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Eric Gorr, RB Designs Engine Work

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I'm looking to have some work done on my 02 cr250. I mainly ride woods, with some occasional mx days.

I was originally just planning on having the base lowered 0.030" and squish corrected. Now I am considering the Mo Betta porting. Does the Mo Betta porting include base milling and squish?

Which would you all recommend? I'm having a hard time deciding what I want to do.

I was also looking at having RB Designs do the head mod.

What would I expect in terms of performance just having the head mod done by rb designs?

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I'm looking to have some work done on my 02 cr250. I mainly ride woods, with some occasional mx days.

I was originally just planning on having the base lowered 0.030" and squish corrected. Now I am considering the Mo Betta porting. Does the Mo Betta porting include base milling and squish?

Which would you all recommend? I'm having a hard time deciding what I want to do.

I was also looking at having RB Designs do the head mod.

What would I expect in terms of performance just having the head mod done by rb designs?

 

Call EG and ask him if he lowers the cylinder with the Mo Betta porting.  I have the Mo Betta porting on my 94 cr125 and I like it a lot.  Obviously there is going to be a major difference in what the porting will feel like comparing a 125 with a 250 but I think it is a good idea since what he does is just smooth out the power delivery.  on my 125, it has a very smooth power delivery which starts really low in the rev range.  He says right on his web site that it is a good port job for intermediate MX riders.  I have been looking for an 02-03 CR250 for my son and if I end up getting one, I will eventually have EG do his Mo betta port on it since the 02-03 is supposed to have a smooth power delivery from the factory, so I wouldn't expect it to have the lazy low end and monster mid range that my 06 had. 

Edited by frdbtr

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RB's machine shop work is very high quality and very precise. RB will machine your cylinder and perform head mods for your specified fuel type. However, RB will not perform any porting, and will only work on stock OEM parts.

Terry Varner also provides a porting and machine shop service, and is known to lower the cylinder as part of his porting work.

In the non-lowering camp is Pro Circuit and PR2. You might be able to make a special arrangement with PR2 for your specific needs, but PC only offers a single porting spec to the general public and is not flexible regarding customized work.

Eric has some of the most reasonable prices available.

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So just having the base lowered and the squish corrected, what will I notice in terms of performance over stock?

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So just having the base lowered and the squish corrected, what will I notice in terms of performance over stock?

 

On my 06 it made a ton of difference but from what I have read the 05-07 250's had a much different power delivery stock than an 02-03.  I think you would notice a big difference if you lowered the cylinder but it might not be the difference you want since it may add a ton of low end torque at the expense of top end.  IMO, if I were in your same situation (with an 02-03 cr250), I would call someone who knows what they are doing and tell them what you want the motor to do for you and then get their advice on what porting you would be happiest with. APBT gave you several options to call and get advice from.

Edited by frdbtr

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I just had my 07 cylinder replated by Millennium Technologies.I talked to them about cylinder mods,and it was suggested that head work could accomplish my goals.I told them(him whom ever it was)that I raced hare scrambles and would like to have it not rattle on pump gas.

 

He said hare scrambles on pump gas no problem.I've had 2 practice rides on it and I like the results.Most of the mid-range hit has been moved to low rpms and the top end still pulls strong.Also  90% of the rattle is gone. I like the fact that a stock head will restore the engine to OEM specs.

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I just had my 07 cylinder replated by Millennium Technologies.I talked to them about cylinder mods,and it was suggested that head work could accomplish my goals.I told them(him whom ever it was)that I raced hare scrambles and would like to have it not rattle on pump gas.

He said hare scrambles on pump gas no problem.I've had 2 practice rides on it and I like the results.Most of the mid-range hit has been moved to low rpms and the top end still pulls strong.Also 90% of the rattle is gone. I like the fact that a stock head will restore the engine to OEM specs.

Thanks for the info!

So now I am trying to decide on the following options:

1-RB Designs Head Mod ($92)

2-RB Designs Head Mod w/ 05+ base gasket (~$100)

3-Eric Gorr base milling and head mod ($100)

4-Eric Gorr Mo Betta porting with cylinder and head mod ($225)

Does anyone have recommendations for hare scramble, woods, occasional mx use?

I just want a good solid power and that works well in the conditions above. I just don't know what I will feel in terms of performance for each mod. I'd like to go the most affordable route of the above mentioned. I want to ship my head and possibly cylinder by Friday.

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Well, I just have to say, I have been really happy with the work EG has done on my bikes.  He has worked on all 3 of my modern 2 strokes and all of them absolutely rip.  My 144 with the Mo Betta porting has a really wide, usable power delivery so I would imagine that your 250 will also have that kind of a power delivery.  There isn't much comparison with a 125 and a 250 but I do trust his work. 

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