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Discussion Starter #1
Hello All!

I'm fairly new to the v-twin world, but have been on inline fours for the past six years. I was lucky enough to get my hands on a 2006 RC51 this past winter for a steal, so I couldn't pass it up. I had to jump through some hoops to get a clean title on it, but after it was all paid off by previous owner, I've not got a clean title in my hands. Now for the problem...

I had it all torn down this winter to change oil, check fluids, rewire the hack-job in the rear tail and just a general clean up. We got it all buttoned back up and I took it out to ride, and ran into some serious problems.

The bike had been giving us a really hard time starting. The battery had plenty of juice and was cranking the engine plenty quick to turn over, but it almost seemed like it was starving out from no fuel delivery. The fuel pump primes properly, from what we can tell. Upon getting the bike started, I took it out to run it down the road a few miles and make sure it was good to go. As I was heading up through the RPMs, the bike seemed to hit a wall around 5000 RPM and just stumble and die out under hard acceleration. The bike never actually died, and ran perfectly smooth down under 5k RPM. Once it was pushed hard and I attempted to go back above about 4.5-5k RPM, it continued to stumble and would not pull at all. I've checked the PCIII and it holds a map and functions properly, so feel we've eliminated that from the list. I'm wondering if it's a bad fuel pump??? Also, the bike pretty much sat for around two years prior to be purchasing it from the guy, which also makes me think fuel pump.

If anyone out there has ANY suggestions, I would GREATLY appreciate any help whatsoever. I'm sort of at a loss, and really want to avoid taking it into a dealership in order to do work we can do on our own. Also, didn't want to blow a huge chunk of money on a new pump if that wasn't the issue as well. Hopefully someone has some input/suggestions on this issue. Thanks in advance!


Super Moderator
6,481 Posts
You can disconnect the power commander and reconnect the ECU to the injector harness to test if the module is faulty.

Two years is a long time to sit idle in mid-west summers and (especially) winters.
Did you look inside the tank for signs of rust buildup?
Was the fuel changed out for fresh?

I'm thinking possibly the fuel filter may be clogged and not allowing enough flow.
Unfortunately, the filter is attached to the fuel pump, which is inside the tank.
To get to it, you'll need to drain the tank and remove it, then remove the fuel pump assembly mounted at the rear of the tank.
To drain the tank, I'd pull the return hose on the fuel pressure regulator and let it drain into a container.
There will some residual fuel remaining, but it should be ok to flip the tank bottom side up and remove the pump.
Check the drained fuel for water or debris/rust.
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