97 - 99 thermostats

[Rider99XX]

Hi guys. I have a thermostat for a 97 Bird. I have a 99 Bird. Will the 97 thermostat work in my 99 bird? It will fit in the housing and the vent hole lines up, and if I swap the rubber sealing ring from the 99's stat.

I have the Bird drained and ready to go back together but need to know if the 97 stat will work.

Thanks in advance.

[rockmeupto125]

Yes.

[CxBXR]

the part numbers dont match

[Rider99XX]

Thanks rockmeupto125. Now to go reassemble.

Just curious as to what the extra spring and disk on the back of the newer stat is for?

[rockmeupto125]

Well in my mind, a thermostat is a thermostat, as long as it fits.

BUT!!!!

I looked up 1999XX, grabbed the thermostat number 19300-MAT-761 and plugged it into RonAyers reverse lookup, which indicated that it fit 1997 to 2003 CBR1100XX. This was my impression as well, so I answered your question.

CxBXR spoke and said the part numbers don't match, so I went back to make sure I had the part number for the thermostat, not something else. RonAyers list the 1997 thermostat as 19300-MG9-000, and the fische is different. Plugging that number into the reverse lookup gives the information that the thermostat 19300-mg9-000 fits 1997 to 2003 CBR1100XX as well as a variety of Gold Wings and such.

Sorry to mislead you. I think you're okay and all will work, but I can't say that without putting them in my hands and examining them. Again, I open my mouth too soon, and thanks to CxBXR for pointing out this inconsistancy. Hopefully another who can recall if they've done this swap can chime in.

[Rider99XX]

The 97 stat looks totally different from the newer stat. The newer stat has an extra spring and a nickle sized disk behind that extra spring. The 97 stat will fit in the housing and the small vent hole lines up. I ran the bike for about 15-20 minutes sitting in the garage. The temp gauge went just over half way up from cold to hot. The fan never came on which made me wonder a bit. Normally if I let it idle that long it would get VERY close to the red mark and the fan would come on. The outside ambient temp was upper 70s last evening.

What is the worst thing that could happen running the older stat in the newer engine?

The bike is a 99 with a full Akrapovic exhaust, remapped PC II, K&N, Iridium plugs, 27K miles and 143 dyno verified HP. It runs great with no other issues other than the thermostat.

[Rider99XX]

Here's a short ride report with the 97 thermostat in my 99 Bird. After a short 4-5 minute warm up I went for a 15 minute ride to warm the chain to lube it. The temp gauge was a little below where it was before the stat change. the ambient temp was low 80's here in MS. Halfway through the ride I pulled over quickly after a quick trip up to redline in the first 3 gears and let the bike set idling for about 6-7 minutes and watched the gauge. It did rise but a little more slowly than before. I then proceeded back home, about 6 miles, all at higher RPM's and again let the bike idle. The gauge again rose, but slower than before. I let it idle for 8 minutes and the needle went to the top of the rectangled box on the gauge while the fan would cycle on and off. When the needle went to the top of the box the fan stayed on.

That's it for now.

Any thoughts????

[rockmeupto125]

Not the thermo switch, Dean.........the thermostat.

[partsman]

Sounds fine.I do know after checking service manuals on a variety of Honda's with different thermostats that they all open at the same temp.I suppose they might flow a little differently,but that's thoery.

That "MG9" thermostat first appeared on GL1200s btw.

Al

[Rider99XX]

So far so good. After a 30+ mile ride all looks good. No higher than normal temps, no gurgling sounds from the engine/radiator area. All seems well and good. In fact it seems to run a little cooler than before, but just slightly.

The 97 stat is half the size and weight of the newer stat so I probably gained some speed and better handling due to the lighter weight and lower senter of gravity

[mikesail]

From your description the newer thermostat is the type which has a bypass valve. This additional valve lets the pump circulate coolant locally, bypassing the radiator when the system is not over the setpoint temp. By not using this style thermostat, not all the coolant will pass thru the radiator when above the setpoint temp, and thus your system cannot cool as well.

Unless you overheat, it will not make a difference. I'd suggest getting the correct unit before a hot day.

[Rider99XX]

I have plans on doing just that mikesail. So far so good but I'd like to put back what came out, back original.

I was thinking the extra disk and spring may have been a bypass of some sort due to the spring is not as strong as the main spring.

Thanks for the info.