esr or prox 350 or 370 kit for atc250r

[96motorhead]

I've been looking at the esr and prox 350/370 cylinder kits.  What kit do you guys think is best for duning and hill shooting at glamis.  The other upgrades that I plan to go along with the bb cylinder would be a 39mm carb, paul turner high rev, K&N air filter and a +8 swing arm.  Also how reliable are these kits?  Do they overheat easily or have any problems?  Thanks for the help in advance, i'm new to the bb motor builds so i'm trying to learn as much as I can.  These upgrades are not set in stone either, it's just what i've compiled from research I've done so far.

[patman13mia]

I have an  esr350 engine builder kit i sent out to neil at c-leigh racing. Has all around porting and trx5 pipe w/ 38 as carb.. Its the fastest 250r bike I have ever rode but i now want a 370 or even bigger.. Only because my buddy has a banshee that still beats me in the straight aways.. If your not worried about being the fastest but still wanna haul ass... Id still go 370. But i think you need to do a lil more engine wise with the 370 like rod n stuff Am not to sure.. I have an oversized rad and also 110 fuel so im running as cool as possible.. Still runs hot to me but its a big bore.. Its producing alot more power than my stock cylinder so i would imagine thats expected.. Overall its a badass cylinder and tons of power everywhere!! The banshee doesn't wanna see me on the track thats for sure!! Hope that gives ya something to go off of

[havinnoj]

I haven't had any issues with BB Pro-X's up in the Oregon dunes but haven't ran one of the ESR cast cylinders before.  

ESR wants $1000-1100 for a 350-370 setup.  For a couple hundred more, you're into Sphynx territory - which is what I would consider if I was in your shoes.  Here is the link for the Dealer Price list for - CP Industries Sphynx, Puma, Saber Cylinders.

[patman13mia]

I only paid 650$ for my 350cc cylinder.. I think thats why you see soooo many esr kits cause they are the cheapest and theres tons of ppl that like them.. But i do always see that hardly anybody ever hates on their pro-x cylinders. From what i heard much more expensive but also better quality. I think if you go esr and send it somewhere else you get the better deal. Just me though. Other guys know much more and have rode both and can tell ya

[kb250r]

I would say lean more towards to 370 if you're going to hill shoot, and be somewhat competitive but imo the biggest thing is having the motor set up and ported by someone that is known for building the style motor for your application...and+ 6 on the swinger it would probably be a little more dune friendly.. jmo

[etccb]

 

ESR wants $1000-1100 for a 350-370 setup.  For a couple hundred more, you're into Sphynx territory -Here is the link for the Dealer Price list for - CP Industries Sphynx, Puma, Saber Cylinders.

But oj that price at around 1243.02 for a unported sphynx is to have a simular kit as a esr 330 @699 or 350 at 799, 799 and 899 with trx9 port. The 1000 to 1100 esr kits that you were thinking of are the complete 4 mil stroker 344 @ 899 + 100 for trx9 or 363 at I would assume based on number of kits would be + 100 at 999 and 1099. So a set up 350 non stroker sphynx would be around 1699 vs a trx9 set up non stroker esr 350 cyl kit at 899. That is the compare the best that I can estimate 1699ish vs 899.  
I think this is a better ballpark compare estimate but it could be off as well and I just put around 450 for port to sphynix to get the 1699ish and esr's trx9 at 100 to get the 899 so these numbers could change this up a little bit.
The prox is no better then the esr any more and 300ish more, that may be off... maybe its 200 more..
Also with esr you get your cases boared for free if you send in the bare set. That is another 90.00 to 100.00 added to the other options.

[havinnoj]

But oj that price at around 1243.02 for a unported sphynx is to have a simular kit as a esr 330 @699 or 350 at 799, 799 and 899 with trx9 port. The 1000 to 1100 esr kits that you were thinking of are the complete 4 mil stroker 344 @ 899 + 100 for trx9 or 363 at I would assume based on number of kits would be + 100 at 999 and 1099. So a set up 350 non stroker sphynx would be around 1699 vs a trx9 set up esr 350 cyl kit at 899. That is the compare the best that I can estimate 1699ish vs 899. The prox is no better then the esr any more and 300ish more, that may be off... maybe its 200 more..
I think this is a better ballpark compare estimate but it could be off as well and I just put around 450 for port to sphynix to get the 1699ish and esr's trx9 at 100 to get the 899 so these numbers could change this up a little bit.

