pleb Posted April 23, 2011 Report Share Posted April 23, 2011 Hi everyone, I am new to trials and have just got myself a 2005 txt pro 250. After riding it for about an hour I can hear a hissing/bubbling noise from the rad is this normal? The fan works ok, the rad is clean and full of new coolant, the bloke I bought it off had recently fitted a new water pump. The bike runs fine with no engine noise, starts second kick. any advice would be much appreciated. Quote Link to comment Share on other sites More sharing options...
pandelboy Posted April 23, 2011 Report Share Posted April 23, 2011 (edited) check that the water pump is actually pumping as it should be. from cold take off your rad top and start bike with fuel tank removed ,just make sure you have enough fuel in carb to run it for this brief check. when the engine runs you should be able to see the coolant pumping inside the neck. if not then the pump impeller could be not turning. the rad should not be hissing or bubbling. if all is ok you could check that the cap is ok, its possible its letting bye but unlikely. Edited April 23, 2011 by pandelboy Quote Link to comment Share on other sites More sharing options...
pleb Posted April 23, 2011 Author Report Share Posted April 23, 2011 check that the water pump is actually pumping as it should be. from cold take off your rad top and start bike with fuel tank removed ,just make sure you have enough fuel in carb to run it for this brief check. when the engine runs you should be able to see the coolant pumping inside the neck. if not then the pump impeller could be not turning. the rad should not be hissing or bubbling. if all is ok you could check that the cap is ok, its possible its letting bye but unlikely. Thanks for your help pandelboy I will try this tomorrow Quote Link to comment Share on other sites More sharing options...
pleb Posted April 24, 2011 Author Report Share Posted April 24, 2011 Thanks for your help pandelboy I will try this tomorrow I removed the rad cap, started bike and could see the coolant swirling (a lot). with the bike idling the fan cuts in after about 5 mins and runs for about 15 secs thens comes on and off periodicly. could it be possible the fan is not coming on enough? When the bike is hot there is pressure in the rad when I unscrew the rad cap. Could it be the timing? the bike runs well with no backfiring. Quote Link to comment Share on other sites More sharing options...
lowbrow Posted April 24, 2011 Report Share Posted April 24, 2011 The timing isn't adjustable and the fact that the bike starts easily and runs okay indicates that the ignition side of things is fine. The fan is coming on and off which suggests the thermostat is okay too. There will be pressure in the radiator when its hot; that's normal too, but if its spits out coolant you've either overfilled the rad or the 'o' rings between the cylinder and head need replacing. I think you're dealing with a fault that's perceived, but not actual. Go ride and enjoy! Quote Link to comment Share on other sites More sharing options...
pleb Posted April 24, 2011 Author Report Share Posted April 24, 2011 The timing isn't adjustable and the fact that the bike starts easily and runs okay indicates that the ignition side of things is fine. The fan is coming on and off which suggests the thermostat is okay too. There will be pressure in the radiator when its hot; that's normal too, but if its spits out coolant you've either overfilled the rad or the 'o' rings between the cylinder and head need replacing. I think you're dealing with a fault that's perceived, but not actual. Go ride and enjoy! Perhaps I am just paranoid. but is the fan supposed to suck air through the rad or blow onto it, mine is sucking air through. Quote Link to comment Share on other sites More sharing options...
lowbrow Posted April 24, 2011 Report Share Posted April 24, 2011 You're paranoid! Stop thinking and go riding! Quote Link to comment Share on other sites More sharing options...
jse Posted April 24, 2011 Report Share Posted April 24, 2011 You're paranoid! Stop thinking and go riding! Seems like all is well, I agree, go ride a bit. Trials bikes sound different due to a number of factors so just be sure all the fluids are good and spend a little time of the strange bike. Jon Quote Link to comment Share on other sites More sharing options...
pleb Posted April 24, 2011 Author Report Share Posted April 24, 2011 Seems like all is well, I agree, go ride a bit. Trials bikes sound different due to a number of factors so just be sure all the fluids are good and spend a little time of the strange bike. Jon Is it normal for the rad vent pipe to release some pressure after riding for a couple of hours ? Quote Link to comment Share on other sites More sharing options...
jse Posted April 25, 2011 Report Share Posted April 25, 2011 Is it normal for the rad vent pipe to release some pressure after riding for a couple of hours ? Not that I'm aware of. A cooling system in good shape is essentially "closed" during the engine's normal operating temp's. It might be that your engine is operating at a higher than normal temperature, but just below the temperature that would cause the radiator cap to vent pressure. Shutting off the engine would allow heat "stored" in the castings to raise the coolant temp enough to allow some pressure to pass by the pressure release release valve in the cap. Not likely, but a possibility, as would be the early development of an inner head o-ring failure. Any time you buy a used bike, you should consider the possibility that everything is wrong with it. That is, not assume that the coolant is a 50/50 mixture of auto antifreeze and distilled water, or that the suspension bearings have been serviced, or the steering bearings are lubed and properly adjusted, or that all the spokes are tight, or that the jetting is correct, or that the wheel bearings are in good shape etc. Now might be a good to spend some "pro-active" time with the bike and give it an all over service to prevent you from having to later be "re-active" and fix problems that otherwise might have been caught in their early stage. You might have a friend who is familiar with Trials bikes inspect the bike after riding. Hopefully it's something simple like a leaking radiator cap o-ring that is easily replaced. Jon Quote Link to comment Share on other sites More sharing options...
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