intermittent bogging and bad idle

digdoug2 · 11-02-2008, 08:58 AM

I choke it to start, it starts right up, idles a little high and as it warms up, I turn the choke down and all is well. It runs as it should until it get's on the hot side of warmed up. Not overheating hot ,but just warmer than normal. What I mean is, it will run fine as long as I am on an open road which keeps the motor on the cooler side. But when i get onto a smaller road where I run it harder and in town wher I have to start and stop, it heats up enough to where the fan is coming on and then it doesn't want to idle and it boggs really bad at a take off and coming out of a corner at low rpm's. Once the rpm's get up, it's fine. And once I get back onto an open road where the temperature goes down a bit, it runs fine. It is as if the extra heat is doing something to the flow of gas.
Does the extra heat slow down the fuel pump????
or somehow mess with the carbs.?????
does the extra heat restrict flow in the fuel line( maybe at a kink) ????
I am going to take the tank off and replace all the fuel lines, put another new filter on and possibly do the ole "lose the fuel pump trick". Anything else you can think of I could do or look for???
Thanks, Doug

masonv45 · 11-07-2008, 08:25 AM

Set your pilot jets via the idle drop method.

That is, if your carbs are synched.

digdoug2 · 11-07-2008, 12:05 PM

Carbs have not been synched, since I started fooling with it. It used to not run at all at idle, without the choke on. I removed the carbs and cleaned them. It ran fine for a while and then started this new condition. Maybe the carbs are starting to clog up again from some old dirt in the tank or the lines????? I have removed the carbs again and will clean out to see if that helps. I thought the synching wasn't really necessary to get it running good, the synching was more to dial it in for perfection. I have not messed with any of the adjustments on the carbs and have not taken them apart from each other.

masonv45 · 11-07-2008, 12:43 PM

Bench syncing will get the bike running well enough so you can do a "real" sync.

If you get it close enough during bench syncing, you may be happy with it as is. Syncing will increase smoothness, power, and mpg.

I consider adjusting the pilot jet "dialing it in for perfection". I'm usually happy doing a real sync and setting the pilot jets at stock turns out.

You say that the bike runs worse when hot. I know that heat will cause a bike to run leaner. If you have partially blocked jets/carb passages, the heat will exacerbate the situation.

You state that it bogs down at idle and just off idle. That signifies to me that the pilot jet and associated passage ways are causing the problem.

Educational URL: Carburetors/Tuning - SabMagFAQ
Read the links

digdoug2 · 11-10-2008, 08:15 AM

Thanks for the help MASON.
You were right on the money with the pilot jet. But, it wasn't that they were clogged, they were never getting the correct amount of fuel. I inadvertantly adjusted the floats incorrectly the last time I had them apart. So, the fuel level in the bowl was so low, that fuel just wasn't getting picked up the way it was supposed to. But when I put it back together last time, it ran good and idled OK so I thought everything was fine. I guess the bad fuel level also explains the bogging when coming out of a turn, because with the bike leaning over, the fuel level was even further away from being correct?
I also guess that the heat did not help anything because it made it even leaner, when it was already way too lean. And maybe the heat could have made the fuel level even worse???
Any-way, I cleaned everything again and adjusted the floats, correctly this time. I didn't adjust anything or try to synch anything because all I wanted to do was get it back together and ride....... and WOW what a difference in performance. I was amazed at the throttle response it has now. I had just figured that this bike never really had much of a throttle response and I had learned to live with it. It also idles sooo smooth. It's like having a whole new bike!

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11-02-2008, 08:58 AM	#1 (permalink)
digdoug2 Member Join Date: May 2008 Last Online: 12-30-2008 06:33 AM Location: Elkton Maryland My Ride: Resurrected 87 VFR700 Posts: 41 Thanks: 0 Thanked 0 Times in 0 Posts	intermittent bogging and bad idle I choke it to start, it starts right up, idles a little high and as it warms up, I turn the choke down and all is well. It runs as it should until it get's on the hot side of warmed up. Not overheating hot ,but just warmer than normal. What I mean is, it will run fine as long as I am on an open road which keeps the motor on the cooler side. But when i get onto a smaller road where I run it harder and in town wher I have to start and stop, it heats up enough to where the fan is coming on and then it doesn't want to idle and it boggs really bad at a take off and coming out of a corner at low rpm's. Once the rpm's get up, it's fine. And once I get back onto an open road where the temperature goes down a bit, it runs fine. It is as if the extra heat is doing something to the flow of gas. Does the extra heat slow down the fuel pump???? or somehow mess with the carbs.????? does the extra heat restrict flow in the fuel line( maybe at a kink) ???? I am going to take the tank off and replace all the fuel lines, put another new filter on and possibly do the ole "lose the fuel pump trick". Anything else you can think of I could do or look for??? Thanks, Doug Last edited by digdoug2; 11-02-2008 at 09:01 AM. Reason: spelling

