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I degreed yfm250 clone, xt225 and tw125 cams. let's combine our numbers to form bigger database?
here's the file - on microsoft office online. Does this link work?

I am not entirely sure I understand what you're doing, are you talking about rocker arm ratio?
Yes, rocker arm ratios affect the measurements.

The link does'nt work. Can you convert it to a pdf and post it? Or take a photo and post a jpeg ?
 

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Discussion Starter · #62 ·
Yes, rocker arm ratios affect the measurements.

The link does'nt work. Can you convert it to a pdf and post it? Or take a photo and post a jpeg ?
if you're measuring direct at the cam then yes. I think and hope so there aren't different rockers - think that would require different point of pivot of rocker in the head, thus slightly different head - I doubt that.
I checked and XT225/TTR225/YFM250 (years 1999-2007) all have the same # - 29U-12151-00-00 - and price for rockers. TW200 and 125 ( checked years 1999 and 2008) have this # - 36X-12151-00-00 and different price than the 29U ones.

This is how I measured it all.
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I exported it to PDFs, now it should work.

we can calculate rocker ratio from this, though I currently have only one cam, so no averaging possible right now and only caliper measurements.
Max IN valve lift: 8,13mm; max EX valve lift: 8,21mm
both IN and EX lobes measure 36,7mm at max and base cam circle is 30,25. this means lift at cam is 6,45mm
8,21/6,45=1,273
1,273mm of movement at valve for every one mm of cam lift. is that right?

now I realized I could borrow genuine tw125 head and compare it to my clone yfm head.
 

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I've only measured the Niche YFM250 head with their parts. I am using a degree wheel on the stator pulsor and set the gauge on the valve spring caps. My measurements show the rocker ratio being 1.25 with a true valve lift of 8.0 mm.
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hmmm...
I have a TTR225 head with a YFM250 cam. I imagine the rockers are stock TTR style, so everything is "factory" spec for a YFM250 head set-up.
I am interested in the difference with the TW rockers compared to the TTR/XT/YFM version and how that works with a YFM cam compared to the other cams. Graphs of the chart info would aide in comparing I would think.
 

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Discussion Starter · #65 ·
I've only measured the Niche YFM250 head with their parts. I am using a degree wheel on the stator pulsor and set the gauge on the valve spring caps. My measurements show the rocker ratio being 1.25 with a true valve lift of 8.0 mm. View attachment 233482 View attachment 233483
Your setup looks definitely more accurate. Just a confirmation, did you set the lash to 0.0?
I'd say 1.25 and 1.273 is pretty darn close and call it the same.
Afterall, do we need rocker ratio, if we measure lift direct ac valve?

What is your Niche yfm250 head? Becasue it looks the same as mine head, which I call clone - same cast markings and fins design. Do you have both sides of cam on ball bearings?

SkiPro, I really doubt tw rocker would be different geometry than the others. We'll see sometime when I get to it
 

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Discussion Starter · #66 ·
I am considering This clone cam, since the original one is in need of repairing bearing surfaces and has slight pitting on one lobe. I think this may be cheaper than getting the original one repaired. I asked the seller if he has specs of this cam, but I doubt it.
Also I didn't know tw225 has supposedly the same cam as xt225.
 
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