Whats normal for temp gauge readings?

[tom93gts]

When I picked up the RE5 my fan thermo-switch was shot. I found the switch from a late 80's Honda CRX is the same body so I put one of those in. I believe the temp for that switch is probably close to the RE5 switch as the fan comes on when the gauge gets just above the half way mark.

My question though, when riding around what should I be seeing on the gauge? I find that riding on the highway at 65 or so the temps will drop down quite low, almost down to the 1/4 mark. I wonder if I am missing a thermostat? Does the re5 have one? More city driving and they hover mostly between 1/2 and 3/4. Extended idling and very slow moving sometimes temps even get above 3/4! I expect that the extreme temps here in the summer of 110-115 are at least partially to blame for the hot running, but what should I expect? What do you guys see on the gauge?

[frankt]

I think the fan thermo-switch from the CRX turns the fan on at a lower temp then the stock switch. I my experience with several RE5s the fan will not turn on with the stock switch until the gauge reads 3/4 or a bit more.
If your temp runs consistently at 1/4 on the highway that seems low to me, you may be missing a thermostat(yes the bike has one). My bike runs near the 1/2 mark on the highway.
Your city riding experience seems about right, these bikes run hot and in stop and go traffic my experience in the summer is 3/4 on the gauge.

[tom93gts]

Thanks, I will check my thermostat for operation this weekend. The thermo-switch doesnt seem to be as important a deal, but I will see if rotary recycle has them.

When the temps cool down on the highway the RE5 being a carb doesnt compensate so it starts to run crappily.

[tom93gts]

Didn't get a chance to check the thermostat this weekend but will try tonight. I am pretty confident I will find its bad or missing. Probably should just bite the bullet and get a new one along with a fan thermo-switch.

[SuzukiRE5]

My gauge doesn't work at all so that is something else that will have to be fixed. I might tackle that after I get the tank fixed and bike running again.

[tom93gts]

Well I pulled off the water pump housing, low and behold there was a thermostat sitting there closed just like it should be. I the thermostat in a pot of water on the stove, it starts opening at about 165F, right in range where it should be. So that leaves me stumped, how can my freeway temps be too low if the thermostat is operating properly? No matter what the airflow through the radiator is the engine temps should not drop too low as long as the thermostat is closed and not allowing water through. I am stumped.

[tom93gts]

Looking in the factory service manual, if the temp
gauge is at the middle bar that means the water temp is about 88C. Thats when my
(Honda CRX) thermo-switch and fan come on. The correct switch should come on
about 106C, which is just before the last bar before the red zone. Thats fine
and dandy, but I think my problem is with the thermostat. The thermostat is
supposed to start opening at 71C (I tested and its within a degree or 2) and be
fully open by 85C. That means if I am cruising down the highway I could
potentially have a water temp of say about 75C, which according to the manual would be just above half
way between the lowest mark and the middle mark on the gauge. Turns out I do
have a temp of just about 75C, since thats where the gauge reads! This is where my RE5 runs crappy because its too cold,
so is the RE5 is designed to run like crap on the freeway? The fan isn't
running since it won't be on until the temps get to 88C or so, hence my confidence
that it isn't the problem. The service manual
says if its running too cold to put the radiator cover on... I hope I dont need
that here in Phoenix summer time.

Seems like a flawed design if the thermostat starts
to open so soon before the engine is up to normal operating temperature doesn't
it?

[suzsmokeyallan]

Not that this is written in stone but i'd get a new thermostat and fit it for the sake of making sure the one you have is in fact working as intended. Many times ive seen these simple wax element units open fine on a "water in a pot test" but decided to play the arse when installled. Besides,,,,, ahh how old is this thermo unit of yours? what??? you dont know??? well thats good enough of a reason for a changeout to me.

[tom93gts]

Thats a good point about the t-stat. I would be willing to bet its about 32 years old or so!