Engine missing at idle


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RJL
Posts: 9
Joined: Sat Jun 23, 2018 8:57 pm
Location: Baton Rouge, La
Motorcycle: 1999 GL1500SE (x2)

Engine missing at idle

Post by RJL »



I picked up a '99 SE last week that has a miss at idle, simular to a fouled plug or bad plug wire. When I rev it up to about 1500 RPM+, it smooths out and runs great. I pulled each plug wire with it idling and #4 cylinder has no effect with or without the plug wire connected. So far I've changed the plugs, checked compression and checked spark on #4. All is good. When I pinch off the vacuum hose on the intake (left side, right above cylinder #4), idle smooths out, runs like silk. Changed that hose, no effect. Changed the "L" vacuum hose under the carbs, no effect. Any suggestions on which direction to start looking is much appreciated. TIA


FM-USA
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Re: Engine missing at idle

Post by FM-USA »

Left carb, large hose in front. Possible vac leak.
I fixed mine with a bent copper tube, trimmed down to the bends then used nut buster to slide it inside.
It's large enough to silicone or RTV it but never tried that.

.

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RJL
Posts: 9
Joined: Sat Jun 23, 2018 8:57 pm
Location: Baton Rouge, La
Motorcycle: 1999 GL1500SE (x2)

Re: Engine missing at idle

Post by RJL »

Thx for the info. I started the bike and shot starter fluid all around the carbs without any change. Except when I shot the area you described. I had to really get it into the lower area of the carb for the bike to react, but I think you may be on to something. I'll know more tomorrow.
FM-USA
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Re: Engine missing at idle

Post by FM-USA »

Ya, that area is REALLY-REALLY tuff to shoot directly. Took me a few days of frustration but then bit the bullet & pulled the carbs.
Bought few feet of several sizes of vac hose. Only one I didn't get was that large one... the one you'll see soon.
As it turned out I only used 1 foot of 2 hose sizes. Eh, more stock for toys.
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RJL
Posts: 9
Joined: Sat Jun 23, 2018 8:57 pm
Location: Baton Rouge, La
Motorcycle: 1999 GL1500SE (x2)

Re: Engine missing at idle

Post by RJL »

Well, after many hours of searching, turns out I had 2 issues. 1st one was the vacuum hose from the left carb that goes to the valve on the air snorkel. 2nd one, and probably the main cause of idle issue, was the vacuum hose from the petcock to a vacuum rail. This rail goes directly to the hose that attaches to the nipple on the intake right above cylinder #4. Thx again for the input received, much appreciated.
FM-USA
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Re: Engine missing at idle

Post by FM-USA »

:o. Holy vac hose Batman...
who'da thunk. :roll:

Just a heads up...
16 year old 1500 @-200k miles, thermostat housing to heads O-rings deteriorated. Antifreeze on right foot alerted me. From first smell to pouring out in 2-3 days time, no forewarning.
Factory installed it crooked, might have lasted longer.

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in2it
Posts: 201
Joined: Sun Oct 06, 2019 6:09 am
Location: Waldo,Arkansas
Motorcycle: 2000 GL 1500 Aspencade
1982 GL1100 (SOLD)
1980 GL1100 Bobber with Vance and Hines Mufflers (SOLD)

Past Rides in my youth
1965 Honda C102 50cc OHV Engine with 3spd Auto-Clutch
1972 CB 350
1975 CB 550 4 with Dunstall headers and mufflers
1978 GL 1000

Re: Engine missing at idle

Post by in2it »

following ...........
Solo So Long
Posts: 358
Joined: Thu Mar 26, 2020 4:07 pm
Location: Northern Nevada
Motorcycle: 1999 GL1500 50th Anniversary SE
1989 GL1500 FOR SALE
1983 GL1100 Interstate (ready to repair)
A pack of Super Cubs
Formerly (in order):
Honda Super Cub (bought 1968, sold ?)
Kawasaki Coyote (early 1970s)
Honda 350 (mid 1970s)
Kawasaki KZ900-PS (1977)
Honda Super Cubs (various years)
Kawasaki KZ1000C (1978)
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BMW R1150RT-P (2001)
BMW R1200RT-P (various years 2007 - 2018, NEVER AGAIN)

Re: Engine missing at idle

Post by Solo So Long »

Did you look where you last had it?

. . .sorry, couldn't help myself . . .it's been that kind of week today . . .
FM-USA
Posts: 2955
Joined: Wed May 18, 2011 8:40 am
Location: here, there, WHY?
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Re: Engine missing at idle

Post by FM-USA »

Solo So Long wrote: Sat Apr 17, 2021 4:09 pm Did you look where you last had it?

. . .sorry, couldn't help myself . . .it's been that kind of week today . . .
I was going to post one also...
(John Wayne) Well pilgrim, .. .. think we should gather a posse and find that missing idle?

.

.
Solo So Long
Posts: 358
Joined: Thu Mar 26, 2020 4:07 pm
Location: Northern Nevada
Motorcycle: 1999 GL1500 50th Anniversary SE
1989 GL1500 FOR SALE
1983 GL1100 Interstate (ready to repair)
A pack of Super Cubs
Formerly (in order):
Honda Super Cub (bought 1968, sold ?)
Kawasaki Coyote (early 1970s)
Honda 350 (mid 1970s)
Kawasaki KZ900-PS (1977)
Honda Super Cubs (various years)
Kawasaki KZ1000C (1978)
Kawasaki KZ1000P (various years, 1980 - 2005)
Honda 360 (1983)
BMW R1150RT-P (2001)
BMW R1200RT-P (various years 2007 - 2018, NEVER AGAIN)

Re: Engine missing at idle

Post by Solo So Long »

Dammit, that engine was RIGHT HERE just a little while ago! It can't have just gotten up and walked away . . !
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DenverWinger
Posts: 1862
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Location: Denver, CO
Motorcycle: (s)
1980 GL1100 STD Vetter (2005-)
1993 GL1500 Aspencade (2017-)
1983 Trav-Lite Camper (2010-)
Past rides
1972 CL350 (1980-1988) sold
1978 Suzuki GS550 (1985-2005) sold
1977 GL1000 (2002-2006) sold

Re: Engine missing at idle

Post by DenverWinger »

:lol: :lol: :lol: :lol:


♫ 99 Little Bugs in the Code, ♪
♪ 99 Bugs in the Code. ♫ :(
♫ Take one down, Patch it around, ♪
♫ 127 Little Bugs in the Code. ♫ ♪ :shock:

~Mark
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