Sr250 carb swap out

[tomtomsr250]

Hey guys was just wondering if anyone had swapped out the BS34 CV to a VM 30,32,34 carbi ? If so how does it compare?

 

[Tanshanomi]

The thing to remember is that slide carbs flow more than a CV of similar nominal diameter. A Mikuni VM30 or Keihin PE30 would be ideal for an otherwise stock SR250. I've used Nibbi Keihin clones with excellent results.

 

[tomtomsr250]

Cheers for the reply mate. Think I’m gonna get some jets for this CV carb that I’ve got I’m gonna go off attached jadus graph and see how she runs. Currently running stock header with restrictive silencer and pod filter. Would you still recommend the VM 30 with that set up ?

 

[Tanshanomi]

Cheers for the reply mate. Think I’m gonna get some jets for this CV carb that I’ve got I’m gonna go off attached jadus graph and see how she runs. Currently running stock header with restrictive silencer and pod filter. Would you still recommend the VM 30 with that set up ?

I would never recommend a pod filter with a CV carb. If you're not going to run the stock airbox, save yourself the hassle and just get a Nibbi PE30. They're not that expensive. It'll be ten times easier to tune and run better overall once you get it dialed in.

https://nibbiracing.com/products/pe30

 

[tomtomsr250]

Yeah that’s what I’m thinking I’ll just swap the whole thing out. Any suggestions on what jets to get with my set up with the nibbi Pwk30?

 

[arcticxs]

I'm in the middle of a cylinder head overhaul on my XT250, and at the same time cleaning up the ports a bit. Now, I am not 100% sure that the XT and SR heads are identical, but I believe they are. The XT250 has a 28 mm VM pumper carb, while the enduro version TT250 has a VM30. Now, the intake port actually measures 34 mm at the flange. So I tend to believe that a flatslide 32-34 mm carb would be the optimum for max hp. But then one would most likely need to "roll on" the throttle gradually, to avoid bogging down. Anyway, if my XT turns out like I hope, there may well be a TM/ RS/ FCR upgrade sometime in the future.