Honda CBR300 engine swap into a CRF250L.

Discussion in 'Thumpers' started by Cuttlefish, Jan 7, 2017.

  1. Cuttlefish

    Cuttlefish Riding to disappear.

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    Here's a Rever app screenshot of this mornings route.
    [​IMG]
    I went for a ride up into the hills and since it was raining and visibility was poor due to mist I started to head home. Stopped at a service station where there was a Yamaha tenere and a KTM 690 adventure (or enduro with a Yenkro screen anyways) parked there already. As I was cleaning off my visor Glen turned up on his tenere and then one more on an xt660 enduro and another on a klr650.
    Seems I'd stumbled onto the Adventure riders Sunshine coast meeting point for a ride.
    So I ended up going for a ride with them.
    The crf performed flawlessly. I didn't find the transmission ratios strange at all both on and off road. Running the 14/40 feels similar in revs to the 13/40 with the 250 engine.
    The huge difference is rarely having to change out of 6th gear while going up hills on the road. I had no trouble whatsoever running with the guys on their larger capacity bikes which seems to be a problem for some 250cc riders when in groups that have larger bikes on the black top.
    Last ride I had with a mate on a Bmw gs1200 I had to wring the crf's neck and virtually pin the throttle to stay with him on the road sections and I'm rusty off road but fine on the tarmac.
    Whereas I still had plenty in reserve with the 300 engine today.
    Off road I didn't feel anything wrong with the gap inbetween 1st and 2nd like encountered with the stock 14/40 sprockets with the 250 engine.
    We had one snotty hill that the crf went up easily. Another decent hill with mud and my well worn dual sport tyres let me know about their lack of depth in the tread with some good slides but I kept it all upright. Just entertaining for those behind me.
    On the gravel roads it was easy to spin up the rear wheel in 3rd and 4th when gassing it.
    Again no dramas running with the 650's/660's,690's off road.
    This is not the snotty hill...just a spot we stopped at.
    [​IMG]
    [​IMG]
    #61
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  2. Cuttlefish

    Cuttlefish Riding to disappear.

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    Engine looks the part now.
    [​IMG]
    The crf while running solo early this morning. It may look cold because of the mist/cloud...nope humid as a sauna.
    [​IMG]
    And here's a link to the adv riders sunshine coast page. Good bunch of blokes. They are on to it with making sure no one gets left behind and lost at forks in the trails which is great. And they didn't take the piss out of my lighter, under-powered bike.
    https://www.meetup.com/en-AU/Adventure-riders-sunny-coast/
    #62
  3. GSXR

    GSXR Trail Rider

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    Great to hear it's going well for you Pete
    #63
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  4. Cuttlefish

    Cuttlefish Riding to disappear.

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    You'll have to have an easy Saturday so you're fresh for a ride this coming Sunday. Blow the cobwebs off the XR and blow by the crf upstart!
    :ricky:pynd
    #64
  5. Cuttlefish

    Cuttlefish Riding to disappear.

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    Here's a dyno chart of a stock cbr300r and dyno charts comparing stock WR250r, KLX250s and a crf250l.
    Interesting looking at the torque curves and where the most power is developed.
    [​IMG]
    [​IMG]
    [​IMG]
    #65
  6. mekros

    mekros Adventurer

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    Awesome stuff, good to see that a 300 gives a nice balance of size and power for you. How much difference is there in fuel consumption?
    #66
  7. Traveller128

    Traveller128 Long timer

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    Stock for stock, 286cc beats 249. Bump the WR up to 280-290, and it puts down 31 RWHP with a pipe, programmer and opening the airbox slightly. Bump the KLX and the CRF to 300 and they both make upper 20's. No replacement for displacement! TQ is a function of displacement.

    In my opinion, 300cc is a great displacement. Around 30HP is enough power to have fun, and still get decent fuel mileage. Good play bike power.

    The CRF builds power a little earlier, which is a sign of being a little less aggressive on the camshaft profile, or the intake/exhaust system not flowing as much peak air. Since the head appears pretty decent, I vote for cam profile. That will help fuel mileage, smoothness, and give it a good nature on the street and trails for all around use. The engine builds power lower, which means you don't have to be as aggressive with it.

    The WRR has a bit more cam to it, which builds a bit more top end power for the displacement, costs a little in fuel mileage, but not much, and makes for a fun off road machine that you have to spin a bit more to make power. When you put the big bore kits in it, it moves the power curve to the left a little, which is what you'd expect from an increase in displacement without putting more aggressive cams in it or making the ports larger. It makes power lower in the RPM range, but the head moves air which is why the HP peak is still over 30HP at the wheel. The WR with the 280 or 290 kit makes 5 HP more at 5K RPMn (16.5 vs. 11.5 approx). That's a ton on a little bike, and makes it more usable. Same thing with putting the CBR motor in the CRF. Nearly the same power at the lower RPM.

    Now here's opinion. The CRF is probably a better road machine. It's a bit heavier, and isn't set up to be a motocrosser or desert pounder. It's a small adventure bike that with engine and suspension mods can be made very capable. The 300cc upgrade is what Honda should have done by now. The CBR motor swap is a no-brainer in my opinion, as the motor has already been certified and continues to be certified in the U.S and abroad. The WRR is probably the better dirt machine. It's already just under 300 lbs full of gas (barely) and there are a few items that can be removed quickly to get it below 290. Put a big bore kit in it, and it's pushing that 300cc mark, and is capable of putting down 30-31HP at the wheel. With suspension upgrades, you can hustle on it in the dirt. It works well for trips, probably not as comfortably as the CRF. Depending on which way you want to ride, I think the WR is for the guy that wants to be more aggressive offroad, but wants closer to street bike service intervals. The CRF is for the guy that wants good street manners and solid trail usability with good fuel mileage and low maintenance, not to mention low end power that's smooth.

