426 cooling ???

ok we put a 2000 yz 426 in a 400ex quad frame. the motor has a je 13 to 1 piston and was bored 2mm over to make it a 444, it has a hot cam auto decompression cam, fully ported and polished head, new valves. we installed a gt thunder raditor for a honda 250 r quad but no collant recovery bottle. we just got it running and sounds real stout but a little lean. problem is it spits coolant out of the overflow tube sometimes while running. do we have a problem or do we just need a overflow bottle on it.

Mark

How much coolant is it spitting and how often does it do it?

ok we put a 2000 yz 426 in a 400ex quad frame. the motor has a je 13 to 1 piston and was bored 2mm over to make it a 444, it has a hot cam auto decompression cam, fully ported and polished head, new valves. we installed a gt thunder raditor for a honda 250 r quad but no collant recovery bottle. we just got it running and sounds real stout but a little lean. problem is it spits coolant out of the overflow tube sometimes while running. do we have a problem or do we just need a overflow bottle on it.

Mark

This motor will run hot just sitting, air must flow thru the radiator to keep it form overheating. Dave with Eastcoast Atv quoted he had to run the Hybrid 426 1" below the radiator cap to keep the anti-freeze from expanded and running out of the overflow.

But I'm experiencing anti-freeze running out of my weep hole and have replaced my seals, bearings water pump shaft twice now and still no fix yet.. Any ideas....(Sounds like both of us may be experiecing the same problem)

Just remember the coolant will expand!!

If you feel it to the rim.... it will overflow when it gets hot!

What is the total coolant capacity?

Quaddad,

What radiator cap are u running? Aftermarket 250r or stock?

actually im not sure. i bought the radiator from a guy on ex riders and it came with a cap. i think i found our problem, the cap wasnt turned all the way. didnt get to start the quad after i found that since it had already gotten dark. i will try to post a pic or 2 of it.

Mark

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Thats a big a$$ radiator!!!

It shouldnt get hot if it has enough air flow.

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