Ah yes I see it now - seemed a bit more expensive than the last time I looked. Good to know it's still priced well.
$799 - 350 Cylinder Kit
$1049 - 370 Cylinder Kit
$1099 - 370 Engine Kit 1 - comes with stroker crank.

So like you say, a plated unported Sphynx is $400-$450 more than the unported ESR cylinder.  But we can't really compare a $450 port job to the $100 ESR TRX9 port job.  Either route, the ESR cylinder is cheaper.

[96motorhead]

What do I have to do to the bike if I install the 370 kit?  Will the stock trans hold up just fine?  Also If I got the esr I was gonna pay another company to port it not esr.  Has anybody had experience with the prox cylinders though?  Thanks for the help guys.

[etccb]

I like the 4 mil kit 344 base at 899 and they dont have it listed but based on 330 vs 350 kit being + 100 I would assume the 363 would be 999 base kit. That is a lot and smoking for 899 +100 trx9 and 999 + 100 trx9 imo. Now that the new 4mil hotrod crank has prooven itself I bet the 5 mil 370's will sell less then before with some choosing 363 350 4 mil now...
http://www.eddie-sanders-racing.com/product_p/330-76mm-stroker-kit-npv.htm

[96motorhead]

An esr or prox 370/363 is the same as a 350/344 but with a 4mil crank correct?  What is the power difference with the 330 76mm stroker and the 370?

[havinnoj]

What do I have to do to the bike if I install the 370 kit?  Will the stock trans hold up just fine?  Also If I got the esr I was gonna pay another company to port it not esr.  Has anybody had experience with the prox cylinders though?  Thanks for the help guys.

Bore cases, setup cylinder for the +4 or +5 crank, some will say a 1-1/8" exhaust stinger, clutch & trans in good shape.  I ran a 76mm x 76mm Pro-X 344 in the dunes for a few seasons with no issues.  I have also ran smaller bore Pro-X's on a few R's without issue.

An esr or prox 370/363 is the same as a 350/344 but with a 4mil crank correct?  What is the power difference with the 330 76mm stroker and the 370?

Yes - a 363/368 is a 78mm piston & 76/77mm crank.  But you can achieve 344cc with a 76mm piston & 76mm crank OR 78mmm piston & 72mm crank.  You can play around with our TRX250R.ORG Engine Displacement Calculator to bore & stroke displacement.

I've never tested differences between the two sizes so I can't comment there.

[etccb]

I just read this in that esr link that I put up above.
"ALL CYLINDER MACHINED HERE AT ESR ARE RENISHAW PROBE INSPECTED WE USE A MACRO PROGRAM TO MEASURE BORE FOR PISTON AND SLEEVE DIMENSIONS ALL AUTOMATED ON ARE CNC MACHINING CENTER OVER 900 THOUSAND INVESTED IN TOOLING FIXTURES AND MAKINO MACHINE "
I guess the probe etc must all be part of the new cnc mill upgrades and changes. When you talk about things being square and true nobody else has this tooling.

[96motorhead]

Alright I think I learned something new today.  Do the esr cylinders use re branded prox cylinders or what?  I'm hearing the esr cylinders are just prox cylinders, esr calls it their cylinder because they port it.  Is this correct?  Once again thanks for all the help.

[etccb]

Years ago they used prox but they have had thier own cyl for awile now. It is 100% thier own castings and has nothing to do with the prox. They are simular performance wise but the prox cost a lot more.
ESR has been making tweaks to perfect it and to give people what they want. With that probe setup, thier equipment, and what they are sending out there is no reason to look at let alone pay a dime more for or a new prox today imo. Enjoy the dealer direct type pricing vs the prox and spend that cash on something else for your R.

[havinnoj]

While they have some similarities, they are different cylinders like [MENTION=70]etccb[/MENTION] said.