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Thread: Project CBR250RRi

  1. #271
    Biker motthomas's Avatar
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    Jun 2010
    UK, formerly Ireland
    Headlight Upgrade

    After much deliberation, research and changing of mind back & forth, the modernised headlamp solution I settled on was to install LED bulbs. The options were either HID or LED but eventually the LED won out due to being actually able to package the ballasts in the front of the bike, being more adjustable for beam pattern and having lower overall current draw although they were almost twice the cost of the HIDs for a quality set from a reputable manufacturer.

    Each H4 LED bulb is rated at 20W compared to the 60W/55W rating of the standard halogen units so, in theory, a set of 2 should have freed up c.6A capacity which would be more than enough to cover the additional load the fuel pump, lambda heater & injectors placed on the system. Before installing the LEDs, I had measured a charge current of -7A (draining battery) at idle with dipped beam on and -6A at idle with main beam on. With the LEDs installed, charging current was measured at +3A at idle with both dipped and main beams on, leaving plenty of headroom on the charging system.

    The physical installation of the bulbs was pretty straightforward. The heatsinks on the back of the bulb make it all a bit bulkier than the standard setup but the heat sinks are well hidden given they are black in colour. The two small ballasts found a nice place to sit either side of the clock stay bracket where they do not interfere with anything else. Getting the beam pattern right took the most time but the adjustment in the bulb housings worked a treat. There is also the advantage that the LED headlamps are quite a bit brighter than the halogens which makes night-time riding that bit more enjoyable.

    EGT Instrumentation

    I had also put a line in the sand for getting the engine calibration dialled in on a dyno for mid-February. That meant tidying up some small loose ends on the electronics side. I wanted to try and get EGT measurement implemented for running the bike on the dyno so that I would have a second metric to determine optimum fuelling and make sure port temps were under control. I could have done this in such a way that the EGT values would be displayed on a screen live and I would simply keep an eye on them while running the bike on the dyno.
    However, there would be several advantages to being able to feed the data into the ECU so that it could be logged with all other engine parameters. Unfortunately, due to the limited I/O capacity of the Microsquirt, the only way of getting 4 additional data streams into the ECU would be via CAN-Bus. That meant using a microcontroller to read the EGT data from thermocouple amplifiers, arrange the data into a CAN message in a format that the Microsquirt could read and load the message onto the bus.

    I played around with a CAN shield on an Arduino Uno first to get the data processing & CAN code working together properly. Getting my head around the Megasquirt CAN-Bus protocol was the most difficult part of the task as it is quite different from the standard protocol that I am used to. Once I had verified that the hardware and code combination worked, I designed a single PCB which used an Arduino Micro as the controller and contained every other peripheral that I needed to make the board work on the bike. The finished board is quite large as I was conservative about component spacing to allow hand soldering of components and only used one side of the board. If I was to make something similar again I would tighten up the component spacing, use a microcontroller with inbuilt CAN-Bus functionality and place components on a dual layer PCB.

    EGT CAN-Bus Module Board

    A protective case for the EGT CAN-Bus module was 3D printed.
    Cased Board

    On the instrumentation side, I installed 1.5mm K-Type thermocouples as close to the exhaust ports as possible without interfering with the fitment of the radiator or making exhaust fitment difficult. The small diameter probes would mean that I could get shorter temperature stabilisation but at the expense of thermocouple life. This was determined to be a reasonable compromise as the main purpose of the thermocouples was to monitor tempemperatures during dyno runs and short road tests only. As they would not be used for long term control, durability was not deemed critical.

    The exhaust headers had to be removed to drill & weld the thermocouple compression fittings in place. While they were off I took the opportunity to rectify the much annoying (to me) issue of the exhaust header flanges bending from the studs being torqued up. The problem with the Honda design is that the flanges do not clamp between the nut and the cylinder head. Instead the flange is designed to be clear of the cylinder head when fully torqued up so the flange has a tendency to bend around the header collar as the studs are being torqued up. Maybe this would not be a problem if the specified torque was always adhered to but on both sets of headers I have owned (OEM & TSR), the flanges had been bent previously. Bent flanges mean that you end up needing to put more preload on the stud to achieve the same torque which only amplifies the issue and risks stripping the threads in the cylinder head. The studs also bend as the nut tries to sit flush with the flange and that can make removing the flanges a pain.
    To try and combat this issue, I had a new set of flanges laser cut from 316 stainless steel plate. The new flanges are thicker (8mm vs 6mm) and the profile of the flange is also beefed up around the outer edge. These changes have the effect of making the flange approx. 3 times more resistant to bending at its weakest point than the TSR flange.

