head pipes

[walt miller]

what head pipes fit slip-ons? I think i someone said FMF & White Bros. Is this true and are there any other besides them?

[jsmith2232]

I keep hearing alot on the HMF and if i could do it all over again i probably would go with the hmf just because of what i hear about it but i have the FMF powercore 4 with the FMF powerbomb header and i love it. it is loud but not unbearably loud and it gave me alot more on the low end. so really i can't complain one bit.

[ckasper18]

I did some tests on my dyno and i found unless your going to do some head work a head pipe does not do much over stock headpipe.Chris

[walt miller]

Originally posted by ckasper18
I did some tests on my dyno and i found unless your going to do some head work a head pipe does not do much over stock headpipe.Chris
was your test done on stock bore or over size, because i am working on a 416 with hotcam 2 and on air box lid

[ckasper18]

I tested a few different combos my daughters quad is a 416 with k n no lid not ported and stock carb with 155 main jet with stock headpipe and white bros r series it had 29 hp and with white bros head pipe and r series it had the same but the power curve was better at mid range with the stock headpipe and we rrace mx.The white bros head pipe had the same hp but came at the top end just a touch but no horsepower gain at all .I recomend not to waste your money on the head pipe unless you are going to port the head.Chris oh yea its also got a hrc cam

[walt miller]

thanks for the info. this is the boy's wheeler and i want it to run good. i have been trying to figure out the pipe. the stock head pipe welds have been ground and polished. my uncle, an old fat who build 40K to 80k race car motors, did the bore; cleaned the head and smoothed it out with the sand blaster said it would not get much better with porting. so that is going to be the port and polish

[cals400ex]

Originally posted by ckasper18
I tested a few different combos my daughters quad is a 416 with k n no lid not ported and stock carb with 155 main jet with stock headpipe and white bros r series it had 29 hp and with white bros head pipe and r series it had the same but the power curve was better at mid range with the stock headpipe and we rrace mx.The white bros head pipe had the same hp but came at the top end just a touch but no horsepower gain at all .I recomend not to waste your money on the head pipe unless you are going to port the head.Chris oh yea its also got a hrc cam


that has to be the worst dyno i have seen for a 416. not trying to be mean but that sounds low. we went from a stock header with a white brothers slip on to a full hmf system on our 10:1 406 with a stage 2 hotcam and the power difference was like adding the cam and piston all over again. it was a huge gain. by the way, the WB header that fits the WB slip on silencers is the s-bend, which is nothing special. the WB full system with the pro meg headers is a power producing system though.

[ckasper18]

We have a Eddy current Dyno best money can buy a full blown 440 only pushes 33 to 35 hp at the rear wheel at the crank its a different story you can add 7 to 8 hp to that .Have your quad run on a dyno stock 400ex has 25 at rear wheels at the crank 31.We invested 50,000.00 on the dyno and the room built to specs not to mention sent two of our mechanics to las vegas for 10 days to learn how to use this machine.This thing is spot on tested by Dynojet every dyno will read a horsepower or two different depending on air and moisture in the air.There is three with in a 60 mile radius and there all with in 1 horsepower difference....Chris

[cals400ex]

i am not saying the dyno is bad. most of the decently built 440's i have seen on a dyno put out 40+ on the dyno sheets depending on their modifications. your right, every dyno is different.