Project bike... 50 horsepower 250f

Hey guys, I'm looking for a project bike to build this summer, will do some vet classes, etc. with it. Going to try and get 50 horsepower out of a 250f. That's about 16 more h.p., their getting 20 more with a 450. What else would ya'll add on to this?

2006 CRF250 -

- TMR 307 Stroker kit; de comp. mod, oilbreather mod, twin-air powerflow kit, powernow, vortex igntition, CHM Exhaust system, Head modified/Ported/custom work done by RHC, and RHC custom Camsahft run on VP U-4 fuel.

Will also go with factory connection works suspension.

Hey guys, I'm looking for a project bike to build this summer, will do some vet classes, etc. with it. Going to try and get 50 horsepower out of a 250f. That's about 16 more h.p., their getting 20 more with a 450. What else would ya'll add on to this?

2006 CRF250 -

- TMR 307 Stroker kit; de comp. mod, oilbreather mod, twin-air powerflow kit, powernow, vortex igntition, CHM Exhaust system, Head modified/Ported/custom work done by RHC, and RHC custom Camsahft run on VP U-4 fuel.

Will also go with factory connection works suspension.

man 50 hp out of a 250 it's possible, but it will cost some serious $$ .. I know if anyone can do it, it will be rhc.

Thanks for the encouragment man... Do you have any experience with him, if so how much does he charge for porting, etc.?

Thanks for the encouragment man... Do you have any experience with him, if so how much does he charge for porting, etc.?

you hafe too email, or call him on price.. I have had my head done from him on my 450 he does some awsome work.. Just do a search on here you will find that everyone is happy with his work...

Bikes with the mods you've listed are usually in the mid 40's, not 50+. I'd love to see you do it, but I'm not sure how without porting/camming it until it has a lightswitch powerband and revs so high that longevity becomes a problem. Keep us posted.

Hey, would you mind pm'ing me or sending me a message via aim at yamaharacing2009 on what he did to your bike, and a price just so i can get a ballpark figure.

Tripower, did you have your bike ported, and how do you like your 307x?

Good luck man!! That thing is gonna fly!!

What are you going to do to the cases and tranny to handle the extra power?

You must have alot of dough layin around...

thats cool and all if u wanna do a 50 hp project bike on a 250f but really if u change bore than its not a 250f ..it is a bored motor with 250f cases and stuff..but i agree itll take alot of work..compression mods..porting.ignition..stroking, if u dont stroke it then itll rev slower and not as high. (first hand experience) ..carb mods, jst about every mod u can think of..o and i no u got that bor kit so please no one try to say that i didnt know htat

Tripower, did you have your bike ported, and how do you like your 307x?

No porting yet, that's next on the list. The 307 is incredibly good. If you search for TMR in the X forum, you'll see that a few of us have posted reviews about it.

IMO, correct cam choice is more important than porting with the 307. It makes so much low end torque that you could run a huge cam by comparison to the 250. I'm still experiments here, the Hotcam I had wasn't big enough. I have the X cam in it for my ride today, but it's WAY too small (short duration).

i will be testing a legal 250 this week with a new cam lets see where im @ with power i did have a 350 rotax several years ago make 50 hp for road racing

Ron, I'm giving you an email today, if you wouldn't mind replying whenever you get on. Thanks

Hey guys, just drew the layout of the engine, and it looks like we should be over 50 h.p. I'm looking at around 53 h.p. on a CRF250. Here is the list of motor modifications, and the motor will be done my Ron Hamp, if he agrees to it.

-CP 82mm (307cc) Piston

- balance / stroke crankshaft

- Install forged sleeve

- Crank case modifying/machining

- Acc. pump modification

- oil breather modification

- De comp. machanicism modification

- RHC Custom camshaft

- RHC Head work, porting, welded ex port smaller to match gixer 1000 streetbike

- P.C. ignition

- Twin-air powerflow kit

- Intake boot ported

- air box modified

- Hinson clutch components

- CHM Complete exhaust system

- VP Fuel

yeah but how long will a 50 horse 250 last ....although it'd be fun for awhile can you imagine pulling a stock 450 on a 250f

Hey guys, just drew the layout of the engine, and it looks like we should be over 50 h.p. I'm looking at around 53 h.p. on a CRF250. Here is the list of motor modifications, and the motor will be done my Ron Hamp, if he agrees to it.

-CP 82mm (307cc) Piston

- balance / stroke crankshaft

- Install forged sleeve

- Crank case modifying/machining

- Acc. pump modification

- oil breather modification

- De comp. machanicism modification

- RHC Custom camshaft

- RHC Head work, porting, welded ex port smaller to match gixer 1000 streetbike

- P.C. ignition

- Twin-air powerflow kit

- Intake boot ported

- air box modified

- Hinson clutch components

- CHM Complete exhaust system

- VP Fuel

53 may be more than a little optomistic, but I'm looking forward to the results!

To even hit 50, you'll have to take a 307 farther than any I've read about. The CP piston isn't a high compression piece, so you'll want a custom job to boost static compression way up. Once you get static compression up, you can run a long duration cam that will lower running (dynamic) compression. This will extend your powerband high enough to make your ears bleed (if the motor holds together and airflow allows) You have lots to think about and plan if you really want to hit your goal.

Unfortunately, I believe the difference between a 46hp bike and a 50hp bike will be measured in thousands of dollars.

So, did you order the parts yet? :thumbsup: So when will this monster hit the dyno?

Nope, I sent Ron a message, still trying to get the money together. It will be around summer before I start on it.

Just think about it, you'll have more than Langstons 44 hp 250f.

is racing a 307 in the 125 class legal?

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