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Discussion Starter #1
Asking for help from the forum today. You guys were very helpful last time, but I have a new issue. This RC is lucky that I love her so much :). Anyway:

I'm hoping to do this step by step to avoid confusion and narrow things down. Thank you ahead of time. I will give estimates as accurate as I can.

I will give away free beer if we figure this out. (I'm serious, if you're local, I'm in Asheville, NC. C'mon by.)

2003 RC51. It's been my project for a year now. Almost had it figured out, right before a winter nap. :mad:

1) If I start the bike, it will fire right away and idle for ~10 seconds, then stall and die. All running lights and gauges will stay on. No FI light. No stored FI codes.
2) If I try to restart it, it turns over but never catches again.
3) If I ignore it for an hour or so and come back to it, it will fire right away and I'll get another 10 seconds of idle.
4) If I give it throttle when catch it in time while idling, it will stay revved as long as I hold it (I don't give it much, I can hover it around 2-2.5k)
5) Once the bike starts registering temp and I get it to 160-180F, I can sustain idle.
6) If I try to ride it, it runs rough, but not horrible (probably need to adjust a map)
7) If I turn it off, as long as it's still warm, I can crank it right back up.
8) After it cools and sits, it's back to step 1.

PC 3USB. New Plugs (heat range 9). New FPR from Honda, installed during my last troubleshooting.

Thoughts?
 

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Have you tried running the bike without the PC3 hooked up?

Are all the vent and fuel lines clear of debris and not kinked?

Whats your idle set at?
1250 +/- 50 is the OEM setting. Set at op temp.

Fresh fuel?

I'll be in Asheville over the weekend of the 24th for this, https://www.facebook.com/events/928606137164727/
 

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Discussion Starter #4
Bike without the PC3 is the same behavior at idle, although riding at op temp is worse. So if anything the PC3 seems to be operating ok. The PC3 doesn't affect idle though right? I thought I read that somewhere.

Idle (after I force it to warm up) is around 1350-1400.

Idle screw does nothing. Either direction. Hmmm. I have a TurnOne Carbon Airbox mod, wonder if something came loose.

Fuel was 'fresh' last winter, I added the proper additives for storage. Does 'bad' gas cause a number of things like that? (I don't mind wasting a tank if I have to though)
 

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It all depends on the map if it effects the idle or not.

I have DHC open box and when setting the tank in place I have to be careful not to kink the supply (big) fuel line. I would double check everything around the air box just to be certain.

Bad gas can cause a number of issues. If left long enough it will gel, then harden, clogging everything. But with my experiences that takes longer than just a winter. And with additives this will take even longer. When you say last winter, do mean 2014/2015 or 2013/2014?

But the ethanol in most gas now days will pull moisture out of the air and we all know how well an engine will run on water. I've read that gas left to open air, after a month it will start to deteriorate. Our tanks are vented so consider them open.

If it was winter 2014/2015, I do not think old fuel is fully reasonable for this, but it is defiantly not helping.

I don't know if a clogged vent would cause this issue but try to run the bike with the gas cap open. If it runs right with it open I'd check the tank vent lines.

You didn't forget a shop rag sitting on the throttle bodies like I did, did you?:rolleyes:
 

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Discussion Starter #7
HA! No shop rags hiding as far as I can see :)

The gas is from winter 2014. Actually thinking about it though, it's probably around 6 months old. I'll dump it just to be sure.

I think I'll just take the whole tank off at this point. Go over everything around the airbox. I'll add pics if I get stuck.

I'm gonna trace the idle screw too since it does nothing. Very strange. Do those break easily? Or get 'over torqued'?
 

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Pull a plug and see what it looks like.

a couple things I can think of that would cause an issue like this.

Too much fuel (or not enough air for the amount of fuel)
Not enough fuel (or too much air for the amount of fuel)
Weak spark

I can run gas in an engine that is two years old, so I doubt the fuel is the issue. It may not rev to 10k, but it should at least stay running. I swear by the Lucas fuel treatment for all my engines. (truck, bike, snowblower, lawnmower, etc)
 

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Discussion Starter #9
Pull a plug and see what it looks like.

a couple things I can think of that would cause an issue like this.

Too much fuel (or not enough air for the amount of fuel)
Not enough fuel (or too much air for the amount of fuel)
Weak spark

I can run gas in an engine that is two years old, so I doubt the fuel is the issue. It may not rev to 10k, but it should at least stay running. I swear by the Lucas fuel treatment for all my engines. (truck, bike, snowblower, lawnmower, etc)
Lucas is actually what I used, so maybe I'm good there.

Ok, so getting a list together:

1) Check hoses/ lines around airbox and fuel tank
2) Pull plugs and check condition
3) Check spark strength
4) See why idle screw does nothing? (or is this a 'symptom', not a 'cause')

Thanks so far guys.
 

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I just went over your other threads and noticed that the flapper valve was removed on top of the snorkel, did the vacuum line for it get capped on the front of the front throttle body?

