Yamaha TRX850 Enthusiasts Forum

I had a wierd thing happen to me the last few mornings riding to work where if the revs are about 5000ish RPM at full throttle the bike would suddenly lose power. It feels very much like hitting a soft rev limiter.

Now we've had some very cool mornings in Brisbane <10* Celcius and seeing as it disappears as the day warms up I'm wondering if it could be carb icing?

Another thing I thought it might be is after our unseasonable wet winter there could be water in the fuel, although I presume this would cause the bike to run poorly at all RPM's!

So do TRX's suffer from icing? and any other hints to what it might be?

unlikely to be carb icing as the TRX has a warming circuit from the rad and those temperatures are what we typically see in the UK.

could well be water in the fuel. could also be that your carbs need setting up and maybe new emulsion tubes.

youngy wrote:unlikely to be carb icing as the TRX has a warming circuit from the rad and those temperatures are what we typically see in the UK.

could well be water in the fuel. could also be that your carbs need setting up and maybe new emulsion tubes.

I was going to give exactly the same answer, except that he says it goes away once warm. I've never had noticeable carb icing and I ride all year. Could well be the start of the emulsion tubes thing. First symptom for me was gradual loss of power, followed by non-starting.

Hmmm, interesting thanks guys. It is getting harder to start from cold and seems to be running a bit rich with black smoke appearing when you rev it like when you leave the choke on too long...

I'll check the emulsion tubes on the weekend.

harder to start from cold? now he tells us!!!! worn emulsion tubes generally make cold starts easier.

your inlet valve clearances have closed up.

youngy wrote:harder to start from cold? now he tells us!!!! worn emulsion tubes generally make cold starts easier.

your inlet valve clearances have closed up.

Mmmm, you are much cleverer than I, but I have to say that this is what happened to mine when the ETs went. Hard to start because the plugs were fouling! Then no starting at all. So something to consider if the valves get ruled out.

youngy wrote:your inlet valve clearances have closed up.

Not that I disagree with you but I did get the clearences check about 1000km ago and all was well (according to the workshop anyway ). I'll still check the tubes and if okay then recheck the clearences myself. Either way thanks for the advice

inept wrote:

youngy wrote:your inlet valve clearances have closed up.

Not that I disagree with you but I did get the clearences check about 1000km ago and all was well (according to the workshop anyway ). I'll still check the tubes and if okay then recheck the clearences myself. Either way thanks for the advice

That is assuming (a) they did the work you paid them for and (b) they knew what they were doing. Not always the case, unfortunately!

what sort of fuel are you using.I changed from regular to premium and all the strange fuel niggles that I had disappeared.

I'm using Caltex Premium 98 now. I used to use the dodgy 7-11 premium but I was also having a few issues with fueling. Mind you can still get a bad batch of fuel with the big brands.

Another suggestion is either water or dirt in the carbs. At certain vibrations/fuel flows a drop of water or piece of dirt obstructs the fuel flow. Sounds weird, but has happened to me. And despite living in cold Sweden and runing without the carb heating circuit, I have never experienced carb icing...