11-07-2008, 08:25 AM	#2 (permalink)
masonv45 Senior Member Join Date: Apr 2007 Last Online: Yesterday 11:27 AM My Ride: 1985 VF700F Posts: 694 Thanks: 0 Thanked 17 Times in 16 Posts	Set your pilot jets via the idle drop method. That is, if your carbs are synched. __________________ 1985 VF700F 1983 V45 Magna Gone but not Forgotten Memphis, TN

11-07-2008, 12:43 PM	#4 (permalink)
masonv45 Senior Member Join Date: Apr 2007 Last Online: Yesterday 11:27 AM My Ride: 1985 VF700F Posts: 694 Thanks: 0 Thanked 17 Times in 16 Posts	Bench syncing will get the bike running well enough so you can do a "real" sync. If you get it close enough during bench syncing, you may be happy with it as is. Syncing will increase smoothness, power, and mpg. I consider adjusting the pilot jet "dialing it in for perfection". I'm usually happy doing a real sync and setting the pilot jets at stock turns out. You say that the bike runs worse when hot. I know that heat will cause a bike to run leaner. If you have partially blocked jets/carb passages, the heat will exacerbate the situation. You state that it bogs down at idle and just off idle. That signifies to me that the pilot jet and associated passage ways are causing the problem. Educational URL: Carburetors/Tuning - SabMagFAQ Read the links __________________ 1985 VF700F 1983 V45 Magna Gone but not Forgotten Memphis, TN

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11-07-2008, 12:05 PM	#3 (permalink)
digdoug2 Member Join Date: May 2008 Last Online: 12-30-2008 06:33 AM Location: Elkton Maryland My Ride: Resurrected 87 VFR700 Posts: 41 Thanks: 0 Thanked 0 Times in 0 Posts	Carbs have not been synched, since I started fooling with it. It used to not run at all at idle, without the choke on. I removed the carbs and cleaned them. It ran fine for a while and then started this new condition. Maybe the carbs are starting to clog up again from some old dirt in the tank or the lines????? I have removed the carbs again and will clean out to see if that helps. I thought the synching wasn't really necessary to get it running good, the synching was more to dial it in for perfection. I have not messed with any of the adjustments on the carbs and have not taken them apart from each other.

11-10-2008, 08:15 AM	#5 (permalink)
digdoug2 Member Join Date: May 2008 Last Online: 12-30-2008 06:33 AM Location: Elkton Maryland My Ride: Resurrected 87 VFR700 Posts: 41 Thanks: 0 Thanked 0 Times in 0 Posts	Thanks for the help MASON. You were right on the money with the pilot jet. But, it wasn't that they were clogged, they were never getting the correct amount of fuel. I inadvertantly adjusted the floats incorrectly the last time I had them apart. So, the fuel level in the bowl was so low, that fuel just wasn't getting picked up the way it was supposed to. But when I put it back together last time, it ran good and idled OK so I thought everything was fine. I guess the bad fuel level also explains the bogging when coming out of a turn, because with the bike leaning over, the fuel level was even further away from being correct? I also guess that the heat did not help anything because it made it even leaner, when it was already way too lean. And maybe the heat could have made the fuel level even worse??? Any-way, I cleaned everything again and adjusted the floats, correctly this time. I didn't adjust anything or try to synch anything because all I wanted to do was get it back together and ride....... and WOW what a difference in performance. I was amazed at the throttle response it has now. I had just figured that this bike never really had much of a throttle response and I had learned to live with it. It also idles sooo smooth. It's like having a whole new bike!