R1000 Posted August 13, 2008 Share Posted August 13, 2008 A friends Bird -97 is a bit slow in returning to idle when getting off the throttle on neutral. The rpm hesitate to drop from e.g. 4krpm down to 1500, so it will take about a second or two. Definitely longer than what is felt to be normal anyway. Anyone having had the same sympthoms and know what the reason could be? The throttles moves freely in the bores, the wires have some slack and the diafragms are OK. All hoses to carb and vents are connected. Quote Link to comment Share on other sites More sharing options...
Hobicus Posted August 13, 2008 Share Posted August 13, 2008 Assuming mechanical portions of the carbs (throttle, etc) are all good, my experience has been that when you have those kinds of things going on, it's usually a carb synch issue. Quote Link to comment Share on other sites More sharing options...
R1000 Posted August 13, 2008 Author Share Posted August 13, 2008 Assuming mechanical portions of the carbs (throttle, etc) are all good, my experience has been that when you have those kinds of things going on, it's usually a carb synch issue. Carbs are just synched and it was the same before and the mechanical components moves freely The return to idle is not momentary delayed, it is the rpm that falls lineary at an unusual slow rate. Quote Link to comment Share on other sites More sharing options...
madlandrover Posted August 13, 2008 Share Posted August 13, 2008 The last few times I've had something like this (on other bikes) it's been an air leak downstream of the carbs. Maybe they were shifted when they were synched? Quote Link to comment Share on other sites More sharing options...
TJ1137 Posted August 13, 2008 Share Posted August 13, 2008 If the carbs are synced and you have checked all the vac lines, you might try turning in the idle mixtures 1/2 turn. See if it gets better or worsens. Quote Link to comment Share on other sites More sharing options...
R1000 Posted August 13, 2008 Author Share Posted August 13, 2008 The last few times I've had something like this (on other bikes) it's been an air leak downstream of the carbs. Maybe they were shifted when they were synched? What may be shifted ? If the carbs are synced and you have checked all the vac lines, you might try turning in the idle mixtures 1/2 turn. See if it gets better or worsens. Aah, you may be into something, I believe they are almost 3 turns out at the moment. Quote Link to comment Share on other sites More sharing options...
EVLXX Posted August 14, 2008 Share Posted August 14, 2008 Sound like ghost reving.... which is a vacume leak.... somewhere. Quote Link to comment Share on other sites More sharing options...
oldbird Posted August 14, 2008 Share Posted August 14, 2008 He may want to check his handlebar grips. I had my throttle side grip slip down a bit, over the bar end, and it certainly slowed the return to idle. It took me way too much time to discover the problem ! Quote Link to comment Share on other sites More sharing options...
jon haney Posted August 14, 2008 Share Posted August 14, 2008 If the throttle cables are not binding or catching somewhere, I vote for vacuum leak. Quote Link to comment Share on other sites More sharing options...
TJ1137 Posted August 14, 2008 Share Posted August 14, 2008 DEFINITELY check for Vac leaks first, as it is common and easily overlooked. This is from a factory jet kit site. They have a bunch of tuning tips. Some are good, and some not. "# NOTE: A lean problem gets better as the engine heats up. * If the throttle is lightly "blipped" at idle, and the rpm "hangs up" before dropping to the set idle speed, and there are no intake leaks and the idle speed is set at less than 1000 rpm, the mixture screws are probably too lean: try 1/2 turn out, to richen mixture. Be sure there are no intake leaks and the idle speed is set at less than 1000 rpm!" Quote Link to comment Share on other sites More sharing options...
CxBXR Posted August 14, 2008 Share Posted August 14, 2008 if it is not a vaccum leak or air leak or mechanical It must be tuning related, hanging idle is usually a lean condition Quote Link to comment Share on other sites More sharing options...
R1000 Posted August 15, 2008 Author Share Posted August 15, 2008 The bike will be here tomorrow and the mixture screws will be adjusted. Thanks for all hints, I'll report the findings :-) Quote Link to comment Share on other sites More sharing options...
porterb123 Posted August 15, 2008 Share Posted August 15, 2008 As stated,if it is not the return spring, then vacuum leaks. You can take a can of WD40 and spray all around the carbs while the bike is running...if there is a vacuum leak, you will notice a change in idle speed when the spray is sealing the leak momentarily. Good way to find the affected area. Quote Link to comment Share on other sites More sharing options...
