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Top End Extremely Hot

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After riding for about 5 to 10 minutes on my 2000 sherco 125 the top end is too hot to even hold a finger on for more than a second, anyone know what the cause could be?

I think the average running temp of the coolant is in the nineties. How long can you hold your finger on a nearly boiling metal kettle?

Edited by 2stroke4stroke

It should get hot.....

 

 

Cool water can actually get 100+ because of the pressure in the system before it boils.

Edited by crazybond700

Is your fan working? Should kick in after 5 or so minutes of running

Just a guess but I'd say it's because it's full of fire.

If you have a pinhole leak that depressurizes the coolant system it will boil the coolant. That's because parts of the coolant system operate over 100C. Definately the head will be that hot. So the rough equivalent is like boiling water on the stove and picking up the pot by the sides. If the engine is not sounding like a can of marbles being shaken it's probably within the correct temp range.

Edited by dan williams

  • Author

Okay so I just went for a ride for about 20 minutes there, riding with low rpms taking it easy and it overheats and spewed water and steam everywhere???

ben you have an issue for sure. but by touch other than the fan not running you wont be able to tell....

jump your fan switch with a piece of wire as a fist step and please dont touch those hot bits more. we dont want to see you hurt.

--Biff

A little water cam come out just after a revil. You often put too much in. If more comes out there is a problem, like a leaking headgasket, broken pump etc.

Ok did it run OK before it overheated? No pinging or detanation? Over heating can be caused by several things. Too lean a fuel mixture due to blocked or incorrect jetting. Ignition timing too advanced. Too low an octane fuel. Carbon buildup in cylinder head. Too little air flow through radiator. Too little coolant flow through cooling system. Failure of coolent system to pressurize due leak.

The possible foot causes are many but narrowing it down shouldn't be that hard. If the engine runs good until it overheats then it is likely a cooling system failure rather than ignition and/or fuel. Your fan runs so check your system for leaks and make sure your impellee is spinninig and in one piece. I don't know about the Shercos but the Betas are known to shred impellers and have porous cases in the waterpump area.

Coolant mixture has some effect but even running pure water in a system will work if the system is operating properly.

Edited by dan williams

A leaky head gasket will show some evidence of oil in the coolant as the high pressure in the combustion chamber drives air/fuel mixture into the coolant. You should be able to see this when you drain the coolant into a clean container.

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