Anyone tried a FCR40 on a BigBore?

[jhondius]

Anyone tried a FCR40 on a BigBore?

Just wondering.

FCR39 seem perfect, 41 seems too big.

But bigger is better right ?

Yosh used a 40mm carb on their 450.

[Erik Marquez]

Try it out, track your dyno runs and jetting changes, and let us know how it works out ( I doubt Yoshimura has done any R & D on a DRZ platform in many years.. Nothing they have to say about the DRZ is current)

The guy with the experience and dyno in his shop says the 41 FCR is a better fit for the built motors... I don't have a dyno,,,, I have not done the R & D, I'll take his word on it.

[f2dog]

Yoshi used Mikuni carbs , I think i was tmr-mj 40

[mickeydee]

i was using a 41fcrmx on my 440 BB.it worked fine.my BB was also had all the other goodies to make it go fast.i did do a dyno run to see the difference in power and the 39 was the beter carb to use with the BB but the 41 did make more power on top.

[Wayward Son]

the diameter of the hole in the carb is only a partial picture.

a 40mm mikuni and a 40mm fcr do not flow the same amount fo air.

[jhondius]

I'm thinking of trying the dyno comparo fcr39 vs fcr40

BigBore, Yosh Ti, Hotcams.

Eddie, others, do you think it will make a nice difference or am i just going nuts?

[PBMW]

I have a 41 on my BB. MRD/SSW, Hotcams...

Works well. You do lose a little on the bottom and gain a little on top.

I bought the 41 because the plan was to stroke it anyway...

[Wayward Son]

it will make more power (actual gain unsure,thats what the dyno is for) assuming you have the intake bell set up correctly.

[jhondius]

it will make more power (actual gain unsure,thats what the dyno is for) assuming you have the intake bell set up correctly.

You remembered my homebrew intake bell!

incredible. from all the people on here, tens of thousands of posts.

Thanks for the input.

I'll post any results here.

With pre- and post dyno that is.

i'm hoping for this logic

400cc - 39mm works great, good low mid top end.

435cc - 40mm ??

470cc - 41mm great gains, see tale of 60hp thread, but weak low end for 435.