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Engine Stalling at High RPM Downshift

manchego

manchego

Behind Bars
Joined
Mar 17, 2013
Location
San Francisco
Moto(s)
2014 Honda CBR500RA (sold)
2024 Yamaha XSR900
Name
Jason
Hi Guys.

I searched the CBR250 forum but couldn't find a definitive answer, although many other riders reported similar problems.

Basically, twice now in the past several weeks, my bike's engine completely stalled out while downshifting from I think a relatively high rpm (~7k), but I can't remember exactly. I'm traveling at speed and need to slow down, so ease off the throttle, pull the clutch to dshift and zooooop... there went my engine. Bike has about 1100 miles on it. 2013 ABS model.

Also, the starter switch struggled. Had to open the throttle several times while starting to get it going. Both times happened at a stop light and had to wave cars around me. Sucked.

Anyways, has this happened to anyone else with other bikes or does this sound like a CBR250 issue?

Thanks Barfers!
 
time to bring it to the dealership, get that fixed under warranty.
 
warranty that bad boy while you still got a chance!
 
We need to understand a bit better what happened. You were riding along, pulled in the clutch to downshift, and the engine died before you could shift and let the clutch back out. Is that right?

Assuming the above is the case, if you downshift more quickly the engine will be connected to the rear wheel again before it has a chance to die. If you blip the throttle to better match RPMs while downshifting it will also keep it from dying.

My first instinct is to blame it on an idle speed that is too low. Some engines, when running at higher RPMs tend to die with closed throttle and no load before they can settle into a proper idle. Holding the throttle open just a tiny bit will prevent that from happening.

Or it could be something completely different, who know?
 
ScottRNelson said:
We need to understand a bit better what happened. You were riding along, pulled in the clutch to downshift, and the engine died before you could shift and let the clutch back out. Is that right?

Assuming the above is the case, if you downshift more quickly the engine will be connected to the rear wheel again before it has a chance to die. If you blip the throttle to better match RPMs while downshifting it will also keep it from dying.

My first instinct is to blame it on an idle speed that is too low. Some engines, when running at higher RPMs tend to die with closed throttle and no load before they can settle into a proper idle. Holding the throttle open just a tiny bit will prevent that from happening.

Or it could be something completely different, who know?
Click to expand...

Yes - engine died before I could let the clutch back out. I do blip the throttle during downshifts right before I kick the shifter and engage. But I've never tried keeping the throttle open slightly during the entire process. I can try that, but seems like a lot of work-around for something that shouldn't be happening in the first place, unless this is common on other small cc bikes?

Taking it to dealer next week.
 
If it is stalling at stoplights, it's time for a service or the idle speed is set too low. With a newer fuel injected bike it should idle without too much drama but sometimes singles will stall at idle but it shouldn't be a very common occurrence.
Your issue when downshifting is something else, it could be a number of things. A normal downshift does not require a full disengagement of the clutch just a quick release of some of the tension. Perhaps you are locking the rear brake at the same time.
It really sounds like you are flogging the poor thing and that's not a good thing with singles. It's fairly easy to overheat the exhaust side if you are just relentless with the throttle. At this point I would go see the dealer.
 
manchego said:
Yes - engine died before I could let the clutch back out. I do blip the throttle during downshifts right before I kick the shifter and engage. But I've never tried keeping the throttle open slightly during the entire process. I can try that, but seems like a lot of work-around for something that shouldn't be happening in the first place, unless this is common on other small cc bikes?
Click to expand...
When I'm downshifting while riding around town and pulling into a left turn lane, I'll often hold the throttle so that the engine will stay at a steady speed, like 4000 RPMs, until I get into first gear, then I'll shut it off and come to a stop before the turn. It reduces the strain on the drivetrain a little bit.

It's not just small engines, it's probably more common with single cylinder bikes. I had similar issues with my XR650L when I first got it until I raised the idle speed a little bit. Not a problem on my KTM, because the idle speed is already quite high if tuned to spec.

Sometimes you just need to help the bike out a little bit with the throttle. I've been riding for so many years that it just happens naturally. Based on the bike you're riding, the join date, and the question you've asked here, I'm pretty sure you're a new rider. Learn to control the engine all the time, not just when accelerating. It's not a lot of work once you can do it without thinking about it.
 
