Yamaha TRX850 Enthusiasts Forum

put a k&n in the air box today took it for a wee burn as it was dry,this was the first decent blast I have had on it, but on the way back I noticed when sat at traffic lights when I blipped the throttle it died, this only happend once it was warmed up could it be running to rich now plus it only happend from a closed throttle what do you think

cheesie wrote:put a k&n in the air box today took it for a wee burn as it was dry,this was the first decent blast I have had on it, but on the way back I noticed when sat at traffic lights when I blipped the throttle it died, this only happend once it was warmed up could it be running to rich now plus it only happend from a closed throttle what do you think

When my bike felt like it just died on full throttle it was WAY lean, i figure you should get "bang bang coff coff" if rich.
....and you´ve actually leaned it by putting on a K&N...

I agree with Killerwhale for what it's worth.

this was the first decent blast I have had on it

Presume you mean since you put the K&N in and that it was OK with the standard filter?

The K&N is a free flowing filter (over the standard one) and as such this will lean the mixture slightly over standard. That said, TRX is jetted slightly rich as standard and the K&N will not affect the jetting that much.

My guess is that the filter change is a red herring

Go back and check you put everything back together again properly. Need to ensure filter is in correctly, airbox is sealed to carbs correctly (you may have knocked them off when changing the filter), fuel is turned on and pipe not kinked and most importantly (this is where my money is), check the vacuum pipe is connected to the fuel cock and that it is not kinked.

I agree with Phuk. I ran (smaller than) standard jetting on my TRX with a K&N and a full Akrapovic for ages. It was spot-on on the dyno....

I agree with Phuk

Saved for future reference

had a check around all the hoses and everything looks fine, no kinks took it out again same thing happend only when it is well warmed up so I have put standard filter back in and if it is dry tomorrow will give it another shot, strange it only happens when engine is hot it seemed to rev cleaner with the standard filter in but bike was sitting maybe 20 minutes I also tried the hose clamps on the carbs although I was able to get another turn or so on them they wernt loose

it runs fine with standard filter, had it out for another run today so I think I will lift the needle jets next, I am getting good at taking the tank on and of and on and of and on and of

The filter has been oiled

Lifting the needle a notch will richen up the mixture but if it is that bad with the change of filter alone, you will most likley need to rejet

brand new filter pre oiled. I was thinking it might need re jetted but I dont want to start spending money on dyno jet kits by the time you fit one and have it properly set up on a dyno it will run into £100-£200

I might get away with lifting the needles and fitting a bigger main jet I am still hoping to pick up a set of flat slides for the right money

K & N in standard air box, and micron carbon race cans, no problems at all.

Dave E.

lifted the needles a notch, the last groove my mate had some 144 main jets left of a dyno jet kit so I fitted them, bike now runs fine, although it does not surge at constant throttle openings and pulls clean enough from 40mph in tyop gear it will snatch a little from a closed throttle around town which says to me she is now running a little rich will have to put it on a dyno for a proper gas analysiss to make sure all is fine

Snatchiness could be due to slack in throttle cable or chain - TRXs are very sensitive to both.

come to think of it I could of left a little to much free play in the throttle cable thanks for that phuk