RPM goes up when clutch is pull??? No idea what it could be, please help.
#31
07-01-2013, 05:39 PM
#32
07-02-2013, 06:02 PM
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I went for a ride and same issue happened. This time I didn't go for long ride but more if a stop and go then straight line. I decided to shift into neutral while about 3K RPM then gave it some gas and guess what it stayed hang up there even when I got to a complete stop as the bike slowed down by inertia.
I remembered one of you said "your idle is jacked up, bring it down" I also moved the air tube from behind the battery case to the side of the battery case (idk if that also made a difference)...I did that until I saw the bike idle between 1.2K and 1.1K. I waited until the fan turned off then I did the same route...to my surprise it was a smooth ride...I did feel it was hanging up but it was barely noticeable. Shifting gear was smooth as cutting butter with a hot knife...I think we got it to where it needs to be...yes, it may not be perfect but it's not as bad as it was before you guys starting to help me.
I don't want to sing victory yet but if this is fixed this is what I can share....
Lessons learnt
1) Submerged carbs in carb cleaner. It makes a huge difference.
2) air pilot, jet, pilot jet and everything that can be cleaned is clean.
3) keep rubber pieces away from carb cleaner. (I didn't learn this by experience but by reading..lol)
4) Make sure bowl and top covers are sealed correctly.
4.1) when you screwing the bowl and top covers back on: use a wrench is easier to handle than a screwdriver, and use a bit that fits your screw correctly otherwise you'll striped the screw. Tap the bit into the screw by using a hammer. Not too hard to break anything just a few taps so the bit is in securely.
5) use the motorcycle permeated gasket sealant. Just an added precaution if your gaskets are old and you don't want to spend money for new ones!
6) while the carbs out make sure the piston slide smoothly up and down. If you hear friction keep cleaning them and make sure the needle is on properly.
7) make sure butterfly open and close at the same distance than carb 2. You can use a feeler gauge to do this. I myself used a straw to measure the distance from then end of the carb to the butterfly. (Butterfly being the door it opens when you pull the throttle). I had an idea about this, you can use a digital caliper. This will ensure your carbs are somewhat sync.
8) air pilot screws. Order: pilot, spring, washer then oring. Screw it in until softly reaches the end then unscrew 2 1/2 turns out (use the head cap as a guide) so it'll be 360 360 180 turns counterclockwise.
9) put your throttle cable before mounting carbs. I find it easier than when the carbs are already in bike. (This I learnt by experience lol)
10) make sure carbs fit correctly into bike
11) make sure there is not space between air box and carb and they are close tightly.
12) run bike until temperature I think this means until bike is warm half way or more the. Adjust your idle **** until it idles at 1.2K RPM
Of course the above are my findings and can be different from your situation but it may be a point of reference to start.
TEST RIDE -----------------
I was able to take a 20 mile ride to better test the result
Biggest change was that RPM were not increasing when pressing the clutch. I did noticed staying for a sec or two in whatever RPM I was in then go down as the speed went down.
I may have to check the sync again, luckily i have a motion pro carb sync tool so i can use it to make sure it's sync. I also purchase a flexible screw driver which should be delivered tomorrow so if i need to slightly move the air pilot i can do so.
As of right now bike is running much but much better than before.
Sprock,
I honestly tell you i hate taking the carbs out, well i hate putting them back in as it's a bit difficult including the air box. I'm going to try the silicone first and if no change then i will take the carbs out and replace the o-ring with the fatter ones in the set. I also going to try bringing the idle just a bit down.
Sprock,
Thanks for your suggestions and patience as i work on this bike. I'm def learning a lot.
I remembered one of you said "your idle is jacked up, bring it down" I also moved the air tube from behind the battery case to the side of the battery case (idk if that also made a difference)...I did that until I saw the bike idle between 1.2K and 1.1K. I waited until the fan turned off then I did the same route...to my surprise it was a smooth ride...I did feel it was hanging up but it was barely noticeable. Shifting gear was smooth as cutting butter with a hot knife...I think we got it to where it needs to be...yes, it may not be perfect but it's not as bad as it was before you guys starting to help me.
I don't want to sing victory yet but if this is fixed this is what I can share....
Lessons learnt
1) Submerged carbs in carb cleaner. It makes a huge difference.
2) air pilot, jet, pilot jet and everything that can be cleaned is clean.
3) keep rubber pieces away from carb cleaner. (I didn't learn this by experience but by reading..lol)
4) Make sure bowl and top covers are sealed correctly.
4.1) when you screwing the bowl and top covers back on: use a wrench is easier to handle than a screwdriver, and use a bit that fits your screw correctly otherwise you'll striped the screw. Tap the bit into the screw by using a hammer. Not too hard to break anything just a few taps so the bit is in securely.
