Honda CBR300 engine swap into a CRF250L.

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

  1. Cuttlefish

    Cuttlefish Riding to disappear.

    Joined:
    May 31, 2016
    Oddometer:
    2,362
    Location:
    Sunshine coast Qld Australia
    I mentioned Fullforce racing earlier as the place to take the crf to for any suspension work I will have done. They quoted me $250 Aud to re-valve my stock shock. I will check with them this morning to see if that includes a heavier spring to give back some pre-load range.
    They are only a few kms from my house so I'm am lucky in this respect too.
    Here's a clip of what they can do to the DR 650's capability. I couldn't take my Triumph scrambler around there fast enough to have them look at the fitting of a set of plex valves for it after seeing this clip.
    The scrambler has different sized fork legs to the DR but the valves are in development after I left the scrambler with them to see what they needed to do.

    Engine due to arrive today.
    #21
  2. Cuttlefish

    Cuttlefish Riding to disappear.

    Joined:
    May 31, 2016
    Oddometer:
    2,362
    Location:
    Sunshine coast Qld Australia
    Engine has arrived. Gerard is putting it in now. I'll go over later and check it out. Photos will be added.
    #22
    SpaceCowboy7777 likes this.
  3. Cuttlefish

    Cuttlefish Riding to disappear.

    Joined:
    May 31, 2016
    Oddometer:
    2,362
    Location:
    Sunshine coast Qld Australia
    Engine is in. Bolts in with no dramas.
    Gerard installed the cbr 300r throttle body. No issue with it connecting to the crf airbox. I also ordered the 300r coil with spark plug. Gerard has used the crf's since it has the longer lead and a better sealing plug compared to the road bike's one..
    [​IMG]
    Minor speedbump and question for Shortman if you're watching...the leads from the stator on the cbr 300r engine has plugs that differ from those on the crf250l harness. So we have these plugs that aren't the same. Did you come across this? Yes the leads are on the outside of the frame while the plugs are worked out.
    [​IMG]
    Gerard will probably change the plug (white one) to one that fits the crf's existing plug.
    Here's Gerard enjoying a well earned beer at the end of a long, hot summers day and we don't call it the Sunshine coast for nothing. Apologies to all you readers snowed in at the moment.
    [​IMG]
    Gerard should be able to fire it up tomorrow...all going well.
    I wil post a side by side pic of the 2 throttle bodies for future reference once I receive it from Gerard.
    #23
    BygDaddee, Squily, Dao1 and 2 others like this.
  4. swimmer

    swimmer armchair asshole

    Joined:
    Oct 9, 2007
    Oddometer:
    19,929
    Location:
    Tucson, AZ
    Seems too easy.
    #24
    Cuttlefish likes this.
  5. shortman

    shortman Beta 500 RS, X-Trainer 250 Supporter

    Joined:
    Jun 14, 2013
    Oddometer:
    1,803
    Location:
    Cumming Georgia
    I just cut it off and used the one off the 250 engine
    #25
    Cuttlefish likes this.
  6. shortman

    shortman Beta 500 RS, X-Trainer 250 Supporter

    Joined:
    Jun 14, 2013
    Oddometer:
    1,803
    Location:
    Cumming Georgia
    I should also point out.... Every 300 engine made by Honda is under recall for faulty crank bearings.... Apparently some were pressed on super tight and don't have enough tolerance thus starving the bearing for oil.... So change the oil often and use a light weight.... I'm checking the clearance on mine when I tear it back down to swap the tranny.....

    Just food for thought...
    #26
    Cuttlefish likes this.
  7. Todd00000

    Todd00000 Adventurer

    Joined:
    Oct 3, 2011
    Oddometer:
    51
    Location:
    Costa Rica
    What's the difference in power between the two engines?
    #27
  8. shortman

    shortman Beta 500 RS, X-Trainer 250 Supporter

    Joined:
    Jun 14, 2013
    Oddometer:
    1,803
    Location:
    Cumming Georgia
    There is not a exact answer to this.... This question can create a large debate all on it's own and this thread is not the place for that...

    Best thing for you to do is to look at Honda's posted specifications for a CRF250L and a CBR300... You can make your own determination from there.....
    #28
  9. Lesharoturbo

    Lesharoturbo Nerdly Adventurer

    Joined:
    Mar 23, 2009
    Oddometer:
    3,214
    Location:
    Austin TX
    Shortman,

    Did I read correctly that you did both a 300 swap with an overbored cylinder? What displacement did that give you? 350 ish?

