Yamaha TRX850 Enthusiasts Forum

help..... just got a trx and it idles on one cyl when cold, runs on 2 if you rev it hard, replaced plugs, is this a common fault or should i strip carbs etc?

caferacer100 wrote:help..... just got a trx and it idles on one cyl when cold, runs on 2 if you rev it hard, replaced plugs, is this a common fault or should i strip carbs etc?

Nope - not common

try swapping the coil packs over and see if the non running cylinder swaps sides

More than likely the valve seating `issue` making itself felt if a carburation or electrical problem isn`t found. Check all electrical connections, try what Phuk posted, drain both carb float bowls to see if it helps etc, etc.
I had an old Honda twin that would do it but once you twisted the grip it would cough a tad, clear it`s throat and pick up on two cylinders. Sadly when it got up to operating temperature the one cylinder `dance` would occur higher up the rev range too.

Checking the Pilot jet's hole, May be too big than other one.