If we don't figure it out, I'll be getting to Asheville the night of 23rd (Thurs) and should be able to look at it on the 24th.
 

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Discussion Starter #11
I just went over your other threads and noticed that the flapper valve was removed on top of the snorkel, did the vacuum line for it get capped on the front of the front throttle body?

If we don't figure it out, I'll be getting to Asheville the night of 23rd (Thurs) and should be able to look at it on the 24th.
5) Check the caps. Nice. The mod was done by the PO, I'm assuming he did it correctly (key word being assume).

Otherwise, yes, I should be around that time (with beer).
 

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Lucas is actually what I used, so maybe I'm good there.

Ok, so getting a list together:

1) Check hoses/ lines around airbox and fuel tank
2) Pull plugs and check condition
3) Check spark strength
4) See why idle screw does nothing? (or is this a 'symptom', not a 'cause')

Thanks so far guys.
If it's not screwed in far enough it will have no effect. Screw it in (turn clockwise) until it changes the idle then back it off till proper idle is set. With the tank up you should be able to see it on the right side of the throttle bodies.
 

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If you are idling hot at 1350-1400 then I'd say you are ok. During cold start you would pull back/out on the little high idle knob. When cold that will have my bike idling at 2,500 or so.
 

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5) Check the caps. Nice. The mod was done by the PO, I'm assuming he did it correctly (key word being assume).

Otherwise, yes, I should be around that time (with beer).
I never assume anything is ever done "correct," even when I do something. Things are all just at different levels of how well its working at a given point.

Mike does bring up a good point, depending on the temp of the bike, you may not have an issue. Honda's are known for being cold blooded.
 

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Zero, you are using the little "choke" knob on the left side of the bike when you do a cold start, right? It's really just a high idle pull knob but the bike won't run cold for more than a couple seconds if that isn't pulled out. Even if the bike is at 100* and I push the knob back in and take off, the RPMs will dip to just over a grand as the engine is still cold. If I push the knob back in right after starting, the engine will stall.
 

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Discussion Starter #17
Update guys, work has been killing me this week. I'm pretty sure that I've been using the 'choke (high idle)', although that would be hilarious if that was it.

But then again, when I say it has to be up to operating temp. before it idles 'freely', I mean, anything less than 160 or so, it falls on its face.

I will check for a shop rag in the throttle body too LOL.

^I will test the above from you all and report back.

Side Note: Ok, so I was discussing this with the PO yesterday, the time this particular RC went down, the tail got knocked pretty good. One of the first things I did was replace the subframe with a nice shiny 'new' one (gently used, straight as an arrow now lol).

I didn't see any obviously damaged parts, ripped wires etc.

However we were talking about the possibility of needing a new rear wire harness/sensors/coils/rr/CDI/ECU or any of the various things housed in that area.

Based on my last problems (although the FPR was a big part of it) I'm wondering if I should move my search there next. Like if it was a spark issue for example.
 

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Update guys, work has been killing me this week. I'm pretty sure that I've been using the 'choke (high idle)', although that would be hilarious if that was it.

But then again, when I say it has to be up to operating temp. before it idles 'freely', I mean, anything less than 160 or so, it falls on its face.

I will check for a shop rag in the throttle body too LOL.

^I will test the above from you all and report back.

Side Note: Ok, so I was discussing this with the PO yesterday, the time this particular RC went down, the tail got knocked pretty good. One of the first things I did was replace the subframe with a nice shiny 'new' one (gently used, straight as an arrow now lol).

I didn't see any obviously damaged parts, ripped wires etc.

However we were talking about the possibility of needing a new rear wire harness/sensors/coils/rr/CDI/ECU or any of the various things housed in that area.

Based on my last problems (although the FPR was a big part of it) I'm wondering if I should move my search there next. Like if it was a spark issue for example.
If it was any of those, I think it wouldn't run, or that the issue would not change with temp. But could be something to keep in mind

To go along with what Mike said, I fired mine up today, mid to low 70's here. No choke/high idle it ran for about 2 seconds then fell on its face. Pulled the choke/high idle, on the left side of the bike while sitting on it, let it run for 3 to 5 minutes and off we went.
 

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I also doubt it is a wiring issue at the back of the bike. The original post said the bike still ran rough even after warmed up, so there is a problem with spark/fuel/air for sure. if there was access to a tester, it would be easy to check the fuel/air ratio and be able to tell if it was rich or lean, and a visual inspection of the plugs would give away any spark issues. (or it should)
 

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Discussion Starter #20
Alright quick post before work.

I was checking the plugs, they aren't soaked with fuel or anything like that, but I may have found some of the issue.

When bought new plugs, the vendor gave me the wrong ones. And I failed to read them, assuming they were right and put them in:

I have SP1 NGK plugs installed (FR9BI-11). I needed SP2 plugs (IFR9H11).

This may be the fix right here (or does it not make that big of a deal)....
(Either way I'm gonna buy the right plugs this weekend)
 
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