Lower idling when bike is in upright position??

Hi,

Just another problem from the 'ol fizzer..
My bike idles a bit higher when placed on its side stand, and when i sit on it (upright position) I could hear the idling decrease in revs.

Sometimes when I'm at the lights etc., it seems like it's gonna cut off. Which it did like once or twice already, which normally I would give it a few revs just to keep the idling 'normal'.. What may seem to be the problem?.. I'll have a shot and say it's the fuel pump?

Cheers

 

Normal idle is 1600 rpm, it might seem a bit fast but that is where it is. So make sure you have it set about right..

 

How do you do that when the tacho only starts at 3000rpm?

 

Good question. Need an external hand tacho that works off the spark lead.

 

Thanks for the reply Dave, but i have set the idle as high as 2-3K's before as i could tell from the engine sound and giving it a bit or rev to see the tacho movement from 3K's onwards. And it still tends to drop low when the bike goes upright.. and may/can/will die out sometimes.

 

Very strange - check for possible air leaks in the rubber boots between the carbs and head.

Is the air box firmly mounted? If the boots are loose they could get moved. I presume the bike runs fine otherwise under more throttle?

 

Yep it runs fine with a little nudge of the throttle... just that the 'dying out' happens usually when the bike is cold...and the decrease in idle rpm occurs a bit longer after the bike is warm. i.e. stuck in traffic.

Cheers

 

Where are you located?

 

Western sydney.

 

Ok, I'm not going to be much help then.

The only things that comes to my mind is your fuel pump is on its way out and does not have much lift when the bike is leaning over but when you lift it up the gravity feed works better.

 

Haha thanks for your offer Trevor,
It's more like the opposite is happening... bike idles fine and smoothly when on its side stand, and when its upright, the idle goes down a bit...
Weird problem i know... =.=" May it be my carbies needing a clean, valve clearances etc?.. I'm not too mechanically minded when it gets to the motor even though i could change my brake pads, chains and sprockets. =\

Cheers

 

So after all this time, i still couldnt find out what my problem was with the weird idling.. and my bike died a few times already in peak hr sydney traffic at night... (with headlights on) and I wasn't able to start it without cranking it in first (what makes it worst is that my fan is always on.. I think it's hard wired).

The battery is new since i only got it a month or so ago. So I'm wondering now if it would be a charging problem with the rectifier/regulator.

I have increased the idle to around 2.5K~ rpm to 'try' to keep the engine idling, but sometimes it will drop back down again and will eventually die out but it takes a longer period of time before this 'drop in idling' happens.

I took out a multimeter and did some measurements. When the bike is idling (side stand), i get a reading of about 13V+ because I increased the idle. With the headlights on while idling, it goes down to 11.8V-11.9~ and at 5K rpm it reaches about 12.1-12.2V.

In the upright position all these readings fall significantly with idling at around 12.2V~ (very inconsistent) and with the headlights on at a reeeaally low 11.4-11.6V~.

Btw, i was wondering where my rectifier/regulator was.. I done a search.. but just want to make sure, there's a pic below.
I'm guessing it's that black thing on the left of the pic with the red writing and it also gets really hot...~

And is it expensive to replace the rectifier/regulator? Or the question maybe... is it my rectifier/regulator, because i read about the miracles the replacement of the unit is on this forum.

CHEERS =]

 

The voltage is too low at 5000rpm should be more like 13.5-14.5volts, just try it with the fan disconnected..

Have a look in the alternator and make sure the coils are not loose, or something silly like that.
You would have to pull the flywheel off to get a good look, and I think you need a proper puller tool to get it off..

 

Thanks for the reply Dave, I'll take a look when I get some time tomorrow hopefully.
The situation is pretty similar with the fan disconnected..

Anything specific things that I should look for when i pull open the alternator cover?

 

Under the flywheel is where the alternator stator coils are located. Not sure you will be able to do much without taking the flywheel off. You MAY be able to get your fingers around the edge and feel if the coils are loose..

However, if you had the radiator fan turned off when you did the voltage test then I would look at replacing the rectifier/regulator first..

Here is a good flow chart for fault finding alternator systems. Keep in mind that where it says 2500rpm in the third block down, think about 3500-4000rpm for the FZR250
<!-- m --><a class="postlink" href="http://www.electrosport.com/technical-resources/library/diagnosis/pdf/fault-finding-diagram.pdf">http://www.electrosport.com/technical-r ... iagram.pdf</a><!-- m -->

 

thanks again Dave , I'll follow the diagram when i get home and see how i go.

Cheers.

 

So okay, I havent followed the diagram yet but after my peak hr ride home today, i quickly done a multimeter test on the bike. It was reading 11.6V~ with ignition off. So I started her up, and started measuring again with the multimeter. It still registered the same voltage and when I gave it a Rev, nothing much changed and the batt stayed around 11.6-11.8V~

Took off fairings then had a look at the rectifier (the black trapezoidal looking thingy with red writing) and it was HOT and the frame that it was mounted as well as the seat supporting ones were also HOT. Like it was so hot i wouldn't be able to touch it for more than 2 seconds.

May I get a response regarding this situation on the R/R before I get serious on taking apart the bike?

Thankies.

 

The regs do get very hot in normal operation. The alternator is putting out enough energy to make the reg hot, but the reg is not putting any out, therefore not charging the battery.

I take it you measured the voltage WHILE the bike was revving at +4000rpm..
If that is the case, I would definitely try another rectifier/regulator..

 

Yup I would be changing the r/r sounds like it is on it's way out.

 

Yeah bike was idling at around 3.5K's~ and also gave it a rev cos i increased the idle to stop it from cutting out.

Asked today at wreckers... 75 bucks for the R/R <!-- s --><img src="{SMILIES_PATH}/icon_sad.gif" alt="" title="Sad" /><!-- s -->

I'll try to eliminate the stator coils first..
How would I measure the three 'white' wires coming from the alternator with a multimeter? I read it has to be somewhere between 50-100V


Thanks <!-- s --><img src="{SMILIES_PATH}/icon_biggrin.gif" alt="" title="Very Happy" /><!-- s -->