Yamaha TRX850 Enthusiasts Forum

jerky is about as best i can describe it - have resolved umpteen issues and thought this was possibly down to the gearing i had had chosen, but it would appear not.

while under hard acceleration the bike is fine - if i have to cruise along its almost as if every bump i hit opens the throttle

carbs are all stripped cleaned and balanced - tps is adjusted correctly

i have changed the gearing, loosened off the throttle cable play - no difference made ( throttle cable play now back as was )
i have checked there is enough play on the throttle cable routing so that bumps wont come into play

but basically going into a roundabout is a slightly hairy experience as cannot maintain a smooth throttle

any ideas what i can look at?

Not much info to go by. What RPM, what gear, what speed, still with std ECU????

Did you forget to replace the carb piston dampening springs?

All gears - all rpms that require a careful/ considered throttle - full chat any gear and no issue whatsoever- just when your trying to cruise
Carbs been apart several times and all present and correct
Running standard Ecu

Chain has been checked for tight spots and whilst there were a couple all appear to have the same play on them now

Have even swapped the needles out for aftermarket ones with 6 settings and thinner taper and made no difference

Doesn’t feel electrical at all just very jerky on - off- on feeling

I know this sounds strange, but I've recently helped a chap with a TRX and his carbs were not seated correctly resulting in similar behaviour, secondly what conditioner the carb manifolds? any splits or cracks?

Vaccum operated fuel tap... Get rid of it.....
Look on my rebuild thread as I just put the link there for the std TRX tap mod...

what cobba said, then spark plug caps, wires, coils? does it happen more when wet?

It really does sound like no slack in the throttle cables, but you've checked that already.
Where did you adjust it, at the carbs or behind the triple clamp?
I had the same problem a while back and found that I had to have a couple of goes at the top adjuster to get it right. Slacker is better.

Fue Vacuum tap mod was done from the offset

Can recheck carb rubbers easily enough and they look in ok condition -
the throttle slack was adjusted carb end so can see what if any difference when adjusted at the triple clamp end

And can swap out the coils as have a spare pair although I’ve not ridden it in the rain

Will post back the results