Bikes dies out on this one specific sharp right turn.

[azian4lifz]

Hi all,
On my way home I take twisty back roads to avoid traffic on the hwy. The road that I have trouble with is shaped like a upside down J letter.
The speed limit before the turn is 45 mph and the road after the turn is 25 mph due to bicycle paths and residential neighborhoods. Being on a 250, that would mean down shifting from 4th gear to 2nd gear but when i approach the sharp right turn I slow and down shift into 2nd before the turn but in the process of downshifting my bike dies out so my bike ends up rolling on right turn because I cannot stop due to possibility of a car being behind me. After I rolled into the right turn I have to press the push button to start my bike up again while still rolling. I do not know why this happens but it happens almost every time.

This road(45mph) is on a downhill and the road after I make the right turn(25mph) is flat and even.

I feel like I should downshift into 1st gear and then make the right turn but 1st is too slow for the road I am on(45 mph) when slowing down to make the right turn.

This is not a problem with the carb because they are cleaned.

I think it might be a caused by coasting in neutral for 1 second before downshifting into 2nd. But I cannot successfully shift into 2nd without the red light in the bottom right corner lighting up meaning bike's off.

Other than this specific turn I have no problem making turns on any other road. Thanks for reading hopefully someone can help me out and if there is a thread on this already please re-direct me.

[Motofool]

That is not normal and can be very dangerous when cars are following you.

Your idle rpms may be too low; it should be between 2K and 1.5K.

If not, you may also have some vacuum leaks that make the suction at the petcock marginal for any but high rpms, making the level in the bowls too low at times.

[Sirref]

it can't be caused by coasting in neutral unless you kick it into 1st before kicking back up to 2nd.
on that note how are you downshifting, are you keeping the clutch pulled and kicking shifting down all at once or are you downshifting one at a time (my preferred method) in addition to this are you blipping the throttle with each downshift to revmatch? this wouldn't be a problem with only one downshift at a time but you could be stalling it by not matching engine and road speed.

other than that check your tank for a vacuum leak, my 250 had this problem when I got it.

[azian4lifz]

Originally Posted by Motofool

That is not normal and can be very dangerous when cars are following you.

Your idle rpms may be too low; it should be between 2K and 1.5K.

If not, you may also have some vacuum leaks that make the suction at the petcock marginal for any but high rpms, making the level in the bowls too low at times.

Thanks for your input. You are right, my idle rpm is too low. I set it at 1k.
I set it at 1k because I thought it would was appropriate since the previous owner left it at 4k with a bad uncleaned carburetor.

If the problem is due to the vacuum leak what should I try to fix? and How would I be able to do this? If I am not able to fix it on my own I will take her to get it checked out but I would prefer not to do that.

I will make the change tmrw morning to set it at 2k. Hopefully this resolves the issues. If not, anything else is should be aware of?

[azian4lifz]

Originally Posted by Sirref

it can't be caused by coasting in neutral unless you kick it into 1st before kicking back up to 2nd.
on that note how are you downshifting, are you keeping the clutch pulled and kicking shifting down all at once or are you downshifting one at a time (my preferred method) in addition to this are you blipping the throttle with each downshift to revmatch? this wouldn't be a problem with only one downshift at a time but you could be stalling it by not matching engine and road speed.

other than that check your tank for a vacuum leak, my 250 had this problem when I got it.

I am downshifting all at once but from a reasonable distance before the turn and I do not go into 1st then 2nd. It would be from 4th into 3rd then 2nd.

What is blipping the throttle?
I only revmatch upshifting. Downshifting I make sure I am riding in appropriate speed before downshifting.

Thanks, I will look into it.(vaccum leak) so far I think that is the problem but i am not quite sure because I never had a issue with a vacuum leak.

[Sirref]

Originally Posted by azian4lifz

I am downshifting all at once but from a reasonable distance before the turn and I do not go into 1st then 2nd. It would be from 4th into 3rd then 2nd.

What is blipping the throttle?
I only revmatch upshifting. Downshifting I make sure I am riding in appropriate speed before downshifting.

Thanks, I will look into it.(vaccum leak) so far I think that is the problem but i am not quite sure because I never had a issue with a vacuum leak.

revmatching is more important for downshifting than upshifting, you blip the throttle with the clutch in to get the revs up to better match the gear you're shifting into. the more gears at a time the more revs you need to add. blipping the throttle itself is the act of (with the clutch in) revving the engine for a second and then releasing the throttle to let it snap back.

if the bike stops dying after you raise the idle then you don't have a vacuum leak issue. if you do then it's just a matter of checking all the rubber pieces around your carbs and making sure that they're still fully intact and swapping them out if they aren't. there may be more to it but that was how I fixed mine.

[DaBlue1]

Originally Posted by azian4lifz

Hi all,
... sharp right .....

This road(45mph) is on a downhill ....


....red light in the bottom right corner lighting up meaning bike's off.

...Other than this specific turn I have no problem making turns on any other road.

Sounds to me like a few things are possible....

1. idle speed may be too low, not enough throttle maintenance (occasional blipping)
2. hill too steep making the oil flow towards the front of the engine away from the oil pickup causing low oil pressure light to come on
3. insufficient fuel in the tank. fuel flowing away from the petcock on the downhill right turn.

[Motofool]

Originally Posted by azian4lifz

Thanks for your input. You are right, my idle rpm is too low. I set it at 1k.
I set it at 1k because I thought it would was appropriate since the previous owner left it at 4k with a bad uncleaned carburetor.

If the problem is due to the vacuum leak what should I try to fix? and How would I be able to do this? If I am not able to fix it on my own I will take her to get it checked out but I would prefer not to do that.

I will make the change tmrw morning to set it at 2k. Hopefully this resolves the issues. If not, anything else is should be aware of?

You are welcome

2K may be a little too high and may difficult the up-shifting:

http://faq.ninja250.org/wiki/What_is...I_adjust_it%3F

http://faq.ninja250.org/wiki/How_do_...dle_mixture%3F

http://faq.ninja250.org/wiki/How_do_...carburetors%3F

The petcock is opened by the suction of the engine (vacuum).
The tube that connects both sometimes develops little cracks or pin-holes or just becomes brittle with time, allowing air to come in and partially closing the petcock.

With age, some petcocks let fuel go through even without vacuum application.

http://faq.ninja250.org/wiki/Rebuild...tcock/fuel_tap

http://faq.ninja250.org/wiki/How_do_..._the_floats%3F

Check that hose and also a little filter that goes inside the delivery hose, just before it connects the carbs.

Anything that causes restriction to the flow of fuel into the carbs could make your level in the bowls too low and the mix lean.

[ally99]

Originally Posted by azian4lifz

I feel like I should downshift into 1st gear and then make the right turn but 1st is too slow for the road I am on(45 mph) when slowing down to make the right turn.

You really only need first gear when you come to a complete stop. If you shift down to 1st and your speed is too high (you don't blip), the rear can slide. If you're rolling at all, keep your bike out in 2nd gear or higher. Hope the idle speed adjustment solved your problem!

[alex.s]

The little circular thing on the right side of the carbs is responsible for making sure it doesn't die when that happens. Maybe it wasn't cleaned (it normally is not)

Also no need for the starter. You are moving and the bike is on... Simply let out the clutch when you are upright