[Bmeath]

So I had my '01 RC51 out at the track this weekend and it started having some running issues. It felt down on power until you cracked it open then would surge heavily and go back to normal power. When I pulled into the pits the engine died and would only refire if the throttle was held 1/4 open or more.

I pulled the bike apart and started diag. the problem. I found the forward injector of the front cyl. pouring gas when ever the fuel pump was running. I swapped this injector with the back injector of the rear cyl. and the problem did not move. I am fairly comfident that this means I have a bad injector driver in my ECU holding that injector wide open.

Now my problem, when I pulled the air box to inspect the injectors I found the throttle bodies have 2 injectors each. To my under stading this makes them '02 + (SP2) throttle bodies. Im guessing to run these the wiring harness and ECU would also have to be changed. So, are there any differences year to year on the SP2 ECU so I can be sure to look for the correct one? I'm sure Honda could cross reference the part number off the ECU and get me the correct one, but I'm hopping to not have to spend the kind of money I'm sure Honda charges for this part.

The Part number off the ECU is 38770-MCF-671 9624-102375. Any info or suggestions would be apprieciated.

[ozthis]

you can compare numbers here....
Ron Ayers Motorsports - Motorcycle, ATV, Jet Ski and Generators Parts and Accessories

[Bmeath]

Good sugestion, thank you for the info. That site lists only 2 ECM's that don't change by year an 38770-MCF-A21 and 38770-MCF-L21. Mine is 38770-MCF-671.

[Bmeath]

A few things to add. The FI light only comes on for it's bulb check when the ignition is turned on as normal. There is no Power Comander installed on this bike.

The bike has always had some cold idle problems and a "dead spot" around 5k-6k RPM. I always figured this was due to the Flapper valve mod and pair removal done before I purchased the bike being done without a power comander. I was also told when I purchased the bike that the heads had been swaped to newer D port SP2 heads. As I had no easy way of proving this I had always wrote it of as BS.

[ozthis]

Originally Posted by Bmeath

Good sugestion, thank you for the info. That site lists only 2 ECM's that don't change by year an 38770-MCF-A21 and 38770-MCF-L21. Mine is 38770-MCF-671.

call your local dealer and give them the number off of the unit you have and see if it changes to one of those listed

[Bmeath]

Well it looks like I was wrong about it being an SP2 ECU. I took the control unit to my local honda dealer and had them look up the part number. It supercedes to 38770-MCF-771 which lists as an '01 ECU. I ended up ordering a used one off E-bay sence my local dealers seamed to think it was worth $900 plus tax. Hopefully this will fix the issue.

Does any one know of a good way of recognising SP1 and SP2 engine components if multiple parts have been replaced on a bike? As I stated earlier I was told at purchase that the bike had SP2 D port heads on it, not installed by the owner I bought the bike from. When I saw the dual injector throttle bodies I thought they were a newer part not installed in SP1 bikes.

[Rigor]

Originally Posted by Bmeath

Well it looks like I was wrong about it being an SP2 ECU. I took the control unit to my local honda dealer and had them look up the part number. It supercedes to 38770-MCF-771 which lists as an '01 ECU. I ended up ordering a used one off E-bay sence my local dealers seamed to think it was worth $900 plus tax. Hopefully this will fix the issue.

Does any one know of a good way of recognising SP1 and SP2 engine components if multiple parts have been replaced on a bike? As I stated earlier I was told at purchase that the bike had SP2 D port heads on it, not installed by the owner I bought the bike from. When I saw the dual injector throttle bodies I thought they were a newer part not installed in SP1 bikes.

*"D" port heads are 02-06 only.
*SP1 Injectors are not the same as SP2 injectors.
*SP1 injectors have 4 holes, where SP2 injectors have 12 holes.
*SP2 injectors have a different connection plug then SP1 injectors.
*SP1 ECUs are 16 bit units, where SP2s are 32 bit units.
*An SP1 ECU can be used on an SP2 injection set up, but it will run rich due to different mapping for the different injectors.
*SP1 injectors will not fit in SP2 Throttlebodies. They're longer.

You may have an SP1 motor with larger 64mm throttle bodies and the original SP1 ECU. If that's the case, you'll see either an SP2 harness, or spliced SP2 injector connectors on your SP1 harness. (Solderless connectors?)

[Bmeath]

The ECM came in today. Plugged it in and the bike fired right up. It now idles smoother than it ever has before. Thanks for the help to everyone who responded.

[Pigwax sp1]

How much did the ECM cost mate ?