Running hot

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bobhenry999
Posts: 35
Joined: Tue May 28, 2019 9:26 pm

Running hot

Post by bobhenry999 »

Guys,

Hoping you can help with this problem.

In 2017 my 750A had a £9500 restoration carried out by Mike at JMC Restorations in Stockton,during which everything was rebuilt/replaced including the cooling system. This was done for the previous owner, not me.
The bike has only covered 300 miles since the restoration.

When I ride it around local roads the temperature gauge rises to the midway point as expected, but if I ride on a dual carriageway for example and maintain a steady 55-60mph, the needle slowly creeps up to about 3/4 round the gauge. Once I get back on the local roads it slowly goes back to halfway.

It has a new radiator and the water pump was overhauled during the restoration. The coolant level is fine, and there are no leaks. And I believe I`m right in saying that an A doesn`t have an electric fan.

Does anyone have any ideas on what I should do next ?

Thanks,

Bob
GTNelly
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Joined: Sun Oct 14, 2018 9:37 pm

Re: Running hot

Post by GTNelly »

Hi Bob,

'A' model doesn't have a fan, not needed anyway in the UK

If you assume all the previous work has been done correctly I would be checking that the thermostat opens when it should

Think there's a thread on here that shows how this is done
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malky
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Joined: Sat Dec 19, 2009 3:25 pm
Location: swansea south wales

Re: Running hot

Post by malky »

Mine used to do exactly the same and I finally tracked it down to the wires on the gauge being the wrong way around and not making a very good connection the slightest bit of dirt alters the resistance and gives a false reading - its been fine ever since
Mal.
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BAZ
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Location: Dudley west midlands
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Re: Running hot

Post by BAZ »

The lamp holder on the temp gauge can give problems if not earthed properly, but if you have paid for restoration should the dealer be your first port of call.
bobhenry999
Posts: 35
Joined: Tue May 28, 2019 9:26 pm

Re: Running hot

Post by bobhenry999 »

Guys,

Thanks for the suggestions.

I cant go back to JMC because it was the previous owner who commissioned the restoration.

If the wires are the wrong way round on the temperature gauge, how does the road speed cause the effect ? It`s fine around town and only gets hot when i cruise at a constant 55-60, same goes for the lamp holder ?
I`m not good at electrics !

Bob
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slosher
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Location: Walsall,Black Country

Re: Running hot

Post by slosher »

bobhenry999 wrote:It`s fine around town and only gets hot when i cruise at a constant 55-60,
Whilst cruising having the air cooling effect should show normal running temp :? Suggests wiring problem Bob
GT750L
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bobhenry999
Posts: 35
Joined: Tue May 28, 2019 9:26 pm

Re: Running hot

Post by bobhenry999 »

Guys,

Thanks for that.

The gauges were all restored during the restoration so I have to assume that they are fine. This weekend I will check that the wiring is correct and that the bulb holder is suitably earthed and then try it again.
i will report back.

Bob
teazer
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Joined: Mon Mar 07, 2011 8:10 pm
Location: Chicago

Re: Running hot

Post by teazer »

This will sound odd, but have you checked the charging voltage as the revs increase? The temperature gauge may have been cosmetically restored but that doesn't mean that they necessarily checked it for accuracy. It could also be bad connection along the way or even a temperature sender not grounded. If they smothered it in sealant the ground conection might be poor.

But check battery voltage as it charges first.
bobhenry999
Posts: 35
Joined: Tue May 28, 2019 9:26 pm

Re: Running hot

Post by bobhenry999 »

Guys,

Well the kettle lived up to it`s name today !

Went for a ride and the same symptoms, temperature gauge sits at half way around town, but as soon as I start to cruise at 50-55mph it slowly rises to 3/4 across the gauge.
Today it seemed to be going even higher so I stopped, and there was the archetypal orange/rusty water staining all over the top of the engine (Above the head/barrel joint).

I managed to limp it home and after removing the fuel tank I could see that the aforementioned water staining was all down the filler neck below the rad cap, from where it was blowing onto the engine.

The bike starts and runs fine, and I pulled the spark plugs which were all a nice light tan colour, so I don`t think it`s the head gasket, although I am open to be proved wrong.

I removed the thermostat housing, and the thermostat itself looks a bit manky but seems to be free and moves ok. The water level in the expansion tank, despite the coolant loss from removing the thermostat housing, is about half an inch from the top of the tank. Not sure if this is important but the small two inch hose between the filler neck and the expansion tank is quite soft and is kinked.

I have attached a couple of photos showing the water staining leak.

Any help would be greatly appreciated.
Attachments
003.jpg
004.jpg
001.jpg
Roger Ackery
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Location: Sydney NSW Australia

Re: Running hot

Post by Roger Ackery »

:tw great restoration :cry:
It looks like someones made a lot of money for very little work !!!
I doubt a spanner has been laid on the bike ?
I know you say it was restored by a reputable firm, You should contact them..Do you have receipts for the repairs ?
Basic dirty blocked cooling system is one of the first things that should have been checked !!!
A dirty rusty cooling system doesn't just happen overnight, I flush mine regularly & replace the Coolant. :idea:
Good Luck with getting this sorted at no expense to you !
Cheers.
Roger
GT750A.
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