ScottRNelson said:
When I'm downshifting while riding around town and pulling into a left turn lane, I'll often hold the throttle so that the engine will stay at a steady speed, like 4000 RPMs, until I get into first gear, then I'll shut it off and come to a stop before the turn. It reduces the strain on the drivetrain a little bit.

It's not just small engines, it's probably more common with single cylinder bikes. I had similar issues with my XR650L when I first got it until I raised the idle speed a little bit. Not a problem on my KTM, because the idle speed is already quite high if tuned to spec.

Sometimes you just need to help the bike out a little bit with the throttle. I've been riding for so many years that it just happens naturally. Based on the bike you're riding, the join date, and the question you've asked here, I'm pretty sure you're a new rider. Learn to control the engine all the time, not just when accelerating. It's not a lot of work once you can do it without thinking about it.
Click to expand...

Yes, definitely newer rider. First bike. Wow that kinda blows my mind about the transmission differences between a manual car (which I've driven all my life) and this bike. So basically I don't have to/shouldn't let off the throttle completely when downshifting?

Thank you all for the knowledge. I'll give it a whirl today.
 
manchego said:
So basically I don't have to/shouldn't let off the throttle completely when downshifting?
Click to expand...
You don't have to. I wouldn't go so far as to say "shouldn't" though.

The engine should not increase in speed when you pull the clutch in, though.
 
Did you have the 600 mile service performed yet? May have nothing to do with it....but if it has happened to you before, and you have 1100 miles on it...I am guessing that a dealer has not seen the bike since you bought it. The CBR250R has a valve inspection due at 600 miles.......may be a factor if it has not been treated to its 600 mile service yet.

Good luck. Hope it gets figured out quickly! Like others said, get it to a dealer while it is still under warranty!
 
This has been reported for both the cbr250 and the ninja 300. I had it happened to me once going up to a stop sign. Pull in clutch while off throttle and the revs dive to 0.

I blip the throttle while I go down through the gears now that I'm used to my 300 (sometimes clutching out in between and sometimes not). It's better to be in the right gear for the speed anyway.

I wonder if it has something to do with FI because I don't think the old N250 had this issue.
 
Huh, my TL1000R did this. The connection between all three is new fuel injection. Supposedly, it was a relatively common issue caused by a lack of backpressure from the exhaust. I don't know the details, but found out that sudden revs (blipping) without any resistance (clutch in) caused this to happen.
 
Teddy said:
Did you have the 600 mile service performed yet? May have nothing to do with it....but if it has happened to you before, and you have 1100 miles on it...I am guessing that a dealer has not seen the bike since you bought it. The CBR250R has a valve inspection due at 600 miles.......may be a factor if it has not been treated to its 600 mile service yet.

Good luck. Hope it gets figured out quickly! Like others said, get it to a dealer while it is still under warranty!
Click to expand...

Yes, 600 mi service done at Tokyo Moto. Valves were within specs.
 
I wouldn't say this is a normal occurrence. Yes, while downshifting it's better to rev match, but if at any point you clutch in and release the throttle, a normal bike should just revert to normal idle speed.

Some bikes have issues with this, like my R1200S. It does it from time to time. After adding a booster plug that makes the fuel mixture more rich it decreased a lot. I have heard there's a dealer fix for my bike where they set a slightly higher rev point for the idle actuator for when the revs initially come down from 3k+.

Either way, take it to the dealer and tell them what's happening.
 
danate said:
I wouldn't say this is a normal occurrence. Yes, while downshifting it's better to rev match, but if at any point you clutch in and release the throttle, a normal bike should just revert to normal idle speed.

Some bikes have issues with this, like my R1200S. It does it from time to time. After adding a booster plug that makes the fuel mixture more rich it decreased a lot. I have heard there's a dealer fix for my bike where they set a slightly higher rev point for the idle actuator for when the revs initially come down from 3k+.

Either way, take it to the dealer and tell them what's happening.
Click to expand...

:thumbup Thank you. Will do! I'm slightly worried I'm gonna get into the whole "can't reproduce the problem" circle, but we'll see how Mission Motorcycles handles it.
 
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