Rpm slow to drop between shifts.


Information and questions on GL1500 Goldwings (1988-2000)
Post Reply
User avatar
go1dwing
Posts: 49
Joined: Mon Apr 24, 2017 9:23 pm
Location: Bakersfield, California
Motorcycle: Goldwing 05 1800

Rpm slow to drop between shifts.

Post by go1dwing »



Rpm slow to drop between shifts. 1999 1500. During shifts, with clutch fully engaged rpm's linger before dropping. Any ideas? Thanks.


User avatar
Rambozo
Posts: 1168
Joined: Sun Apr 01, 2018 8:36 pm
Location: Disneyland
Motorcycle: 1992 GL1500 Aspencade
Ducati Monster

Re: Rpm slow to drop between shifts.

Post by Rambozo »

How does it behave revving in neutral?
User avatar
go1dwing
Posts: 49
Joined: Mon Apr 24, 2017 9:23 pm
Location: Bakersfield, California
Motorcycle: Goldwing 05 1800

Re: Rpm slow to drop between shifts.

Post by go1dwing »

Revs up great and rpm drops back to 800 as soon as I let off on throttle. But going from second and the other gears the rpm lingers before dropping. Twisting the throttle all the way to closed position makes no difference. When shifting it takes about 3-4 seconds to drop back to 800 rpm. Thanks.
User avatar
go1dwing
Posts: 49
Joined: Mon Apr 24, 2017 9:23 pm
Location: Bakersfield, California
Motorcycle: Goldwing 05 1800

Re: Rpm slow to drop between shifts.

Post by go1dwing »

In 3rd gear, on my way to 4th gear, I pull clutch all the way in, it disengages transmission but rpm's increase briefly then slowly, 3-4 seconds, it drops down to lower rpm, safe enough for shifting. Thanks for ideas.
User avatar
Rambozo
Posts: 1168
Joined: Sun Apr 01, 2018 8:36 pm
Location: Disneyland
Motorcycle: 1992 GL1500 Aspencade
Ducati Monster

Re: Rpm slow to drop between shifts.

Post by Rambozo »

Only thing I can think of is the clutch is gummed up and dragging. How is it going into gear from neutral when stopped? Try some seafoam in the oil a few hundred miles before the next change.
User avatar
go1dwing
Posts: 49
Joined: Mon Apr 24, 2017 9:23 pm
Location: Bakersfield, California
Motorcycle: Goldwing 05 1800

Re: Rpm slow to drop between shifts.

Post by go1dwing »

Not a clutch issue. Shifts flawlessly. It disengages the transmission completely. Must be a sensor not triggering during shifts. Maybe a spring not fully closing the carb throttle. Thanks for the reply.
User avatar
Rambozo
Posts: 1168
Joined: Sun Apr 01, 2018 8:36 pm
Location: Disneyland
Motorcycle: 1992 GL1500 Aspencade
Ducati Monster

Re: Rpm slow to drop between shifts.

Post by Rambozo »

The throttle is purely mechanical and a push pull cable. As long as they are adjusted properly, there is no way the throttle can be open with the grip closed. You could be getting an air leak from the air injection system or other vacuum circuit. Is it a California bike? What happens if you are at speed, pull in the clutch and rev and release the throttle. Does it hang every time you release the throttle? How about when you release the throttle without pulling the clutch?
During high vacuum deceleration the ECU operates the pulse air solenoids. If you decel in gear the vacuum will be high, but with the clutch pulled in there should only be a blip of high vacuum. How are your vacuum hoses?
User avatar
WingAdmin
Site Admin
Posts: 22419
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (sold)
1998 XV250 Virago (sold)
2012 Suzuki Burgman 400 (wife's!)
2007 Aspen Sentry Trailer
Contact:

Re: Rpm slow to drop between shifts.

Post by WingAdmin »

Generally there are three things that will typically cause this:

Throttle cable problems - usually a broken push cable and sticky pull cable.

Carbs not balanced correctly.

