Honda CBR300 engine swap into a CRF250L.

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

  1. LordMorgan

    LordMorgan Been here awhile

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    Badass!! Let us know how it runs, especially at highway rpm's. I'll be picking up the kit from ari tomorrow and racetech is local to me. :D
  2. JungleDeath

    JungleDeath Been here awhile

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    So far all is well. I did put the gearing back to 14/40 without realizing I last rode it and dyno'd with the 13/40 ratio. With that said, I have to put effort into not whacking the throttle and be patient with the break in procedure. However, with some hard short shifts on flat ground with the mapping still in its infancy, it pulls harder than the 250 with 13/40. That and the throttle response feels closer to that 1:1 feel compared to before. Roll on is noticeable as well.
    I have not taken it over 7000rpms yet and spend most of my time between 15-50% throttle in the 4000-6500rpm range. I have the PCv set at 14:1afr and a maximum allowable extra fuel of 30%. The largest amount of fuel it has asked for so far is 23% but on average it has been ~16-18% extra under the higher loads (hills, medium acceleration).
    PCv12_2.jpg
    This is what the map looks like after 3 rides and 31 miles. Some of it I manually filled in but most is done by the Autotune. You have to discipline yourself not to rip around due to the fact the zero cells will not have enough time to populate with a new fuel trim. Unfortunately I can't take my laptop with me because it is a little too big for my tail bag. It would be nice to stop after 15-20 minutes and play with the tune but I usually have to go home, plug in, manipulate the map, go back out.

    I'm going to change the oil @ 100, 300, 600, 1200. I also want to get a 300r ecu and see what the difference is. Anyway. I can't wait till I can really romp on it and get on I80 for a rip.
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  3. LordMorgan

    LordMorgan Been here awhile

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    What were vibrations like at 6500rpm?

    And where did you get a PCv from I tried looking for one and I couldn't find one for sale anywhere, I ended up getting an ejk instead.

    That's very very encouraging, I've used 13/40 on mine and I loved it, just not above 50mph
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  4. JungleDeath

    JungleDeath Been here awhile

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    Vibes. Here is my history. I have extensive experience with a 2007 DRZsm, some experience with a 2017 690 enduro r, and some with a 2007 crf250R. When it comes to vibes the DRZ was unacceptable to me, especially after putting 19k miles on one, the 690 was pretty bad but not as bad as the DRZ, but still bad to me. The crf250R was also a joke but since its used in a way that is completely different than a street ride you just sorta accept it.
    So, in my opinion, 250L is so low in vibes that its not even worth talking about. That said, I felt the vibes on my 250L at around 7,800-8000rpm and up. Off road when standing up and not looking down I can feel the vibes coming on through the handlebars and when this happens I know i'm in the 7000rpm range.

    The 301 feels ever so slightly more vibey earlier (than the 250L) but mostly when on the gas; larger throttle openings. But I mean only slightly. As it sits right now, it is way way better than both the DRZ and the 690 when accelerating under normal to hard conditions. Both of those bikes, in my opinion, sucked on the highway. I got an Atlas throttle lock for the DRZ. So far, the 6500rpm vibes on the 301 are only slightly elevated but not to the point where I was disappointed or worried. Long winded...sorry.

    The 2017 250L PCv is part number 16-069.
    https://www.dynojet.com/dynojet-motorcycle-power-commander/
    For some reason it is not in their list of bikes. Not sure why. There are authorized resellers on the net and E-bay. If you are thinking of getting the Autotune (AT-200) module as well see if you can get a package deal. It's a chunky cash outlay but I bought them separate and payed more.

    I'm pretty much going to ride every day and I will pay attention to the specific rpm vibes and report back.
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  5. LordMorgan

    LordMorgan Been here awhile

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    I think my bike has something a little off with it, maybe a damaged bearing or bent part in the engine because starting at 60mph it starts vibrating and art 65-70mph, 7k rpms, the engine vibrations make my hands, feet and butt go numb. Riding over 15 min on the freeway and my hands tingle for the rest of the day and I worry about nerve damage. It feels like there's a dentist drill buzzing against my skull and my eyeballs, it makes my vision blurry, the vibration is BAD. At lower rpms, though, the engine is smooth as glass.