5) use the motorcycle permeated gasket sealant. Just an added precaution if your gaskets are old and you don't want to spend money for new ones!
6) while the carbs out make sure the piston slide smoothly up and down. If you hear friction keep cleaning them and make sure the needle is on properly.
7) make sure butterfly open and close at the same distance than carb 2. You can use a feeler gauge to do this. I myself used a straw to measure the distance from then end of the carb to the butterfly. (Butterfly being the door it opens when you pull the throttle). I had an idea about this, you can use a digital caliper. This will ensure your carbs are somewhat sync.
8) air pilot screws. Order: pilot, spring, washer then oring. Screw it in until softly reaches the end then unscrew 2 1/2 turns out (use the head cap as a guide) so it'll be 360 360 180 turns counterclockwise.
9) put your throttle cable before mounting carbs. I find it easier than when the carbs are already in bike. (This I learnt by experience lol)
10) make sure carbs fit correctly into bike
11) make sure there is not space between air box and carb and they are close tightly.
12) run bike until temperature I think this means until bike is warm half way or more the. Adjust your idle **** until it idles at 1.2K RPM
Of course the above are my findings and can be different from your situation but it may be a point of reference to start.
TEST RIDE -----------------
I was able to take a 20 mile ride to better test the result
Biggest change was that RPM were not increasing when pressing the clutch. I did noticed staying for a sec or two in whatever RPM I was in then go down as the speed went down.
I may have to check the sync again, luckily i have a motion pro carb sync tool so i can use it to make sure it's sync. I also purchase a flexible screw driver which should be delivered tomorrow so if i need to slightly move the air pilot i can do so.
As of right now bike is running much but much better than before.
Sprock,
I honestly tell you i hate taking the carbs out, well i hate putting them back in as it's a bit difficult including the air box. I'm going to try the silicone first and if no change then i will take the carbs out and replace the o-ring with the fatter ones in the set. I also going to try bringing the idle just a bit down.
Sprock,
Thanks for your suggestions and patience as i work on this bike. I'm def learning a lot.
Last edited by jlpinedas; 07-02-2013 at 10:14 PM.
#33
07-05-2013, 01:34 PM
#34
07-06-2013, 09:28 AM
#35
07-06-2013, 05:05 PM
Join Date: Jul 2012
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Sprock, yes I think I can take them out in 5 min or so lol. I hadn't have a chance to ride it since that night but I will try to bring the idle just a bit down then replaced the o-ring in the air screw if needed. I will write an update once I go for a ride. Thanks everyone for your assistance.
#36
01-28-2015, 02:48 PM
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JLP, just joined the site and found your thread searching for idle mix advice on my 1991 1000F. I had a similar problem a while back.
Things to check: If the throttle cables are not being pinched or pushed by the tank causing cable tension to bind, you may be experiencing hot surging from an over-lean idle mixture. This will cause the "hanging revs" you get sometimes, as well as the prolonged warm up period on full choke before the bike will respond to throttle inputs. When the bike is fully warmed up, you should be able to blip the throttle and the revs should drop to idle almost instantly.
If it's a slow, hanging return to idle, that's usually indicative of an air leak in the intake tract (carb boots, idle mix orings, carb balance rubber nipples). Check for air leaks with a can of brake or carb cleaner while the motor is running. A quick shot around the boots & clamps, as well as the idle screws and balance nipples will reveal a cracked or worn rubber part needing replacement.
This hanging rev can also be due to an overly lean idle mix setting. If your idle mix screws are all set to 2.5 turns out as OEM, try turning them out to 3 turns and checking revs returning to idle without the hanging.
Things to check: If the throttle cables are not being pinched or pushed by the tank causing cable tension to bind, you may be experiencing hot surging from an over-lean idle mixture. This will cause the "hanging revs" you get sometimes, as well as the prolonged warm up period on full choke before the bike will respond to throttle inputs. When the bike is fully warmed up, you should be able to blip the throttle and the revs should drop to idle almost instantly.
If it's a slow, hanging return to idle, that's usually indicative of an air leak in the intake tract (carb boots, idle mix orings, carb balance rubber nipples). Check for air leaks with a can of brake or carb cleaner while the motor is running. A quick shot around the boots & clamps, as well as the idle screws and balance nipples will reveal a cracked or worn rubber part needing replacement.
This hanging rev can also be due to an overly lean idle mix setting. If your idle mix screws are all set to 2.5 turns out as OEM, try turning them out to 3 turns and checking revs returning to idle without the hanging.
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