the main jet from both carbs so I am pretty darn positive they are 120.

 

[otis]

hay out there, i´m new here. i have want i think is an 80 xs650 sf. vin#:4m4003218. just got it out of the shop, had the engine rebuilt.. took it for a spin today and am extatic to be riding it again. had it since 91. one thing, the clutch is a bit spent and i cant get it to engage properly. does anyone have any advise? at least till i can get the clutch plates. i wanted to post a foto, but i can´t figure this thing out.. i would like to get a shop manual as well. i know thats asking alot. oh well.. thanks

 

[Jawknee21]

hay out there, i´m new here. i have want i think is an 80 xs650 sf. vin#:4m4003218. just got it out of the shop, had the engine rebuilt.. took it for a spin today and am extatic to be riding it again. had it since 91. one thing, the clutch is a bit spent and i cant get it to engage properly. does anyone have any advise? at least till i can get the clutch plates. i wanted to post a foto, but i can´t figure this thing out.. i would like to get a shop manual as well. i know thats asking alot. oh well.. thanks

you shoulda started a new thread. haha. this is completely different from jetting...

 

[5twins]

There were some European models, in Germany I think, that came with 117.5 mains, but I've never heard of any with 120 mains. I think that was also in '76-'77 carb sets. Their rich Z-8 needle jets might allow that.