engine cuts off, while clutch in and blipping.
04-04-2010, 03:54 PM
#1
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Squid
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Join Date: Apr 2010
Location: Auckland, New Zealand
Posts: 3
engine cuts off, while clutch in and blipping.
hey guys my 1st post. all way from new zealand.
well had my vtr for 3mths and love it. "sometimes" while clutch in and blipping the engine loses power and i can not rev it to match idel. when cutch is released the engine comes alive again, I find if i dont blip the throttle while shifting down the engine doesint cut off. any ideas is it the coils? or carb balance or anythying else.
well had my vtr for 3mths and love it. "sometimes" while clutch in and blipping the engine loses power and i can not rev it to match idel. when cutch is released the engine comes alive again, I find if i dont blip the throttle while shifting down the engine doesint cut off. any ideas is it the coils? or carb balance or anythying else.
04-04-2010, 04:40 PM
#2
Out of my mind, back in 5
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The VTR does that if you pull in the clutch at highway speeds, nobody knows for sure why but there are several theories... Just downshift clutchless or with a very short decisive clutch movement for each gear and it works as intended...
04-04-2010, 05:00 PM
#3
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SuperBike
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Location: South Lake Tahoe, CA, USA
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I have heard of something similar, when the float vent tubes are not vented correctly, causing differential pressure in the float bowls of the carburetors. At the time, I was advised to route the tubes, so that they point downward, between the carbs, rather than side-to side. Remove the airbox to see what I mean.
Maybe this will help.
04-04-2010, 08:59 PM
#5
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That is interesting. I have no doubt about the tuning of your carbs.
Are you running stock #48 pilot jets? To me it seems likely to be a lean condition causing a misfire, but I can't say for sure. I was running #45 pilots. This will affect off-idle throttle response.
I was able to drop the throttle from 9500 RPM in 6th, with the clutch lever pulled and blip the throttle to downshift to 5th for turn one. The blip was clean and crisp. It was also crisp dropping two gears for turns 10 and 14 at lower speeds from WOT.
Vent tubes were side by side, facing downward. I'm not sure what else it could be.
Are you running stock #48 pilot jets? To me it seems likely to be a lean condition causing a misfire, but I can't say for sure. I was running #45 pilots. This will affect off-idle throttle response.
I was able to drop the throttle from 9500 RPM in 6th, with the clutch lever pulled and blip the throttle to downshift to 5th for turn one. The blip was clean and crisp. It was also crisp dropping two gears for turns 10 and 14 at lower speeds from WOT.
Vent tubes were side by side, facing downward. I'm not sure what else it could be.
Last edited by RCVTR; 04-04-2010 at 09:06 PM.
04-04-2010, 09:26 PM
#6
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SuperSport
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I think Tweety is referring to holding the clutch in for more than a second or two (longer than necessary to match revs on downshifts). This has been discussed before RC, and I'm guessing you've just missed it. I know mine doesn't like it either, and will just die if held in long enough while rolling.
The OP on the other hand must have other problems if the bike dies while trying to rev match. Like RC said, I'd check jetting and carb sync to start.
The OP on the other hand must have other problems if the bike dies while trying to rev match. Like RC said, I'd check jetting and carb sync to start.
04-04-2010, 09:51 PM
#7
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Squid
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Location: Auckland, New Zealand
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o.k cheers. will try not holding the clutch in for too long as i think this is what i have been doing. I will practice one quick rev match and then let it out. as sometimes I was reving it 2 or 3 times then letting clutch out. If the problem is still there after doing this I will look into the other advise ideas. cheers. also bike is standard from what im awear off.
Last edited by crystalball; 04-04-2010 at 09:53 PM.
04-04-2010, 11:17 PM
#8
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I guess I do recall discussions about this in the past.
I have a theory. I don't know if it has been tested by anyone but here it is:
It is not an off-idle problem. It seems the problem occurs at speed, as the engine RPM gets low (extended period at closed throttle). The engine just dies.