Intake air leak - causing a too-lean condition. Most common cause is leaky/cracked or disconnected vacuum lines.
User avatar
WingAdmin
Site Admin
Posts: 22419
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (sold)
1998 XV250 Virago (sold)
2012 Suzuki Burgman 400 (wife's!)
2007 Aspen Sentry Trailer
Contact:

Re: Rpm slow to drop between shifts.

Post by WingAdmin »

Rambozo wrote: Mon Oct 25, 2021 2:33 am The throttle is purely mechanical and a push pull cable. As long as they are adjusted properly, there is no way the throttle can be open with the grip closed. You could be getting an air leak from the air injection system or other vacuum circuit. Is it a California bike? What happens if you are at speed, pull in the clutch and rev and release the throttle. Does it hang every time you release the throttle? How about when you release the throttle without pulling the clutch?
During high vacuum deceleration the ECU operates the pulse air solenoids. If you decel in gear the vacuum will be high, but with the clutch pulled in there should only be a blip of high vacuum. How are your vacuum hoses?
The air injection system on the GL1500 injects air into the EXHAUST, to help burn unburned hydrocarbons and reduce emissions. The pulse air solenoids won't affect the intake vacuum.
User avatar
perojak
Posts: 1
Joined: Sun Mar 21, 2021 4:09 pm
Location: Stockholm
Motorcycle: 1989 GL1500

Re: Rpm slow to drop between shifts.

Post by perojak »

Hello, my name is Per-Olof. I drive a 1989 1500/6 from time to time.

Does your bike have the Cruise control?

Can the vacuum-servo? connected to the carb be mis-alignet in som way.

Something holding the vacuum in the cruise-system and binding the carb in som way when you are releasing the throttle?

Regards
Per-Olof
User avatar
Wingsconsin
Posts: 1078
Joined: Tue Jul 10, 2012 1:47 pm
Location: Sussex, Wisconsin (West of Milwaukee)
Motorcycle: Current Rides -
2002 GL1800 - Pearl Orange
1983 Suzuki GS850GL - Blue & Black

Past rides -
2003 GL1800 - Illusion Blue
1996 GL1500 Aspencade - Pearl Blue
1992 GL1500 Aspencade -Candy Red
1980 GL1100 - Custom Cobalt Blue
1985 GL1200 Aspencade Brown
1983 CX500 Custom Red
1982 CX500 Custom Blue
1978 CX500 Standard Black
1982 Suzuki GS650 Red
Contact:

Re: Rpm slow to drop between shifts.

Post by Wingsconsin »

The original posting shows a GL1800 -
This is in the G1500 section --
2 very different bikes

Gl1500 carbureted
GL1800 Fuel Injected

My 1st thought was vacuum leak - a typical sign on a carb system.
Postings are my opinions based on experience and acquired knowledge.
Your results may vary. Universal disclaimers apply.


Munk's Maxim -- There is no such thing as a cheap motorcycle
68c15
Posts: 8
Joined: Sat Oct 30, 2021 10:05 am
Location: Sioux Falls, SD
Motorcycle: 1997 GL1500SE
2001 VL800
2001 GSX-R750

Re: Rpm slow to drop between shifts.

Post by 68c15 »

WingAdmin wrote: Mon Oct 25, 2021 10:04 am Generally there are three things that will typically cause this:

Throttle cable problems - usually a broken push cable and sticky pull cable.

Carbs not balanced correctly.

Intake air leak - causing a too-lean condition. Most common cause is leaky/cracked or disconnected vacuum lines.
Mine does the same thing. After watching the video and reading the article explaining our fuel system controls theory and operation a vacuum leak is the most logical cause. Word on the grapevine is there happens to be a large hose buried far below carburetors that has a tendency to degrade and suck a hole in the elbow right near the intake fitting. “They” say this hose is hard to get at, you have to remove carbs and the rubber shield between them and the intake.

On the plus side it is the off season so I am taking time to give Betty a full once over and cover everything so my next 84,000 miles are trouble free


Post Reply