Havent had bike that long. Ive recently installed a digital thermometer and only taken for one ten minute ride since then and temperature only got up too 58 degrees after 10 minutes. That seems a bit cool. I see in the manual the water valve should open between 80-84 degrees. So im guessing best operating temp is above that and below 95 degrees when the fan kicks in. Which it does on my bike. (i ran in up hot with bike sitting to test fan)
Maybe my valve is stuck open and i should pull it out to test opening temp.
Is it bad for the motor when it runs to cool like this?
Cheers for any advice.
P.S i would take it for a longer ride but its a bit dodgy as its nearly ready for the track. no lights, no nothing legal.
1k 89 running too cold?
Moderators: Site Director, FZR Forum Moderators
Re: 1k 89 running too cold?

1989 3LN1 FZR250R, currently stock.
TTR Ignition Systems
TCI Repair and Ignition Transistor Upgrade
VRR Adaptor Harness
YZF600 TCI Adaptor
Running Light Fuse Carrier
TTR Ignition Systems
TCI Repair and Ignition Transistor Upgrade
VRR Adaptor Harness
YZF600 TCI Adaptor
Running Light Fuse Carrier
Re: 1k 89 running too cold?
Running it cold like this is not to good for the motor?DonTZ125 wrote:- if your engine temp is only up to 58C after a ten minute ride, then your thermostat is either a) jammed wide open, or b) missing, removed by a PO.
Re: 1k 89 running too cold?
Hrm - I don't think your specific output is high enough to really risk a cold seize like a GP bike or turbo bike. You're probably losing some burn efficiency, and possibly running a little leaner (denser air intake charge due to cooler intake runners).
1989 3LN1 FZR250R, currently stock.
TTR Ignition Systems
TCI Repair and Ignition Transistor Upgrade
VRR Adaptor Harness
YZF600 TCI Adaptor
Running Light Fuse Carrier
TTR Ignition Systems
TCI Repair and Ignition Transistor Upgrade
VRR Adaptor Harness
YZF600 TCI Adaptor
Running Light Fuse Carrier
Re: 1k 89 running too cold?
I was thinking more along the lines of all the moving parts (especially the pistons/rings maybe valves) arent up to temp, so they havent expanded fully and therefore its running with greater clearances than it should. Pistons are oval when cold and round when hot. Well they are on air cooled two strokes which is more my fortee. Im just thinking out loud here. I will check the thermostat anyways regardless and replace if needed. Yamaha put it there to get the engine hot, i think they know a bit more than i doDonTZ125 wrote:Hrm - I don't think your specific output is high enough to really risk a cold seize like a GP bike or turbo bike. You're probably losing some burn efficiency, and possibly running a little leaner (denser air intake charge due to cooler intake runners).

Cheers Don.
Re: 1k 89 running too cold?
Yeah, diesels are the same, just not as much. Your Fizzer pistons aren't quite as ovalled as those in your H2, but you still might run a little higher surface pressure against the wall than normal; this is likely balanced by the oil being more viscous. All things being equal, it's best to run the engine the way it was designed - like you say, they probably knew more than you or me!
1989 3LN1 FZR250R, currently stock.
TTR Ignition Systems
TCI Repair and Ignition Transistor Upgrade
VRR Adaptor Harness
YZF600 TCI Adaptor
Running Light Fuse Carrier
TTR Ignition Systems
TCI Repair and Ignition Transistor Upgrade
VRR Adaptor Harness
YZF600 TCI Adaptor
Running Light Fuse Carrier
Re: 1k 89 running too cold?
I pulled the thermostat and tested it. its working perfectly as per manual specs! So I don't know whats going on there. Im fairly sure the temp gauge is correct.
It is cold here like 15 degrees C. No worries, at least its not overheating.
Maybe my bike is just so cool that its too cool

It is cold here like 15 degrees C. No worries, at least its not overheating.
Maybe my bike is just so cool that its too cool

