Flow numbers?

[Matt Fisher]

Has anyone put a 400EX head on a flowbench? I'd like to find out what numbers they achieve, and at what lift they stall out.

[Ononewheel]

Matt, how serious about this are you? I have limited access to a flow bench but do not have a head to put on it. I really do not know alot about this. I know with cars the lift when it stalls out is important, and flow numbers can be too when doing head work. It would be a huge hassle for me to do it, but I could probably get it done. I am curious about your thoughts on this, I am not sure of what we would gain other than peace of mind. Let me know fro.

[MIKE400EX]

Matt, I've got easy, anytime access to a good flow bench. I should have put my cylinder head on it, but for lack of spare time I didn't. I did spend some time examining the ports. From the looks of them, a bowl cleanup (there was a significant lip by the valve seats) and an intake opening match (slight core shift) would get you about 95% there. Most "porting" would probably do more harm than good! If you know someone that has a cylinder head to borrow, I'd be more than happy to gather data.
I've still got to write up all my "findings".

[Matt Fisher]

I'm looking into this so that I can make more intelligent decisions on cams. Additionally, if we gather enough info on the 400EX, we can better guess what a modification might do.

For example, if the intake side had a maximum flow of 200cfm @ 28", and an aftermarket carb flowed 300, we'd know ahead of time that the top-end gains would be minimal. We may also find that something like the intake adaptor (manifold?) turns out to be a restriction. Maybe the head is exhaust restricted like most Fords and a dual pattern cam would work very well.

It's certainly significant with the different cams out there. Web makes the 450/451, with these lift/duration #'s-.350 .345/256 256 They also make the 479, with these #'s-.378 .378/250 250 Same LCA's on both cams.
The 479 should have a broader power curve without any loss in top-end over the 450. Unless the head doesn't flow well at higher lifts.

Heck, we could even have custom ground cams if we get enough info...

[MIKE400EX]

Matt, The 479 cam does look like the best choice yet. Laurie at Web Cams said that the ramps are more aggressive on that cam than the 450/451 & others. That's the cam she uses in her own 400EX! Shorter duration, with more lift and quicker ramps should really help the mid w/little to no loss on the top. 6 degrees less duration should even be noticeable on the bottom. That one WILL require hardened rockers. There are some short height Honda car valve stem seals, viton material, that would probably eliminate the need to cut the guides down. They are about .040"-.050" shorter than stock, or the ones Marcum's sells (Suzuki I believe).

[Matt Fisher]

Which Honda car seals work?

My friend's going to use the 479 cam, but will gamble with the rockers. The FST oil cooler setup will be used to offfset the chances of it wearing. It's a $160 gamble, why not try it?

When we're done, we'll know the differences in power between the 450/451 (which I have), and the 479. Our bikes will have the same WB exhaust, port work, 440 motors, and stock carbs.

[Chef]

Doesn't Web have 3 cams right now? Is the 479 also the 463/9i?

[Sandragggen]

See the attached

[86atc250r]

Here's my favorite part about WebCam's website
(note the 450/451 grind numbers compared to those above)

Gotta love accurate specifications.

[400exRacerX]

Wow theres a big difference between the xr400 450/451 grind cam to the 400ex!

[MIKE400EX]

Their web site specs for the XR cam are wrong. The EX specs are correct. The catalog shows them as both being the same (EX-correct). I've called Web Cams to verify that before. Guess WEB has to get their web fixed.

[86atc250r]

Thanks for the clarification

[Matt Fisher]

I'll bet the one shown for the XR is actually the one they make for WBros in the all-around cam. The specs are the same, except the duration is listed at 248 for the WB.