GT750 Thermostats

For discussion of all general things. Keep it clean folks. No politics or religion.

Moderators: oldjapanesebikes, H2RICK, diamondj, Suzsmokeyallan

User avatar
tz375
Moto GP
Posts: 6204
Joined: Mon Nov 03, 2008 10:47 am
Location: Illinois

Re: GT750 Thermostats

Post by tz375 »

simmons1 wrote:
tz375 wrote:Does it still have that cool looking TCE 3 into 1 exhaust?
For now. I have a set of Higgspeeds on order. The TCE may be for sale some day.
It will be interesting to hear your comparison between the two pipes on your bike. Any chance you will do a back to back run on the dyno - purely to get the jetting right of course :wink: That I would like to see.
simmons1
On the main road
Posts: 102
Joined: Tue May 06, 2014 8:21 pm
Country: United States
Suzuki 2-Strokes: GT750, GS1000s
Location: Fort Worth

Re: GT750 Thermostats

Post by simmons1 »

tz375 wrote:
simmons1 wrote:
tz375 wrote:Does it still have that cool looking TCE 3 into 1 exhaust?
For now. I have a set of Higgspeeds on order. The TCE may be for sale some day.
It will be interesting to hear your comparison between the two pipes on your bike. Any chance you will do a back to back run on the dyno - purely to get the jetting right of course :wink: That I would like to see.

Most likely no dyno runs. The TCE has already been removed and the Higgspeeds shipped a couple days ago.
T700, Africa Twin, Goldwing, Super Tenere, WR250R, GS1000s, GT750, H2 750
simmons1
On the main road
Posts: 102
Joined: Tue May 06, 2014 8:21 pm
Country: United States
Suzuki 2-Strokes: GT750, GS1000s
Location: Fort Worth

Re: GT750 Thermostats

Post by simmons1 »

Well a couple more years have gone by with Waynes old Buffalo. I still really enjoy riding the bike.

I am still running it with no Thermostat. That said it consumes a fair amount anti- freeze. I am not helpless mechanically but I am far from an expert and know very little about the Buffalo engine. Could one of you nice guys give me kind of trouble shooting checklist so that I can get the bike fixed and sorted once and for all.

I live in DFW if any of you guys are local to me that may be able to give me a hand fixing the problem.

Thanks!

Rich
T700, Africa Twin, Goldwing, Super Tenere, WR250R, GS1000s, GT750, H2 750
User avatar
tz375
Moto GP
Posts: 6204
Joined: Mon Nov 03, 2008 10:47 am
Location: Illinois

Re: GT750 Thermostats

Post by tz375 »

Two possibilities spriing to mind. First is that there's a leak somewhere. You may be able to pressure test the system to rule that out.

Another possibility is a leaky head gasket causing the system to be over pressure and blowing water out of the overflow. Try a compression test when the motor is hot and see if one pot is significantly low.
simmons1
On the main road
Posts: 102
Joined: Tue May 06, 2014 8:21 pm
Country: United States
Suzuki 2-Strokes: GT750, GS1000s
Location: Fort Worth

Re: GT750 Thermostats

Post by simmons1 »

tz375 wrote:Two possibilities spriing to mind. First is that there's a leak somewhere. You may be able to pressure test the system to rule that out.

Another possibility is a leaky head gasket causing the system to be over pressure and blowing water out of the overflow. Try a compression test when the motor is hot and see if one pot is significantly low.
As far as a leak goes nothing seems to hit the ground and I don't smell anti freeze.

Head gasket sounds more likely. I rode the bike to our local Friday night bike night after topping off the coolant.

This morning it was down a little bit and the neck that from the cap down has some black funky little balls of stuff. It has actually had this for quite a while when topping off the radiator. I assumed it was Stop Leak residue. I wiped some out in a paper towel and it smelled and felt more smelled like more like exhaust than anything else.

If it is blowing coolant out of the overflow wouldn't I see it or smell it?

From above can I assume that the compression test might show a head gasket leak?

How hard is it to pull the head and what should I be looking for once it is off?

Sorry about the dumb questions.
T700, Africa Twin, Goldwing, Super Tenere, WR250R, GS1000s, GT750, H2 750
User avatar
tz375
Moto GP
Posts: 6204
Joined: Mon Nov 03, 2008 10:47 am
Location: Illinois

Re: GT750 Thermostats

Post by tz375 »

If it's blowing out of the overflow when it's hot and running hard, it's possible that you won't smell it, but you could try routing the overflow hose into a plastic bottle and see if it collects anything.

If the head has a slight leak when hot, it may not be obvious from a compression check but low on one cylinder would point to that probability.

Removing the head is simple. I'd take the fuel tank off first, just to make it easier, and then drain the coolant from the bolt on the lower side of the crankcase. Remove the top hose and the bypass hose and then pop off all the head bolts and sleeve nuts.

