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170 or 175, that is the question

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In looking at the various big bore kits, I noticed that there are 170 and 175 kits available. Does anyone have any experience with either of these kits and or is it worth spending the extra $$ (for a new cylinder sleeve) for the 175 kit?

Jeff

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I dpnt have expiriance with either one but get the 170. The 175 is to big of a bore for the bike. You will be putting a new sleeve in every so often. So go with the 170.

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I disagree. I have a kit that will make your 150 into 187.7cc. The sleeve is of higher quality than stock and will wear longer. $400.00 for kit and labor. For a few bucks more you can turn it into a 250CC rocket!!

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I will have dyno results in a short while. We are using a 150 for a number of buildups starting from stock thru 251cc.

If your 186 makes 25HP I would be VERY surprised.

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Hmm, do you have a website? I'm looking to do this early this winter (November or December for Ohio).

Just curious, what does this do to the cooling of the bike? Will it require an oil cooler after the big bore?

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I disagree. I have a kit that will make your 150 into 187.7cc. The sleeve is of higher quality than stock and will wear longer. $400.00 for kit and labor. For a few bucks more you can turn it into a 250CC rocket!!

Oh yeah! So tell us more about this 250cc upgrade. Sounds like it requires a stroker crank... or maybe a 230 crank? At 250cc what are the power characteristics and rpm ceiling?

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The cooling will be fine. If you wish to add an oil cooler, that is up to you. If you plan to race the bike, with or with out the big bore, a small oil cooler would be a good idea.if you plan to just play ride, should be fine without. Will have a web site in the near future. Thanks

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It will be as you stated, a 230 crank and a 69.5mm forged piston of my design. 9.5:1 compression, no weight adding "pop-up's". I do not recommend replacing the ignition box with an aftermarket "hi-rev" box. Of course people can do whatever they choose. Already have piston installed in my 230,excellent increase,I'm guessing at least 25% gain, but have not dyno'd yet.(too much of a hurry to ride it) I am currently in the process of doing the 150 build up step by step. We are going to start with the big bore first, and then add the crank and some cams and exhaust and carb and document all of the changes and performance improvements with each modification on a dyno-jet dyno, starting this Saturday. Stay tuned !! Thanks for your inquiry !

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A 186cc 26hp CRF150 motor????? A stock 250f has something like 28 - 30hp or so. You'd be lucky to have more than 15hp. (on a good day)

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Cool, I'll be sure to be on the look out for your updates and link to your webpage. Probably a good idea that you're using a 9.5 piston. I've got a BBR 170 kit, cam, and a new ported head with a 3 angle valve job to install when I have some time. I'm also using a 26mm carb and lightened flywheel. I'll have a stock head and cylinder to fool around with later. Thanks for the info.

It will be as you stated, a 230 crank and a 69.5mm forged piston of my design. 9.5:1 compression, no weight adding "pop-up's". I do not recommend replacing the ignition box with an aftermarket "hi-rev" box. Of course people can do whatever they choose. Already have piston installed in my 230,excellent increase,I'm guessing at least 25% gain, but have not dyno'd yet.(too much of a hurry to ride it) I am currently in the process of doing the 150 build up step by step. We are going to start with the big bore first, and then add the crank and some cams and exhaust and carb and document all of the changes and performance improvements with each modification on a dyno-jet dyno, starting this Saturday. Stay tuned !! Thanks for your inquiry !

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A 186cc 26hp CRF150 motor????? A stock 250f has something like 28 - 30hp or so. You'd be lucky to have more than 15hp. (on a good day)

Remember that it does have a stroker.... :cry:

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You belive what you want but i am 100% positive that it has about 21HP. The people at powroll have the same setup but with the 4mm stroker and it put ot 20 so im somewhere about 23HP. Im looking for a 28MM carb so it should boot it up to 25-26HP. I rode it today and this bike rips. I cant say enough. :cry: :cry:

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I agree with you !! I'm not sure you responded to the right post...... Check mine

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Hello all I was wondering who sells the CRF 150 190cc big bore kit for the cheapest and also wut the gains r???

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