A misfire is generally a lean condition. As the engine speed drops, the vacuum decreases. If there is a low pressure in the float bowls, due to the speed of the bike - high velocity causes low pressure and the difference in pressure is what pushes fuel out of the float bowl and into the throttle body, you will get a lean condition. This is the reason for relocation of the vent hoses. But it is also a function of the idle mixture setting.
Most people just set their idle mixture to a recommended number of turns out from closed. Mine were adjusted - if I recall correctly - to the maximum RPM +1/4 turn or so out, to create a slightly rich idle. I borrowed the tool and set it after warming the bike up. I never experienced a dying engine, during closed throttle, unless it was very early in my tuning process - I think I do recall it happening.
If I were to test this theory, I think i would take the current idle screw setting and turn it out another 1/4 turn and see if the problem goes away. I would be very interested in knowing if this is the case.
Good luck!
I have a theory. I don't know if it has been tested by anyone but here it is:
It is not an off-idle problem. It seems the problem occurs at speed, as the engine RPM gets low (extended period at closed throttle). The engine just dies.
A misfire is generally a lean condition. As the engine speed drops, the vacuum decreases. If there is a low pressure in the float bowls, due to the speed of the bike - high velocity causes low pressure and the difference in pressure is what pushes fuel out of the float bowl and into the throttle body, you will get a lean condition. This is the reason for relocation of the vent hoses. But it is also a function of the idle mixture setting.
Most people just set their idle mixture to a recommended number of turns out from closed. Mine were adjusted - if I recall correctly - to the maximum RPM +1/4 turn or so out, to create a slightly rich idle. I borrowed the tool and set it after warming the bike up. I never experienced a dying engine, during closed throttle, unless it was very early in my tuning process - I think I do recall it happening.
If I were to test this theory, I think i would take the current idle screw setting and turn it out another 1/4 turn and see if the problem goes away. I would be very interested in knowing if this is the case.
Good luck!
04-05-2010, 10:51 AM
#9
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Location: Phoenix, AZ
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I have heard of this, and Greg's website even talks about it. But I have never experienced it. I can pull the clutch in at any speed for as long as I like, run the engine at any RPM, idle while coasting down the mountain etc etc. So not all VTRs do it.
04-05-2010, 01:06 PM
#10
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Charing experiences:
I´m having my VTR for 12 years now, and in the begining it used to do that too.
It was particulary danger if i pull the clutch during a curve. I remember that mine used to do it at low speeds too.
Can you imagine what hapens if the engine dies at low speed in a curve, and you release the clutch in movement?
Those 2 cilinders dont alow mistakes...
Once in a conversation with a mecanical friend, he adviced me to pull out the plugs in the left side, near the tail (sorry, but i dont know the technical names), clean them and put a bit of spray for the electrical contacts.
It never died in motion again.
Well, not until a year ago.
But i did it again, and it´s ok again.
I´m not a great mechanic, but i think it´s more of an electrical problem.
I´m having my VTR for 12 years now, and in the begining it used to do that too.
It was particulary danger if i pull the clutch during a curve. I remember that mine used to do it at low speeds too.
Can you imagine what hapens if the engine dies at low speed in a curve, and you release the clutch in movement?
Those 2 cilinders dont alow mistakes...
Once in a conversation with a mecanical friend, he adviced me to pull out the plugs in the left side, near the tail (sorry, but i dont know the technical names), clean them and put a bit of spray for the electrical contacts.
It never died in motion again.
Well, not until a year ago.
But i did it again, and it´s ok again.
I´m not a great mechanic, but i think it´s more of an electrical problem.
04-05-2010, 02:00 PM
#11
Out of my mind, back in 5
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Location: Skurup, Sweden
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I think Tweety is referring to holding the clutch in for more than a second or two (longer than necessary to match revs on downshifts). This has been discussed before RC, and I'm guessing you've just missed it. I know mine doesn't like it either, and will just die if held in long enough while rolling.