    My GS vibrates, my harley vibrates, those don't bother me at all, it's the frequency and intensity of the 250l engine that gets me.

    I'll talk to ari about it too and find out if this is really the route to go because with a little more power (not necessarily 38) and vibrations coming on later in the rev range this would be a perfect bike
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  6. Ed@Ford

    [email protected] Long timer

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    If your Rally vibrates that bad, there is something wrong. First thing to determine is whether it's coupled to bike speed or engine speed. Then go from there.
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  7. JungleDeath

    JungleDeath Been here awhile

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    Agreed. People feel things differently. And each bike vibes people differently. I will keep riding and mapping and pay attention to the vibes and when it does. I'm going to bring my laptop with me and I will take notes when I stop.
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  8. JungleDeath

    JungleDeath Been here awhile

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    Out for a bit more mapping today.
    There is a buzz in the bars only, at about 6500-7000rpm. Not the seat or pegs. just the bars. I swore to myself I wouldn't take it on the highway, and I did, just for one exit. Oddly, the buzz was about the same at the 7000ish mark. I'm pretty sure I did not hit over 8000 cuz I hung around 65mph and then got off.
    For reference, I have Protaper risers, Nekken bars from a 500exc, worn pillow top grips, and I have moved my pegs slightly lower and back.

    With 50 miles on this motor and stock gearing, not only did it get up to 65 without a problem, but didn't need a lot of throttle input to stay there. Nice.
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  9. LordMorgan

    LordMorgan Been here awhile

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    I got grip puppies, rox anti vibration risers, an airhawk for the seat. Filled my handlebars with great stuff, added bar end weights, and finally zip-tied small towels on top of the grip puppies to make it bearable. It's still awful but not in nerve damage territory anymore, if I take frequent breaks. Having a full tank of gas helps dampen the vibes too

    I think I'll get my 286 crank balanced before I install it
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  10. RalliJari

    RalliJari n00b

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    Hello everyone, I've ordered most of the parts to do the crank swap on my 2019 250l abs and wanted ask if anyone has had any issues with the smaller 250 engines balancershaft bearings while using the 300 balancer?
    Samtech79 did answer [email protected] above question in page 8 to not worry about it but that message is from some time ago and was wondering if any failures have happened since?

    Also, I got the 300 ecu 38770-K75-L61, but started to wander if I need it since I'm keeping the 250 flywheel:dunno

    Also, since the need to use new piston rings have you guys done any light honing or scuffing to the cylinder?
  11. CRD

    CRD Been here awhile Supporter

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    I can't speak to your other points, but you will benefit from the 300 ECU. It provides the fueling for a 286 cc engine. If you ran the 250 ECU, you would run lean.
  12. Ed@Ford

    [email protected] Long timer

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    There are other CRF250/300/CBR300 swap threads here on ADV rider where guys from the US and UK have many many miles on such modified engines and bikes/engines. There are other guys who have stock 300's, actually 286cc, with larger bores to get to 305cc, and horsepower waaaaay over 30 that seem robust. There used to be a guy over on thumpertalk that built a 340. You'll have to do some serious digging for results. I have never gotten a reply regarding my query on small bearings with a 300 balancer. I ended up paying $$$$$ to buy a 2021 Rally 300 (286 of course) and not do the swap. It is a sweet bike.....with lots of changes beyond a stroker crank.
  13. Cuttlefish

    Cuttlefish Riding to disappear.

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    I still enjoy seeing my thread come back onto the front page every so often regardless. :D
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  14. RalliJari

    RalliJari n00b

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    Well I'm going to update this thread with my results. Been busy with life and waiting for the temperature to come up a bit, currently -20c. Couple of days ago it was relatively toasty -8c and I was able to remove fairings, tank, etc. of the bike, hard to do with thick winter gloves. Still need to drain the engine before removal and then carry it to my living room, gonna be nice to work somewhere warm :)