SP1 Hard start issue- video Inside - Honda RC51 Forum : RC51 Motorcycle Forums
 
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post #1 of 7 (permalink) Old 09-08-2010, 09:34 PM Thread Starter
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SP1 Hard start issue- video Inside

Howdy everyone, just picked up a 2000 SP1 project bike (emphasis on project !) I am trying to suck up as much info as I can, as I have always wanted a RC. Then my wife bought me a new busa, so the 51 still was in the back of my head. I will likely finish working the bugs out of this one, and get myself a SP2....

Anyway, the bike is real slow to start. Previous owner says it has been for a while. You have to modulate the throttle just right, and the cranking is slow. Once it fires, it runs and rides fine, but my other bikes crank very fast, this one cranks half as fast. See video.

I put all fresh fluids and plugs in it, and same issue. So any advice? I thought I read somewhere about a throttle posisiton sensor or some rectifier module. I have access to a SP2 parts bike, and of course the usual sources.

Thanks All

Video:
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post #2 of 7 (permalink) Old 09-09-2010, 12:13 PM
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Try an fuel filter and if that doesn't work try a fuel pressure regulator. Mine was doing the same thing and once I changed them it fires right up on the first try. Both are pretty cheap your looking at around 100.00 for both and its pretty simple to change.
Check with subsailor on this forum for a better diagnosis

Last edited by kpowe1; 09-09-2010 at 01:55 PM.
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post #3 of 7 (permalink) Old 09-09-2010, 12:26 PM Thread Starter
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Thanks. I am hoping Subsailor checks in soon, LOL
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post #4 of 7 (permalink) Old 09-09-2010, 02:21 PM
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Need to ask a few questions.
Was the video recent or during the winter?
Was the engine cold or at operating temperature?
If cold, was the fast idle knob pulled out?
What is the engine idle speed at operating temperature?
Have any mods recently been done that may have dislodged a vacuum hose?
What is the battery voltage with the key off?
What is the charging voltage with engine speed at around 4000+ RPM?
Didn't notice the FI light on, but does it come on?

Last edited by SubSailor; 09-09-2010 at 02:24 PM.
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post #5 of 7 (permalink) Old 09-09-2010, 03:07 PM Thread Starter
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Thanks Sub, Answers that I know are below!

Was the video recent or during the winter? It was last Night, Daytona Beach, FLorida, so you know our weather here.. Mid 80's Had rain earlier in the night, but when I got the bike on Sunday, it was upper 80's, dry, and same issue

Was the engine cold or at operating temperature? Cold, although it does the same thing even when hot.

If cold, was the fast idle knob pulled out? Yes, although it tends to slowly slide back in, it still holds fast idle when out, slows idle when in.

What is the engine idle speed at operating temperature? Prior to oil change, it was 1500 rpm, after oil change, 1300 rpm. No lumps, bumps or funny stuff.

Have any mods recently been done that may have
dislodged a vacuum hose? No. It was hard to start before it fell of the truck (not sure if you saw any of my threads on the other boards, but the bike tipped off the ramp as I loaded it onto the truck when I bought it a few days ago. Landed on the right mirror- Broke the nose where mirror attaches, and the twisted the upper fairing stay, as a leak out of the right rad currently, otherwise, no other issues. Bike rides great and hauls the mail fine, just sluggish to kick over.

What is the battery voltage with the key off? I will check tonight, no idea, but my auto charger reads full charge, LOL...

What is the charging voltage with engine speed at around 4000+ RPM? Same as above, will try to check tonight

Didn't notice the FI light on, but does it come on? Yes, when it does its power on start up test it lights, but goes out

Thanks Sub, Answers that I know are above!

So additional info I knwo about this bike. Guy has the radiators setup in series, with some crapoy second fan on the right side one, wired into the left side harness. He also supposed did the Pair valve mod and some other common RC mod (reed blockoff or something). Bike has K&N filters in it as well. TB's look pretty clean for a 30k bike, no other real issues I am aware of yet...


On that note, I also just bought a SP2 to tinker with that I was originally going to buy parts from, but its more "intact" and easier to find stuff for, so chances are, I will just sell off the Sp1, but I'd liek to fix whatever I can in the meantime.

Last edited by UrbanKnight; 09-09-2010 at 03:12 PM.
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post #6 of 7 (permalink) Old 09-09-2010, 05:12 PM
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In the video, it sounds like the engine is just slow to turn over (good video, but not the same as being there).
That's why I was asking about the battery condition when not on a charger (as in overnight).

If the battery was old and a cell was going bad, it may not have enough cold cranking amps to spin the engine over.
That's why I was asking about the voltage with the switch off. Anything around 11v is basically dead and below 12 could indicate a cell going bad.

Now if the charging system is not sending 13.5 to 14.5v to the battery, then battery may be fine but a problem may be with the electrical system.

Does the bike have a heavy fuel smell and run as if rich (spark plugs dark and possibly wet, or exhaust very dark at the outlet)? A fuel pressure regulator can cause that to varying degrees. Or does it run lean?

Since the bike tipped over off the ramp, it may have dislodged some debris in the tank and clogging the fuel filter, or the fuel pressure regulator may be going bad.
That's why I was asking about the smell or plug and exhaust color.
Have the plugs been changed recently?

If you have a power commander installed, have you tried disconnecting it and connected the OEM connectors?

The FI system isn't throwing any codes, so it thinks all's well.
So it's not detecting any sensor/wiring issues.

Last edited by SubSailor; 09-09-2010 at 05:19 PM.
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post #7 of 7 (permalink) Old 09-09-2010, 08:14 PM Thread Starter
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In the video, it sounds like the engine is just slow to turn over (good video, but not the same as being there).
That's why I was asking about the battery condition when not on a charger (as in overnight).

If the battery was old and a cell was going bad, it may not have enough cold cranking amps to spin the engine over.
That's why I was asking about the voltage with the switch off. Anything around 11v is basically dead and below 12 could indicate a cell going bad.

Now if the charging system is not sending 13.5 to 14.5v to the battery, then battery may be fine but a problem may be with the electrical system.

Does the bike have a heavy fuel smell and run as if rich (spark plugs dark and possibly wet, or exhaust very dark at the outlet)? A fuel pressure regulator can cause that to varying degrees. Or does it run lean? Plugs looked good when I pulled them, but I put fresh ones in anyway. Nice and even color burn, No smell really at all

Since the bike tipped over off the ramp, it may have dislodged some debris in the tank and clogging the fuel filter, or the fuel pressure regulator may be going bad.
That's why I was asking about the smell or plug and exhaust color.
Have the plugs been changed recently? Just put fresh ones in, but the bike was the same starting issue before tipping over, so I know it was a preexisting condition so to speak.

If you have a power commander installed, have you tried disconnecting it and connected the OEM connectors?
No power commander
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