Stalling Issue - Honda RC51 Forum : RC51 Motorcycle Forums
 4Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 12 (permalink) Old 07-08-2019, 06:33 PM Thread Starter
MTD
Junior Member
 
Join Date: Jul 2019
Posts: 3
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
Garage
Stalling Issue

I have an SP-1 with about 10,000 miles that I bought used in 2005. I hadn't ridden it much in recent years, so I went through and freshened everything up. I had never had an issue with it running. Now after it heats up (10-15 minutes of riding) the idle drops and eventually stalls. When this occurs I have to pull the choke and open the throttle 1/4 to 1/2 turn while thumbing the stater to get it going.

The other day I checked and replaced coolant. Coolant is circulating fine. Then a day later figured I'd start it and make sure the fan is kicking on when supposed to. Got it up to just under 220F and the rpms slowed and eventually stalled. I pulled the choke and stated it. Just past 220F the fan kicked on and the temp dropped to 190 pretty quickly, but the bike still wasn't idling properly. So I guess coolant temp isn't the issue.

Anyone have any ideas?
MTD is offline  
Sponsored Links
Advertisement
 
post #2 of 12 (permalink) Old 07-09-2019, 01:47 PM
Senior Member
 
LDH®'s Avatar
 
Join Date: Mar 2010
Posts: 2,212
Mentioned: 7 Post(s)
Quoted: 331 Post(s)
What rpms does it idle at when the engine temp reaches 190°?

Have you ever replaced the Fuel Pressure Regulator?
LDH® is offline  
post #3 of 12 (permalink) Old 07-09-2019, 03:35 PM Thread Starter
MTD
Junior Member
 
Join Date: Jul 2019
Posts: 3
Mentioned: 0 Post(s)
Quoted: 1 Post(s)
Garage
LDH, thanks for the response.

I have not replaced the fuel Pressure Regulator.

I don't know that 190° is the magic number or if it is time thing, but after running for 10 minutes or so RPMS gradually drop from 1,000 at idle to stall.
MTD is offline  
 
post #4 of 12 (permalink) Old 07-09-2019, 03:52 PM
Senior Member
 
jondog9's Avatar
 
Join Date: Aug 2010
Location: Northern CA
Posts: 8,653
Mentioned: 15 Post(s)
Quoted: 317 Post(s)
Maybe you have your idle set too low. From your description of dropping off from 1000 rpm and dying.
At 180 or above, set your idle to 1300.

Check your fpr for a leak at the vacuum line, it sounds highly suspicious to me. I'd probably install a new one.
But it's weird that you give it some choke to restart. A bad fpr usually dumps extra gas into both throttle bodies which causes a mild flood and stall at idle.
Check the vacuum line to the fpr is not leaking.
LDH® and Enxss like this.

John, 2000 RC51 #000100

jondog9 is offline  
post #5 of 12 (permalink) Old 07-09-2019, 05:05 PM
Junior Member
 
Join Date: May 2019
Posts: 13
Mentioned: 0 Post(s)
Quoted: 3 Post(s)
I have just restored an Sp1 to full running condition and have posted on anther thread recently. Replacing the Fpr was the final successful step. Easy to test and replace as per Jondog’s post. Thanks to all on this forum for sharing,it has been a fund of information for me.
Strudel is offline  
post #6 of 12 (permalink) Old 07-09-2019, 05:07 PM
Junior Member
 
Join Date: May 2019
Posts: 13
Mentioned: 0 Post(s)
Quoted: 3 Post(s)
Ps. At a certain stage of the saga I had the a similar issue with the choke
Strudel is offline  
post #7 of 12 (permalink) Old 07-18-2019, 06:56 PM
Member
 
