Project CBR250RRi
Close
Login to Your Account
CBR250 Forums - Powered by vBulletin
Page 1 of 28 12311 ... LastLast
Results 1 to 10 of 276
Like Tree26Likes

Thread: Project CBR250RRi

  1. #1
    Biker motthomas's Avatar
    Member #
    539
    Join Date
    Jun 2010
    Location
    UK, formerly Ireland
    Posts
    737

    Project CBR250RRi

    Its about time I stuck a thread up on this. I'm hoping that having something like this to keep updated will give me the motivation to push on and get it done.

    The idea has been in my head to do an EFI conversion on a CBR250 ever since I read the feral injection website. I always thought I didnt have the know-how to do it what with building an ecu and designing the software to control the injectors. At least that was until I found out about megasquirt.
    The megasquirt ecu did away with the need to be able to assemble complex enough electronics and design base software so brought it all back within reach. The idea got put on the back burner for a while until last summer when I started seriously researching it again and one thing led to another and now I hope Im in far enough to have to finish it. Actually finishing it within 2012 is my new years resolution! :P

    Theres a few things to get and do before I start doing anything to the bike.
    • Throttle bodies sized and spaced
    • Injector selection
    • Sensors. Coolant temp, intake air temp, MAP
    • Fuel Pump
    • Fuel filter and pressure regulator
    • Air filter / airbox
    • ECU


    The easiest bit is the ECU. I'm going to use the microsquirt ECU from Bowling & Grippo. The tuning software for it is free and it supports both fuel control and ignition control. If a wideband oxygen sensor is plugged into the ECU, it allows for datalogging and closed loop injection if needed.

    I have chosen my throttle bodies already. I'm going to use GSR400 throttle bodies. The reason is because the OD of the intake stubs is the same as the CBR carbs so there will be no need to make up reducers to fit the throttle bodies to the engine. Also, having the same diameter bores will make for the best throttle control across the range. The problem with having too big bores is you end up with effective 100% throttle happening too early and losing some control over the throttle. Besides, bigger throttle bodies just wont fit in between the frame rails of the CBR.
    The GSR throttle bodies will need to be modified though to suit the spacing of the CBR intakes. The spacing between #1-#2 and #2-#3 will need to be reduced while the spacing between #3-#4 will need to be increased. And with that, I'll need to get completely new butterfly valve rods made up to suit the new spacing.
    The throttle bodies got bought from yahoo auctions japan and hopefully I'll have the gen soon enough to send them off to a machine shop to get the work done on them.
    Here they are stripped down with most parts removed:




    I picked up a set of GSXR750 injectors over the weekend that will hopefully fit the GSR TBs. They are a higher flow rate than I have calculated I'll need for the CBR but I got them for nothing so if they dont work I've lost nothing. If they are too big it will be obvious straight away when trying to tune the idle.
    The GSXR TBs have a few other bits that will be handy aswel. I'll be able to use the MAP sensor off them and the way the fuel rail is structured it should be handy enough to modify the spacing. I havent got a chance to pull them apart yet to see how they go together.



    The fuel pump is the part thats bugging me at the moment. I can either go with an external pump or in-tank pump/filter/regulator assembly.
    I want to make this conversion in such a way that I can easily revert back to stock carbs at any time. From that perspective the external pump works best as all I'll need to change is to tap in a return line fitting into the tank and that could be blocked up easily enough.

    The disadvantage of the external plumbing is space. Where to mount the pump, regulator and filter and route the plumbing so it all stays tidy and servicable. Thats where the in-tank assembly comes up trumps. If I can get hold of a spare petrol tank for handy money it will be worth modifying it to accept the internal pump assembly. It would tidy up things a lot what with only having the one fuel line running from the tank to the fuel rail. I would lose fuel capacity but I think that will be a small price to pay.


    Thats about all for now. The next steps are to make up drawings for the machine shop to modify the TBs and make up new throttle rods and also to see about getting hold of a spare tank.
    Watch this space.

  2. #2
    Senior Biker zane's Avatar
    Member #
    135
    Join Date
    Sep 2007
    Location
    dubland
    Posts
    2,705

    RE: Project CBR250RRi

    why dont you use the cbr carbs as throttle bodies and remove float bowl etc?

