GT750J over heating.....or is...it?

[yeadon_m]

Yes, if the tach turns then so is the water pump gear.
I understand that the waterpump gear may turn but the impeller under the cover not be turning IF its locating pin for example corrodes off.
Seems unlikely but hey.
One way to be sure if its turning is as described earlier in this thread.
Start the bike cold and then spend a patient 20min or so while it comes fully up to temperature, with your hand on the top hose. The thermostat cover will get warmer and warmer but the far end of the hose which goes to the radiator will still be cold or luke warm.
Eventually, the T'stat will open and with a RUSH the whole top hose and rad will get hot IF the pump's impeller is turning. If the rad end of that top hose just gets warmer very slowly once it starts to warm up, the pump may not be doing its job.
Easy and non-invasive test. And free. Free is a good price
Mike

[Eddie]

oops, sorry I haven't read the whole thread, that does make sense about the tach and the plastic gear, I just remembered the plastic gear that drives the pump, I didn't know this was discussed already, sorry I need to read the whole thread.... and like what was said just letting it run and putting your hand on the upper hose will tell you,, good idea ....also if you don't think its turning then the pump needs to come out, there is no other way to get to the impeller , that's why I was saying if it looks like the pump is weeping , or leaking fluid (from under the bike , the pump cover has a weep hole where water will come out if the seals are bad in the pump) if its leaking fluid you might as well pull the pump and fix it or replace it if you can afford it, the leak will end up getting worse over time, (at least mine did) and its annoying plus you will need to be checking the fluid level and you will be leaving a puddle under the bike , kinda like your bike is taking a piss everywhere she goes, like marking her territory like a dog,,, its annoying

[Coyote]

Had a VW bug one time that leaked every where it went. When someone said 'hey man, your car is leaking' my reply was 'no it's not. That's the automatic concrete oiler'

[rngdng]

It's not leaking, it's marking it's spot......


Lane

[chance johns]

New Chapter. I bought a trail tech digital temperature gauge that attaches to the spark plug base. i have this on the center plug. 10m ride on the highway, seems to be doing well. oem gauge sits about center. digi temp around 215-220f. i pull off and do some city riding. 10m or so. temps getting hotter and oem gauge is reading hotter, 225-230f ish. needle eventually gets pegged to the far right of the oem gauge indicating its as hot as all hell. temp gauge never gets above 243f.

all while operating around 4-5k rpms
i feel alot of heat coming of the motor.
fan doesnt come on. but it has before in the past.

what exactly am i learning from this experiment?
my oem gauge is off when it reaches hot temps?
im still a little nervous to drive it pegged like that, because there is alot of heat comming off the motor, and can i really trust my gt's motors life with this digi temp gauge?
i fear i am being too cautious.

any insight on what to do next?

i do have some photo's of the digital temp and where the needle is on the oem temp gauge in various temperatures but when i try to add the photo it says "board attachment quota has been reached"

[tz375]

That seems hot for a water cooled head.

[Alan H]

Sounds like either stuck thermostat or part blocked radiator.
Check if there are any parts of the rad colder than others.
It may need flushing or worst case recoreing.

[rngdng]

I don't think your cooling system is working in several ways. The pump may not be working, and the fan isn't working. With your digital results, I would start troubleshooting the fan circuit, and consider replacing the water pump. As stated before, the radiator may be partially clogged as well.


Lane

[chance johns]

well i thought 400f was the danger zone.
ive been throught the raditor and waterpump all seems fine!

i dont expect you all to have read the previous 5 pages.......

ive been through EVERYTHING.
i mean obviously theres something going on, if 250 is too hot.

[Suzukidave]

ive been through EVERYTHING.
.

I guess not everything or it wouldnt be looking like its over heating

[tz375]

well i thought 400f was the danger zone.
ive been throught the raditor and waterpump all seems fine!

i dont expect you all to have read the previous 5 pages.......

ive been through EVERYTHING.
i mean obviously theres something going on, if 250 is too hot.

Water boils in the open at 212 f and at higher temperatures as teh pressure rises. Of course we are not measuring water tempos but the head around the spark plug - or possibly just the plug temperature, so that complicates things. My google fu seems to be off tonight and every article I read had either different numbers or no numbers for what the CHT should be on a water cooled two stroke.

What I think I would do in your situation is to get a digital water temperature gauge and see how hot the water is getting. I don't recall you mention water spitting out of the overflow and that suggests that temperatures are within an acceptable running range. and your 250 degree CHT number may just be OK after all.

Without an accurate water temperature reading it's hard to know for sure. Daytona do a decent gauge and you can buy one on line but get an electronic one and a simple adapter.

You could also calibrate the gauge and sender that are fitted by removing it and wiring it up and place the sender in water or oil along with a temperature gauge and sender that you trust to be accurate and slowly raise the temperature and see how the two compare - but that's water temp gauge against OEM water temp gauge and not CHT. That CHT reading may be misleading.

You need to know what temp the water is at when that gauge reads in the red.

[rngdng]

There is a test in the service manual for the fan switch, which is temperature driven. If that test passes, and the fan is not coming on, maybe you're OK.



Lane

[chance johns]

yeah one time on a test drive my coolant did leak all over the place. i was riding on the interstate, the bike got hot. shut off, and coolant was spilling. wouldnt start again till it cooled off again. but that was when i thought reving it in the 6-8k rpm range was ok.

now im keeping it in the 3-4k range , hasnt shut off again, but still seems to be getting too hot

[Suzukidave]

You may have already replied to this , but is the stock thermostat installed and correctly ?

[chance johns]

stock thermostat, tested, and installed the only way it can be!