Join Date: Aug 2014
Location: Tri-State Area
Posts: 32
Mentioned: 1 Post(s)
Quoted: 4 Post(s)
Quote:
Originally Posted by MTD View Post
Just past 220F the fan kicked on and the temp dropped to 190 pretty quickly ...
I agree with the others, it is most likely your FPR. However, I would like to comment on your temperatures. Unlike the SP2, the SP1 uses a Fan Motor Switch to activate the radiator cooling fan. Over time, the internal resistance of the switch changes altering the temperatures at which the switch opens and closes. Per the shop manual, the switch should close between 208 - 216 F (fan turns on) and reopen between 199-207 F (fan turns off). If your fan is not turning on until past 220 F and doesn't turn off until 190 F you should replace the switch. It's fairly inexpensive and easy to change, especially since you will have everything apart to check/replace the FPR.

jondog9, with regards to the "choke;" given that the bike is fuel injected I don't believe the "choke" is actually a choke. Though I am not certain, I think it is actually a manual idle control. By pulling out the "choke" he is actually increasing the idle by opening the throttle body butterflies slightly. Thereby leaning out the fuel/air mixture, not enriching it as an actual choke would. This is equivalent to partially opening the throttle as he describes. And, yes, I know, even the owner's manual and the shop manual refer to it as a choke. There is even a small choke butterfly stenciled on the knob. Correct me if I am wrong, but to the best of my recollection there are no choke butterflies on the throttle body itself.

Current Rides:
2001 Honda RVT 1000R, SP1 - a.k.a. RC 51
* 90 Degree, Single Pin Crank, V-Twin
* World Superbike Championship, 2000 & 2002
* AMA Superbike Championship, 2002
2010 Aprilia RSV4 R
* 65 Degree, Dual Pin Crank, V-4
2017 Honda CBR 1000RR, ABS - a.k.a. Fireblade
* Flat Plane Crank, Inline Four

Previous Rides:
1990 Kawasaki ZX-10
* World's Fastest Production Bike When First Introduced
And a whole bunch of dirt bikes.

Last edited by Enxss; 07-18-2019 at 07:41 PM.
Enxss is offline  
post #8 of 12 (permalink) Old 07-19-2019, 05:07 PM
Senior Member
 
Join Date: Nov 2018
Posts: 150
Mentioned: 0 Post(s)
Quoted: 39 Post(s)
They're enriching circuits , just like a carb , it opens a fuel passage..
Enxss likes this.
Joe XR is offline  
post #9 of 12 (permalink) Old 07-19-2019, 05:50 PM
Member
 
Join Date: Aug 2014
Location: Tri-State Area
Posts: 32
Mentioned: 1 Post(s)
Quoted: 4 Post(s)
Quote:
Originally Posted by Joe XR View Post
They're enriching circuits , just like a carb , it opens a fuel passage..
So it is indeed a choke, despite the engine being fuel injected. I always assumed that the enrichment was done by the ECU via an extended pulse duration to the fuel injectors. But now I see how the enrichment is done in addition to the injectors via the mechanical enrichment circuit. Thank you for clarifying that, Joe XR.

jondog9, that goes back to your comment about the choke. The bike should indeed be easier to restart after being flooded by the faulty FPR with the choke fully closed.

Current Rides:
2001 Honda RVT 1000R, SP1 - a.k.a. RC 51
* 90 Degree, Single Pin Crank, V-Twin
* World Superbike Championship, 2000 & 2002
* AMA Superbike Championship, 2002
2010 Aprilia RSV4 R
* 65 Degree, Dual Pin Crank, V-4
2017 Honda CBR 1000RR, ABS - a.k.a. Fireblade
* Flat Plane Crank, Inline Four

Previous Rides:
1990 Kawasaki ZX-10
* World's Fastest Production Bike When First Introduced
And a whole bunch of dirt bikes.
Enxss is offline  
post #10 of 12 (permalink) Old 07-19-2019, 06:03 PM
Senior Member
 
Join Date: Nov 2018
Posts: 150
Mentioned: 0 Post(s)
Quoted: 39 Post(s)
A choke has a plate to restrict the inlet of a carb to pull up more fuel , an enriching circuit opens a fuel passage and is NOT a choke.
Enxss likes this.
Joe XR is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Honda RC51 Forum : RC51 Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome