Starting issues when bike is warm

M

mbrooke79

Member
Visit site
Hi everyone. I have a 2006 yamaha fz1 with 9,000 miles. The bike starts up with no issues when the engine is cold. The issue I am having is once the bike has been ridden around and warmed up it is having issues starting back up. I purchased a new battery and checked if it was charging. No problems there. Battery is strong. I adjusted the idle to about 1200-1300 and still doing the same thing. I have searched the forum and done what others have suggested. Any other suggestions on what the problem may be? Thanks
 
can you explain the hard starting in more detail? I saw you said you replaced battery, was it slowly turning over like it was a drained battery?
 
JMundy said:
can you explain the hard starting in more detail? I saw you said you replaced battery, was it slowly turning over like it was a drained battery?
Click to expand...
the battery does not sound like its drained. I checked the power with my multimeter and is within normal range. The battery charges normally. I can hear the starter attempting to start the engine but does not start until maybe the 4th try. Ill hold the starter in for a good 5-10 seconds but does not start. Once it does start the idle slowly creeps up to about 1100 rpm. Keep in mind I already set the engine idle to about 1200-1300 rpms once in normal operating temperature.
 
I tried opening the throttle a bit before but same thing. What i dont get is it only happens after the bike is warmed up. Maybe time for a spark plug change
 
Plug gap being slightly too wide will have the hot start symptom you describe, but I don't know why.
My plugs are so hard to get to that I change them every winter when I do a valve set. Different bike, and I do an average of 20,000 km. Per year. I use Iridium plugs.
 
Can't be many miles on them, says 06 with 9000 on it. Would start by pulling the plugs to inspect them and check the gap, doesn't cost anything but your time if you can do it yourself. If not that, do you think the bike is turning over fast enough? when the starter is hot it may be lacking the same power as it does when it's cold. if it doesn't spin the motor fast enough for the crank sensor and ect to read properly you could get this symptom.
 
I've had the exact same problem with mine when warmed up as well with my 07. No problem cold. It would crank hard but not start and would take 3 or 4 times. Then when it would, it would start up slow and weak at first. It for sure wasn't plugs or battery since they were both replaced, and I always keep up on my oil changes. I never really did anything, and it just eventually went away. It happened a lot to me last year when the weather was transitioning from cold to warm. And now, it's happening to you when its transitioning from warm to cold. I did some reading on it before and saw some suggestions about how gas is a little different during the different seasons. Don't quote me on it but that could possibly have something to do with it.
 
What octane gas do you use? I have the same year bike and same mileage. The symptoms you are describing was exactly like mines. I bought the bike used and did not know that 87 octane was the recommended fuel. When I received the bike I put 91 octane. The symptoms started when I used 91 octane. A member from here recommended I go back to 87 and have not had the issue since.
 
mbrooke79 said:
What octane gas do you use? I have the same year bike and same mileage. The symptoms you are describing was exactly like mines. I bought the bike used and did not know that 87 octane was the recommended fuel. When I received the bike I put 91 octane. The symptoms started when I used 91 octane. A member from here recommended I go back to 87 and have not had the issue since.
Click to expand...

Now that I think of it, it also seemed to happen back when I used 91. I switched to 89 and it seemed to stop although I don't know if that's why. I've been using 89 since then, and especially now with Ivan's flash.
 
When starting cold a rich fuel mixture works best. This is why carbs have chokes. I'm guessing that even when the engine is warm a richer than normal mix helps get things going. Maybe when the ECU senses that the engine is warm and delivers a very lean mixture that just doesn't catch nicely when trying to start? That's my best guess.
 
Interesting to find this thread because I have had the exact same problem as some of you have described here and I have been using 91 octane since I purchased my FZ1. I will try using a lower octane fuel and see if that makes a difference. :dontknow:
 
You must log in or register to reply here.
Back
Top