CR125 Mod or CR139? 2007

JohnCharlesC
Edited Date/Time 11/23/2018 6:36pm
Been thinking about freshening up the 125. I'm planning to have full engine rebuild done but contemplating if I should keep it as a 125 or bore it out? Im thinking 139. Anyone have any experience with the big bores?

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crc245
Profile picture for user crc245
Posts
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Joined
10/29/2007
Location
Yorba Linda, CA US
crc245 11/22/2018 10:29pm
11/22/2018 10:29pm
Had HP go 144 on my 07', and I'm on the fence about it: Solid gains once the jetting and gearing was sorted, but was less than impressed with the communication and turnaround (to put it nicely). 58mm pistons (and 57mm in the case of wanting to go 139) and rings cost a bit more with specific gasket kits required every touch up.

I'll send one to Varner and keep it at 125cc on my second 05-07' project, for a true back to back comparison. Being SoCal local, you're more than welcome to spin a few laps on mine before you make a decision if it isn't time sensitive. Likely at Cahuilla and then Pala this weekend, but up for basically any local track any given weekend...

2
toold&slow 11/23/2018 3:03am
11/23/2018 3:03am
I have an 2007 with a Eric Gorr 144 ported for top end, Head squish and dome corrected by Two stroke performance in Australia. It also has Vforce reeds and 38mm Air striker. Great top end and easy to keep on the pipe. Love the motor. Hope this helps
JohnCharlesC 11/23/2018 6:20pm
11/23/2018 6:20pm
crc245 wrote:
Had HP go 144 on my 07', and I'm on the fence about it: Solid gains once the jetting and gearing was sorted, but was less...
Had HP go 144 on my 07', and I'm on the fence about it: Solid gains once the jetting and gearing was sorted, but was less than impressed with the communication and turnaround (to put it nicely). 58mm pistons (and 57mm in the case of wanting to go 139) and rings cost a bit more with specific gasket kits required every touch up.

I'll send one to Varner and keep it at 125cc on my second 05-07' project, for a true back to back comparison. Being SoCal local, you're more than welcome to spin a few laps on mine before you make a decision if it isn't time sensitive. Likely at Cahuilla and then Pala this weekend, but up for basically any local track any given weekend...

Ahh I see, when you say you're "on the fence about it" you mean the actual motor and how it feels/rides or just the process that got you there? I have read some other reviews and it seems like, often times, people have to send the motor back for minor touch ups (Definitely don't want to do that!). My main objective is to be able to get more "punch" while still being able to maintain the over revs. I'm not trying to build a 250f beater, just a bike where it is fun to ride yet powerful enough to be competitive.

And yes, seems like we are not that far from each other, I would love to take you up on your ride offer! I actually just came back from Milestone today, shucks should have checked the forum before going out this morning..

Won't be able to go this weekend but maybe the next?? I'll send you a PM.

Thanks!

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JohnCharlesC 11/23/2018 6:23pm
11/23/2018 6:23pm
toold&slow wrote:
I have an 2007 with a Eric Gorr 144 ported for top end, Head squish and dome corrected by Two stroke performance in Australia. It also...
I have an 2007 with a Eric Gorr 144 ported for top end, Head squish and dome corrected by Two stroke performance in Australia. It also has Vforce reeds and 38mm Air striker. Great top end and easy to keep on the pipe. Love the motor. Hope this helps
Eric Gorr was one of the options I was looking into but I am on the fence as I have great local tuners in my area (SoCal). When you say "head squish and dome corrected by..." do you mean you got the motor back and had to have another tuner fix and/or clean up the motor work? I thought you would be able to "plug and play" after getting your motor back..
toold&slow 11/23/2018 6:36pm
11/23/2018 6:36pm
toold&slow wrote:
I have an 2007 with a Eric Gorr 144 ported for top end, Head squish and dome corrected by Two stroke performance in Australia. It also...
I have an 2007 with a Eric Gorr 144 ported for top end, Head squish and dome corrected by Two stroke performance in Australia. It also has Vforce reeds and 38mm Air striker. Great top end and easy to keep on the pipe. Love the motor. Hope this helps
JohnCharlesC wrote:
Eric Gorr was one of the options I was looking into but I am on the fence as I have great local tuners in my area...
Eric Gorr was one of the options I was looking into but I am on the fence as I have great local tuners in my area (SoCal). When you say "head squish and dome corrected by..." do you mean you got the motor back and had to have another tuner fix and/or clean up the motor work? I thought you would be able to "plug and play" after getting your motor back..
I’m in Australia with different fuel to what you have and what the head was set up for. Mine had detonation and jetting issues. I would personally check the squish on any motor build before you ride it.
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