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Diameter of FMF Powerbomb header?

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Anyone know what the inner or outer diameter of the 230F FMF Powerbomb header is? Got one you could measure? Just called FMF and they don't have those figures.

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Anyone know what the inner or outer diameter of the 230F FMF Powerbomb header is? Got one you could measure? Just called FMF and they don't have those figures.

You ever find out?

Anybody running this head pipe or exhaust with this head pipe?

Finding a stainless steel head pipe is getting more difficult these days.

FMF.

Arrow.

Any others?

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So, of all the SS headpipes made for our bikes, including the ones that come with a muffler, which ones mount the same as the OE headpipe and connect to the muffler in the same location and would/could/should be able to be used with the OE CRF230F muffler?

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XRsOnly has a SS header for the XR200 that will fit the 150/230 head but its end loacation will be off a bit.  Its outlet is 1 3/8" OD. I made adapters to connect to other mufflers.

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XRsOnly has a SS header for the XR200 that will fit the 150/230 head but its end loacation will be off a bit.  Its outlet is 1 3/8" OD. I made adapters to connect to other mufflers.

 

Chuck - Nice to hear from you.  I will take a lot of pictures and measurements when the pipe arrives Monday.  I assume the XRs Only head pipe is a stepped design?  If so how did that compare to Powroll's non-stepped design?

 

If you already answered these questions in here let me know and I will dig for the answers myself.

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So, of all the SS headpipes made for our bikes, including the ones that come with a muffler, which ones mount the same as the OE headpipe and connect to the muffler in the same location and would/could/should be able to be used with the OE CRF230F muffler?

 

If Chuck and I give you some dimensions can you model the various pipes in your exhaust application?  I am just curious to see what it might tells us given the varying designs we have at hand.

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If Chuck and I give you some dimensions can you model the various pipes in your exhaust application?  I am just curious to see what it might tells us given the varying designs we have at hand.

 

The program, PipeMax, doesn't really work like that.  You fill in all the data boxes and then it will calculate exhaust diameter, length, collector etc.  It will also calculate intake diameter and length, horsepower, minimum sizes for cam lift, choke points etc.

 

I could adjust displacement, compression and some other input data to see what combo would calculate a given size exhaust system. 

 

Unless someone is gonna make their own exhaust system to the calculated spec, we are limited to what the aftermarket offers.  I don't think the 1.25" OD headpipes are too overly large so as to kill the bottom end even though PipeMax suggests they may. 

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The program, PipeMax, doesn't really work like that.  You fill in all the data boxes and then it will calculate exhaust diameter, length, collector etc.  It will also calculate intake diameter and length, horsepower, minimum sizes for cam lift, choke points etc.

 

I could adjust displacement, compression and some other input data to see what combo would calculate a given size exhaust system. 

 

Unless someone is gonna make their own exhaust system to the calculated spec, we are limited to what the aftermarket offers.  I don't think the 1.25" OD headpipes are too overly large so as to kill the bottom end even though PipeMax suggests they may. 

 

 I suspected that may be the case.  Thank you for clarifying it for us.

 

My new FMF head pipe will be here Monday so we will see what we actually have at that time.  I am interested in getting some dimensions so we can compare it with the Powroll head pipe and XRs Only head pipe.

 

Based upon feedback from Chuck I'm looking forward to some testing of my own.  I wasn't able to get on for my buddy's CRF230 so we'll be able to do some back-to-back tests.  His bike is identical to mine in every respect except for gearing.  He's still using 12-52 and I'm now using 13-50 instead of 12-50.  I switched due to the extra grunt from the PoweRing and he said he will also be going from 12-52 to 13-52 for the same reason.

 

This is one thing we didn't really touch on much.  Besides the dyno results (both butt and real) I was able to go up one tooth on the counter sprocket with the PoweRing.  I forgot about this as it has been quite some time since I did it.  I am pulling the top of the same gears with the PoweRing and 13-tooth as I did with the stock exhaust and 12-tooth.  This was quite a surprise to me as going from a 12-tooth to a 13-tooth is an increase of 8.3% in overall drive ratio, which is fairly significant.