    It's interesting how many people have come to the conclusion that ALL of the manufacturer's want to ignore. 300cc is a good place to be for all around use. That's why there are big bore kits and motor swaps to get to that level. 30+HP is a fun and solid place to be with a bike. That's why there's an aftermarket, since so many people want to get to that power level.
    #67
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  8. Cuttlefish

    Cuttlefish Riding to disappear.

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    I haven't had a chance to measure that yet.
    Will let you know.
    Thanks for the info and your take on the bikes Traveller128.
    I just want to re-iterate for anyone reading this thread that this engine swap has to be hands down the best bang for buck while maintaining OEM reliability modification that you could do on a crf250l.
    The absolute bonus is you can sell your 250cc engine, throttle body and ecu to recoup the outlay on the 300 engine.
    If you keep the 250 engine as a back up then you have a great parts supply.
    #68
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  9. Kawidad

    Kawidad Long timer

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    Good stuff Cuttlefish! :super
    #69
  10. DaBinChe

    DaBinChe Long timer

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    I had a 2013 crf250l for about 9months and just wasn't satisfied with the power. Cocurrently and still also have a cb300, thinking of selling it cause I got another street bike. Thinking of gettting the 2017 crf250l and doing the crank&BB to 325 or maybe 350.
    #70
  11. Cuttlefish

    Cuttlefish Riding to disappear.

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    Just sold my 2015 Triumph scrambler today. Only the cr300r/l to keep me entertained...!
    [​IMG]
    Pic is pre-engine swap of course.
    #71
  12. minkyhead

    minkyhead Long timer

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    i guess you are probably the best guy to ask about the differnce in power and delivery ..and tourque on these engine s ...how do the compare in your opinion ..thank you
    #72
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  13. advmgm

    advmgm Long timer

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    amazing that this engine swap was sooooooo easy. thanks for keeping us updated on this little project.
    #73
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  14. Cuttlefish

    Cuttlefish Riding to disappear.

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    Will go for a ride with a few mates tomorrow. Two on GS1200's and the other on his F800. They all ride like loonies on and off road so it will be interesting.
    #74
  15. DaBinChe

    DaBinChe Long timer

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    There is a big difference in the two, especially torque. Folks are right when they say that the crf250 is anemic, I was just not happy with it. Tried the sprocket change and it helps on take off but top end just revved too high for my liking. The cb300 is great compared to the crf250 but if you would want a little more oomph that is why I am considering bumping up to 325 or maybe even 350. I think 30hp to the wheel is just about perfect, the cb300 puts down about 25hp and I think the crf250 puts down about 20hp. How complicated and extra fueling stuff would be no go for me, I want to be able to not have to use aftermarket electronics, just find them to have problems in the long run.

    So for the couple of folks that did the 325cc bump up did you use a EJK meant for cbr300 or one meant for the crf250 or the one meant for the BigBore CRF? I was thinking that if using the injector from the crf450 on the 325 or 350 might not need a EJK cause it will put out more fuel with the stock 250 or 300 electronics. CRF450 Injector jets are larger so being on at the same amount of time they put out more fuel, from 250 to 450 is almost double in displacement so the larger injectors should be able to handle even the 350 bump up with stock fueling.
    #75
  16. shortman

    shortman Beta 500 RS, X-Trainer 250 Supporter

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    You can't just plug in a 450 injector and expect it to run right... The guys that have gone down the road of the CR450 injector needed a piggyback ECU/EFI controller capable of being fully programmed and then spent many hours on a dyno perfecting a tune on their bike.... They did this because just plugging in the 450 injector caused it to run way to rich with the stock pulse rates that are in the OEM ECU.... AND... This same guy has the stroker crank, 305 big bore, cams and ported head (so basically as much as you can possibly do)


    So to answer your question on the fueling of the 320 kit... My bike came with the EJK and after I installed my engine, 300 ECU and throttle body I simply plugged back in my EJK... I just adjusted it a little from the settings I was using with the 250 and it works perfectly..... You gotta understand that the EJK simply takes what ever the OEM ECU is sending to the injector and adds a small amount to that and because I'm using the 300 ECU my EJK only needed a little tweaking to accommodate the big bore.
    #76
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  17. Lesharoturbo

    Lesharoturbo Nerdly Adventurer

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    Maybe and injector from a 650 twin (feeds ~325cc) instead? If it will fit the manifold and has the proper connector for the harness.

    It sounds like, from shortman's description, that the FI system is open loop, meaning no exhaust input for A/F ratio adjustment i.e. reduction of fuel in the engine. Hence the richness with a CRF450 injector. The ECU seems to be opening the injector for the same amount of time no matter the size, causing a rich condition. A injector meant to feed and engine (cylinder) between the 2 sizes (250 and 450) may be a better alternative.

    That being said, the fuel controller allows for adjustment that you will not get from a simple injector swap.

    In addition, a larger TB may also help.
    #77
  18. shortman

    shortman Beta 500 RS, X-Trainer 250 Supporter

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    CRF250L has a 34MM throttle body

    CBR250R and all 300s use a 38MM

    Plus the injector on the 300 is just bigger, but just barely....

    The thing with the 450 injector is it plugs right into the harness and fits directly into the throttle body slot but has A LOT bigger holes...
    #78
  19. Ed@Ford

    [email protected] Long timer

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    AND: 2017 CRF250L & Rally has 38mm throttle body.
    DO YOU MEAN: CBR & CB 300 injector is dimmensional identical (physically interchangeable), but max flow rate is slightly more?
    #79
  20. shortman

    shortman Beta 500 RS, X-Trainer 250 Supporter

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    Yep... Exactly what I mean
    #80