RC51 Forums banner

1 - 20 of 20 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter #1
Everytime I take her for a spin it struggles to stay at a constant RPM. For example; when I get on the freeway and try to stay at a steady speed it lurches on me and the RPMs jump around. I recently purchased a power commander as well but I did not get the disc for it, can I find the maps and stuff I need online? Also, I know nothing about fuel injection cause this is my first fuely bike and I am not very tech savvy. Any help fellas? Thanks..
 

·
Premium Member
Joined
·
8,335 Posts
Tell us more about your bike....post some pictures too. What kind of exhaust are you running?

Did it do this before the PC was installed?
 

·
Registered
Joined
·
13 Posts
Discussion Starter #3
Stock everything. Yes it was doing this studdering thing before the I put the PC in. I was hoping the PC would help smooth it out but it didn't change anything so I'm not sure if I did it right.
 

·
Registered
Joined
·
382 Posts
What RPMs are you trying to stay at? mine does the same thing at low RPMs. (also new to fuel injection) I have already found out that while it sounds great and can cruise at 3k under slight load without problem, at 5k, it rides a lot nicer.
 

·
Registered
Joined
·
1,294 Posts
Pulled the plugs to inspect them yet?
 

·
Super Moderator
Joined
·
6,481 Posts
As mentioned by f3racer, out of the box, the power commander unit is at a "zero setting" with no changes being made to alter air/fuel ratios.
The act of altering the base setting via importing a saved map or creating a custom map via a series of dyno runs is what alters your fuel metering.

These bikes generally don't care much for putting below 3500 RPM, and especially below 3000 RPM (Harleys they ain't).
At low RPMs and in lower gears (3rd or below), they can easily get into very jerky or lurching motion through a combination of flywheel inertia and multiplication of force by the lower gearing selection.
When that occurs, I usually just grab the clutch lever, disengage the engine, and let it settle down.
Above 4000 PRM, no problems with mine in any gear.

Now if it's misbehaving while traveling down the freeway, and it has an aftermarket exhaust, the exhaust may be causing a lean condition at certain RPM ranges.
When I first bought mine, it had a Jardine 2 to 1 exhaust installed, and beginning at 5600 RPM, it began getting really lean to the point of misfiring.
A simple dyno run to remap the power commander and everything was just dandy.
 

·
Registered
Joined
·
13 Posts
Discussion Starter #8
Sometimes it backfires when I coast like up to a stop sign and no matter what rpm's I am running it still lurches like that. I was told recently by another RC owner that I am missing the piece that plugs into the "dash" right below the indicator lights. It has something to do with the vent between the headlights?
 

·
Premium Member
Joined
·
928 Posts
Sometimes it backfires when I coast like up to a stop sign and no matter what rpm's I am running it still lurches like that. I was told recently by another RC owner that I am missing the piece that plugs into the "dash" right below the indicator lights. It has something to do with the vent between the headlights?
The flapper valve?:confused:
 

·
Registered
Joined
·
13 Posts
Discussion Starter #13
Ok I will cover it. What is a good temporary fix? Hate to put duct tape on there but if I have to I will. Also, can you explain what the valve does? I'd like to learn why
 

·
Registered
Joined
·
140 Posts
My first RC, new/stock was jerky and hard to hold a steady rpm.
My new to me RC has been geared, pc with good map and flapper pair removed and the drivability is much better!!! I would go with Cobra and check/replace plugs first.
 

·
Registered
Joined
·
2,246 Posts
As mentioned by f3racer, out of the box, the power commander unit is at a "zero setting" with no changes being made to alter air/fuel ratios.
The act of altering the base setting via importing a saved map or creating a custom map via a series of dyno runs is what alters your fuel metering.

These bikes generally don't care much for putting below 3500 RPM, and especially below 3000 RPM (Harleys they ain't).
At low RPMs and in lower gears (3rd or below), they can easily get into very jerky or lurching motion through a combination of flywheel inertia and multiplication of force by the lower gearing selection.
When that occurs, I usually just grab the clutch lever, disengage the engine, and let it settle down.
Above 4000 PRM, no problems with mine in any gear.

Now if it's misbehaving while traveling down the freeway, and it has an aftermarket exhaust, the exhaust may be causing a lean condition at certain RPM ranges.
When I first bought mine, it had a Jardine 2 to 1 exhaust installed, and beginning at 5600 RPM, it began getting really lean to the point of misfiring.
A simple dyno run to remap the power commander and everything was just dandy.

Most of your post is pretty accurate, but for clarification Powercommanders come preloaded with a stock map, not the zero map.


More importantly though there is no reason to ever lug an RC51 around at 3000rpm during steady state cruise. If you are riding that slow then downshift a gear or two and get the rpms up. You've got lots of things working against you at that low of an rpm setting not the least of which is a EPA friendly ECU mapping to lean out the A/F and a huge flywheel required by large displacement v-twins to keep spinning around while the lean surging is occurring.
 
1 - 20 of 20 Posts
Top