    This thread gives me hope for a 350 Rally...
    #29
  10. Cuttlefish

    Cuttlefish Riding to disappear.

    Joined:
    May 31, 2016
    Oddometer:
    2,362
    Location:
    Sunshine coast Qld Australia
    That's why we're doing it.
    Weighed up the money and time to fix my 250l engine for no performance gain.
    #30
  11. Navin

    Navin Long timer

    Joined:
    Sep 22, 2009
    Oddometer:
    29,712
    How many miles on your engine when it went to scrap?
    #31
  12. Cuttlefish

    Cuttlefish Riding to disappear.

    Joined:
    May 31, 2016
    Oddometer:
    2,362
    Location:
    Sunshine coast Qld Australia
    Thanks. I'll drop into the Honda dealership this morning and ask about the recall and take it from there.
    #32
  13. Cuttlefish

    Cuttlefish Riding to disappear.

    Joined:
    May 31, 2016
    Oddometer:
    2,362
    Location:
    Sunshine coast Qld Australia
    9,000 KMS. Still repairable. Top end damage. I found a compete used top end for it which is easy and I may get that and sell the complete 250l engine.
    #33
  14. shortman

    shortman Beta 500 RS, X-Trainer 250 Supporter

    Joined:
    Jun 14, 2013
    Oddometer:
    1,803
    Location:
    Cumming Georgia
    I did the smaller of the 2 over bores on mine so I've ended up with a 320cc engine... I whet this route because to go bigger (305 kit plus 37cc from longer stroke nets you 349cc total) requires the use of the CR450F injector, head work, cams and a substantial investment in electronics / tuning to get the most out of it... I just didn't wanna spend that much....
    #34
  15. shortman

    shortman Beta 500 RS, X-Trainer 250 Supporter

    Joined:
    Jun 14, 2013
    Oddometer:
    1,803
    Location:
    Cumming Georgia
    As far as I know Honda has not officially released a replacement crank... They are tearing down new and used bikes to check the clearance and if to tight they are pressing on a new bearing and putting it back together.... For those unfortunate folks who have experienced a failure I believe they are rebuilding the engine free of charge (if it was still under warranty)...

    Obviously you'll be in the same boat as I am because you bought an engine from a salvaged bike there would be no warranty anyway....
    #35
  16. Navin

    Navin Long timer

    Joined:
    Sep 22, 2009
    Oddometer:
    29,712

    Why did it fail. This seems the long way around to get it back to a running bike, esp when you could have slipped a BB in it as part of the repair?
    #36
  17. swimmer

    swimmer armchair asshole

    Joined:
    Oct 9, 2007
    Oddometer:
    19,929
    Location:
    Tucson, AZ
    The numbers I found lists the CBR300R hp @ 30.5 (19.9tq). The '17+ CRF250L is rated at 24.4 hp (16.7tq) and pre-'17 is rated at 22.8 hp (16.2tq).
    #37
    Kray, Snake Oiler and Cuttlefish like this.
  18. shortman

    shortman Beta 500 RS, X-Trainer 250 Supporter

    Joined:
    Jun 14, 2013
    Oddometer:
    1,803
    Location:
    Cumming Georgia
    Taken with a grain of salt that would be about right....
    #38
  19. Cuttlefish

    Cuttlefish Riding to disappear.

    Joined:
    May 31, 2016
    Oddometer:
    2,362
    Location:
    Sunshine coast Qld Australia
    All the bike shops were shut by the time I got home from work (Christmas eve) and so I went to Super cheap (Aussie car parts shop) to see if they had any filters. They sold me a filter for an X not an L.
    A BB kit isn't readily available over here and I have family in Thailand to send parts over but spotted the cbr300r engine while searching for a complete top end to swap on Ebay.
    I'd already read through the long 305cc thread on Thumpertalk months ago and was hesitant after seeing some failures. The cb500l thread was much more stimulating.
    #39
  20. Cuttlefish

    Cuttlefish Riding to disappear.

    Joined:
    May 31, 2016
    Oddometer:
    2,362
    Location:
    Sunshine coast Qld Australia
    As a side note for crf250l owners Gerard will be taking a look at the steering stem bearings as it appears they will need replacing after 9K kms.
    #40