There is only one stud and that's close to the thermostat. The head has to be slid up over that. Hardest part is breaking the bond - gaskets stick like $hit to a blanket, and cleaning the old gasket material off both faces.

Heads are not very stiff, so it would be a good idea to have it machined flat by any local auto machine place.

You could start with pressure testing the cooling system. Lots of videos on ebay. Cheap and easy to do.
simmons1
On the main road
Posts: 102
Joined: Tue May 06, 2014 8:21 pm
Country: United States
Suzuki 2-Strokes: GT750, GS1000s
Location: Fort Worth

Re: GT750 Thermostats

Post by simmons1 »

Thank you for the help.

I'll let you know what I find. I think I will start simple with the bottle on the overflow and see what is catches.

I don't think it is getting into the transmission, but I may check it anyways. Would the transmission oil look milky like in a 4 stroke if coolant was getting into the transmission?

Last dumb question. Could a head gasket leak be what was causing the overflow to get over pressurized when the bike had a thermostat in it before Wayne removed it?

Rich
T700, Africa Twin, Goldwing, Super Tenere, WR250R, GS1000s, GT750, H2 750
User avatar
tz375
Moto GP
Posts: 6204
Joined: Mon Nov 03, 2008 10:47 am
Location: Illinois

Re: GT750 Thermostats

Post by tz375 »

It's hard for water to get into the transmission except from the small seal between the two crankcase halves and that was fixed at engine number GT750-36198 which was the third design of crankcases

Yes, a blown/leaking head gasket would likely have caused all of the symptoms that Wayne experienced. Other things could also have been the cause, but a leaky gasket can/will result in missing coolant high temperatures and so on.
User avatar
Suzukidave
Moto GP
Posts: 3980
Joined: Fri Oct 24, 2008 5:55 pm
Country: US
Suzuki 2-Strokes: GT750 x2 97 -1200 Bandit 86 GSXR1100
Location: Lancaster Pa.

Re: GT750 Thermostats

Post by Suzukidave »

I am surprised just running without the thermostat doesnt make it over heat unless Wayne closed off the warmup bypass .
the older i get the faster i was
simmons1
On the main road
Posts: 102
Joined: Tue May 06, 2014 8:21 pm
Country: United States
Suzuki 2-Strokes: GT750, GS1000s
Location: Fort Worth

Re: GT750 Thermostats

Post by simmons1 »

Never over heats and Wayne claims the bypass isn't blocked.

I wonder if there is way to check that?
T700, Africa Twin, Goldwing, Super Tenere, WR250R, GS1000s, GT750, H2 750
User avatar
Suzukidave
Moto GP
Posts: 3980
Joined: Fri Oct 24, 2008 5:55 pm
Country: US
Suzuki 2-Strokes: GT750 x2 97 -1200 Bandit 86 GSXR1100
Location: Lancaster Pa.

Re: GT750 Thermostats

Post by Suzukidave »

When you remove and attach the head be sure and use the proper bolt sequence :up: Image
the older i get the faster i was
simmons1
On the main road
Posts: 102
Joined: Tue May 06, 2014 8:21 pm
Country: United States
Suzuki 2-Strokes: GT750, GS1000s
Location: Fort Worth

Re: GT750 Thermostats

Post by simmons1 »

Suzukidave wrote:When you remove and attach the head be sure and use the proper bolt sequence :up: Image
Thanks for the photo. The other fasteners have no specific order?
T700, Africa Twin, Goldwing, Super Tenere, WR250R, GS1000s, GT750, H2 750
User avatar
Suzukidave
Moto GP
Posts: 3980
Joined: Fri Oct 24, 2008 5:55 pm
Country: US
Suzuki 2-Strokes: GT750 x2 97 -1200 Bandit 86 GSXR1100
Location: Lancaster Pa.

Re: GT750 Thermostats

Post by Suzukidave »

They are numbered the order they come off and are reattached , i snug them up the first round and then go back and torque them down .
the older i get the faster i was
User avatar
Suzukidave
Moto GP
Posts: 3980
Joined: Fri Oct 24, 2008 5:55 pm
Country: US
Suzuki 2-Strokes: GT750 x2 97 -1200 Bandit 86 GSXR1100
Location: Lancaster Pa.

Re: GT750 Thermostats

Post by Suzukidave »

Talking about torquing , have you tried giving the head bolts a torque test before you remove it just to see if that could be the problem ?
the older i get the faster i was
simmons1
On the main road
Posts: 102
Joined: Tue May 06, 2014 8:21 pm
Country: United States
Suzuki 2-Strokes: GT750, GS1000s
Location: Fort Worth

Re: GT750 Thermostats

Post by simmons1 »

No I haven't, that is a great idea.
T700, Africa Twin, Goldwing, Super Tenere, WR250R, GS1000s, GT750, H2 750
Post Reply