 

The reason for the change was because I was using up gears before the end of fast sections but could not upshift.  With the 12-tooth and stock system, for example, I could hit the top of fourth at the very end of the fast straight.  After the PoweRing I was at the top of fourth before the end of the same fast straight.  After the 13-tooth I was back to the top of fourth at the very end of the fast straight.  In other words just under 50 MPH with the stock system and just over 50 MPH with the PoweRing.

 

I know, I know...  It's just one or two or three MPH...

 

I forgot about that little tidbit...

Edited by VortecCPI

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Some data so far:

  • Head Pipe OD:  29.0 mm (1.14 in)
  • Muffler Pipe OD:  32.5 mm (1.28 in)

The muffler pipe has approximately 26% more area than the stock head pipe.  The gasket at the rear end of the stock head pipe is very thick so we should be able to gain OD at this junction.  It will be interesting to see the dimensions of the FMF pipe and if they change the diameter along the way.

 

According to Terry Miller the exhaust side of the CRF230 head is very good and he recommends leaving it alone.  That being the case perhaps we can expect some substantial gains with a new larger head pipe.

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The FMF PowerBomb head pipe is scheduled for delivery today.  Unfortunately it has been raining so a test is out of the question.  In the mean time I will make a lot of measurements and take a lot of pictures.  I am curious to see if I have a huge weld bead at the muffler pipe entrance.  If so that will be ground out while I'm in there.

 

I have my doubts about proper fitup.  So much I have decided not to disassemble the stock system until the pipe arrives.

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Our butt dynos are notoriously inaccurate but side by side comparisons can highlight differences below 5%, with a well planned and executed test procedure you can measure done to maybe 2%.

 

I've done side by side comparisons between bikes and the challenge is removing as many variables as possible between the bikes and the test enviroment.  Seems daunting but a thoroughly planned test will yield usable results.

We used a section of paved road to eliminate wheel slip as a variable. Also the road section had a steep up grade which slowed acceleration to exaggerate differences between the bikes.

Weight differences, in my tests one rider wore a back pack with weights to equalize total bike weights within 5 lbs.

Same rear tires and pressure.

Same gearing.

Establish test criteria. We recorded difference in relative bike positions as fractions of bike lengths; just after the start, just before and just after each gear shift, at top end, and top end rpm. 
Establish test procedures.  We used rolling 2nd gear starts, one rider paced the bikes using a tachometer (I think 2500rpm), the other rider did count down to start. 

All mods were pre planned for quick changes to reduce the time between runs. Practice with the two bikes to refine the test procedures, and record differences in performance between the bikes.

Designate one as the baseline bike and do mods to the other, do at least two runs with each mod and record the differences for each run. 

Do next mod and repeat test. 

 

Some exhaust and header data:

 

Most MC exhaust use 18 gauge (0.050") wall tubing (car exhaust is 16 gauge (0.065")

 

XR200 exhaust port ID: 30mm

 

Stock XR200 header: 1.13" OD (28mm ), (1.28" OD muffler flange)

 

Powroll XR200 header ( I think the Powroll CRF230F header is the same OD): 1 1/2" OD

 

XRsOnly: 1.23" OD & 1.375" OD [ 2"  from valve to header, 10"  to step, then 12" to end)

I built a stepped system using a XRsOnly header, added 2" to the header for a total length of 36" from the valve, then 8" of 1 3/4" mid pip to a 1 3/4" muffler inlet (a Supertrap IDS2 muffler from a XR400 w 12 discs).

I now have a XR250X muffler (1 1/2" mid pipe) connected directly to the XRsOnly header and like its performance (and quietness) better the the ISD2. 

 

XR250R header OD and mid pipe ID: 1 1/2"

 

XR400R header OD and mid pipe ID: 1 3/4"

 

XR250R header OD and mid pipe ID: 1 1/2"

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