Hi it appears this part is no longer avaialble under the many different part numbers, as I am replacing the thermostat and piped and I have a leak at the Carb heat Exchanger I was going to replace this part while the bike is stripped down however I have been unable to find a part , so can anyone advise if mine fails when tested can it be bypassed by a hose ?
19330-MT8-004 VALVE, THERMOSTAT - ALL '90
19330-MW5-004 VALVE, THERMO - ALL'91
19330-MY4-004 VALVE, THERMO - ALL'91
19330-MN5-004 88-89
19330-MZ3-621 88-89
GL1500 Valve Thermo
- pricedjohn
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- Location: Dunfermline Scotland UK
- Motorcycle: Gl1500 1988, RT1200 2009, Norton Commando 750 1973, Suzuki GSX1100F 1991, Kawasaki ZZR 1100 1990, GSF650 Bandit x 2 , Suzuki GT500 , Kawasaki z650,
- DenverWinger
- Posts: 1688
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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: GL1500 Valve Thermo
If you already have the Thermostat out take it to your local Auto Parts dealer. I bet they can find an automotive one for an appropriate temperature that will work. Needs to be same diameter and thickness on the flange, and make sure it is no "taller" either above or below the flange and it should work fine.
Also check with your local Honda automobile dealer for the part #'s you listed, often the exact same part is used in a Honda Car and they may be able to get exact part.
However, if you haven't yet removed it, I'd just leave it alone. These very rarely fail....
Also check with your local Honda automobile dealer for the part #'s you listed, often the exact same part is used in a Honda Car and they may be able to get exact part.
However, if you haven't yet removed it, I'd just leave it alone. These very rarely fail....
♫ 99 Little Bugs in the Code, ♪
♪ 99 Bugs in the Code. ♫
♫ Take one down, Patch it around, ♪
♫ 127 Little Bugs in the Code. ♫ ♪
~Mark
♪ 99 Bugs in the Code. ♫

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

~Mark
- pricedjohn
- Posts: 28
- Joined: Thu Dec 31, 2015 2:02 pm
- Location: Dunfermline Scotland UK
- Motorcycle: Gl1500 1988, RT1200 2009, Norton Commando 750 1973, Suzuki GSX1100F 1991, Kawasaki ZZR 1100 1990, GSF650 Bandit x 2 , Suzuki GT500 , Kawasaki z650,
Re: GL1500 Valve Thermo
Thanks for the reply , I do have a Thermostat , it is the Coolant Valve Thermostat I require
Rgds John
Rgds John
- DenverWinger
- Posts: 1688
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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: GL1500 Valve Thermo
Part #2 below, correct?
If you need to replace that you should be able to find a generic Automotive replacement part which will fit.
If you are referring to part #6 you might have to settle for searching a used replacement, check with motorcycle breakers. I don't know what would result from bypassing it. I think it's to regulate preheating the intake manifolds, you'd probably be OK in the UK, but bypassing it would likely cause problems in a hot climate.
If you need to replace that you should be able to find a generic Automotive replacement part which will fit.
If you are referring to part #6 you might have to settle for searching a used replacement, check with motorcycle breakers. I don't know what would result from bypassing it. I think it's to regulate preheating the intake manifolds, you'd probably be OK in the UK, but bypassing it would likely cause problems in a hot climate.
♫ 99 Little Bugs in the Code, ♪
♪ 99 Bugs in the Code. ♫
♫ Take one down, Patch it around, ♪
♫ 127 Little Bugs in the Code. ♫ ♪
~Mark
♪ 99 Bugs in the Code. ♫

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

~Mark
Re: GL1500 Valve Thermo
Neighbor went through this issue.
Stock numbers were posted on the Wing/Facts site and they were thee wrong sizes, either too large or too small.
He had to take his thermostat to the parts store, NAPA I think, and match it up.
Stock numbers were posted on the Wing/Facts site and they were thee wrong sizes, either too large or too small.
He had to take his thermostat to the parts store, NAPA I think, and match it up.
It is good we have dreams, for if they were real, most would not be alive.
Smile for yourself next time you wake up, you have another fine day to live.
Smile for yourself next time you wake up, you have another fine day to live.
- pricedjohn
- Posts: 28
- Joined: Thu Dec 31, 2015 2:02 pm
- Location: Dunfermline Scotland UK
- Motorcycle: Gl1500 1988, RT1200 2009, Norton Commando 750 1973, Suzuki GSX1100F 1991, Kawasaki ZZR 1100 1990, GSF650 Bandit x 2 , Suzuki GT500 , Kawasaki z650,
Re: GL1500 Valve Thermo
Part 6 not part 2 I have a replacement for part 2
Rgds John
Rgds John
- ct1500
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Re: GL1500 Valve Thermo
When the engine is cold and warming up the valve is open allowing heated coolant to circulate and warm the carb riser and intake manifolds. By doing this certain hesitations and stumbling engine problems associated with carbureted cold engines are reduced/eliminated which aids driveability of the machine. The thermo valve is closed at 180 degrees F which happens to be the opening temp of the coolant thermostat. The valve closes cutting off hot coolant to the riser which helps prevent fuel vapor lock on a hot engine.pricedjohn wrote: ↑Tue Aug 27, 2019 4:55 amHi it appears this part is no longer avaialble under the many different part numbers, as I am replacing the thermostat and piped and I have a leak at the Carb heat Exchanger I was going to replace this part while the bike is stripped down however I have been unable to find a part , so can anyone advise if mine fails when tested can it be bypassed by a hose ?
If it were my machine with no replacements available I would not just remove and plumb a hose in its' place. A better alternative would be to make/source a restrictor which would let a little coolant pass to aid warm-up somewhat but not enough flow to thoroughly heat soak the riser and manifolds when at operating temp.

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Nothing leaves my shop till its' perfect
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Nothing leaves my shop till its' perfect
This is what I do
- pricedjohn
- Posts: 28
- Joined: Thu Dec 31, 2015 2:02 pm
- Location: Dunfermline Scotland UK
- Motorcycle: Gl1500 1988, RT1200 2009, Norton Commando 750 1973, Suzuki GSX1100F 1991, Kawasaki ZZR 1100 1990, GSF650 Bandit x 2 , Suzuki GT500 , Kawasaki z650,