CxBXR Posted August 15, 2008 Share Posted August 15, 2008 As stated,if it is not the return spring, then vacuum leaks. You can take a can of WD40 and spray all around the carbs while the bike is running...if there is a vacuum leak, you will notice a change in idle speed when the spray is sealing the leak momentarily. Good way to find the affected area. A cleaner method is to use, LPG or LP-gas from a small hand held torch, turn the torch gas on & fumigate it around the suspected areas if you notice an idle change, there is a leak Quote Link to comment Share on other sites More sharing options...
Justin Posted August 16, 2008 Share Posted August 16, 2008 As stated,if it is not the return spring, then vacuum leaks. You can take a can of WD40 and spray all around the carbs while the bike is running...if there is a vacuum leak, you will notice a change in idle speed when the spray is sealing the leak momentarily. Good way to find the affected area. A cleaner method is to use, LPG or LP-gas from a small hand held torch, turn the torch gas on & fumigate it around the suspected areas if you notice an idle change, there is a leak Beat me to it.... geeesh, using wd-40 would make a mess lol! Quote Link to comment Share on other sites More sharing options...
porterb123 Posted August 18, 2008 Share Posted August 18, 2008 As stated,if it is not the return spring, then vacuum leaks. You can take a can of WD40 and spray all around the carbs while the bike is running...if there is a vacuum leak, you will notice a change in idle speed when the spray is sealing the leak momentarily. Good way to find the affected area. A cleaner method is to use, LPG or LP-gas from a small hand held torch, turn the torch gas on & fumigate it around the suspected areas if you notice an idle change, there is a leak Beat me to it.... geeesh, using wd-40 would make a mess lol! Neat freek girly mans you both are! Do you keep wet wipes next to bed on a doily for cum spots?? Quote Link to comment Share on other sites More sharing options...
Fast Eddy Posted August 18, 2008 Share Posted August 18, 2008 As stated,if it is not the return spring, then vacuum leaks. You can take a can of WD40 and spray all around the carbs while the bike is running...if there is a vacuum leak, you will notice a change in idle speed when the spray is sealing the leak momentarily. Good way to find the affected area. A cleaner method is to use, LPG or LP-gas from a small hand held torch, turn the torch gas on & fumigate it around the suspected areas if you notice an idle change, there is a leak Beat me to it.... geeesh, using wd-40 would make a mess lol! Neat freek girly mans you both are! Do you keep wet wipes next to bed on a doily for cum spots?? :icon_lmao: :icon_lmao: Quote Link to comment Share on other sites More sharing options...
02BIRD Posted August 18, 2008 Share Posted August 18, 2008 kool test with the LP i always used carb cleaner Quote Link to comment Share on other sites More sharing options...
Justin Posted August 19, 2008 Share Posted August 19, 2008 As stated,if it is not the return spring, then vacuum leaks. You can take a can of WD40 and spray all around the carbs while the bike is running...if there is a vacuum leak, you will notice a change in idle speed when the spray is sealing the leak momentarily. Good way to find the affected area. A cleaner method is to use, LPG or LP-gas from a small hand held torch, turn the torch gas on & fumigate it around the suspected areas if you notice an idle change, there is a leak Beat me to it.... geeesh, using wd-40 would make a mess lol! Neat freek girly mans you both are! Do you keep wet wipes next to bed on a doily for cum spots?? actually, I just don't have sex, it's too dirty... Quote Link to comment Share on other sites More sharing options...
R1000 Posted August 28, 2008 Author Share Posted August 28, 2008 The reason to the slow engine speed return to idle is found. The initial compression test indicated something was wrong; the cylinder pressure was 170 PSI on one cylinder and 195 on another. The intake valves on two cylinders leaks quite a bit. This was found by applying air pressure to the cylinders, which was connected instead of the ignition plugs. When this was done it was easy to hear and feel the airflow coming out from the intake runners. / Sherlock Holmes Quote Link to comment Share on other sites More sharing options...
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