    Thermocouple Tip Position In The Exhaust

    Thermocouples & Flanges in Place

    Dyno Calibration

    With the EGT measurement equipment in place it was time to get the bike on the dyno and dial in steady state fuelling.
    The dyno was an eddy current braked dyno which allowed me to hold whatever speed and load required to dial in each fuel map bin. The only downside was that as it was a car dyno designed for much higher power vehicles, it was impossible to hold the engine at the lower speeds and throttle angles. Therefore only the area above 4,000rpm & 10% throttle angle could be successfully mapped. As this represents the area where the majority of riding is carried out then that wasn’t much of a problem.
    After the fuel mapping was carried out, an attempt was made to see if there was any additional power to be had in the ignition timing. The bike seemed to be very insensitive to part throttle, steady state ignition timing changes although this can be very difficult to judge on a chassis dyno, especially one with quite high inertia.
    I carried out a few full throttle pulls from 8,000rpm to 16,000rpm with varying ignition timing to determine what effect it had on engine power. Baseline timing was the Bluefox ECU timing. I found that with a global adder of -2°, there a negligible change to engine power. Both +2° & -4° global ignition timing offset produced measurable power losses across the engine speed range. Given that the Bluefox ignition map is c.1.5° more advanced than the Honda curve in that region, it suggests that Honda did a pretty good job of mapping the engine to MBT timing from factory!

    For those of you that care about these things, the final figure was 37bhp at the rear wheel at 14,700rpm. I hadn’t expected any gains over the standard bike with EFI and given the engine is in an unknown state of repair, I consider it a good result. I never dyno-ed the bike before the conversion and even if I did, the comparison wouldn’t have been possible on the same dyno and so not comparable.
    What did become very apparent from studying the power & torque curves was that the original 18,000rpm rev limit is totally unnecessary as power drops off quite sharply after the peak. There is no point in going faster than 16,000rpm in any gear as there will be more torque available in the higher gear above that engine speed. As such I will be imposing a soft limit at 16,500rpm and a hard limit at 16,700rpm, with the aim to shift at 16,000rpm.

    Calibrating the Bike on the Dyno

    The dyno run completed my base fuelling & spark for a given barometric pressure and manifold air temperature. All other starts and runs from here on out will help me to apply appropriate air temp & barometric pressure corrections and dial in the transient fuelling corrections.

    I also took the bike out on a track day at Mallory Park in the cold, wet & snow recently to see how it would manage. I had also hoped to use it as an opportunity to get a lot of datalogging done to dial in the transient fuelling but unfortunately my brand new lambda sensor died within minutes of it being fitted so I didn’t record any fuelling data throughout the day.
    Saying that, the bike rode really well on the track and throttle response & power were as good as I could have hoped given the lack of any form of transient fuelling corrections.

  2. #272
    Biker Slipry's Avatar
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    Jul 2012
    Adelaide SA
    very interesting and there we have it - the engine can spin to 18000rpm but it is completely pointless (unless you want the ladies to take off their panties)
    Quote Originally Posted by schultzy View Post
    I stuck a battery up my arse.
    Yeah, that's a cool story...

  3. #273
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    May 2011
    I love it when you make my head hurt Thomas,,,,
    "There is no point in going faster than 16,000rpm in any gear as there will be more torque available in the higher gear above that engine speed",,lol,, yup,,ain't that the truth, the redline is the place you go if you want to spend $600 replacing the valves you just bent.
    My seat of pants "big white dyno" testing in 2015 told me there aint no power after 16,200 indicated rpm with Jade cams, I'm geared to take advantage of that now, 15,000 indicated rpm in 5th will be 110 mph, & if it pulls 6th,,,,,,,,,,,,

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  5. #274
    Biker motthomas's Avatar
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    Jun 2010
    UK, formerly Ireland
    Haha! Yeah I had long suspected that was the case but now I have definite proof. There is just too much friction to overcome at the higher engine speeds. I am sure you could help it out with cams that were optimised to the higher speeds and there are a few things you could do to help the friction but none of those are cheap.

  6. #275
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    Mar 2017
    Hey Thomas,

    Great build man, I've been following your thread for a while and am looking to replicate a lot of what you did for my own build (megasquirt, machining the carbs to fit injectors, using the stock pulse generator, etc.). I was wondering if you could share your .msq file. Would really save a lot of time with the tuning.

  7. #276
    Junior Biker
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    Nov 2016
    Question, what sort of EG temps were you getting and how even was it across all 4 cylinders?

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