is porting a YZ250 worth it?

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#1
I have a 02 Yz250 with a stock engine save the V-force reeds. I love the power delivery (I sang in the 4stroke choir until this bike converted me) but I would like more accross the board. I am not looking to shift the power lower, nor higher just more of what it has already. The Eric Gorr Mo' Better sounds like just the thing. But I have spent a little time with search button and read several times where the opinion for this bike was "If you want the power delivery moved lower, get the low-mid port job, otherwise it is hard to improve on the stock porting." Is this the general opinion?
I am at the very least going to send him the head for the high altitude mod (4500ft) Is it worth it to send the cylinder as well?
Yes, my jetting is dialed in.
Cy
 

Lorin

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#2
I had the mo better porting done on my 98 yz and it did help across the board. It actually did give me more bottom, which made for a smoother transition on my 98. It helped enough that I chose to stay with the stock pipe.
 

Studboy

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#3
I've also wondered the same thing. I too like the stock power curve. The bike is very powerful in stock form overall. I'll bet that the gains would maybe be in the port matching because by looking at my piston crown, the right side ports are flowing more than the left.
 

bclapham

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#4
i remember a thread saying that the newer yz250s are pretty close on porting and i think you will only really move power a bit. if you want more accross the board, you should maybe consider an ooxygenated race gas such as VP ultimate 2 or MR2- at that point, you can do the leg work and tighten up the head clearance and jetting etc. i remember a couple old threads and a few guys seemed to like th SST and fatty pipes on these bikes- mine came with an SST so i have nothing to compare against
 

hoosierf

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#5
My recollection is that Eric will bump up the compression on higher altitude applications, but generally does not mess with the 2002.
 

slideways11

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#6
If you want an across the board gain go with the 265 kit.
 

EricGorr

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#7
The YZ250 has some excessive squish clearance, you can try just a thinner Cometic base gasket, like the kind they sell in their High Compression Gasket kit.
 
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#8
I like the idea of a thinner base gasket, something I can undo when I want to sell the bike. Do you sell these gaskets Eric? This will probably require a higher octane fuel, yes-no?
Thanks,
Cyrus
 

bclapham

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#9
you can get the thinner gasket from cometic-they sell a high comp gasket kit, i just buy the thinner ones individually- the stock gasket is 0.5mm and the thinner one is 0.3mm so i expect it will bump the compression a little, but not that much you will need to run race gas. it will also give a bit more bottom end punch
 
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#10
On the Cometic website catalog they list a high comp kit, but not individualy. I assume that if I use the both the HC base and head gasket it will up the comp more than just the base gasket. Any body know where to pick up this kit? The place I usually buy from (rockymountianmc.com) only lists the standard gasket kit.
Thanks,
Cy
 

bclapham

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#11
you have to call them, most places will order the kit for you. cometic makes gaskets from 0.3 to 2.0mm- the head uses an O-ring seal so you cant change anything there.

try the high comp base gasket, it will me a nice pep me up for the bike
 
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#12
Duh, o-ring head, I knew that. I lived in Blackburn, UK for several years 2 different times (actually i moved there from San Diego, in a round about way) Some of my siblings still live up near SDSU. Next time I visit, I'll make you tell me where all the good tracks are. Thanks for your help.
Cy