  3. #3
    Ace Hessian's Avatar
    Member #
    61
    Join Date
    Feb 2007
    Location
    North QLD
    Posts
    11,396

    RE: Project CBR250RRi

    It sounds sensible, but there will be naysayers you know

  4. Remove Advertisements
    CBR250.com
    Advertisements
     

  5. #4
    Biker ricjames's Avatar
    Member #
    4254
    Join Date
    Mar 2011
    Location
    Melbizzle...
    Posts
    101

    RE: Project CBR250RRi

    .....just what i was thinking. Be hell easier to mod the stock one's than adapting others... does the micro squirt use a TPS as well?

  6. #5
    Biker akeizm's Avatar
    Member #
    73
    Join Date
    Mar 2009
    Location
    Brisbane, Australia
    Posts
    1,367

    RE: Project CBR250RRi

    Yep, sure does.

  7. #6
    Biker motthomas's Avatar
    Member #
    539
    Join Date
    Jun 2010
    Location
    UK, formerly Ireland
    Posts
    737

    RE: Project CBR250RRi

    Quote Originally Posted by zane
    why dont you use the cbr carbs as throttle bodies and remove float bowl etc?
    I suppose I wanted to use something that had been designed for use with injectors so I would get the best performance out of the whole system. I didnt like the idea that if the injectors were spraying up through the main jet passage the already atomised fuel would need to pass along a relatively narrow path and around a corner before mixing with the air. There would be a lot of wall wetting going on.

    Yep the microsquirt can either use speed-density calculation using the MAP signal or it can use alpha-N using RPM and TPS only. I think I will end up using the alpha-N settings as from what I've read its hard to get a clean MAP signal from ITBs. I will be hooking up the MAP sensor anyway though and trying both calculations to see what works best.

  8. #7
    Biker wogstaa's Avatar
    Member #
    541
    Join Date
    Jun 2010
    Location
    Australia
    Posts
    954

    RE: Project CBR250RRi

    Oh man... I hope you get this thing working good.
    Can't wait to see the progress

    Good Luck!

  9. #8
    Ace Eclipze's Avatar
    Member #
    27
    Join Date
    Feb 2003
    Location
    Melbourne, Australia
    Posts
    9,477

    RE: Project CBR250RRi


    Nice work!

    I looked into the megasquirt a few years back. I'm hoping things have changed, as when I look at them the max RPM was much too low for a CBR250 engine.

    One thing to keep an eye on, is the power consumption of the fuel injector pump. CBR250's don't produce a lot of power, particularly at idle. So get the smallest/least power hungry pump that's suitable ;-)

  10. #9
    Ace
    Member #
    1180
    Join Date
    Feb 2009
    Location
    Perf
    Posts
    5,430

    RE: Project CBR250RRi

    So that's why you wanted those carb measurements yonks ago.

    Ah well I hope to see this one finished and tidier than the FI job.

    I will be following this one closely.

  11. #10
    Ace Merudo's Avatar
    Member #
    253
    Join Date
    Apr 2007
    Location
    QLD, Australia
    Posts
    14,538

    RE: Project CBR250RRi

    According to their website it appears it can go up to 16,000rpm.

    Also I'm with you Mott on using TB's with injector mounts designed for FI. surely that would have to be better than butchering a set of carbs and trying to emulate a FI fuel rail and throttle body.

    Subscribed.

Page 1 of 28 12311 ... LastLast

Similar Threads

  1. Looking for R1 project
    By saffa in forum Project Bikes
    Replies: 7
    Last Post: 24th October 2012, 04:54 PM
  2. FS: [SYD] Project VTR250
    By 0063 in forum Buy & Sell
    Replies: 4
    Last Post: 17th June 2012, 04:41 AM
  3. need help with my project
    By black-45 in forum CBR250 Forum
    Replies: 34
    Last Post: 7th February 2012, 08:44 PM
  4. Should I buy an MC19 Project?
    By wogstaa in forum CBR250 Forum
    Replies: 26
    Last Post: 24th August 2011, 06:52 AM
  5. The project !!!
    By georgev in forum Project Bikes
    Replies: 9
    Last Post: 28th March 2011, 11:23 AM

Search tags for this page

cbr250r fuel injector pressure
,

cbr250r mc19 bellmouth

,

cbr250rr fuel consumption

,

cbr250rri

,

fuel injection for mc22

,

gm tbi conversion

,
mc 22 fuel injection
,

mc22 fuel injection

Click on a term to search our site for related topics.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •