Duncan CT or ESR?

[Fox250R]

Sent you a PM with my number, send me a text when you get a chance.

Hey bro I sent you a text a few nights ago

Maybe you sent me the wrong number?

[arlaunch]

There are 2 PC 2000's on ebay right now. Both used and both around 1100 bucks.

http://www.ebay.com/itm/Honda-TRX-AT...BWylev&vxp=mtr

http://www.ebay.com/itm/Honda-TRX-25...1WylvM&vxp=mtr

You guys are awesome being able to ride these things with that much power.

My 250 has too much power for me.

I will always be a fan of the professionally ported OEM cylinder with the OEM cylinder head combustion chamber shape being set just right.

Quicker rev's, better over rev, room for the head stay and steering stabilizer blah blah blah.

Looking forward to hearing what your decision is and how long of a swing arm you are going to put on the Fox.

[Fox250R]

There are 2 PC 2000's on ebay right now. Both used and both around 1100 bucks.

http://www.ebay.com/itm/Honda-TRX-AT...BWylev&vxp=mtr

http://www.ebay.com/itm/Honda-TRX-25...1WylvM&vxp=mtr

You guys are awesome being able to ride these things with that much power.

My 250 has too much power for me.

I will always be a fan of the professionally ported OEM cylinder with the OEM cylinder head combustion chamber shape being set just right.

Quicker rev's, better over rev, room for the head stay and steering stabilizer blah blah blah.

Looking forward to hearing what your decision is and how long of a swing arm you are going to put on the Fox.

I've been watching those for for weeks now. Just not sure about going the used route!

[BOB MARLIN]

I love my big bore, BUT- There is a few drawbacks. Fitment issues and running to dam hot are the big ones. I have to run a spark plug that looks like it belongs in a lawn mower because a regular one doesn't fit between the head and the frame. And I have to run oversize rads to keep it as cool as possible (220 deg.). And because the cylinder is so tall the rads hit my exhaust. And to check my coolant level I have to remove the right shroud.
Don't get me wrong, this thing make awesome power, and I love it. I think its worth the hassle, but if I were to do it again I would do a properly ported stock cylinder. I've seen dyno results from one of the guys that knows how to port 250r's and it's pretty darn impressive.

[The_Steve_Man]

I can tell you that I am extremely happy with my stock cylinder with a +4 crank. Bubba Ramsey did the work on mine and runs fantastic. Whatever you get, you need pipe, carb, reeds to work together to get the best performance.

[Outlaw #24]

It might be that your pipe is to small at exit. I have a big bore 72mm in Skeletor and It doesn't seem to have problem. Also Higher octane gas burns more completely and cooler (110). Have you tried a cooler Plug? I have cylinders if you want to change already ported and some with no port work. BTW the carb on my big bore is a 38 Mikuni milled to 42. What Steve said, everything has to work together.

[BOB MARLIN]

It might be that your pipe is to small at exit. I have a big bore 72mm in Skeletor and It doesn't seem to have problem. Also Higher octane gas burns more completely and cooler (110). Have you tried a cooler Plug? I have cylinders if you want to change already ported and some with no port work. BTW the carb on my big bore is a 38 Mikuni milled to 42. What Steve said, everything has to work together.

I assume this was a response to my post ?.
Anyhow, Yes I agree with everything you said, My FMF Fatty isn't helping the situation any. I want to try an ESR pipe. I've been told they run well with big bores, but my rads already hit my skinny fmf pipe and the ESR is a lot fatter on top than the fmf. I going to try going to 100 octane next season, but here in so cal. all our gas sucks-bad. Race gas can be a to get ahold of at times here. Having a digital temp gage is very useful. I can tell what changes did what. So far running strait distilled water with no antifreeze made a bigger difference than the oversize rads.

[The_Steve_Man]

The FMF pipe is a terrible pipe on anything but a stock or mildly ported cylinder. The neck that comes out of the exhaust flange is small and chokes it down. Great for all bottom end but nothing else. The stinger on a big bore is 1 1/4" . An ESR will be way better. I had to make a spacer to move the bottom of the radiator forward to clear my pipe. Waterless coolant also works to keep Temps down.

[RIDE-RED 250r]

Hmm... I'm running an ESR 78mm big bore on a std short rod crank (so no cylinder spacer is needed) with ESR's pipe. I have no clearance issues.

Are you guys running stroker cranks or long rods with spacers??

[barnett468]

Did some more research on this. The 305cc and 340cc motors are around $1800 and cases need machining. How much will that cost just for the case mod? Now the 265cc and 275cc are like what $100 less but no machining is required. I'm leaning towards the 275cc tbh.. Just not sure for $1800 how much faster will a 275cc be compared to my current motor? Need to think about this more I guess lol

So ya, the 340 PV was the same one I was looking at? Can you still ride trails and stuff? I'll be doing both dunes and trials. How's the power feel? I don't need anything crazy. I was looking at the 310 at first but it's the same price as the 340! Did you have to machine your case?

If you like to cruise when you are on the trails or they are fairly tight trails where you aren't going more than maybe 30 mph, you do NOT want a heavily ported 250 cylinder because you will absolutely hate life . If your cylinder is stock but you have a pipe and are fairly happy with it the way it is on the trails, then just some minor porting and possibly increasing the compression and some Boysen Pro Reeds is all I would do.

If your compression is around 160 or less, you can gain a little power everywhere by increasing it a little, but you definitely need premium gas . If you happen to run ethanol in it, you can increase the compression even more but you won't be ale to go back to regular gas.

The bigger the bore the more power you will have at a lower rpm, and a big bore that is NOT heavily ported will do fine on both slow trail and the dunes.

If you plan to keep the bike, and have the money and want a big increase in power without it all being above 5000 rpm, get a big bore kit.

I think they now have bigger rads for the ATC250R which will help with the cooling.

Also, running around 70% water with 30% antifreeze and 1/4 bottle of water wetter and a higher pressure rad cap will help it run cooler.

You also need to play with the ignition timing a little to see where it runs the best and the coolest so the temp gauge that Bob Marlin mentioned is a very good thing to have.

It is VERY easy to "over port" a cylinder and end up with something you are not happy with, so it is always safer to be a bit conservative at first unless you know that you want screamin power at 10,000 rpm . You can always port it more later if you want, and I have found that it is far more difficult to "unport" them.
.

[The_Steve_Man]

Arlen (LED) has a dyno sheet on his website of an ESR 310 with a +4 crank with around 60 hp and nice flat torque curve. I would at least go talk to him since he is so close. A lot of the quad use him and very happy. He has been building motors for a long time.