Help with stalling...

[DRivero]

Okay. My Ninjette is cold-blooded. I know this. It takes FOREVER to warm up, and I know better than to ride it before the temp gauge is straight up and down, lest it stall like mad for the first 10 minutes of riding. I have no problem working around this: I just start the bike before I start gearing up and packing up my tank bag. In winter, I start it up even before that. Such is life with my cold-blooded Garu. No problem.

However, I have what I think is an unrelated issue, and it's getting to be kind of a pain. It stalls when it shouldn't. A lot. It happens when I'm downshifting. It goes like this: I'm well into the ride, bike is hot (meaning it's at normal running temp), I come up to a stoplight or stop sign, roll off the throttle and pull in the clutch to downshift, and on come the lights. Off goes the engine. Of course, I've downshifted, so as soon as I let out the clutch, it bump-starts itself again. This happens quite often; nearly every stop some rides.

Thinking at first that this could be some sort of rider error, I've monitored myself when slowing down, to make sure I'm fully engaging the clutch lever. Nor is it the clutch cable; it's brand new, and I've had it checked to make sure it's adjusted correctly. Apparently, it's fine. I thought upping the idle would work, but it didn't, and I ended up with it higher than I like, so I backed it down again. The bike, when warmed up, idles at about 1500 rpm, which I think is about right for this machine (although certainly, I could be wrong).

The bike otherwise runs fine, so now I'm stumped. Any ideas?

[kkim]

how many miles on the bike and when was the last time the valves were checked?

[Apex]

1500 is good. I normally keep mine between 1000-1200, just personal preference.

[Snake]

Check to see that the oil level is not low. The pregens are known for stalling while breaking due to the oil surging forward away from the oil pick-up tube.

[Alex]

Rick, I didn't know that behavior caused stalling; All I thought was that's why the oil light pops on frequently. My vote here is valves as well.

[Snake]

Maybe it's just my bike then. Has not happened since I keep my oil at the upper mark.

[nate-bama]

how often does your bike sit and for how long? my bike can sit for two weeks and won't idle for nothing untill i run it awhile, i don't know if the gas can gum up the carbs that quick but it sure seems like it clogs my pilot jet . Water in your fuel will do the random dying while warmed up

[FrugalNinja250]

If you ride infrequently enough that the gas in the tank is months old that could definitely be a partial cause. Otherwise, without knowing more about the bike and its history I'd say it's running slightly too lean and/or the carbs could use some cleaning/tweaking.

[DaBlue1]

Originally Posted by DRivero

. ... It goes like this: I'm well into the ride, bike is hot (meaning it's at normal running temp), I come up to a stoplight or stop sign, roll off the throttle and pull in the clutch to downshift, and on come the lights. Off goes the engine. Of course, I've downshifted, so as soon as I let out the clutch, it bump-starts itself again. This happens quite often; nearly every stop some rides.

Thinking at first that this could be some sort of rider error, I've monitored myself when slowing down, to make sure I'm fully engaging the clutch lever. Nor is it the clutch cable; it's brand new, and I've had it checked to make sure it's adjusted correctly. Apparently, it's fine.

Sounds like you are doing a good job troubleshooting. The only questions that I have are;
Are you blipping the throttle at all?
When is the last time the carbs and air filter were cleaned / adjusted?
When was the last time you lubed the throttle cables?

Also some adding Seafoam to the tank could help clean the fuel system too.

[DRivero]

Originally Posted by kkim

how many miles on the bike and when was the last time the valves were checked?

First of all, thanks for all the help!

Kim, it has just under 22k miles, and I have no clue when the valves might have been checked. The guy I bought it from was real good with the maintenance, so he says. The bike was in great shape mechanically when I got it, so I'm inclined to believe him. However, and I could be wrong here, a valve job isn't exactly considered part of routine maintenance, right? So it could be that it's been quite a while. Same for the carbs, I'm guessing.

