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Slow warm up!


Walker1

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Hello guys, title doesn’t give much away..

The problem I’m having was originally a lag of power in the throttle... I would turn the throttle but there would be a delay followed by a surge of power.. Did some research and thought it was the fuel filter.

I then realized that the bike would be starting at 2krpm when starting the bike and the temperature was low.. If I let the bike warm up the lag seems to disappear.

So the problem now is that the bike takes awhile to heat up... starting around 35-45 degrees (C) taking around 3-4 seconds to rise by 1 degree and slowly decreasing in rpm. Once the bike is around 71 degrees the rpms are down at 1-1.4krpm and the bike is ready to go!

 

What could be causing this? What I’ve read is that it could be the thermostat remaining open. I’m not sure if this would cause the lag of power though but sure look sure, I do not know!

 

The bike is a vfr800 01 with 22500miles on her

 

Cool

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The warmup behavior sounds normal.   Coolant flows between a water neck behind the stator and the thermostat housing,  along the way through the wax unit under the starter valves.  The idle should initially be higher at cold startup then slowly decrease as the coolant temp comes up.  It sounds like that's hsppening. 

If the lag diappears as the temp / idle get to normal then if it were me I wouldn't worry about it too much unless you want to dig in and do some maintenance.  At 20 years,  any engine needs some basic service performed.  Some good items would be a bench clean of the injectors,  inspect all vacuum hoses, replace the coolant / thermostat.   If you look in to the tank empty and it's clean at the bottom,  as long as the engine runs well I wouldn't go at the fuel filter as it's not an easy job.  If you see rust / debris down there,  then it's probably time for a new one. 

 

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On 5/8/2020 at 7:42 PM, Cogswell said:

The warmup behavior sounds normal.   Coolant flows between a water neck behind the stator and the thermostat housing,  along the way through the wax unit under the starter valves.  The idle should initially be higher at cold startup then slowly decrease as the coolant temp comes up.  It sounds like that's hsppening. 

If the lag diappears as the temp / idle get to normal then if it were me I wouldn't worry about it too much unless you want to dig in and do some maintenance.  At 20 years,  any engine needs some basic service performed.  Some good items would be a bench clean of the injectors,  inspect all vacuum hoses, replace the coolant / thermostat.   If you look in to the tank empty and it's clean at the bottom,  as long as the engine runs well I wouldn't go at the fuel filter as it's not an easy job.  If you see rust / debris down there,  then it's probably time for a new one. 

 

Brilliant.. you are right! I think i was not letting it warm up, not used to the bike. It was recently basic serviced..

Going to run the bike dry and check the inside of the tank for piece of mind! Appreciate the explanation 😁

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If you place your hand on the radiator from a cold start, it should stay basically stone cold until the engine hits around 70-80C, which is when the thermostat opens and starts to allow the hot coolant out to the radiators. At that point the radiator will suddenly get too hot to touch for long. That is normal thermostat operation. 

 

On the other hand if the radiator slowly/gently warms along with the engine, the thermostat is stuck open. 

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