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CRF250 desplacement mods> CBR300?

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hi everybody,seen the new CBR300 out made me think to look into it ,and yes apparently they did not change the piston but stroked it.(to be confirmed with Honda but i guess so!) changed the displacement and went up to 286cc. meaning with a few mods we could possibly beef up the CRF250 to 286cc ,since the bikes share lots of parts.so changing the crankshaft and connection rod +ECU could work .. +? , hopefully cylinder height is the same and the problem could be the crankcase where to fit the slightly bigger crankshaft!
this is very interesting ,I went to the honda dealer/thailand, but sadly comunication was poor ,should go back (i am far away now)

and look at their parts manuals personally check what are the actual differences between the CRF250 n CRB300 (286cc).
but hey ,can order original parts if is possible!Did anyone maybe look into it,had success with it or suggestions?

cheers

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You can do 305cc for a lot cheaper

not here in thailand where all kits are import and extra taxed+shipping costs.. +this way i am considerating ,you would buy original honda parts! 

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I would be more in to buying the whole motor and use the 250 as a back up or a project 350L

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maybe try to answer on the topic? only reply if u have some real experience with displacement,AND technical skills. no time wasters.appreciated. thnx

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Well with my 383 stoker ( Chevy 350) the block was blueprinted, with these motors I'm guessing the inside has a little more room be it casted or machined plus I different counter weight plus it could have bigger bearings there could be a lot of machining for it to work, not to mention thinning out the case to make room for bigger rotating parts and cracking the case. No one really knows right now. I'm just going to buy the motor and save my self the headache, cuz my fun time is worth $200 an hour. You would be better off talking to someone that races cbr250's

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maybe try to answer on the topic? only reply if u have some real experience with displacement,AND technical skills. no time wasters.appreciated. thnx

Do you honestly believe anyone has experience doing that here?

So far we can only give advice about big bores.

One guy looked into stroking his 250 but then realised it may not have been straight forward as he originally thought due to unusually different part numbers. It can be done but your stepping into unchartered territory.

By all means go for it if you are adventurous enough to go it on your own, may as well report back to us what is required.

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I have both parts manuals its not only crank and balancer shaft but different bearings and etc i think even the casings are different numbers i looked at a while ago good luck and hope it works for you

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I have both parts manuals its not only crank and balancer shaft but different bearings and etc i think even the casings are different numbers i looked at a while ago good luck and hope it works for you

yes the problem could be the case as my op say.other parts could  prob be found&replaced ...thnx

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I would be more in to buying the whole motor and use the 250 as a back up or a project 350L

HONDA here says you cant buy a complete engine, for whatever reason!

maybe try to answer on the topic? only reply if u have some real experience with displacement,AND technical skills. no time wasters.appreciated. thnx

Hahahaha, ur kidding me! Sounds like a Brit!

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Just my two cents, but it seems like a lot of work/trouble for 36 more cc. You might get the same "feel" of increased power with a full exhaust, fuel programmer, and different gearing. I have a 305cc BB kit in mine, and don't get me wrong, it's great, but if you are craving more HP, you may as well look into a different bike between 350 and 450cc.

Edited by JohnnyUtah787
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HONDA here says you cant buy a complete engine, for whatever reason!

I bet it's because of the serial numbers on the motor they need to match up to the bike

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And if that's the case I'll take a pic of a vin number or something. I'm going to call my dealership about it. Thanks for the heads up on it

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There going to get back with me around 4:00 today. A guy at work said you can order motors, at least for Harley's anyways I don't see why not for any other bike?

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There going to get back with me around 4:00 today. A guy at work said you can order motors, at least for Harley's anyways I don't see why not for any other bike?

 

I sell Ford parts and I have to register engines I sell on Fords website for warranty and who knows what other reasons ... I guess I have never really thought much about it. 

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I sell Ford parts and I have to register engines I sell on Fords website for warranty and who knows what other reasons ... I guess I have never really thought much about it.

yeah, well the dealership has to get back with me on the motor the owner is in Stockton ks for a race of some sort but the guy did tell me that the owner did something similar on getting a 250L motor for his son on some project he was doing. I'm just seeing how much it's going to cost and how long it will take to get one. I'm guessing the price will be about $2000
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HONDA here says you cant buy a complete engine, for whatever reason!

Hahahaha, ur kidding me! Sounds like a Brit!

Honda never did sell to the public or give a full engine under warranty they will give every part for a rebuild but not complete engines goes back to 1964 for me and if engine cases were needed as in the 1969 CB750 chain break issue you would restamp the engine number and Honda would pick up the old cases only time I saw write off whole good engines were the CBX 6 frame issue you cut off the frame serial number send that in and keep the rest.

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Honda never did sell to the public or give a full engine under warranty they will give every part for a rebuild but not complete engines goes back to 1964 for me and if engine cases were needed as in the 1969 CB750 chain break issue you would restamp the engine number and Honda would pick up the old cases only time I saw write off whole good engines were the CBX 6 frame issue you cut off the frame serial number send that in and keep the rest.

 

nice...  that had to be quite a problem for them to acknowledge it like that...   

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There going to get back with me around 4:00 today. A guy at work said you can order motors, at least for Harley's anyways I don't see why not for any other bike?

Well, Harley starts with an H, maybe they can Huskies, etc.   hahahahah

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