250R Big bore kits
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Thread: 250R Big bore kits

  1. #1
    Junior Member Rick75's Avatar
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    250R Big bore kits

    Just picked up a nice 88 250R and found out it has a first gen CT pro x 310 kit on it originally bought for and 85 250R. Looking for input on these big bore kits now days and which ones are good and bad. I'm hearing ESR's quality has gone way down on their stuff. I've been out of the 250R market for 20yrs so lost track of everything.

  2. #2
    Senior Member atvguy's Avatar
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    Nice top end!
    id just keep what u got unless going 350/370
    RIDE WHATEVER IS NOT BROKEN!!

  3. #3
    Member The Norm's Avatar
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    ESR's quality has gone up. Eddie recently developed an entire new top end with a reverse flow coolant path. ESR produces a cylinder a working man can afford. Be sure to have a top notch engine builder do your port work. I personally use Pete at Hybrid Engineering. He is a no bs guy that will give you a reliable engine. ESR also does custom porting and Don't forget Arlen at LED. Good luck
    douglas and scrappy like this.
    I had a bdt engine once....It sucked!
    Current: Hybrid Engineering 391R
    Future: Some other awesome engine built by Hybrid Engineering!

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  5. #4
    Senior Member christph7's Avatar
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    ESR's quality is nothing to worry about. There may have been a few problems years ago with cooling, but I haven't read any complaints recently. Arlan at LED is now selling ESR cylinders and I doubt he would do that if he didn't have confidence in their quality.
    1982 ATC 250R
    1984 ATC 250R
    1986 ATC 250R
    1988 TRX 250R
    1989 TRX 250R

  6. #5
    Junior Member Rick75's Avatar
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    Thank you, I'm hearing the old pro x cylinders were pretty good

  7. #6
    Junior Member Rick75's Avatar
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    Thank you for the info

  8. #7
    Senior Member acecarlos's Avatar
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    Quote Originally Posted by Rick75 View Post
    Just picked up a nice 88 250R and found out it has a first gen CT pro x 310 kit on it originally bought for and 85 250R. Looking for input on these big bore kits now days and which ones are good and bad. I'm hearing ESR's quality has gone way down on their stuff. I've been out of the 250R market for 20yrs so lost track of everything.
    As long as you not just buying a finished cylinder kit to bolt on and go...No worries on QC, as long as your using a reputable builder to finish the cylinder work; boring, honing, porting, flow, ect...any of the aftermarket BB cylinders will be fine. Perform your due diligence, search on brands and builders...a ton on this forum alone.

    At the end of the day, it's all about matched combinations, setup and the engine work performed, and not about brands.

    Carlos

  9. #8
    Junior Member Rick75's Avatar
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    Big bore kits

    Quote Originally Posted by acecarlos View Post
    As long as you not just buying a finished cylinder kit to bolt on and go...No worries on QC, as long as your using a reputable builder to finish the cylinder work; boring, honing, porting, flow, ect...any of the aftermarket BB cylinders will be fine. Perform your due diligence, search on brands and builders...a ton on this forum alone.

    At the end of the day, it's all about matched combinations, setup and the engine work performed, and not about brands.

    Carlos

    Thanks for the info Carlos

  10. #9
    Senior Member acecarlos's Avatar
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    Quote Originally Posted by Rick75 View Post
    Thanks for the info Carlos
    Most welcome; best of luck.

    Carlos


 

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