39mm Keihin FCR for 400ex

[White400]

Where is the best/cheapest place to find a Keihin 39mm FCR carb for a 416ex?

[EXDUNER127]

ebay!

[White400]

I've already checked ebay, nothing available......need one soon!

[panteramatt]

yfzcentral do a search or thumpertalk.

[BLEEDRED]

C&D $420.

[shamisc]

Originally posted by BLEEDRED
C&D $420.

:muscle: C&D !! Colby is the FCR GENIUS!!!;) I think $420 is w/ cable included.

[Ty's400]

C&D is definetely the cheapest to get a new one! Carb does come with a new cable and they will pre-jet it according to your specs.

[White400]

Would you guys go with a 39mm or 41mm for a 440ex?

[komatsu kid]

Originally posted by White400
Would you guys go with a 39mm or 41mm for a 440ex? 39mm

[White400]

Any particular reason you would go with a 39mm instead of the 41mm?

[BLEEDRED]

White400, I know this is off topic but how do you know you have 11:1 compression with your Wiseco piston?

And I think the FCR 39 is just fine for the 440, FCR 41 might be more for drag racing.

[White400]

I had a compression test run. It's actually like 10.89 or something.

[BLEEDRED]

I had a compression test run. It's actually like 10.89 or something.

Who set up your machine? What does the test entail?

[White400]

I had a local shop set up my engine. The have a program/machine to test for compression. If I'm not mistaken I think it goes where the spark plug normally goes. (Gives you a compression reading.

[White400]

WHy do you ask? Curious what compression you're running? I think you can buy different compression pistons, but you would have to run higher octane fuel.

[BLEEDRED]

Hum, maybe somebody else can help, but I thought all that did was test the pounds of compression. Doesn't give you a ratio. I thought the only way to get a ratio was to measure your clearences, CC your head, account for your gasket thicknesses and punch it all in to a compression ratio calculator.

The only reason I ask is because in the past Wiseco had a bad reputation for not properly advertising their CR's. I have the same piston as you and I did all my homework, checked my clearences and measured everything and ended up setting up without a base gasket just to get 10.6:1 CR.

[White400]

I'm not really sure about accuracy, but my ratio came out to be 10.89:1 . Maybe Wiseco is not all that accurate and their CRs vary a little. Thus expalining why your CR is a little lower than mine. Could we be leaving an equation out? Not quite sure?!? Scratching my head!

[BLEEDRED]

Well I don't know for sure and that is why I asked who set your motor up. I know my compression ratio is 10.6:1 because I did the work myself and took all the measurements. I used the CR calculator on www.rosspistons.com Had it set it up with factory gaskets it would have been something like 9.8:1. I ended up using a .027" cometic head gasket and no base gasket. The only way I could have got a true 11:1 would have been to seperate my three piece had gasket or deck my cylinder. Both options I didn't want to take. So 10.6:1 is fine with me. Plenty of torque and seems to rev out fast enough.

Like I said, I was just asking because you have almost the same set up as me. Didn't know if you were just saying 10.8:1 becuase some mechanic said so or if you had hard facts to back it up.

Let me ask you this, how does your bike run? Happy with it?

[White400]

Overall, I'm happy. I'm looking to get a Keihin FCR flat slide for both my 416 and the 440. I am running a stock carb on the 416 and an Edelbrock performer on the 440. I am not very pleased at all with the Edelbrock carb. Other than that it runs out well.

[BLEEDRED]

How does the 416 run with the 440?

[White400]

Believe it or not, the 416 has alot more torque, but the 440 revs quite a bit faster.

[BLEEDRED]

Believe it or not, the 416 has alot more torque, but the 440 revs quite a bit faster.

Strange, I would think that would be the exact opposite.

[White400]

I thought so too! I wasn't sure if I wanted to go with the 440 bore, but it turned out better than I expected.

[Colby@C&DRacing]

I would use the 39mm FCR on both bikes. THe 41mm is a drag race setup. It will make more power on the dyno than the 39mm but only on the very top. As for the edelbrock carb it is better than stock but not as good as the FCR.

[White400]

Thanks Colby you 2 cents mean alot to me. What can you do on one for me? Is it accurately quoted earlier in the post?