Yamaha TRX850 Enthusiasts Forum

Hi knowledgeable ones and anoraks.... my bike is as always tucked up for winter, went to do the regular engine run which is 5 or 10 minutes idling then gradual build of revs & get the engine up to higher temp over 15 or 20 minutes or so, I warm it up gradually till the fan kicks in & cools it down, now here's the question:-

I noticed that the right hand exhaust down pipe appeared to be an awful lot hotter (redder) than the left hand pot, though the engine is singing away sweet as a nut, is this a problem or indicative of a potential issue?

Mileage is just under 6K, yes under 6K.

Thanks in advance of any info, Sam...

woolybully wrote:Hi knowledgeable ones and anoraks.... my bike is as always tucked up for winter, went to do the regular engine run which is 5 or 10 minutes idling then gradual build of revs & get the engine up to higher temp over 15 or 20 minutes or so, I warm it up gradually till the fan kicks in & cools it down, now here's the question:-

I noticed that the right hand exhaust down pipe appeared to be an awful lot hotter (redder) than the left hand pot, though the engine is singing away sweet as a nut, is this a problem or indicative of a potential issue?

Mileage is just under 6K, yes under 6K.

Thanks in advance of any info, Sam...

Well a cold pipe could be three things, assuming that the hot pipe is running correctly

Valve clearance way out, unlikely
spark plug non functional, unlikely as you said the engine is running sweetly
carburettors out of tolerance, most likely the case.

Start with,
checking the manifold rubber boots for leaks, if they are cracked it can make one side run lean i.e. hot..
check the carb balance
check the pilot jets are set the same, start with 2 turns out
check the choke on one carburettor is not sticking on, can happen..
check jets are not partly blocked or mismatched
check the emulsion tubes and needles for wear.
and then give the carbs a once over for damage or worn/cracked parts i.e. the air cut off cover..

I really can't agree with starting an engine without going for a ride. The engine will NOT properly warm up no matter what the temp gauge indicates. There will be 'hot spots' created around the cylinder head while the gearbox will remain cold.The whole unit will not reach a high enough temperature to evaporate all of the water and corrosive by-products formed by the combustion process and transmitted into the lubricating oil. I would never inflict this abuse on any bike, but each to their own.

osbxrt wrote:I really can't agree with starting an engine without going for a ride. The engine will NOT properly warm up no matter what the temp gauge indicates. There will be 'hot spots' created around the cylinder head while the gearbox will remain cold.The whole unit will not reach a high enough temperature to evaporate all of the water and corrosive by-products formed by the combustion process and transmitted into the lubricating oil. I would never inflict this abuse on any bike, but each to their own.

Cheers osbrxt, the bike is on paddock stands so always gets the rear wheel turning & through the gearbox.

My days of spannering are long gone (apart from on me old car), I wouldn't know where to start, just asking for advice so come April it will go in for a full service & I wouldn't mind trying to sound knowlegeable.... some hope.


I should add that in the past I have seen both downpipes glowing red, so one pot although running smoothly seems to be cooler.....