Yamaha TRX850 Enthusiasts Forum

Hi everyone,
My TRX doesn't get a lot of use really but recently after a period of being hard to start / getting running on both cylinders I fitted a new set of spark plugs.
Now it starts first stab on the starter and runs sweet on both cylinders with crisp pick-up on the throttle.

However, taking it out for a ride yesterday it started to run a little 'odd'
When cruising on a steady throttle setting (around 4000 rpm ish) the motor started to die momentarily on one cylinder.
Opening the throttle a bit gave instant response and acceleration, but again as soon as the throttle was held steady it started to falter again.
(Only time I have ever had a similar feeling was in the olden days when a 2-stroke was on the point of nipping up?)

Anyone out there ever experienced something similar ??
Any suggestions as to a possible cause ??

Worn needle tubes? Running rich at certain rpm's.
How experienced is your TRX?

I should have stated ,,,
TRX has made 37,500 miles (60,000 kms)
I do not ride so much now, approximately 500 to 1000 miles each year (800 to 1500 kms)

In that case it is definitely worth the effort to have a proper look at the carbs.
has the valve clearance been done yet?

OK, I will see if I can find the parts needed for an overhaul of the carbs.
That is probably a job I could do myself.
Unfortunately my mechanical skills, small workshop, and smaller wallet will not stretch to the top end overhaul
Is the carb rebuild relatively easy to do ??

Is the carb rebuild relatively easy to do ??

Yes.
Be careful when you re-assemble that you do not over-tighten anything.
The carb is cast aluminium, it is very soft and the threads can be stripped out by hand with a screwdriver.
Ask me how I know

I'd be more inclined to check the plug caps and HT leads, if they're original then they're pretty old by now and may not have taken kindly to being messed with. Are you even sure you've pushed them on all the way?