In response to the other suggestions/questions: the oil level is good, I ride it fairly regularly (at least 2x a week, up until mid-October. It did sit for several weeks from then until last weekend, but this problem started occurring long before that), the throttle cables are brand new, and I put Seafoam in it all the time. Not ALL the time, but at least every few tankfuls.

Water in your fuel will do the random dying while warmed up

Interesting that you mention that, Nate. In the beginning I thought that could be the culprit. Back in July, I got caught in some VERY nasty weather coming home from a trip....a very, very bad rainstorm. It seems like the problem started right after that, and my bike-builder neighbor suggested that I'd somehow gotten water intrusion. He said to keep riding, put Seafoam in with every tankful, and it would eventually quit doing it. So far it hasn't, which leads me to believe it's another matter entirely.

Well, I suppose this means some serious wrench-work (for me, anyway) is in order. Any volunteers? Hey, I live in sunny South Florida....maybe someone wants to take a road trip? Bring your tools, and I'll supply the sunscreen.

BTW.....I'm not familiar with throttle-blipping. For all I know, I AM doing it and just don't know it. Maybe someone could help an old lady out and explain?

[DaBlue1]

When downshifting to a stop you want to rev the engine just a bit so that your rpm is slightly matching your speed. (ie if you are braking while decelerating, pull in the clutch, , squeeze on the brake normally to slow down, squeeze the clutch, give a really quick twist on the throttle, downshift quick, let out the clutch (slightly just until it engages), And repeat until you have downshifted completely). This is a somewhat quick process and will take some practice. Depending on who you ask this is called rev matching or "blipping" the throttle. Check the video to get a general understanding of blipping.

http://www.youtube.com/watch?v=Hb7dx..._order&list=UL

Since you really do not know when the valves were last checked I would have them inspected and adjusted and also have the carbs cleaned, adjusted and synchronized. At 22k I believe you are approaching your next scheduled maintenance.

[kkim]

Valve clearance inspection/adjustment is due every 7,500 miles. If you have no clue when they were inspected/adjusted last, have them done ASAP as a precautionary measure.

How many miles did the bike have when you bought it?

[Alex]

I think it's every 6K on the pregens, right?

[Samer]

+1 on the valves. On the blipping throttle, I'd forget about it. I don't see how that has anything to do with this problem. It would be interesting to do a survey of who has done the valve clearance adjustment at the correct intervals. My guess is that most people don't keep their 250s long enough, then pass it along to someone who probably doesn't know or doesn't want to spend the money to get the valve clearances checked. It is relatively expensive and time consuming from what I've read. That it has lasted 22K miles without a clearance check is probably remarkable.

[kkim]

Originally Posted by Alex

I think it's every 6K on the pregens, right?

yup...

[kkim]

Originally Posted by Samer

+1 on the valves. On the blipping throttle, I'd forget about it. I don't see how that has anything to do with this problem. It would be interesting to do a survey of who has done the valve clearance adjustment at the correct intervals. My guess is that most people don't keep their 250s long enough, then pass it along to someone who probably doesn't know or doesn't want to spend the money to get the valve clearances checked. It is relatively expensive and time consuming from what I've read. That it has lasted 22K miles without a clearance check is probably remarkable.

the pregens aren't as involved as the new gens, but still, the short interval makes for a rigorous maintenance schedule if you ride a lot.

[FrugalNinja250]

It looks like she's got a pre-gen. I wonder if a faulty decel enricher would cause a lean drop stall after a coast down in gear?

On valves, yeah, every 6k miles and never assume that the PO did the valves unless they've got records or some other proof. I'd get that done forthwith as the consequences of too tight valves are pretty severe on this motor.

[kkim]

Originally Posted by FrugalNinja250

On valves, yeah, every 6k miles and never assume that the PO did the valves unless they've got records or some other proof. I'd get that done forthwith as the consequences of too tight valves are pretty severe on this motor.