Yamaha TRX850 Enthusiasts Forum

Hi Guys,

winter is over TRX out of the shed, and a small problem. the bike runs nice and smooth at loer revs, but if i open the throttle at around 3k abruptly it will misfire a bit, generally doesnt if throttle opened slowly and smoothly. Also, the rev counter tends to jumps at slower speeds, it will bounce from 2k to around 3,500 and then drop back, even if the throttle is not opened further...

Anybody have any ideas what the cause could be?

A bouncy rpm needle is usually a sign of the tps connection on the carbs needing adjustment.

Thanks. Checked the setting, it read 1000. So set it as described to 4000. Last night after setting, (Bike was still warm) everything fine, pulled through agian and needle was steady.

This morning, fired up immediately from cold, but as soon as i drive faster than 20 km/h the needle intermittently starts jumpeding around again, from 1,000 revs to around 4,500. Then stops for a bit, then starts again.

As soon as i open the throttle abruptly or more than mabye a fifth of a twist, the engine starts spluttering and misfiring....

has anybody got any more ideas what the problem could be?? Ran perfectly a couple of months ago..

hoyhoy9 wrote:Thanks. Checked the setting, it read 1000. So set it as described to 4000. Last night after setting, (Bike was still warm) everything fine, pulled through agian and needle was steady.

This morning, fired up immediately from cold, but as soon as i drive faster than 20 km/h the needle intermittently starts jumpeding around again, from 1,000 revs to around 4,500. Then stops for a bit, then starts again.

As soon as i open the throttle abruptly or more than mabye a fifth of a twist, the engine starts spluttering and misfiring....

has anybody got any more ideas what the problem could be?? Ran perfectly a couple of months ago..

Clean the connections of the TPS wiring harness (quick disconnect plug) and any other wires that are used in the ignition, coil feed wires etc.

Check the connections on the starter relay, I think theirs 4 of them. Mine was running a bit ropey so I had a mooch round the lecky stuff, they were all furred up so I gave them a clean and all was good.

Trixynut, Nob and Rid.s, many thanks!

Checked everything, copius amounts of contact spray and this morning she ran like a dream....

I will put the iridiums and the rest back in the shelf while the good weather lasts...