The OP on the other hand must have other problems if the bike dies while trying to rev match. Like RC said, I'd check jetting and carb sync to start.
The OP on the other hand must have other problems if the bike dies while trying to rev match. Like RC said, I'd check jetting and carb sync to start.
RCVTR like you I have my bike tuned to a slightly rich idle... Can't remember the specific setup that works for me, but close to what you describe... I'll gladly try setting it even richer and testing it, but I doubt it will help...
As far as it being an electrical gremlin... Nope, not on my bike... I'm an electrical engineer by trade, and my pet peeve is the electrical system and connectors... I fully admit to being a bit **** about it but there is no bad connection or moisture or anything along those lines... Trust me on that...
My theory is that it's something in the ECU behaving in a way the designers didn't anticipate... Admittedly I have given up trying to correct it, considering a it a quirk more than a problem on my bike... Like said, I have no trouble at all using the clutch regardless of speed... But hold the clutch in at speed for longer than a normal and it dislikes it...
Poking around revving several times like the OP describes will make my bike grumpy... Keep it up any longer and it will cut out... But I see no reason what so ever to do that... That's not something I need to do... I "close" the throttle long enough to get another gear, then it's opened again with great enjoyment...
04-06-2010, 09:12 AM
#12
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I am wondering if this is a quirk that only early bikes have.. Like I said I can pull the clutch in all day from any speed and it keeps running till I either coast to a stop or I let the clutch out again.
04-16-2010, 08:08 AM
#15
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Agreed. Same story with my '00. If only everything else worked on mine...Haha
04-16-2010, 08:18 AM
#16
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SuperSport
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Location: NY State
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I am wondering if it is related to the switch on the lever in combination with the switch on the sidestand. I do not have the problem, but what if one of you guys that does, defeated both of those switches and then see if you still have the problem. This is just a guess, I have not looked at it.
JB
JB
04-16-2010, 08:55 AM
#17
Out of my mind, back in 5
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Ok... So I'm curios... I was playing around anyways, so I set the idle up a wee bit and tried it... It didn't change much... It still gets grumpy if you hold the clutch at freeway speeds, doesn't cut out unless you work at it a while, but most decidedly tells me "stod that, dummy"...
Fiddled around more with the jetting, basicly ending up where I started again... And I finaly tried the TPS mod... It did absolutlely nothing as far as I can tell... Mine was at 820 ohms to begin with and it's at 496 now (could get there without any changes, just moving it...) I'll see in a few weeks if I found any difference... None noticed so far though...
Fiddled around more with the jetting, basicly ending up where I started again... And I finaly tried the TPS mod... It did absolutlely nothing as far as I can tell... Mine was at 820 ohms to begin with and it's at 496 now (could get there without any changes, just moving it...) I'll see in a few weeks if I found any difference... None noticed so far though...
04-16-2010, 08:58 AM
#18
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Superstock
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Location: Olympia, WA
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I've encountered this before too on a few different Hondas over the years. I too have decided not to "go there" because it is not something done under normal riding conditions. Sometimes it seems like electrical in the way it cuts out, like someone hit the kill button. Other times it seems like fuel issue, I don't ever remember it happening on a Fuel injected bike. Weird, I always just put that experience away on a shelf as to something you just don't do why question it or try to figure out.
Of course now I'll think about it much of the day, thanks everyone!
Of course now I'll think about it much of the day, thanks everyone!
04-16-2010, 10:31 AM
#19
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Not that I'm too well versed on the subject, but, I've owned bikes in the past that had this problem and they all had fuel delivery issues. The stalling was the symptom of a much larger condition. Does the bike have any other issues? Stumbles, flat spots? Just theorizing here. However, one thing I have learned is a carb cleaning and sync can't hurt anything. Unless of course you drop pieces down the throats. Lol
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